Analysis of morpho-agronomic and climatic variables in successive agricultural years provides novel information regarding the phenological cycle of Jatropha in conditions of the Brazilian cerrado

Abstract

Phenological studies can provide information that enables the understanding of the dynamics of plants and how these dynamics are related to the biotic and abiotic environment. In order to study the phenological phases of Jatropha during two agricultural years, agronomic and climatic variables, such as temperature and rainfall, were evaluated. Data for each variable in each year and each genotype were subjected to analysis of variance (ANOVA) and the differences were tested at 5% probability by F test. In addition, the correlation of growth behavior and reproductive development of two Jatropha accessions (CNPAE-102 and CNPAE-169) as a function of time elapsed after the start of the phenological cycle with climatic variables were analyzed through Pearson´s correlation. It was found that: (i) the resuming of plant growth by producing new branches and flowers of both genotypes coincides with the start of the rainy season, (ii) the flowering may be related to the increase in temperature and rainfall; (iii) the number of inflorescences per plant and number of female flowers determine the number of green fruits, (iv) the environmental changes are responsible for the delimitation of phenophases; and finally that (v) the responses to phenological changes are genotype-dependent.

Photosynthetic performance of contrasting Jatropha curcas genotypes during the flowering and fruiting stages

“…Genotype CNPAE-102 produces on average 130% more green fruits than genotype CNPAE-169 (Domiciano et al, 2014). However, the data of this study also indicates that A in both genotypes is broadly equivalent under field conditions, assuming that the number of green fruits in the labeled branches can be considered as a yield indicator (Laviola et al, 2012) and that CNPAE-102 has been previously shown to be more productive than CNPAE-169.…”

“…Although the number of inflorescences and flowers tracked A (Figures 1 and 2), it is unlikely that there is a cause-effect relationship because of the moderate negative correlation that occurred between A and the number of green fruits on labeled branches for this same genotype (Table 2). Previous studies (Domiciano et al, 2014) showed that the number of green fruits and the number of inflorescences and flowers are genuinely correlated, suggesting the correlation between flower traits and A is spurious.…”

“…Jatropha curcas are deciduous (Durães et al, 2011), losing all their leaves in the dry season. The resumption of growth by the emergence of new branches and later inflorescences starts with the rainy season (Domiciano et al, 2014). Due to the previous loss of leaves, plants need to survive this period by using water and organic reserves, mainly sucrose and starch (Gupta & Kaur, 2000), stored in stems and roots during the previous phenological cycle.…”

“…The experiments were carried out using the J. curcas active germplasm collection maintained at the experimental station of Embrapa Cerrados, located at Planaltina, DF, Brazil (15°35'30"S, 47°42'30"W, at an altitude of 1,007 m). Information on climate, soil, and management practices can be found in Domiciano et al (2014). For this study, two field-grown accessions phenotypically contrasting in toxicity and yield, were evaluated: CNPAE-102 (a high-yielding toxic genotype) and CNPAE-169 (a low-yielding nontoxic genotype).…”

“…Consequently, reduced shoot growth is commonly observed in many plant species during the flowering and fruiting periods. However, since J. curcas produces inflorescences in the terminal buds of the branches grown during the current year (Domiciano et al, 2014), the production of new inflorescences ultimately depends on the vegetative growth of the plants. Under these conditions, J. curcas can only obtain high fruitloads if it continues growing while, at the same time, reallocating newly produced photoassimilates (together with those that were previously stored in the stem and roots) to both shoot growth and fruit development.…”