Resumo em Inglês:

The evapotranspiration estimation has great importance to crop productivity and agricultural water management. In this study, evapotranspiration is analyzed in a coffee (Coffea arabica L.) crop located in Piracicaba, state of São Paulo (Brazil) using a numerical method based on the simulation of both water flow and crop activity in the unsaturated zone of the soil. Actual evapotranspiration is estimated from potential evapotranspiration using water stress functions, meteorological data, soil hydraulic parameters, crop coefficients and leaf area index values. Crop transpiration and soil evaporation are individually quantified improving the analysis of the evapotranspiration process. The numerical procedure can predict periods of crop water stress and becomes an attractive tool to analyze the effect of non-standard conditions on coffee crops and to design efficient irrigation schedules. Simulated evapotranspiration values are in good agreement with experimental values determined in the study site.

Resumo em Inglês:

Tomato cropping (Solanum lycopersicum L.) under protected cultivation using substrates and drip fertigation has improved sustainable production systems especially fruit quality and plant health. However, little is known for tomato plants when considering the interaction between substrate volume and irrigation frequency. The aim of this study was to evaluate the effects of coconut (Cocos nucifera L.) fiber substrate volumes and drip irrigation frequencies on the vegetative growth and fruit yield of tomato plants under greenhouse conditions. The experimental design consisted of randomized blocks arranged in a 3 × 2 factorial with four replicates. Treatments consisted of three substrate volumes (5.0; 7.5 and 10.0 L per plant) and two irrigation frequencies (once and five times per day). Leaf area index tended to increase in plants grown with the largest substrate volume (10 L). Although substrate volumes affected shoot dry matter, no effects on tomato yield and its components were observed. However, plants grown with 5 L of substrate and irrigated once a day produced a greater number of non-marketable fruit due to the higher incidence of calcium deficiency symptoms (blossom end rot). When plants were grown in 5 L or 7.5 L of substrate volume, high irrigation frequency favored the vegetative growth, stomatal conductance, CO2 assimilation and transpiration and fruit yield. Fruit yield and healthy fruits were favored by high irrigation frequency and did not depend on the substrate volume.

Resumo em Inglês:

Soil salinity may limit plant growth and development, and cause yield loss in crop species. This study aimed at remediating saline soil using organic matter (OM) treatment, before the cultivation of RD6 rice (Oryza sativa L. spp. indica). Physiological and morphological characters of rice plants, as well as crop yield, were evaluated from salt-affected soil with varying levels of salinity. The chlorophyll a and total chlorophyll pigments of rice plants grown in salt-affected soil (2% salt level) with the application of OM were maintained better than in plants grown without OM treatment. The degree of reduced photosynthetic pigments in rice plants was dependent on the level of salt contamination. Pigment content was positively related to maximum quantum yield of PSII (Fv/Fm) and quantum efficiency of PSII (ΦPSII), leading to reduced net photosynthetic rate (Pn) and reduced total grain weight (TGW). Photosynthetic abilities, including chlorophyll a and total chlorophyll pigments and ΦPSII, in rice plants grown with OM treatment were greater than in those cultivated in soil without the OM treatment, especially in high salt levels (1-2% salt). The remediation of salt-affected soil in paddy fields using OM should be applied further, as an effective way of enhancing food crop productivity.

Resumo em Inglês:

Alternative use of the X-ray test to evaluate seed quality has become increasingly diverse. This study was performed primarily to establish experimental procedures and verify the effectiveness of the X-ray test to detect damage or abnormalities in bell pepper (Capsicum annuum) seed structure associated with germination. Five seed lots each of hybrids Reinger and Sentinel were used. Two hundred seeds per lot were exposed to durations and intensities of X-radiation and visually classified into four categories according to the proportion between the area occupied by the embryo and endosperm in relation to the total cavity area in the internal seed structure, e.g. 0, < 50%, 50-75% and 100%. The last category was subdivided into two others based on the occurrence of morphological abnormalities. Seed samples obtained from different X-ray categories were then submitted to germination test at 25ºC for 14 days and subsequently compared with results of the X-ray analysis. Exposure to a 10 kV radiation for 260 s was the most suitable X-ray dose for visualizing seed structure. Seeds in which the area of the internal cavity occupied by the embryo and endosperm varied from 50-75% produced abnormal seedlings or did not germinate. Full seeds (100% of the internal cavity area occupied) with abnormal structure usually originated defective seedlings. As a consequence, the classification of bell pepper seeds according to the proportion occupied by the seed content (embryo + endosperm) allowed a reliable estimation of the degree of seed physical integrity based on X-ray analysis and its association with germination performance.

