Abstract
Despite of the agronomic importance for water management, few studies of sugarcane roots have been performed under field conditions during the crop cycle. The aim of this study was to determine the cumulative root density (LA), root distribution on soil profile and the effective rooting depth (ERD) for three sugarcane cultivars using the minirhizotron method. A field experiment was done with sugarcane cultivars IACSP94-2094, IACSP94-2101 and SP79-1011 grown under subsurface drip fertigation. Soil chemical and physical characteristics were also evaluated. Root evaluations were taken at 38, 58, 123, 185 and 205 days during the second ratoon, considering the soil profile until 0.8 m depth. The highest LA and root growth rates were found up to 0.4 m soil layer for all cultivars. Root growth rate varied during the crop cycle, with the highest values being found between 38 and 58 days after ratoon (DAR). There was a genotypic variation in root growth, with IACSP94-2101 showing the highest LA of 12.9 mm cm–2. The total root length observed around the tube (0.16892 m2) was 10.8, 5.9 and 2.5 m up to 0.8 m depth for IACSP94-2101, SP79-1011 and IACSP94-2094, respectively at 205 DAR. The effective rooting depth varied during the cycle for IACSP94-2094, but all cultivars presented an effective depth of 0.4 m at 205 DAR.
Saccharum spp.; irrigation; water management; effective rooting depth; root growth rate
1 INTRODUCTION
The demand for water use by domestic, industrial, energy, leisure, fishing and
agricultural sectors is increasing. Considering the different uses the highest
volume is demanded by agricultural practices such as irrigation. Nevertheless it is
important to highlight that food and bioenergy demand is also increasing and water
use efficiency in agricultural systems must be improved by using the most
appropriate irrigation method and water management. The subsurface drip irrigation
system contributes to water savings, maintaining or even increasing the agricultural
production as compared to other irrigation methods (Kandelous & Šimůnek, 2010Kandelous, M. M., & Šimůnek, J. (2010). Comparison of numerical,
analytical, and empirical models to estimate wetting patterns for surface and
subsurface drip irrigation. Irrigation Science, 28, 435-444.
http://dx.doi.org/10.1007/s00271-009-0205-9.
http://dx.doi.org/10.1007/s00271-009-020...
) and allows the nutrient application by
fertigation at the right time and place, increasing the nutrient uptake efficiency
and reducing its losses by leaching.
Irrigation has become an interesting cultural practice to improve crop yield and
sustainability in adequate and marginal sugarcane growing areas. The knowledge of
root system distribution is fundamental to understand water and nutrient uptake
(Smith et al., 2005Smith, D. M., Inman-Bamber, N. G., & Thorburn, P. J. (2005).
Growth and function of the sugarcane root system. Field Crops Research, 92,
169-183. http://dx.doi.org/10.1016/j.fcr.2005.01.017.
http://dx.doi.org/10.1016/j.fcr.2005.01....
), to improve water
management and also to provide data for crop yield forecasting models. Concerning
water management, there are two important parameters: fine root length or root
surface area (van Noordwijk, 1993van Noordwijk, M. (1993). Roots: length, biomass, production and
mortality (p. 132-144). In J. M. Anderson & J. S. I. Ingram (Eds.), Tropical
soil biology and fertility: a hand book of methods. Wallingford: CAB
International.) and the
effective rooting depth (ERD). Irrigation studies in Brazil usually consider ERD as
the depth in which 80% of the fine roots are found (Cunha et al., 2010Cunha, F. F., Ramos, M. M., Alencar, C. A. B., Martins, C. E.,
Cóser, A. C., & Oliveira, R. A. (2010). Sistema radicular de seis gramíneas
irrigadas em diferentes adubações nitrogenadas e manejos. Acta Scientiarum
Agronomy, 32, 351-357.
http://dx.doi.org/10.4025/actasciagron.v32i2.1020.
http://dx.doi.org/10.4025/actasciagron.v...
). ERD is an essential parameter to determine soil
water availability and then water management in crop systems (Allen et al., 1998Allen, R. G., Pereira, L. S., Raes, D., & Smith, M. (1998). Crop
evapotranspiration : guidelines for computing crop water requirements (FAO
Irrigation and Drainage Paper, No. 56). Roma: FAO.).
As compared to canopy traits, there is still few data about root systems and this
lack of information is mainly due to the methodological difficulties related to root
data sampling (Muñoz-Romero et al., 2010Muñoz-Romero, V., Benítez-Vega, J., López-Bellido, L., &
López-Bellido, R. J. (2010). Monitoring wheat root development in a rainfed
vertisol: tillage effect. European Journal of Agronomy, 33, 182-187.
http://dx.doi.org/10.1016/j.eja.2010.05.004
http://dx.doi.org/10.1016/j.eja.2010.05....
).
In addition, the variability of soil physical, chemical and biological properties
may result in variable information about root system distribution (van Noordwijk, 1993van Noordwijk, M. (1993). Roots: length, biomass, production and
mortality (p. 132-144). In J. M. Anderson & J. S. I. Ingram (Eds.), Tropical
soil biology and fertility: a hand book of methods. Wallingford: CAB
International.; Vasconcelos et al., 2003Vasconcelos, A. C. M., Casagrande, A. A., Perecin, D., Jorge, L. A.
C., & Landell, M. G. A. (2003). Avaliação do sistema radicular da
cana-de-açúcar por diferentes métodos. Revista Brasileira de Ciencia do Solo,
27, 849-858. http://dx.doi.org/10.1590/S0100-06832003000500009.
http://dx.doi.org/10.1590/S0100-06832003...
). In fact, roots have high
plasticity, changing their form and size when varying soil conditions (Smith et al., 2005Smith, D. M., Inman-Bamber, N. G., & Thorburn, P. J. (2005).
Growth and function of the sugarcane root system. Field Crops Research, 92,
169-183. http://dx.doi.org/10.1016/j.fcr.2005.01.017.
http://dx.doi.org/10.1016/j.fcr.2005.01....
). For example, distribution
of sugarcane root system was strongly affected by water supply throughout the crop
cycle (Laclau & Laclau, 2009Laclau, P. B, & Laclau, J. P. (2009). Growth of the whole root
system for a plant crop of sugarcane under rainfed and irrigated environments in
Brazil. Field Crops Research, 114, 351-360.
http://dx.doi.org/10.1016/j.fcr.2009.09.004.
http://dx.doi.org/10.1016/j.fcr.2009.09....
). As root
distribution and quantity are genotype- and environmental-dependents, choosing the
best irrigation and fertigation practices on sugarcane crop is not an easy task and
they should be evaluated in each growing condition (Smith et al., 2005Smith, D. M., Inman-Bamber, N. G., & Thorburn, P. J. (2005).
