YIELD AND QUALITY OF GRAIN AND TORTILLA OF IRRIGATED AND RAINFED HYBRID MAICES GROWN IN THE HIGH VALLEYS OF MÉXICO

Abstract

No studies in México have determined the effects of watering regime on commercial quality of maize grain and tortillas made from modern and old maize hybrids (Zea mays L.). The effect of watering regime on these genotypes was measured to determine how it affects yield and quality of grain and tortillas. The hybrids cultivated under rainfed conditions had lower yields (5.5 t ha^-1) than those cultivated with irrigation (8.1 t ha^-1). Moreover, under rainfed conditions hybrids had smaller and softer kernels with lower test weight (<74 kg hL^-1), than under irrigation where the modern hybrids (less than 10 years after their release) had higher yields (9.1 and 8.7 t ha^-1 respectively). Additionally, their kernels were harder (flotation index: 60 and 57 %) than those from late and older hybrids. In nixtamal and tortilla quality, only the percent of solids in nejayote (residual liquid produced by nixtamal production) was affected (P < 0.05) by the three factors assessed. Changes in the pericarp retained in the nixtamal, as well as tortillas moisture, texture and yield were only slightly affected by these factors. Modern maize hybrids surpassed older ones in grain yield and earliness, as well as in kernel size and hardness, but tortilla quality was the same in both maize groups.