The effect of planting date on yield and yield components of wheat cultivars base GGE Biplot in Gonbad

The current study was conducted to evaluate determination of best cultivars and planting date of wheat (Triticom aestivum L.) using GGE biplot method in the research field of Faculty of Agriculture, University of Gonbad Kavous in 2013. The experiment was carried out in split-plot base on randomized complete block design in three replications. Sowing dates of January 15 and 29 and February 11 assigned in main plots and cultivars including Akbari, Arge, Sistan, Superheah, Bam, Gonbad, Morvareed and N-87-20 in sub plots. The traits of number of total spike, spike length, number of grains in spike, weight of grains in spike, number of spikelets in spike, grain yield and thousand grain weight were measured. The effect of planting dates was significant on studied traits. The interaction of planting date in cultivars was significant on all studied traits but weight of grains in spike and 1000 seed weight. The result of biplot and Mean comparison of cultivars and different planting deta showed that Gonbad had the highest yield and stability. Morvareed and N-87-20 with 2684.6 and 2761.1 yield respectively after gonbad had the highest yield but showed little stability. Correlation coefficients showed positive and significant correlation between grain yield with number of total spike and weight of grains in spike. Therefore, planting of Gonbad cultivar of on January 1 is recommending in Gonbad Kavous region climate condition.