Efecto del estrés térmico sobre el peso y calidad de los granos en un maíz (Zea mays, L.) flint, semi-flint y pisingallo

MAYER, L.I. Y MADDONNI, G.A

Rosario, Santa Fe

Taller; IX Congreso Nacional de Maíz - 1° Simposio Nacional de Sorgo; 2010

AIANBA, AGROACTIVA

In the present work we studied the dynamic of maize (Zea mays, L.) kernel weight (KW) and its structural components (i.e., endosperm, pericarp and embryo), and several industrial quality traits under heat stress. For this purpose three hybrids of different kernel composition (semi-flint [2A120HX], flint [Mill522], and popcorn [P802]) were cultivated (2009-2010) and heat stressed for two weeks at early (EHS) and late (LHS) stages of the grain-filling period. Final KW and its fractions of 2A120HX and Mill522 were reduced by both EHS and LHS mainly due to a shorter active period of growing. Contrarily, P802, with the smallest KW, showed no response of these variables to heat stress. Among kernel fractions, the response of the endosperm tissues to heat stress of all genotypes was similar to those of the entire kernels. Endosperm-kernel, embryo-kernel and pericarp-kernel ratios were not affected significantly (p> 0.1) by extreme temperatures. Only EHS altered (i) kernel protein concentration of all hybrids (+5.5%), and (ii) kernel oil concentration of 2A120HX (-6%) and Mill522 (-8%). P802 hybrid showed a strong stability of several traits analyzed in this work (e.g., KW, endosperm, embryo, kernel oil concentration) to heat stress. Although it is known the negative effect of heat stress on maize kernel weight and its fractions during grain-filling period there is no evidence about the comparative response among hybrids of contrasting kernel composition and productive fate. Moreover, knowledge on underlying mechanisms is also needed to comprehend the physiological basis of the differential response among hybrids.