Growth and function of the sugarcane root system. Field Crops Research, 92,
169-183. http://dx.doi.org/10.1016/j.fcr.2005.01.017.
http://dx.doi.org/10.1016/j.fcr.2005.01....
).
Data about sugarcane root system growth and distribution are still scarce and most of
data was reported a long time ago, with sugarcane cultivars that are not cultivated
extensively nowadays (Smith et al., 2005Smith, D. M., Inman-Bamber, N. G., & Thorburn, P. J. (2005).
Growth and function of the sugarcane root system. Field Crops Research, 92,
169-183. http://dx.doi.org/10.1016/j.fcr.2005.01.017.
http://dx.doi.org/10.1016/j.fcr.2005.01....
).
In Brazil, there are few studies about sugarcane root system (Otto et al., 2009Otto, R., Trivelin, P. C. O., Franco, H. C. J., Faroni, C. E., &
Vitti, A. C. (2009). Root system distribution of sugar cane as related to
nitrogen fertilization, evaluated by two methods: monolith and probes. Revista
Brasileira de Ciencia do Solo, 33, 601-611.
http://dx.doi.org/10.1590/S0100-06832009000300013.
http://dx.doi.org/10.1590/S0100-06832009...
; Vasconcelos et al., 2003Vasconcelos, A. C. M., Casagrande, A. A., Perecin, D., Jorge, L. A.
C., & Landell, M. G. A. (2003). Avaliação do sistema radicular da
cana-de-açúcar por diferentes métodos. Revista Brasileira de Ciencia do Solo,
27, 849-858. http://dx.doi.org/10.1590/S0100-06832003000500009.
http://dx.doi.org/10.1590/S0100-06832003...
). When considering samplings along the crop
cycle, the data is even scarcer. Azevedo et al.
(2011)Azevedo, M. C. B., Chopart, J. L., & Medina, C. C. (2011).
Sugarcane root length density and distribution from root intersection counting
on a trench-profile. Scientia Agricola, 68, 94-101.
http://dx.doi.org/10.1590/S0103-90162011000100014.
http://dx.doi.org/10.1590/S0103-90162011...
have tested the root intersection counting combined with the soil
core-sampling method in three sugarcane growth stages, whereas Laclau & Laclau (2009)Laclau, P. B, & Laclau, J. P. (2009). Growth of the whole root
system for a plant crop of sugarcane under rainfed and irrigated environments in
Brazil. Field Crops Research, 114, 351-360.
http://dx.doi.org/10.1016/j.fcr.2009.09.004.
http://dx.doi.org/10.1016/j.fcr.2009.09....
have used the intersection counting
method at the end of crop cycle and used the soil core-sampling method to assess the
root development along the cycle in six growth stages. Unfortunately, there is no
recent data about the assessment of sugarcane root system using non-destructive
methods, such as minirhizotrons, which allow the monitoring of root growth along the
crop cycle under field conditions. In fact, the only study with minirhizotron in
sugarcane crop was carried out by Ball-Coelho et
al. (1992)Ball-Coelho, B., Sampaio, E. V. S. B., Tiessen, H., & Stewart,
J. W. B. (1992). Root dynamic in plant-ratoon crop of sugar cane. Plant and
Soil, 142, 297-305. http://dx.doi.org/10.1007/BF00010975.
http://dx.doi.org/10.1007/BF00010975...
under rainfed conditions.
To improve our understanding about sugarcane root dynamics under field conditions, the aim of this study was to evaluate root growth and distribution in soil profile of three sugarcane cultivars fertigated by subsurface drip system.
2 MATERIALS AND METHODS
Site
The study was carried out in Campinas (SP), Brazil (22º54'S, 47º05'W and 669 m
a.s.l.), where the average air temperature during 1890 to 2010 varied from 23.8
°C in February to 17.8 °C in July and the average annual rainfall was 1398 mm.
The rainfall is not well distributed along the year with humid season during the
summer and dry season in the winter (Blain,
2009Blain, G. C. (2009). Considerações estatísticas relativas à oito
séries de precipitação pluvial da Secretaria de Agricultura e abastecimento do
Estado de São Paulo. Revista Brasileira de Meteorologia, 24, 12-23.
http://dx.doi.org/10.1590/S0102-77862009000100002.
http://dx.doi.org/10.1590/S0102-77862009...
). The air temperature and rainfall were monitored with an
automatic weather station installed at 100 m from the experimental area.
The soil was classified as Latossolo Vermelho eutrófico (EMBRAPA, 2013Empresa Brasileira de Pesquisa Agropecuária – EMBRAPA (2013).
Sistema Brasileiro de Classificação de Solos (3rd ed.). Brasilia:
Embrapa.). It is well drained and clay content ranges
from 400 to 510 g kg–1 until 0.8 m depth (Table 1). The soil bulk density was sampled at depths of
0.1, 0.2, 0.3, 0.4, 0.6 and 0.8 m, with two replicates per depth. The critical
bulk density based on the least limiting water range (BDc-LLWR) and on observed
root and/or yield restriction in the field (BDc-Rest) were both calculated
according to Reichert et al. (2009)Reichert, J. M., Suzuki, L. E. A. S., Reinert, D. J., Horn, R.,
& Håkansson, I. (2009). Reference bulk density and critical
degree-of-compactness for no-till crop production in subtropical highly
weathered soils. Soil & Tillage Research, 102, 242-254.
http://dx.doi.org/10.1016/j.still.2008.07.002.
http://dx.doi.org/10.1016/j.still.2008.0...
using the soil clay content. A soil penetrometer device (Stolf et al., 1983Stolf, R., Fernandes, J., & Furlani, V. L., Fo. (1983).
Penetrômetro de impacto modelo IAA/Planalsucar-Stolf: recomendação para seu uso.
In J. M. Anderson, & J. S. I. Ingram (Eds.), Tropical soil biology and
fertility: a hand book of methods (p. 132-144). Wallingford: CAB
International.) was used to evaluate the soil
penetration resistance (PR), with six replications per cultivar. Soil chemical
analysis was performed at January 2013 with one soil sample composed by ten
sub-samples collected with auger sampling in seven depths: 0.1, 0.2, 0.3, 0.4,
0.6, 0.8 and 1.0 m in each cultivar area.