Resumo em Inglês:

Besides the use of fodder radish (Raphanus sativus var. oleiferus Metzg.) as green manure plant cover crops and animal feed, the seeds have high oil content and low viscosity, ideal characteristics for the production of biodiesel. Studies related to the technology of seed production for this species are insufficient to define the best spatial arrangement of plants in the field that provides higher yields associated with high-quality seeds. Thus, we investigated the space and density between plants that would be ideal for the production of high quality fodder radish seeds. We evaluated the agronomic characteristics and physical, physiological and seed health quality in recently harvested fodder radish in row spacings of 0.2, 0.4, 0.6, and 0.8 m and densities of 10, 30, 50 and 70 seeds m-2. The quality and productivity of the fodder radish's seeds were affected by the spatial arrangement of plants in the field. Seeds harvested under the spacing of 0.2 m and density of 30 seeds m-2 had better performance and physical, physiological and health quality. Alternaria sp. incidence increased with greater spacing, while Fusarium sp. incidence decreased.

Resumo em Inglês:

Although Coffea arabica species has its origin in the African understories, there is great resistance on the part of the Brazilian producers for growing this species under agroforestry systems as they fear that shading reduces production. This study aimed at evaluating some vegetative traits and the productivity of organically grown coffee (Coffea arabica L.) cultivars under shaded and unshaded systems. Twelve treatments consisting of two cultivation systems (shaded and unshaded) and six coffee cultivars were arranged in randomized blocks with four replicates, in a split-plot scheme. Shading was provided by banana (Musa sp.) and coral bean plants (Erythrinaverna). Shading delayed fruit maturation. Late maturation cultivars, such as the Icatu and the Obatã, matured early in both cultivation systems, while medium and early maturation cultivars presented late maturation. Cultivation in the shaded system increased the leaf area and the number of lower branches, decreased the number of productive nodes per branch, and increased the distance between the nodes and the number of leaves present in the branches. Cultivation in the unshaded system presented greater number of plants with branch blight in relation to plants grown in the shade. The productivity of the cultivars was not different, at 30.0 processed bags per hectare in the shaded system, and 25.8 processed bags per hectare in the unshaded system. The most productive cultivars in the shaded system were the Tupi, the Obatã, and the Catuaí, while no differences between cultivars were obtained in the unshaded system.

Resumo em Inglês:

The pigeonpea [Cajanus cajan (L) Millspaugh] is one of the most important perennial legume crops utilized in the food, fodder, soil conservation, crop-livestock integrated systems, reclaiming of degraded pastures and symbiotic nitrogen fixation. Microsatellite markers were used to estimate the genetic diversity of 77 pigeonpea genotypes selected from the germplasm collections at Embrapa Cattle-Southeast and, to evaluate their transferability to Phaseolus vulgaris and Vigna unguiculata species. The number of alleles per locus ranged from 2 to12, with an average of 5.1 alleles. The PIC values ranged from 0.11 to 0.80 (average 0.49) and the D values from 0.23 to 0.91 (average 0.58). The averages of observed and expected heterozygosity were 0.25 and 0.47, respectively, showing a deficit in heterozygosity. A model-based Bayesian approach implemented in the software STRUCTURE was used to assign genotypes into clusters. A dendrogram was constructed based on the modified Roger's genetic distances using a neighbor-joining method (NJ). A total of four clusters were assembled by STRUCTURE and a strong tendency of correspondence between the Bayesian clusters in the NJ tree was observed. The genetic distance ranged from 0.09 to 0.62 (average 0.37), showing a low genetic diversity in the pigeonpea genotypes. Transferability of pigeonpea-specific microsatellites revealed a cross-amplification and the presence of polymorphic alleles in P. vulgaris and V. unguiculata.

Resumo em Inglês:

