EFFECT OF RAINFALL PRECIPITATION ON THREE PHENOLOGY STAGES OF CORN IN THE PLAINS OF DURANGO

Abstract

In order to know the rainfall effect on the development of corn in Los Llanos de Durango, Mexico, three breeding cultivars of different maturity cycle (early, intermediate and late) were compared to re­gional cultivars. These cultivars had been evaluated throughout 10 years on 23 trials in three locations. The grain yield of each cultivar and accumulated rainfall were obtained for the whole cycle and also for three phenological stages. The amount of rain­fall was calculated at 60% of probability in each stage. Linear regressions were calculated between the grain yield and rainfall. The grain yield of the cultivars in all trials was analyzed in a random ized block design. Results showed that drought begins at the flowering stage and it is aggravated during the grain filling stage in all the cultivars. The earliest cultivar can escape the rainfall deficit during the flowering stage and received more rain during the grain filling period than the other cultivars. Therefore, the grain production of early cultivars is safer when low rainfall ocurrs, but their potential is low in environments of high rain­fall. The intermediate cultivar, even when is affect ed by water deficits during flowering and grain filling stages, represents a better option because its response is better in low and in high amounts of rainfall. The late cultivar is the best option only under a high rainfall, buth this condition happens with a probability lower than 60%. Then plant breed­ing was efficient to increase the productivity of cultivars in this region.