Sugarcane cultivars
The sugarcane cultivars (Saccharum spp.) evaluated were IACSP94-2094, IACSP94-2101 and SP79-1011. While IACSP94-2101 is responsive to nutrient and water availability, IACSP94-2094 and SP79-1011 are unresponsive (Landell & Bressiani, 2008Landell, M. G. A., & Bressiani, J. A. (2008). Melhoramento genético, caracterização e manejo varietal. In L. L. Dinardo-Miranda, A. C. M. Vasconcelos, & M. G. A. Landell (Eds.), Cana-de-açúcar (p. 101-155). Campinas: Instituto Agronômico.). Sugarcane field was arranged in 20 planting rows with 30 m long each and spaced 1.5 m aside, totaling 900 m2 per cultivar. Sugarcane planting was done in May 2010, with approximately 18 gems per meter at a depth of 0.25 m. The first and second harvests were obtained in December 2011 and October 2012 and the experimental period was from October 2012 to May 2013, with five evaluation times until 205 days during the second ratoon (DAR), which was the last evaluation date.
Irrigation and fertigation
Irrigation was applied by subsurface drip system from December 2012. The irrigation system was installed during planting at a depth of 0.2 m. The nominal flow rate of the emitters was 1.6 L h–1 and they were spaced 0.5 m aside. The irrigation management was based on soil moisture evaluated with the capacitance probe model Diviner-2000 (Sentek Sensor Technologies, Stepney, Australia). For this management three access tubes with internal diameter of 0.051 m were installed until 1.25 m depth in each cultivar area. Soil moisture was estimated every 0.1 m until 1.0 m depth. Daily irrigation was done to replace soil water and reach the upper limit of soil water retention capacity. The total amount of phosphorus and 40% of nitrogen and potassium requirements were applied after the second harvest as solid fertilizers. The remaining of N and K was applied weekly by fertigation as KCl and Ca(NO3)2, between 161 and 315 DAR.
Analysis of root system
Considering the need for reducing time, labor and cost of the traditional methods
of root analysis, the minirhizotron technique is an alternative method for
evaluating root development (Muñoz-Romero et
al., 2010Muñoz-Romero, V., Benítez-Vega, J., López-Bellido, L., &
López-Bellido, R. J. (2010). Monitoring wheat root development in a rainfed
vertisol: tillage effect. European Journal of Agronomy, 33, 182-187.
http://dx.doi.org/10.1016/j.eja.2010.05.004
http://dx.doi.org/10.1016/j.eja.2010.05....
). This method is based on the visualization of root growth
in soil profile by catching pictures or videos through a transparent interface.
As a non-destructive method, it allows the monitoring of root growth many times
in a same spot (Dannoura et al., 2008Dannoura, M., Kominami, Y., Oguma, H., & Kanazawa, Y. (2008).
The development of an optical scanner method for observation of plant root
dynamics. Plant Root, 2, 14-18.
http://dx.doi.org/10.3117/plantroot.2.14.
http://dx.doi.org/10.3117/plantroot.2.14...
;
Kirkham et al., 1998Kirkham, M. B., Grecu, S. J., & Kanemasu, E. T. (1998).
Comparison of minirhizotrons and the soil-water-depletion method to determine
maize and soybean root length and depth. European Journal of Agronomy, 8,
117-125. http://dx.doi.org/10.1016/S1161-0301(97)00019-1.
http://dx.doi.org/10.1016/S1161-0301(97)...
).
Three access tubes with 1.05 m length were installed in each cultivar area. To
avoid light and water entering tube tops were covered with dark plastic. The
images were caught with Root Scanner CI-600™ (CID Bio-Science Inc., Camas, WA,
USA) in five assessments: 38, 58, 123, 185 and 205 DAR. Four images per access
tube representing 0.2 m depth each were obtained, resulting in 0.0-0.8 m depth
analysis. The images were analyzed with the software RootSnap!™ version 1.2.8.23
(CID Bio-Science Inc., Camas, WA, USA). The root length (L) was initially
obtained and then the cumulative root density (LA) was estimated as L
normalized by the 422.3 cm2 sampling area of each window (Box, 1993Box, J. E. Jr. (1993). Use of the minirhizotron-miniature video
camera technique for measuring root dynamics. Geoderma, 56, 133-141.
http://dx.doi.org/10.1016/0016-7061(93)90105-T.
http://dx.doi.org/10.1016/0016-7061(93)9...
; Smit et al., 2000Smit, A. L., George, E., & Groenwold, J. (2000). Root
observations and measurements at (transparent) interfaces with soil. In A. L.
Smit, A. G. Bengough, C. Engels, M. Van Noordwijk, S. Pellerin, & S. C. Van
De Geijn (Eds.), Root methods: a handbook (p. 235-271). Germany: Springer-Verlag
Berlin Heidelberg.), totaling 0,16892 m2 per
access tube. The total amount of roots was estimated in each sample site and
then the relative distribution in soil profile was calculated. The root growth
rate was obtained by considering the LA increase between two
consecutive samplings and the time (days) between samplings.
It was calculated the LA standard error (s.e.) for each cultivar and each soil layer and it was adjusted an exponential equation using the CurveExpert software version 1.4 (Hyams, 2009Hyams, D. (2009). CurveExpert version 1.4.).
3 RESULTS AND DISCUSSION
Environmental conditions
The cumulative rainfall and irrigation during the experimental period (from
October 2012 to May 2013) were 905.5 mm and 315 mm, respectively (Figure 1). The mean daily air temperature
ranged from 17 to 29 °C (Figure 1).
According to Liu et al. (1998)Liu, D. L., Kingston, G., & Bull, T. A. (1998). A new technique
for determining the thermal parameters of phenological development in sugarcane,
including suboptimum and supra-optimum temperature regimes. Agricultural and
Forest Meteorology, 90, 119-139.
http://dx.doi.org/10.1016/S0168-1923(97)00087-7.
http://dx.doi.org/10.1016/S0168-1923(97)...
, there is
variation in estimates for sugarcane base temperature depending of phonological
stage and also among cultivars. However, it has been stated that temperatures
above 18 °C do not restrict the sugarcane development. Thus, during the
experimental period, lower temperature values were only observed in few
days.
Rainfall, irrigation and average, maximum and minimum air temperature during the experimental period. Data represent the cumulative rainfall and irrigation and mean temperature values for 10 days period. Arrows indicate the sampling times.
The soil bulk density increased from 1.48 Mg m–3 in the upper soil layer to 1.63 g cm–3 at 0.2 m and then decreased, reaching 1.21 Mg m–3 at 0.8 m depth (Figure 2). The 0.2 and 0.3 m depth layers presented higher values for soil bulk density than the calculated BDc-LLWR and BDc-Rest (Figure 2), which could result in possible restriction to root growth.
