GRAIN GROWTH COMPONENTS OF CORN LINES WITH DIFFERENT GRAIN WEIGHT

Abstract

In corn, grain yield is determinate by the number of grains per ear and the individual grain weight (IGW), the IGW is function of the grain filling rate (GFR), total grain filling period (GFP) and effective grain filling period (EGFP). These characteristics are known as
grain growth components. In 1997, in the Experimental Station of the Colegio de Postgraduados in Tecámac, Mexico, the components and the dynamics of the grain growth were evaluated seven corn lines with different grain weight, to investigate the relations of the components of the grain growth with the IGW. The results indicated greater average values of GFP, EGFP and GFR in the large grain lines in comparison with the small grain weight lines, with differences of 4.4 days, 4.8 days and 1.41 mg day^-1, respectively. However, within each group of lines with equal IGW superior values of the components of the grain growth not always meant grater IGW; this and the correlation of IGW with the components mentioned before (GFP = 0.49**, EGFP= 0.29* y GFR = 0.53**), permits to indicate a positive relation ship of these components with the IGW. On the other hand, since 43.1 % of the GFP
corresponds of the final and initial slow stages, and only 13 % of the IGW was accumulated in those periods while the remainder 87 % was accumulated during the EGFP, thus effective grain filling period and the grain filling rate are considered of greater importance in the determination of the individual grain weight. However, taking info account a negative correlation between these two components, greater values of then not always will result in greater IGW.