Crescimento, fisiologia e produção de genótipos de gergelim sob níveis de adubação organomineral

Abstract

Sesame is one of the most grown oilseeds in tropical regions, because of its good adaptation to drought. It is an alternative for semi-arid areas for its great economic potential in both domestic and international markets. Its seeds (rich in oil) can be used in different sectors such as food, biofuel, cosmetics, pharmaceuticals and agrochemicals. This work was carri ed out to develop technology for the cultivation of this species in agricultural systems of family farming, and to evaluate growth variables, physiology and production of two sesame genotypes („BRS Seda‟ and sesame „Preto‟), with varying organic-fertilizer levels, through fertirrigation. The genotypes were grown under field conditions in the agricultural area of Centro de Ciências Agrárias e Ambientais/UEPB, in Lagoa Seca-PB. Five levels of organic-fertilizer (0, 30, 60, 90 and 120% of the nutritional requirements of the culture) were studied based on stillage from sugarcane and one additional treatment containing mineral fertilizer (100% of crop requirement). Thus, there were two factors: 2 sesame genotypes and five fertilizer levels, with 2 additional treatments (2 x 5 + 2), totaling 12 treatments. The experimental design was randomized blocks, with four replications, totaling 48 plots. Plant growth variables (plant height, insertion height of the first fruit, stem diameter, number of branches per plant), phenology (germination / vegetative growth, flowering, fruiting, maturity / harvest), physiology (transpiration, stomatal conductance, net photosynthesis, internal CO2 concentration, instantaneous efficiency of water use and carboxylation) and production components (number of branches per plant, number and weight of fruits per plant, seed weight per plant and weight of 1000 seeds) were evaluated. The data were evaluated by analysis of variance, then the data related to fertilization levels factor were analyzed by polynomial regression; however the data related to genotypes were analyzed by comparison of means by Tukey test (p<0,05). Regarding to phenology chronological, difference was found in the periods of early flowering and early fruiting of sesame genotypes „BRS Seda‟ and „Preto‟. The growth variables of plant height, stem diameter and number of branches per plant, positively varied depending on the organomineral fertilizer based on sugar cane stillage. In relation to physiological parameters, only the variable internal CO2 concentration (Ci) was affected by organic-fertilizer levels. Production components of number of fruits, fruit weight, seed weight and weight of 1000 seeds of the two cultivars were favored by organic-fertilizer. Finally, it is noteworthy that the level of 120% of organic-fertilizer provided to the sesame genotypes „BRS Seda‟ and „Preto‟ superior results to those achieved with only mineral fertilizer.