Mean soil bulk density, critical bulk densities considering the least limiting water range (BDc-LLWR) and the restriction to root elongation or yield decrease (BDc-Rest) down to a depth of 0.8 m. Each symbol represents the mean value of two replications (± s.e.).
The highest soil penetration resistance (PR) was measured at the depth of 0.3 m
(Figure 3a), slightly below the depth
of higher soil bulk density (Figure 2),
where soil water content was higher due to its proximity to the emitter (Figure 3b). Considering the critical PR of 2
MPa in which root growth may decline (Baquero
et al., 2012Baquero, J. E., Ralisch, R., Medina, C. C., Tavares, J., Fo., &
Guimarães, M. F. (2012). Soil physical properties and sugarcane root growth in a
red oxisol. Revista Brasileira de Ciencia do Solo, 36, 63-70.
http://dx.doi.org/10.1590/S0100-06832012000100007.
http://dx.doi.org/10.1590/S0100-06832012...
; Sojka et al.,
1990Sojka, R. E., Busscher, W. J., Gooden, D. T., & Morrison, W. H.
(1990). Subsoiling for sunflower production in the Southeast Coastal Plains.
Soil Science Society of America Journal, 54, 1107-1112.
http://dx.doi.org/10.2136/sssaj1990.03615995005400040031x
http://dx.doi.org/10.2136/sssaj1990.0361...
), we have additional evidence that soil conditions likely
limited root growth. The maximum PR value observed was 2.91 MPa in IACSP94-2101
area, with the soil layer 0.2-0.7 m showing values higher than 2.0 MPa. The
other two areas cultivated with SP79-1011 and IACSP94-2094 had PR higher than
2.0 MPa in soil layer 0.2-0.6 m and 0.1-0.4 m, respectively (Figure 3a).
Soil penetration resistance (a) and volumetric soil water content (Θ; b) down to a depth of 0.7 m in areas cultivated with three sugarcane varieties. Each symbol represents the mean value of six replications.
The soil base saturation was higher than 60% and the minimum pH (CaCl2) was 4.5 up to 0.4 m depth (Table 2). These values were not limiting to sugarcane crop in the State of Sao Paulo, Brazil Quaggio & van Raij (2008)Quaggio, J. A., & van Raij, B. (2008). Cálcio, magnésio e correção da acidez do solo. In L. L. Dinardo-Miranda, A. C. M. Vasconcelos, & M. G. A. Landell (Eds.), Cana-de-açúcar (p. 313-321). Campinas: Instituto Agronômico. and van Raij et al. (1996van Raij, B., Cantarella, H., Quaggio, J. A., & Furlani, A. M. C. (1996). Recomendções de adubação e calagem para o Estado de São Paulo (2nd ed., Boletim Técnico, No. 100). Campinas: IAC.) have stated that sugarcane is more tolerant to aluminum toxicity and soil acidity than other Poaceae plants. Soil Ca and Mg content reduced with depth (Table 2); however, their values were higher than the recommendation for sugarcane (van Raij et al., 1996van Raij, B., Cantarella, H., Quaggio, J. A., & Furlani, A. M. C. (1996). Recomendções de adubação e calagem para o Estado de São Paulo (2nd ed., Boletim Técnico, No. 100). Campinas: IAC.). However, soil P, K and organic matter contents below 0.3 m soil depth were low when considering the standard values, 13 mg kg–1 for P and 1.6 mmolc dm–3 for K (van Raij et al., 1996van Raij, B., Cantarella, H., Quaggio, J. A., & Furlani, A. M. C. (1996). Recomendções de adubação e calagem para o Estado de São Paulo (2nd ed., Boletim Técnico, No. 100). Campinas: IAC.).
Soil chemical analysis for areas in which three sugarcane cultivars were grown. OM = Organic matter; CEC = Cation-Exchange Capacity; BS = Base Saturation
Cumulative root density
The highest LA values were obtained in IACSP94-2101, followed by SP79-1011, and IACSP94-2094 (Figure 4). LA increased until 185 DAR in IACSP94-2101 and SP79-1011, remaining around 12.9 and 7.5 mm cm–2 afterwards respectively (Figures 4a,b). Interestingly, IACSP94-2094 showed an increasing LA trend until 205 DAR, reaching maximum LA of 3.6 mm cm–2 (Figures 4c). In all cultivars, high LA was found at 0.0-0.2 m soil layer, which is in agreement with high nutrient availability as presented by soil chemical analysis (Table 2). In fact, the highest Ca and P availability occurred up to 0.2 m depth, favoring sugarcane root growth in this soil layer. When comparing to the other cultivars, IACSP94-2101 presented higher LA value even with low soil P availability in soil layers below 0.3 m depth (Figure 4; Table 2).
Cumulative root density (LA) in sugarcane cultivars IACSP94-2101 (a), SP79-1011 (b) and IACSP94-2094 (c) in five assessments up to 0.8 m depth. Each bar represents the mean value of three replications (± s.e.). DAR = days after ratoon.
The total root length observed around the access tube was 10.8, 5.9 and 2.5 m up to 0.8 m depth for IACSP94-2101, SP79-1011 and IACSP94-2094, respectively (Figure 5). Such values represent a large root length considering minirhizotrons with small area of observation (0.16892 m2).
Total root length (mm) distribution in sugarcane cultivars SP79-1011, IACSP94-2094 and IACSP94-2101 at 205 days after ratoon (DAR) in different soil layers, up to 0.8 m. Each bar represents the mean value of three replications (± s.e.).
LA decreased as depth increased, following an exponential shape (Smith et al., 2005Smith, D. M., Inman-Bamber, N. G., & Thorburn, P. J. (2005).
Growth and function of the sugarcane root system. Field Crops Research, 92,
169-183. http://dx.doi.org/10.1016/j.fcr.2005.01.017.
http://dx.doi.org/10.1016/j.fcr.2005.01....
). In fact, the adopted
cultivars showed an accurate adjust to exponential fitting (Table 3). According to the equation
parameters, it could be observed that the main difference between the equations
is the “a” coefficient, which value is higher for IACSP94-2101 and lower to
IACSP94-2094. The LA value will be higher as the “a” coefficient
increases, since they are directly proportional. The Z parameter, which
represents the depth in the soil profile, is in the equation exponent, which it
indicates that LA will decrease exponentially with depth. As well as
Z, the “b” coefficient in the exponent means that LA is expected to
decrease exponentially with the decrease of the “b” coefficient. Thus, comparing
the “a” and “b” coefficients, it was observed higher “a” and “b” values for
IACSP94-2101, indicating that this cultivar had higher LA values and
the exponential decrease of LA values, considering the same Z value,
was less pronounced than the other cultivars.
