Leaf phenology, growth and photosynthesis in <i>Pseudobombax munguba</i> (Malvaceae)

Marenco, Ricardo Antonio; Sousa, Francinete de Freitas; Oliveira, Marcilia Freitas de

doi:10.1590/0034-737X201966010001

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Physiology and Morphology Applied to Agriculture • Rev. Ceres 66 (01) • Jan-Feb 2019 • https://doi.org/10.1590/0034-737X201966010001 copy

Leaf phenology, growth and photosynthesis in Pseudobombax munguba (Malvaceae)

Crescimento, fotossíntese e fenologia foliar em Pseudobombax munguba (Malvaceae)

Authorship SCIMAGO INSTITUTIONS RANKINGS

ABSTRACT

Munguba (Pseudobombax munguba) is a tree often found in low-land forests of the Amazon region, and there is a paucity of data regarding its ecophysiology. The aim of this work was to determine photosynthetic rates and growth of munguba saplings and to describe leaf phenology of a munguba tree. In greenhouse-grown saplings, diameter growth, leaf expansion, photosynthesis and stomatal conductance were determined. To describe the relationship between photosynthesis and leaf expansion, regression analysis was used. It was also described the leaf phenology of an adult tree by observing foliage changes at one-week intervals for two years. The leaves completed their expansion in 18 days, and leaf greening was completed in 40 days. Photosynthesis positively correlated with leaf expansion, but there was no correlation between stomatal conductance and leaf growth. Growth in diameter was 1.8 mm month^‒1. Relative growth rate was low, 0.010 g g^-1 day^-1. In the adult tree, leaf shedding was concentrated in July-August and by the second week of September the tree had already produced new leaves. Leaf longevity of munguba is about 11 months. It is hypothesized that leaf phenology of munguba is associated with the increased solar radiation of the dry season.

Keywords:
Amazon; growth analysis; leaf longevity; net assimilation rate; relative growth rate

Universidade Federal de Viçosa Av. Peter Henry Rolfs, s/n, 36570-000 Viçosa, Minas Gerais Brasil, Tel./Fax: (55 31) 3612-2078 - Viçosa - MG - Brazil
E-mail: ceres@ufv.br

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[1] * Corresponding author: rmarenco@inpa.gov.br

Climatic parameter	Dry season	Wet season
T_max (°C)	32.1±0.90	30.9±0.61
T_mean (°C)	27.1±0.634	26.3±0.45
T_min (°C)	23.2±0.41	23.3±0.22
RH (mean, %)	79.2±2.49	85.9±2.34
Rainfall (mm month^‒1)	86.9±28.4	267.6±55.1
Insolation (hour day^-1)	6.51±0.68	3.92±0.67
Solar radiation (MJ m^‒2 day^-1	17.86±0.95	14.24±0.94
PAR (mol m^-2 day^-1)	37.0±1.96	29.5±1.95
Evaporation (Piché, mm month^‒1)	82.3±13.21	52.8±8.54
Mean annual rainfall (mm)	2307

Date	Phenology of the tree	Panels in Figure 5 for illustration
July 07-14, 2015	Leaf senescence started and the tree began to bloom. Leaf fall was observed.
August 03, 2015	The tree showed senescent leaves and intense leaf fall was observed. The tree had flowers and fruits.
August 13-21, 2015	The tree still had some senescent leaves (there was intense leaf fall in the first two weeks of August), some fruits had reached their final size. Some new leaves began to emerge on 17-21 August, 2015.	See Figure 5A. August 21 (day 233) was considered the starting time for leaf emergence. About one month after leaf senescence began.
August 25, 2015	The tree had fruits and new leaves had emerged all over the tree.
September 09, 2015	New leaves were at the final stage of development. Leaf age was about 20 days old.	See Figure 5B. The leaf had 6-8 leaflets. In a fully developed leaf, the central leaflet was about 18‒22 cm in length and 6‒8 cm in width.
June 16, 2016	One year later, leaf senescence began again.	See Panel 5C (day 168). The leaves were about 300 days old.
July 09-19, 2016	Most of the leaves still on the tree were in the final senescence stages. The tree had fruits. By July 19 (day 201) at least 50% of the leaves had fallen.	See Figure 5D. On July 19, 2016 the leaves were about 330 days old. This was assumed as the end of leaf life span, as the leaves still in the tree were completely senescent.
August 16-19, 2016	The tree was entirely bare, all leaves had fall. The tree had fully developed fruits.	See panel 5E. The flowers were white-cream and about 10 cm in diameter, whereas the fruits were oblong, about 10 cm in diameter and 13 cm in length.
September 08, 2016	The tree had new leaves, about 10-20 days old.	Figure 5F.
Two years later from the beginning, on August 22 and September 15, 2017	The tree was bare again in August and with new leaves in September.	See Figure 5G,H.