Effects of supplemental irrigation and nitrogen fertilization on yield and qualitative characteristics of wheat in Mazandaran

Many farmers plant rainfed wheat in Mazandaran province that produces lower yield than irrigated wheat. Therefore, in this study, effects of supplemental irrigation in sensitive growth stages accompanied with the split application of nitrogen on yield and qualitative characteristics of wheat (Morvarid veriety) was studied in Pahnab station (Sari). This study was carried out as Complete Random Blocks Plot in split plot with four replications in 2015, 2017 and 2018. The main treatments included A1= irrigation on flowering, A2= irrigation on grain filling, A3= irrigation on flowering and grain filling and A4= rainfed (control treatment). The minor treatments included B1= 200 kg/ha urea application and in four splits (25% before planting, 25% at tillering, 25% at stem extension and 25% at booting) and B= 250 kg/ha urea application and in five splits (25% before planting, 25% at tillering, 25% at stem extension, 25% at booting and 25% at flowering). The considered characteristics were protein percentage, 1000-grain weight, the number of spikelet in spike, infertile spikelet and spike length. Analysis was conducted by SPSS and showed that in every three years, irrigation was effective on 1000-grain weight, protein percentage and infertile spikelet in significance level of 0.05 and the best treatment was A3 that resulted 25% increase in protein, 8.5% increase in 1000-grain weight and 22% decrease in infertile spikelet. For one irrigation, the best treatment was irrigation in grain filling for improving 1000-grain weight, protein percentage and infertile spikelet. For spike length and number of spikelet in spike, results showed that supplemental irrigation and fertilizing had no significant effects. For fertilizing, urea application on flowering had significant effect on 1000-grain weight in every 3 years and on the number of spikelet in spike in 2 years in significance level of 0.05; however, had no significant effects on others characteristics. In addition, there was a significant effect of the interaction between irrigation and fertilization in 2 years on protein percentage. Based on results, the best irrigation treatment is (A3) irrigation on flowering and grain filling and the best fertilization treatment is 250 kg/ha urea application in 5 splits.