Equation adjust coefficients (a and b) to exponential equation for LA estimation and its correlation coefficients (r) in sugarcane cultivars SP79-1011, IACSP94-2094 and IACSP94-2101 at 205 days after ratoon (DAR) up to 0.8 m depth. The Z parameter represents the depth in the soil profile
Considering the use of minirhizotron method to evaluate
sugarcane root system under field conditions, Ball-Coelho et al. (1992)Ball-Coelho, B., Sampaio, E. V. S. B., Tiessen, H., & Stewart,
J. W. B. (1992). Root dynamic in plant-ratoon crop of sugar cane. Plant and
Soil, 142, 297-305. http://dx.doi.org/10.1007/BF00010975.
http://dx.doi.org/10.1007/BF00010975...
estimated a mean value of 2.7 m
m–2 up to 1.5 m depth. These values are lower than it was
observed in our study, but it is important to highlight that Ball-Coelho et al. (1992)Ball-Coelho, B., Sampaio, E. V. S. B., Tiessen, H., & Stewart,
J. W. B. (1992). Root dynamic in plant-ratoon crop of sugar cane. Plant and
Soil, 142, 297-305. http://dx.doi.org/10.1007/BF00010975.
http://dx.doi.org/10.1007/BF00010975...
considered the
mean value up to 1.5 m depth and the tube used had a different shape.
Although Azevedo et al. (2011)Azevedo, M. C. B., Chopart, J. L., & Medina, C. C. (2011).
Sugarcane root length density and distribution from root intersection counting
on a trench-profile. Scientia Agricola, 68, 94-101.
http://dx.doi.org/10.1590/S0103-90162011000100014.
http://dx.doi.org/10.1590/S0103-90162011...
, Laclau & Laclau (2009)Laclau, P. B, & Laclau, J. P. (2009). Growth of the whole root
system for a plant crop of sugarcane under rainfed and irrigated environments in
Brazil. Field Crops Research, 114, 351-360.
http://dx.doi.org/10.1016/j.fcr.2009.09.004.
http://dx.doi.org/10.1016/j.fcr.2009.09....
, Otto et al. (2009)Otto, R., Trivelin, P. C. O., Franco, H. C. J., Faroni, C. E., &
Vitti, A. C. (2009). Root system distribution of sugar cane as related to
nitrogen fertilization, evaluated by two methods: monolith and probes. Revista
Brasileira de Ciencia do Solo, 33, 601-611.
http://dx.doi.org/10.1590/S0100-06832009000300013.
http://dx.doi.org/10.1590/S0100-06832009...
and Vasconcelos et al. (2003)Vasconcelos, A. C. M., Casagrande, A. A., Perecin, D., Jorge, L. A.
C., & Landell, M. G. A. (2003). Avaliação do sistema radicular da
cana-de-açúcar por diferentes métodos. Revista Brasileira de Ciencia do Solo,
27, 849-858. http://dx.doi.org/10.1590/S0100-06832003000500009.
http://dx.doi.org/10.1590/S0100-06832003...
have studied
sugarcane root system, they used other methods, which difficult the comparison
based on the value itself. However, all of them reported large variability for
root evaluations such as root mass and length. High variability in LA
was also observed herein, based on the standard error of the mean (Figure 4), especially in the early growth
stage and in deeper layers.
As root growth is dependent on cultivar, soil biological-physical-chemical
status, crop management (Vasconcelos et al.,
2003Vasconcelos, A. C. M., Casagrande, A. A., Perecin, D., Jorge, L. A.
C., & Landell, M. G. A. (2003). Avaliação do sistema radicular da
cana-de-açúcar por diferentes métodos. Revista Brasileira de Ciencia do Solo,
27, 849-858. http://dx.doi.org/10.1590/S0100-06832003000500009.
http://dx.doi.org/10.1590/S0100-06832003...
) and also soil water availability (Laclau & Laclau, 2009Laclau, P. B, & Laclau, J. P. (2009). Growth of the whole root
system for a plant crop of sugarcane under rainfed and irrigated environments in
Brazil. Field Crops Research, 114, 351-360.
http://dx.doi.org/10.1016/j.fcr.2009.09.004.
http://dx.doi.org/10.1016/j.fcr.2009.09....
; Smith et al., 2005Smith, D. M., Inman-Bamber, N. G., & Thorburn, P. J. (2005).
Growth and function of the sugarcane root system. Field Crops Research, 92,
169-183. http://dx.doi.org/10.1016/j.fcr.2005.01.017.
http://dx.doi.org/10.1016/j.fcr.2005.01....
), studies about root dynamics must be
done in different growing conditions and using the same method to improve our
understanding about sugarcane root system.
Root distribution and effective rooting depth
As a perennial crop, sugarcane root distribution increases in the upper soil layers at later growth stages (Gascho & Shih, 1983Gascho, G. J., & Shih, S. F. (1983). Sugarcane. In I. D. Teare, & M. M. Peet (Eds.), Crop-water relations (p. 445-479). United States of America: John Wiley & Sons Inc.) and this pattern of response was verified herein (Figure 4, Table 4). The minirhizotron method allowed the observation of changes in root distribution and even in the effective rooting depth (Table 4). Understanding the root distribution along the crop cycle could provide useful information for water management based on the phenological crop stage. As irrigation depth is adjusted in according to the ERD, this parameter is especially important to water management. The knowledge about ERD variation along the crop cycle could be especially useful for supplementary irrigations. Cultivars with higher ERD exploit larger soil volume and hence they could have higher soil available water. Higher ERD also enables better use of rainfall.
Cumulative LA distribution (%) up to 0.8 m depth sampled during crop cycle of three sugarcane cultivars. DAR means days after ratoon. LA = cumulative root density (mm cm–2)
Most of roots in all three cultivars were found at the first 0.2 m soil layer,
reaching more than 50% at 205 DAR. If the depth of 0.4 m is considered, more
than 80% of the root system was found (Table
4). Therefore, the effective rooting depth (ERD) was 0.4 m in all
cultivars at 205 DAR, which is in accordance to Landell et al. (2005)Landell, M. G. A., Campana, M. P., Figueiredo, P., Vasconcelos, A.
C. M., Xavier, M. A., Bidoia, M. A. P., Prado, H., Silva, M. A.,
Dinardo-Miranda, L. L., Santos, A. S., Perecin, D., Rossetto, R., Silva, D. N.,
Martins, A. L. M., Gallo, P. B., Kantak, R. A. D., Cavichioli, J. C., Veiga, A.
A., Fo., Anjos, I. A., Azania, C. A. M., Pinto, L. R., & Souza, S. A. C. D.
