Modification of agronomic traits in tropical maize by effect of selecction under drought stress

The objective of this study was to determine the effects on agronomic traits for improvement of drought tolerance in maize (Zea mays L.). The tropical maize populations Tuxpeno Sequia 'Cycle 0' (TS0) and 'Compuesto Iguala Sequia Cycle 4' (CIS4) and their advanced cycles 'TS Cycle 8' (TS8) and 'CIS Cycle 6' (CIS6) were evaluated in the field under restricted moisture and irrigated conditions, at Guemez, Tam., Mexico. The two irrigation treatments consisted of either maintaining the soil well-watered up to near field capacity throughout the growth season, or suspending irrigation from the flag leaf stage until physiological maturity. Variables measured were: biomass accumulation on plant aerial organs (BA) at crop maturity, grain yield (RG), number of grains per ear (NG), individual grain weight (PIG), anthesis-silking interval (ASI), days to crop maturity (DMF), grain filling period (PLLG), and harvest index (IC). The results indicated that the advanced cycles TS8 and CIS6 showed greater RG (21.8 % and 18.2 % respectively) compared to their parent populations, but BA was not modified, thus resulting in an increased IC. The increase in RG was a result of changes in the components PIG in TS8 (23 %), and in NG in CIS6 (18 %). It is concluded that the advanced selection cycles of these maize populations showed positive changes in agronomic traits in response to selection for tolerance to drought stress.