بررسي كشت لگوم ها به عنوان محصول جايگزين آيش در گندم زارهاي ديم شمال خراسان

Effects of legumes as alternative crops for fallow period in wheat-based cropping systems of Northern Khorasan

In order to evaluate the beneficial effects of legumes instead of fallow in traditional cropping systems of northern Khorasan an experiment was conducted from 1999-2002 at two research stations in Northern Khorasan (Natural Resources Research Station of North Khorasan, Sisab-Bojnord and dryland Research Station of North Khorasan, Borzolabad-Shirvan). Six cropping systems, fallow-wheat; wheat wheat; chickpea-wheat; lentil-wheat; vicia-wheat and annual medic-wheat, were used with three replications per treatment in both locations. Soil water were measured on the 0-30 cm top soil layer in Shirvan; and top 60 cm soil layer in Bojnord. Yield and yield components of crops were measured by the end of each season. In 1999-2000 growing season all crops died due to severe drought Results from 2000-2001 trials showed that in both locations food legumes (chickpea and lentil) were not produce any seed. Food legumes biomass were higher than feed legumes (medic and vicia) in Bojnord but in Shirvan biomass of lentil and vicia were higher than chickpea and medic. Wheat biomass was higher than biomass of all legumes in both locations. In 2001-2002 yield and yield components of wheat were not affected by the yield of previous legumes but effect of location on some growth indices and yield components of wheat was significant (p< 0.01). In Bojnord some vegetative components (e.g. no. of tiller per plant and vegetative dry matter) and in Shirvan some reproductive components (e.g. no of seeds per spike, and 100 seed weight) were higher than Sisab and led to a higher yield in Shirvan (about 210 kg 1 ha more than Bojnord). According to high variation of rainfall and its distribution in dryland systems of Iran, short term evaluation of the role of legumes on yield stability of wheat isnʹt suitable. It seems that to achieve a better and valid results, it is nessecery to repeat the experiments during several rotation cycles.