Effect of nitrogen on photosynthetic pigments of relay strip intercropping soybean under drought stress

A pot experiment was designed under drought stress condition to study the effect of different nitrogen levels on photosynthetic pigments in the leaves of relay strip intercropping soybean.The Chla, Chlb, were measured, Chl content, Chla/b was calculated.The result showed that effects of nitrogen and drought stress on Chla were not as big as that of Chlb.When severe drought happened, Chla content reduced significantly, mild and moderate drought stress did not decrease Chla content significantly.With N supply, mild and moderate drought enhanced Chlb content and Chl content, but Chlb content and Chl content decreased significantly when drought happened without N supply.Appropriate N supply is recommended to improve photosynthetic pigments efficiency under drought stress. Materials and MethodsMaterials.Soybean cultivar Gongxuan No.1, a major component of southwestern soybean cultivars, was tested in the experiments. Experimental Design.The experiment was conducted in a relay strip intercropping system at the farm of Sichuan Agricultural University.Soybean seeds were sown in the pots.Urea was dissolved in water for base fertilizer, and the tray in the pelvic floor was used to avoid the leaching of nitrogen after the rain.Only three plants were allowed to grow per pot.Each treatment was conducted with three replicates, and each replicate had 6 pots.Four nitrogen treatments were used 0 g N pot -1 , 0.35