Seasonal variation and modeling of leaf area growth in Jatropha curcas L. plants: Implication for understanding the species adaptation in the Sahel of Niger

Jatropha curcas is a tree species introduced in Niger as a trial experiment to offset land degradation and for biofuel production. The objective of this study is to contribute to the understanding of this species’ potential for adaptation under the edaphic and climatic conditions of Niger through analysis and modeling of the leaf area dynamics. The nondestructive method is used to evaluate the leaf area growth using four provenances and 120 samples of leaves of J. curcas plants. The results show that leaf area is optimal during the wet season of the year with non-significant difference (P > 0.05), while during other periods it is significant (P < 0.05) between provenances. The logarithmic model is the most accurate, and the models developed have a correlation coefficient between 0.95 and 0.99. The error analysis shows a mean absolute percentage of error between 5.92 and 27.43%, depending on the provenances. The accuracies of the developed models were appreciated, with root mean square of error varying from 0.72 to 2.06 cm2. Contrary to the expectation, for production of J. curcas in Niger’s Sahelian climate and soil, it is necessary to ensure additional irrigation water to the plants, especially during the dry period of the year.   Key words: Exotic species, Jatropha curcas, adaptation, leaf area models, Niger.