Studies on genetic diversity and genetic structure of natural populations are important in order to define strategies for in situ and ex situ conservation actions and for plant pre-breeding programs. Aiming to assess the genetic diversity and genetic structure of three wild American Oryza species with isozyme markers, 14 populations of the diploid O. glumaepatula (AglAgl), 11 populations of the tetraploid O. grandiglumis (CCDD) and five populations of the also tetraploid O. latifolia (CCDD) were studied. They were all originated from Rio Paraguay hydrographic basin and the Amazon. Four enzymes were used and they gave 40 polymorphic bands. The most polymorphic species was O. glumaepatula, followed by O. latifolia and O. grandiglumis. A cluster analysis with the Jaccard similarity coefficient separated the diploid from the two tetraploid species, and also the two tetraploid species. This separation was also evident on a scatter plot from a principal component analysis, suggesting that they should be treated as two separate species, although further studies are necessary to provide support for this affirmative. The AMOVA analyses showed a high intrapopulational variability for O. latifolia (67.6%) and O. grandiglumis (52.2%), when compared to their interpopulational variability (32.4% and 47.8%, respectively), which suggests the hypothesis of a higher degree of outcrossing events within these species. When studying the correlation between the Jaccard dissimilarity coefficient and geographic distances, a spatial genetic structure was observed for O. glumaepatula only. These results are important for defining strategies of both in situ and ex situ conservation.

Resumo em Inglês:

Lippia alba (Mill.) N.E.Br. is an aromatic and medicinal shrub native to the American continent. Despite its potential as a source of essential oil for the pharmaceutical and cosmetics industries, few selection and genetic improvement studies have been carried out. The aim of this study was to provide genetic information on this species for breeding programs, showing its selection potential, by investigating clonal half-sib progenies. The following characteristics were evaluated per plant: leaf dry mass (LDM), total dry mass (TDM), leaf yield (LY), essential oil yield (EOY) and oil production (OP). Estimates were made for the several genetic parameters including absolute genetic gain at 30% selection intensity, correlations and relative contribution of additive and environmental effects to phenotypic correlation. Two experimental trials on 30 progenies were conducted: one in Campinas, state of São Paulo (SP), Brazil, with two harvests of the aerial part, and one in Monte Alegre do Sul, SP, Brazil, with only one harvest. The trials were conducted in a randomized block design consisting of subplots with three replications, each plot (progeny) consisting of 8 to 15 clonally-replicated plants with subplot harvesting. Variations were detected between progenies and harvests, as well as progeny/harvest interactions in the split plot experiment. High heritability and genetic gains were obtained at both sites for LDM, TDM and OP. The lowest variations among progenies were obtained for LY and EOY, highlighting selection problems. Negative additive genetic correlations were obtained for EOY × LDM, EOY × TDM, LY × TDM and LY × LDM. Selection for LDM resulted in increased oil production per plant (OP), even where there was a negative correlation between LDM × EOY.

Resumo em Inglês:

Stresses such as cold and drought can impair plant yield and induce a highly complex array of responses. Sugarcane (Saccharum spp.) is cultivated in tropical and subtropical areas and is considered a cold-sensitive plant. We previously showed that cold stress induces the expression of several genes in in vitro sugarcane plantlets. Here we characterize one of those genes, SsNAC23, a member of the NAC family of plant-specific transcription factors, which are induced by low temperature and other stresses in several plant species. The expression of SsNAC23 was induced in sugarcane plants exposed to low temperatures (4ºC). With the aim of further understanding the regulatory network in response to stress, we used the yeast two-hybrid system to identify sugarcane proteins that interact with SsNAC23. Using SsNAC23 as bait, we screened a cDNA expression library of sugarcane plants submitted to 4ºC for 48 h. Several interacting partners were identified, including stress-related proteins, increasing our knowledge on how sugarcane plants respond to cold stress. One of these interacting partners, a thioredoxin h1, offers insights into the regulation of SsNAC23 activity.

Resumo em Inglês:

The flower bud abortion is one of the main problems that limit commercial pear (Pyrus pyrifolia) production in the southern region of Brazil. Insufficient chilling during the dormancy period is known as the main factor of this problem. One of the hypotheses to explain this problem is that the starch mobilization and carbohydrate fluxes to the buds are impeded when mild temperatures occurred during winter. This study compared the total soluble sugars (TSS) and reducing sugars (RS) concentrations, the cell wall acid invertase (CWAI - EC 3.2.1.26) and sucrose-phosphate synthase (SPS - EC 2.4.1.14) activities in wood of branches and floral buds of Japanese pear trees cv. Housui, grafted on Pyrus calleryana and submitted to chilling conditions during the dormancy period. Treatments were: (i) natural conditions; (ii) continuous artificial chilling; (iii) alternating temperatures, and (iv) total chilling privation. TSS and RS contents, as well as CWAI and SPS activities in tissues of branches that received insufficient chilling were lower than those that received sufficient chilling during winter. The starch concentration was superior in wood tissues of branches kept under chilling privation. The chilling privation disturbs carbohydrate mobilization in pear trees, reducing the sucrose synthesis capacity in wood tissues (source) and sucrose importation by the floral buds (sink).

