EVALUATION IN SPRING SOWING OF EARLY MAIZE POPULATIONS SELECTED FOR THE SUMMER-SOWN CROP

A reciprocal recurrent selection was conduct on two early maize (Zea m ays L.) populations (Synthetic A and B), grown as summer-sown crop. Se lection was based on an index involving grain yield, erect plants and grain moisture. Marked responses for performance index (calculated sim ilarly to selection index) and other traits were obtained. Objective o f the present research was to evalute the responses to selection in ca se the materials are grown as spring-sown crop. The source (CO) and se lected (C1 and C2) populations of both Synthetics, together with their AxB crosses, were tested in three environments. The correlation coeff icients between mean values obtained in the present study (spring-sown ) and in the previous study (summer-sown) were significant for all inv estigated traits, with the highest coefficients being achieved for per formance index (r=0.90) and grain yield (r=0.96). For performance inde x the gain per cycle of population per se was positive but significant only for Synthetic B, and the change per cycle in heterosis was posit ive but non-significant for both synthetics. These findings were consi stent with those obtained in the previous study. Selected populations of both synthetics showed a greater yield stability than the non-selec ted populations across six environments (three of previous study and t hree of the present one). Results indicate that selection was effectiv e in improving the agronomic performance of both synthetics also as sp ring-sown crop and suggest that the two selected populations could be utilized for developing early genotypes suitable also for this type of crop.