(2005). Variedades de cana-de-açúcar para o Centro-Sul do Brasil (Boletim
Técnico, No. 197). Campinas: Instituto Agronômico.. An interesting finding is that IACSP94-2094
has varied its ERD during the cycle, from 0.6 m at 58 DAR to 0.4 m at 123 DAR
(Table 4). Soil water content was
also higher at the upper soil layers (Figure
3), which also affect the pattern of root distribution (Laclau & Laclau, 2009Laclau, P. B, & Laclau, J. P. (2009). Growth of the whole root
system for a plant crop of sugarcane under rainfed and irrigated environments in
Brazil. Field Crops Research, 114, 351-360.
http://dx.doi.org/10.1016/j.fcr.2009.09.004.
http://dx.doi.org/10.1016/j.fcr.2009.09....
; Smith et al., 2005Smith, D. M., Inman-Bamber, N. G., & Thorburn, P. J. (2005).
Growth and function of the sugarcane root system. Field Crops Research, 92,
169-183. http://dx.doi.org/10.1016/j.fcr.2005.01.017.
http://dx.doi.org/10.1016/j.fcr.2005.01....
).
The conversion of LA values to percentage values not only allows the
ERD determination but also the comparison with other studies. Otto et al. (2009)Otto, R., Trivelin, P. C. O., Franco, H. C. J., Faroni, C. E., &
Vitti, A. C. (2009). Root system distribution of sugar cane as related to
nitrogen fertilization, evaluated by two methods: monolith and probes. Revista
Brasileira de Ciencia do Solo, 33, 601-611.
http://dx.doi.org/10.1590/S0100-06832009000300013.
http://dx.doi.org/10.1590/S0100-06832009...
have also found 65% of
root mass in the first 0.2 m soil layer when evaluating the cultivar SP81-3250.
Similar results were reported by Vasconcelos et
al. (2003)Vasconcelos, A. C. M., Casagrande, A. A., Perecin, D., Jorge, L. A.
C., & Landell, M. G. A. (2003). Avaliação do sistema radicular da
cana-de-açúcar por diferentes métodos. Revista Brasileira de Ciencia do Solo,
27, 849-858. http://dx.doi.org/10.1590/S0100-06832003000500009.
http://dx.doi.org/10.1590/S0100-06832003...
, with 52% of root mass in the superficial soil layer. Both
studies were carried out without irrigation, but only Otto et al. (2009)Otto, R., Trivelin, P. C. O., Franco, H. C. J., Faroni, C. E., &
Vitti, A. C. (2009). Root system distribution of sugar cane as related to
nitrogen fertilization, evaluated by two methods: monolith and probes. Revista
Brasileira de Ciencia do Solo, 33, 601-611.
http://dx.doi.org/10.1590/S0100-06832009000300013.
http://dx.doi.org/10.1590/S0100-06832009...
have reported more than 80% of root
mass up to 0.4 m depth. Despite of not showing the relative values, Azevedo et al. (2011)Azevedo, M. C. B., Chopart, J. L., & Medina, C. C. (2011).
Sugarcane root length density and distribution from root intersection counting
on a trench-profile. Scientia Agricola, 68, 94-101.
http://dx.doi.org/10.1590/S0103-90162011000100014.
http://dx.doi.org/10.1590/S0103-90162011...
and Laclau & Laclau (2009)Laclau, P. B, & Laclau, J. P. (2009). Growth of the whole root
system for a plant crop of sugarcane under rainfed and irrigated environments in
Brazil. Field Crops Research, 114, 351-360.
http://dx.doi.org/10.1016/j.fcr.2009.09.004.
http://dx.doi.org/10.1016/j.fcr.2009.09....
also found
higher root density up to 0.4 m depth. Typical values for sugarcane root mass up
to 0.2 and 0.6 m depth are 50% and 85%, respectively (Smith et al., 2005Smith, D. M., Inman-Bamber, N. G., & Thorburn, P. J. (2005).
Growth and function of the sugarcane root system. Field Crops Research, 92,
169-183. http://dx.doi.org/10.1016/j.fcr.2005.01.017.
http://dx.doi.org/10.1016/j.fcr.2005.01....
).
Our results indicate that root distribution tend to be higher than 50% up to 0.2 m depth and more than 80% of total root system up to 0.4 m depth under subsurface drip fertigation. The knowledge of root growth and distribution are important parameters to improve the water and nutrient management and hence the use efficiency of these inputs, especially when using subsurface drip fertigation system. In addition, root growth and distribution are relevant parameters for models to forecasting production.
Root growth
The highest root growth rates occurred between 38 and 58 DAR, with IACSP94-2101
also showing high growth rates between 0 and 38 DAR (Figure 6a). It was observed root growth variation in soil
profile, with growth rate decreasing with increasing in soil depth (Figure 6). The maximum root growth rate was
82 mm day–1 in IACSP94-2101 at the 0.2-0.4 m soil layer, which was
similar to that one reported by Smith et al.
(2005)Smith, D. M., Inman-Bamber, N. G., & Thorburn, P. J. (2005).
Growth and function of the sugarcane root system. Field Crops Research, 92,
169-183. http://dx.doi.org/10.1016/j.fcr.2005.01.017.
http://dx.doi.org/10.1016/j.fcr.2005.01....
, i.e., 80 mm day–1. The highest growth rates
occurred when air temperature varied between 25.0 and 27.9 °C and there was
water availability (Figure 1). This period
coincided with the intense tillering phenological stage, when vigorous root
growth is required to support subsequent tiller growth (Vasconcelos & Casagrande, 2008Vasconcelos, A. C. M., & Casagrande, A. A. (2008). Fisiologia do
sistema radicular. In L. L. Dinardo-Miranda, A. C. M. Vasconcelos, & M. G.
A. Landell (Eds.), Cana-de-açúcar (p. 79-97). Campinas: Instituto
Agronômico.). Laclau & Laclau (2009)Laclau, P. B, & Laclau, J. P. (2009). Growth of the whole root
system for a plant crop of sugarcane under rainfed and irrigated environments in
Brazil. Field Crops Research, 114, 351-360.
http://dx.doi.org/10.1016/j.fcr.2009.09.004.
http://dx.doi.org/10.1016/j.fcr.2009.09....
reported low initial root
growth rates (up to 5.3 mm day–1), which increased to 17.5 mm
day–1 in irrigated plants. Smit
& Groenwold (2005)Smit, A. L., & Groenwold, J. (2005). Root characteristics of
selected field crops: data from the Wageningen Rhizolab (1990-2002). Plant and
Soil, 272, 365-384.
http://dx.doi.org/10.1007/s11104-004-5979-1.
http://dx.doi.org/10.1007/s11104-004-597...
have shown different rates of downward root
movement among several crops, with grasses showing the lowest ones about 20 mm
day-1.
