Influence of soil incorporating wheat residue rates on seed yield components and biological nitrogen fixation in two red bean cultivars in greenhouse

Crop residues as useful substances can change soil biologic، chemical and physical properties. In order to save wheat (Triticum aestivum L.) crop residues and incorporate them into the soil and their effects on biological nitrogen fixation (BNF) of two red bean cultivars (Phaseolus vulgaris L.)، an experiment was conducted as factorial experiment in randomized complete block design with three replications at two times in 2009 in greenhouse of College of Agriculture، Shiraz University، Shiraz، Iran (Bajgah). Factors were red bean cultivars (Sayyad and D81083) and wheat residue rates (0، 1530، 3060 and 4590 kg ha-1 wheat residue that became 0، 25، 50 and 75% wheat residue per hectare، respectively). At the beginning of experiment، soil test was carried out and the end of experiment، plant and soil N were measured. Results showed that Sayyad cultivar had higher pod weight، seed per pod، pod number، plant height، seed weight per plant and lower 100-seed weight than D81083. Soil incorporating wheat residue (25-50% with soil and then planting common bean) increased BNF and application of 75% of crop residues decreased BNF. D81083 cultivar had the highest BNF with 25% wheat residue; however it hadn’t difference to Sayyad cultivar and 50% wheat residue. Therefore it seems that at least 25% wheat crop residue is required to retain in soil to improve BNF in these red common bean cultivars.