Resumo em Inglês:

For sugarcane (Saccharum spp.) crops, the effects of an environmental stress, especially water deficiency, may cause severe productivity reduction, inferring negatively in the sugarcane industry. The tolerance of two sugarcane cultivars to a lack of water was made by analyzing the levels of the osmoprotectors, trehalose and free proline, and the biometrical variables of their initial growth. Biochemical and physiological responses of the cultivars, when subjected to water stress, were assayed to determine how these plants tolerate drought. The study was conducted in an acclimatized greenhouse (29.7 ± 4.3ºC and 75.0 ± 10.1% relative humidity) during 100 days and was divided into random blocks using a factorial 2 × 3 × 2 design (sugarcane cultivars × water availability × time periods) with four replicates. Forty days after germination, sugarcane was planted in pots (12 dm³) containing topsoil material taken from a medium textured Rhodic Ferralsol, submitted to three levels of water availability (WAS): 55% (control), 40% (moderate stress) and 25% (severe stress), for 60 days. The effect of the WAS on the accumulation of trehalose and free proline was detected in both cultivars, although it was found to be more distinctive for the cv. IAC91-5155. Trehalose and free proline are biochemical and physiological indicators of water deficiency. The cv. IAC91-5155 had altered growth and allocation of biomass when subjected to severe water stress conditions. The univariate and the multivariate analysis of the biochemical and physiological responses, presented by the IAC91-5155 cultivar, indicate relative tolerance to drought conditions.

Resumo em Inglês:

Sainfoin (Onobrychis viciifolia Scop.) is an important forage legume crop with 52 species adapted to dry and poor soils in Turkey, but little is known about the effects of salinity on germination and seedling growth in arid and semiarid regions suffering from salinity problem. The seeds and pollen of two species of sainfoin O. viciifolia and O. oxyodonta var. armena (Syn: O. armena) were exposed to 0, 5, 10, 20 and 30 dS m-1 of NaCl under in vivo and in vitro conditions and evaluated for germination under salt stress by comparing germination percentage, mean germination time, root and shoot length, fresh and dry seedling weight and dry matter. Increased salinity levels generally resulted in decrease in all traits except time to germination, dry seedling weight and dry matter, which increased at high salinity levels. O. viciifolia seeds germinated and grew more rapidly compared to O. armena seeds under NaCl stress. No decrease in germination and seedling growth up to 10 dS m-1 was recorded. On the other hand, there was a clear difference for germination and seedling growth between in vivo and in vitro conditions. Lower values were obtained from in vitro experiments; suggesting that mineral salts, sucrose and agar may have resulted in higher osmotic potential inhibiting germination and seedling growth of species compared in vivo conditions. Decrease in pollen germination with increasing salinities was very sharp, indicating that pollen germination had higher sensitive to salinity. But, pollen grains of O. armena germinated rapidly compared to O. viciifolia. The results emphasize that in vivo experiments could be used for screening of NaCl tolerance in sainfoin cultivars without expensive chemicals and sophisticated equipments, but pollen germination is more appropriate for its wild relatives.

Resumo em Inglês:

Toxic levels of Cd can cause protein denaturation and oxidative stress, which result in membrane damage, enzimatic activity changes and other metabolic damage. Some plants may show alteration in the activity of their antioxidant enzymes as a heavy metal tolerance mechanism. This study aims at evaluating the role of enzymes of the antioxidant system in adaptive responses of the accumulator P. glomerata species to levels of cadmium (Cd). Plants were cultivated in nutrient solutions containing concentrations of Cd in the form of CdSO4 (0, 45 and 90 µmol L-1), for 20 d. Cd concentrations and yields of root and shoot dry matter were determined at the end of the experiment. Malondialdehyde (MDA) production and the activities of antioxidant enzymes were determined after days 1, 12 and 20. Higher Cd concentrations in tissues of P. glomerata were found to reduce biomass production in both roots and shoots. The lipid peroxidation rates in leaves and roots were smaller at the start of the experiment for all Cd levels. Superoxide dismutase (SOD) activity increased in leaves on day 1 and in roots on day 20 as Cd levels increased. Cd stress induced an increase in the activity of APX in leaves, whereas in roots ascorbate peroxidase (APX) activity was reduced at high concentration of Cd. At the end of the experiment, catalase (CAT) activity in leaves was reduced as Cd concentration increased. Nevertheless, the glutathione reductase (GR) and guaiacol peroxidase (GPX) activities increased. In roots, GR activity was reduced on days 1 and 20.