Root growth rate in each soil layer up to 0.8 m depth for sugarcane cultivars IACSP94-2101, SP79-1011 and IACSP94-2094 in five assessments periods (a) and overall root growth rate in 205 days (b). DAR = days after ratoon.
While IACSP94-2094 had root growth rate of 7.4 mm day–1 at the upper
soil layer, IACSP94-2101 presented growth rates higher than 25 mm
day–1 (Figure 6b). Then,
our data revealed a large genotypic variation in root growth in commercial
sugarcane cultivars (Figure 6b). As growth
rates of IACSP94-2101 were similar to those ones reported by Smit & Groenwold (2005)Smit, A. L., & Groenwold, J. (2005). Root characteristics of
selected field crops: data from the Wageningen Rhizolab (1990-2002). Plant and
Soil, 272, 365-384.
http://dx.doi.org/10.1007/s11104-004-5979-1.
http://dx.doi.org/10.1007/s11104-004-597...
, we may argue
that SP79-1011 and IACSP94-2094 presented smaller root growth in ratoon crop.
This trait may be associated with its unresponsiveness to favorable
environmental conditions (Landell &
Bressiani, 2008Landell, M. G. A., & Bressiani, J. A. (2008). Melhoramento
genético, caracterização e manejo varietal. In L. L. Dinardo-Miranda, A. C. M.
Vasconcelos, & M. G. A. Landell (Eds.), Cana-de-açúcar (p. 101-155).
Campinas: Instituto Agronômico.), suggesting a conservative strategy of resource use.
The higher growth rates presented by IACSP94-2101 could be related to its fast
initial vegetative growth and high yield (Landell & Bressiani, 2008Landell, M. G. A., & Bressiani, J. A. (2008). Melhoramento
genético, caracterização e manejo varietal. In L. L. Dinardo-Miranda, A. C. M.
Vasconcelos, & M. G. A. Landell (Eds.), Cana-de-açúcar (p. 101-155).
Campinas: Instituto Agronômico.).
Understanding the root growth rates along the crop cycle provides information about the phenological stage in which the higher root growth rate was observed. Thus, this information could be useful for irrigation and nutrition management purposes aiming to avoid potential restrictions related to the high growth demand.
4 CONCLUSION
The highest cumulative root densities (LA) and root growth rates were found up to 0.4 m soil layer for all cultivars. Root growth varied during crop cycle, with the highest values being found between 38 and 58 days after ratoon. There was a genotypic variation in root growth, with IACSP94-2101 showing the highest LA of 12.9 mm cm–2. The effective rooting depth varied during crop cycle for IACSP94-2094, but all cultivars presented an effective depth of 0.4 m under subsurface drip fertigation.
REFERENCES
- Allen, R. G., Pereira, L. S., Raes, D., & Smith, M. (1998). Crop evapotranspiration : guidelines for computing crop water requirements (FAO Irrigation and Drainage Paper, No. 56). Roma: FAO.
- Azevedo, M. C. B., Chopart, J. L., & Medina, C. C. (2011). Sugarcane root length density and distribution from root intersection counting on a trench-profile. Scientia Agricola, 68, 94-101. http://dx.doi.org/10.1590/S0103-90162011000100014.
» http://dx.doi.org/10.1590/S0103-90162011000100014 - Ball-Coelho, B., Sampaio, E. V. S. B., Tiessen, H., & Stewart, J. W. B. (1992). Root dynamic in plant-ratoon crop of sugar cane. Plant and Soil, 142, 297-305. http://dx.doi.org/10.1007/BF00010975.
» http://dx.doi.org/10.1007/BF00010975 - Baquero, J. E., Ralisch, R., Medina, C. C., Tavares, J., Fo., & Guimarães, M. F. (2012). Soil physical properties and sugarcane root growth in a red oxisol. Revista Brasileira de Ciencia do Solo, 36, 63-70. http://dx.doi.org/10.1590/S0100-06832012000100007.
» http://dx.doi.org/10.1590/S0100-06832012000100007 - Blain, G. C. (2009). Considerações estatísticas relativas à oito séries de precipitação pluvial da Secretaria de Agricultura e abastecimento do Estado de São Paulo. Revista Brasileira de Meteorologia, 24, 12-23. http://dx.doi.org/10.1590/S0102-77862009000100002.
» http://dx.doi.org/10.1590/S0102-77862009000100002 - Box, J. E. Jr. (1993). Use of the minirhizotron-miniature video camera technique for measuring root dynamics. Geoderma, 56, 133-141. http://dx.doi.org/10.1016/0016-7061(93)90105-T.
» http://dx.doi.org/10.1016/0016-7061(93)90105-T - Cunha, F. F., Ramos, M. M., Alencar, C. A. B., Martins, C. E., Cóser, A. C., & Oliveira, R. A. (2010). Sistema radicular de seis gramíneas irrigadas em diferentes adubações nitrogenadas e manejos. Acta Scientiarum Agronomy, 32, 351-357. http://dx.doi.org/10.4025/actasciagron.v32i2.1020.
» http://dx.doi.org/10.4025/actasciagron.v32i2.1020 - Dannoura, M., Kominami, Y., Oguma, H., & Kanazawa, Y. (2008). The development of an optical scanner method for observation of plant root dynamics. Plant Root, 2, 14-18. http://dx.doi.org/10.3117/plantroot.2.14.
» http://dx.doi.org/10.3117/plantroot.2.14 - Empresa Brasileira de Pesquisa Agropecuária – EMBRAPA (2013). Sistema Brasileiro de Classificação de Solos (3rd ed.). Brasilia: Embrapa.
- Gascho, G. J., & Shih, S. F. (1983). Sugarcane. In I. D. Teare, & M. M. Peet (Eds.), Crop-water relations (p. 445-479). United States of America: John Wiley & Sons Inc.
- Hyams, D. (2009). CurveExpert version 1.4.
- Kandelous, M. M., & Šimůnek, J. (2010). Comparison of numerical, analytical, and empirical models to estimate wetting patterns for surface and subsurface drip irrigation. Irrigation Science, 28, 435-444. http://dx.doi.org/10.1007/s00271-009-0205-9.
» http://dx.doi.org/10.1007/s00271-009-0205-9 - Kirkham, M. B., Grecu, S. J., & Kanemasu, E. T. (1998). Comparison of minirhizotrons and the soil-water-depletion method to determine maize and soybean root length and depth. European Journal of Agronomy, 8, 117-125. http://dx.doi.org/10.1016/S1161-0301(97)00019-1.
