Evaluation of the Direct Planting Method for Different Seed Rates of Wheat under Different Height of Rice Residues in Khuzestan Province

In some parts of Iran, wheat will be grown up upon harvesting of previous crop, rice.  Leaving over paddy stems, as plant residues, could be a good solution due to limitation of time between harvesting of rice and preparing the land for sowing wheat. On the other hand, the presence of rice residues can affect the performance of the direct planter and consequently on the yield of wheat. This study was conducted in Khuzestan province, Iran, for two years (2015-2017) to investigate the effects of height of standing rice residues, stubble height, on grain yield of wheat when direct planting machine, Gaspardo machine, was used to sow the seeds. The experiment of this project was based on split plot with randomized complete blocks design with two factors and three replications. The main factor was the rice stubble height at three levels: 25, 35 and 45 cm, and the sub factors were the wheat seed rates at three levels: 160, 180 and 200 kg.ha-1.Analysis of variance in two years showed that stubble height and seed rates had significant effects on grain yield but interaction of them had no significant effect in this index. In addition to grain yield, stubble height caused significant effects on biological yield, seedlings per m2of land, and the number of grains per spike.  Based on average of two years grain yield, it has been found that among stubble height, 25 cm with 4634 kg.ha-1and 45 cm with 3894 kg.ha-1had the highest and lowest value, respectively. From the point of biological yield, the highest (10524 kg.ha-1) and lowest (8894 kg.ha-1) value were found when the height of stubbles were 25 cm and 45 cm, respectively.