Abstract

In this study 18 new corn varieties consist of 15 foreign early and mid-mature single cross hybrids and 3 Iranian commercial hybrids (KSC704, KSC647and DC370) were evaluated at two sowing date (5 and 20 June) based on randomized complete block design (RCBD) with 3 replications at Khorasan Razavi Agricultural Research Centre, Mashhad, Iran in 2009. This study showed that the percentage of yield reduction in early planting was -3.12%. Among all hybrids, EXP1 (16.03 ton/ha) had the highest yields in early planting (5 June) and EXP1 (16.52 ton/ha) produced the highest, yields in late planting (20 June). The first 2 principal components (PC1 and PC2) were used to create a 2-dimensional GGE biplot and explained 51 and 36% of GGE sum of squares (SS), respectively. Ranking of the genotypes based on the ideal genotype revealed that grain yields of EXP1, OSSK617, BOLSON and KDC370 were higher and more stable when found together. Results of this experiment also indicated that yield component such as 300 kernel weight, kernel no. per row, kernel depth and ear length were adversely affected in delay planting condition. Delay planting reduced 300  kernel weight, kernel no. per row, kernel depth and ear length. In conclusion, it can be suggested that EXP1 hybrid should be grown in Khorasan Razavi Plains.

Key words: Maize, planting date, combined analysis, stability.