» http://dx.doi.org/10.1016/S1161-0301(97)00019-1 - Laclau, P. B, & Laclau, J. P. (2009). Growth of the whole root system for a plant crop of sugarcane under rainfed and irrigated environments in Brazil. Field Crops Research, 114, 351-360. http://dx.doi.org/10.1016/j.fcr.2009.09.004.
» http://dx.doi.org/10.1016/j.fcr.2009.09.004 - Landell, M. G. A., & Bressiani, J. A. (2008). Melhoramento genético, caracterização e manejo varietal. In L. L. Dinardo-Miranda, A. C. M. Vasconcelos, & M. G. A. Landell (Eds.), Cana-de-açúcar (p. 101-155). Campinas: Instituto Agronômico.
- Landell, M. G. A., Campana, M. P., Figueiredo, P., Vasconcelos, A. C. M., Xavier, M. A., Bidoia, M. A. P., Prado, H., Silva, M. A., Dinardo-Miranda, L. L., Santos, A. S., Perecin, D., Rossetto, R., Silva, D. N., Martins, A. L. M., Gallo, P. B., Kantak, R. A. D., Cavichioli, J. C., Veiga, A. A., Fo., Anjos, I. A., Azania, C. A. M., Pinto, L. R., & Souza, S. A. C. D. (2005). Variedades de cana-de-açúcar para o Centro-Sul do Brasil (Boletim Técnico, No. 197). Campinas: Instituto Agronômico.
- Liu, D. L., Kingston, G., & Bull, T. A. (1998). A new technique for determining the thermal parameters of phenological development in sugarcane, including suboptimum and supra-optimum temperature regimes. Agricultural and Forest Meteorology, 90, 119-139. http://dx.doi.org/10.1016/S0168-1923(97)00087-7.
» http://dx.doi.org/10.1016/S0168-1923(97)00087-7 - Muñoz-Romero, V., Benítez-Vega, J., López-Bellido, L., & López-Bellido, R. J. (2010). Monitoring wheat root development in a rainfed vertisol: tillage effect. European Journal of Agronomy, 33, 182-187. http://dx.doi.org/10.1016/j.eja.2010.05.004
» http://dx.doi.org/10.1016/j.eja.2010.05.004 - Otto, R., Trivelin, P. C. O., Franco, H. C. J., Faroni, C. E., & Vitti, A. C. (2009). Root system distribution of sugar cane as related to nitrogen fertilization, evaluated by two methods: monolith and probes. Revista Brasileira de Ciencia do Solo, 33, 601-611. http://dx.doi.org/10.1590/S0100-06832009000300013.
» http://dx.doi.org/10.1590/S0100-06832009000300013 - Quaggio, J. A., & van Raij, B. (2008). Cálcio, magnésio e correção da acidez do solo. In L. L. Dinardo-Miranda, A. C. M. Vasconcelos, & M. G. A. Landell (Eds.), Cana-de-açúcar (p. 313-321). Campinas: Instituto Agronômico.
- Reichert, J. M., Suzuki, L. E. A. S., Reinert, D. J., Horn, R., & Håkansson, I. (2009). Reference bulk density and critical degree-of-compactness for no-till crop production in subtropical highly weathered soils. Soil & Tillage Research, 102, 242-254. http://dx.doi.org/10.1016/j.still.2008.07.002.
» http://dx.doi.org/10.1016/j.still.2008.07.002 - Smit, A. L., George, E., & Groenwold, J. (2000). Root observations and measurements at (transparent) interfaces with soil. In A. L. Smit, A. G. Bengough, C. Engels, M. Van Noordwijk, S. Pellerin, & S. C. Van De Geijn (Eds.), Root methods: a handbook (p. 235-271). Germany: Springer-Verlag Berlin Heidelberg.
- Smit, A. L., & Groenwold, J. (2005). Root characteristics of selected field crops: data from the Wageningen Rhizolab (1990-2002). Plant and Soil, 272, 365-384. http://dx.doi.org/10.1007/s11104-004-5979-1.
» http://dx.doi.org/10.1007/s11104-004-5979-1 - Smith, D. M., Inman-Bamber, N. G., & Thorburn, P. J. (2005). Growth and function of the sugarcane root system. Field Crops Research, 92, 169-183. http://dx.doi.org/10.1016/j.fcr.2005.01.017.
» http://dx.doi.org/10.1016/j.fcr.2005.01.017 - Sojka, R. E., Busscher, W. J., Gooden, D. T., & Morrison, W. H. (1990). Subsoiling for sunflower production in the Southeast Coastal Plains. Soil Science Society of America Journal, 54, 1107-1112. http://dx.doi.org/10.2136/sssaj1990.03615995005400040031x
» http://dx.doi.org/10.2136/sssaj1990.03615995005400040031x - Stolf, R., Fernandes, J., & Furlani, V. L., Fo. (1983). Penetrômetro de impacto modelo IAA/Planalsucar-Stolf: recomendação para seu uso. In J. M. Anderson, & J. S. I. Ingram (Eds.), Tropical soil biology and fertility: a hand book of methods (p. 132-144). Wallingford: CAB International.
- van Noordwijk, M. (1993). Roots: length, biomass, production and mortality (p. 132-144). In J. M. Anderson & J. S. I. Ingram (Eds.), Tropical soil biology and fertility: a hand book of methods. Wallingford: CAB International.
- van Raij, B., Cantarella, H., Quaggio, J. A., & Furlani, A. M. C. (1996). Recomendções de adubação e calagem para o Estado de São Paulo (2nd ed., Boletim Técnico, No. 100). Campinas: IAC.
- Vasconcelos, A. C. M., Casagrande, A. A., Perecin, D., Jorge, L. A. C., & Landell, M. G. A. (2003). Avaliação do sistema radicular da cana-de-açúcar por diferentes métodos. Revista Brasileira de Ciencia do Solo, 27, 849-858. http://dx.doi.org/10.1590/S0100-06832003000500009.
» http://dx.doi.org/10.1590/S0100-06832003000500009 - Vasconcelos, A. C. M., & Casagrande, A. A. (2008). Fisiologia do sistema radicular. In L. L. Dinardo-Miranda, A. C. M. Vasconcelos, & M. G. A. Landell (Eds.), Cana-de-açúcar (p. 79-97). Campinas: Instituto Agronômico.
Publication Dates
-
Publication in this collection
29 Apr 2015 -
Date of issue
Apr-Jun 2015
History
-
Received
01 Sept 2014 -
Accepted
23 Dec 2014