Resumo em Inglês:

Strawberry (Fragaria x ananassa D.) yield is affected by vigor of transplants. Those young and vigorous at planting lead to plants reaching higher vegetative growth and fruit yield than weak or old ones. This study aimed at determining plant growth, development, and fruit yield of the strawberry plant from bare root and plug transplants with different crown diameters. Bare root transplants were produced by rooting stolons and plug transplants from runner tips collected and rooted in a substrate growing bed. Three classes of crown diameters were compared in a 2 × 3 factorial and randomized block experimental design, with four replications, 16 plants per plot and a density of 6.6 plants m-2. For bare root transplants, crown diameters were between 3.0 and 5.0 mm (class 1); 5.1 and 8.0 mm (class 2) and greater than 8.1 mm (class 3). For plug transplants, runner tips were screened between 2.0 and 3.9 mm (class 1); 4.0 and 5.5 mm (class 2) and 5.6 to 7.0 mm (class 3). Transplants of both types were planted at April 16th, 2008, and at this date, crown diameter, shoot and root dry mass and number of leaves were higher in all classes of plug transplants. Ripe fruits were harvested from June 15th to November 7th, 2008, and fresh fruit yield was determined. Plant growth and development were determined at last harvest. Higher growth, development and fruit yield were obtained in plants from plug transplants. For bare root transplants, crown diameters higher than 5.1 mm can be used while for plug transplants the crown diameter of runner tips does not affect plant growth and fruit yield.

Resumo em Inglês:

Traditional growers of the Vale do Ribeira, São Paulo State, grow and make use of several D. alata landraces. This study assessed the genetic diversity of 16 landraces, using isozymatic and morphological markers and comparing them with 19 commercial varieties of D. alata. Their distribution in different levels of organization such as households and communities of the Vale do Ribeira was evaluated. Isozymatic analyses were performed with polyacrylamide (six systems) and starch gels (one system), while the morphological analyses were carried out with 24 traits. Due to the polyploid nature of this species, the isozymatic bands were scored as binary data. Morphological traits were also scored as binary data. Principal coordinates and cluster analyses were conducted for both markers, using for the later the Jaccard´s similarity coefficient and UPGMA method. The separation of the landraces from the commercial varieties, which showed lower genetic diversity, was reported for both markers. No correlation between genetic and geographical distances was found for both data, which suggests that the observed variability is not spatially structured. Also, no correlation was found between both markers. The analysis of molecular variance (AMOVA) indicated that genetic diversity was mainly found within households for both isozymatic (54%) and morphological (70%) markers. The results obtained for both markers revealed the importance of traditional agriculturists in the Vale do Ribeira in maintaining high diversity for D. alata, even higher than the varieties commercialized in São Paulo State, contributing for the in situ/on farm conservation of this crop.

Resumo em Inglês:

Coffee ringspot is a minor coffee disease caused by the nuclear type of Brevipalpus mite-transmitted virus, Coffee ringspot virus (CoRSV). Recently outbreaks of the disease in some growing regions of the state of Minas Gerais, Brazil, were registered with qualitative and quantitative yield losses. Coffea arabica was the only species registered as natural host. A survey was made on a germplasm collection of Coffea and related species kept at the Centro de Café "Alcides Carvalho", Instituto Agronômico, Campinas, state of São Paulo (SP), Brazil, to assess natural susceptibility of Coffee species, other than C. arabica and some interspecific hybrids of Coffea as well as other non-Coffea plant species to the Coffee ringspot virus (CoRSV). The following plants were found with ringspot symptoms on their leaves and/or fruits besides C. arabica L.: C. kapakata (IAC 4511), C. dewevrei cv. Excelsa, C. canephora cv. Robusta, hybrid derivative of the C. arabica × C. racemosa (IAC1195-5-6-2), C. arabica × C. dewerei (Piatã IAC 387), Híbrido de Timor CIFC 832/1 (derivative from a natural crossing between C. arabica × C. canephora) and C. racemosa. Also Psilanthus ebracteolatus, a species close to the genus Coffee was also found with ringspot lesions on their leaves. All these plants were also found infested by Brevipalpus mites identified as B. phoenicis. Infection of these plants by CoRSV was confirmed by the observation of characteristic cytopathic effects in the tissues of the lesion and by RT-PCR using a pair of primer specific for CoRSV. Only with C. racemosa RT-PCR failed to amplify the CoRSV genome. The susceptibility of P. ebracteolatus to CoRSV adds new dimension regarding its controversial taxonomic position.