Evaluation of Nutrient Rresource and Crop Diversity Interaction on Radiation Use Efficiency in Different Cropping Systems

A growing interest to use multiple cropping was due to potential of these planting patterns for increasing yield by improved resource use efficiency such as radiation use efficiency (RUE). In order to investigate the effects of plant diversity and nutrient resource on radiation use efficiency, an experiment was conducted as split plot based on complete randomized block design with three replications at the Agricultural Research Station, Ferdowsi University of Mashhad, Iran, during 2006 and 2007. Treatments included manure and chemical fertilizers as main plots and intercropping of 3 soybean varieties (Wiliams, Sahar and Gorgan3), intercropping of 3 Millet species (common millet, foxtail millet and pearl millet), intercropping of millet, soybean, sesame (Sesamum indicum) and intercropping of millet, sesame, fenugreek (Trigonella foenum-graecum), ajowan (Trachyspermum ammi) as sub plots. Results indicated that in the manure and chemical fertilizer treatments, LAI of plants in intercropping decreased compared to monoculture. The effect of planting pattern on RUE was significant. In monocultures, common millet and soybean (Wiliams and Gorgan3 varieties) had highest RUE based on photosynthetic active radiation (PAR). The lowest RUE was obtained in sesame and foxtail millet monocultures. In the intercropping systems, when functional diversity increased, radiation use efficiency was increased, so that maximum of RUE (3.31 g.MJ-1) was obtained in 4 species intercropping (common millet, sesame, fenugreek and ajowan). Minimum of RUE (1.96 g.MJ-1) was observed in intercropping of 3 millet species. The interaction of planting pattern and nutrient resource on RUE was significant. In general, the highest RUE was observed in 4 species intercropping (common millet, sesame, fenugreek and ajowan) with manure treatment.