| In order to explore the rule of relay cropping potatoes’ growth, photosynthetic physiological characteristics, chlorophyⅡ fluorescence parameters, yield and quality, to get the high yield, good quality and high efficient of the optimum nitrogen in the soil, this experiment studied the potatoes’ growth, photosynthetic physiological characteristics, chlorophyll fluorescence parameters, yield and quality by different total nitrogen in the soil through soil testing and balancing P and K at randomised design. Main conclusions are as follows:(1)Influence on LAI and concent of chlorophyⅡ of potatoes’ leavesThe LAI, in the growth period, showed the changing trend of rise at first and fall later. Within a certain range, the LAI of potato increased by improving total nitrogen in the soil.The LAI of relay cropping reduced in the starch accumulation stage, but maintained high level in the mature stage compared with solo cropping. The concent of chlorophyⅡin the tuber expanding stage was higher than the starch accumulation stage. The concent of chlorophyⅡof relay cropping increased significantly compared with solo cropping in the starch accumulation stage and had high level under the nitrogen of 13.5 kg / 667 m2 in the soil as well as solo cropping.(2)Influence on photosynthetic physiological characteristics, chlorophyⅡ fluorescence parameters of potatoOn the one hand, the Pn, Gs, Tr, Fv/Fm, q P, q N, Ru BP carboxylase activity and SPS activity of relay cropping potatoes’ leaves reduced significantly in the starch accumulation stage, on the other hand, the Ci, ΦPSⅡ and ETR improved significantly in the same stage. The Pn, Gs, Tr, Fv/Fm, ΦPSⅡ, ETR, Ru BP carboxylase activity and SPS activity under the total nitrogen treatments of 11.5 kg / 667 m2 and 13.5 kg / 667 m2 were higher than others, but the Ci, q P and q N were lower.(3)Influence on yield, dry matter accumulation in tuber and marketable tuber percentage of potatoPotatoes’ yield, tuberes’ dry matter accumulation and marketable tuber percentage of relay cropping reduced significantly as a whole.Within the scope of the treatments, with the improvement of total nitrogen in the soil, potatoes’ yield, tuberes’ dry matter accumulation and marketable tuber percentage of relay cropping showed the changing trend of rise at first and fall later as well as solo cropping. There were no significant difference between the total nitrogen treatments of 13.5 kg / 667 m2 and 11.5 kg / 667 m2 about potatoes’ yield, tuberes’ dry matter accumulation and marketable tuber percentage of relay cropping and solo cropping as well as composite production of relay cropping. Considering, the total nitrogen treatment of 11.5 kg / 667 m2 was the best of all. The potatoes’ yield, tuberes’ dry matter accumulation marketable tuber percentage and composite production under the best treatment of relay cropping was 25666 kg/hm2, 54.42 g/strain, 81.81%, 10921 kg/hm2, and 27167 kg/hm2, 60.55 g/strain, 81.45% of solo cropping.(4)Influence on quality of potatoNot only the content of vitamin C increased significantly but also the content of starch reduced significantly of relay cropping potatoes’ tuber, however the content of soluble protein had no obvious difference between relay cropping and solo croppping. With the improvement of total nitrogen in the soil, the content of soluble protein were characterized by increased trend and had highest value at17.5 kg / 667 m2, the content of vitamin C showed a rising trend, but not significantly and the content of starch were highest at 11.42% of relay cropping and 12.02% of solo cropping in the total nitrogen treatment of 11.5 kg / 667 m2 and then turned down with more nitrogen used.(5)Influence on nitrogen use efficientcyThe nitrogen harvest index and partial factor productivity of relay cropping reduced significantly, moreover the nitrogen accumulated in plant improved.Within the scope of the treatments, with the improvement of total nitrogen in the soil, the nitrogen accumulated in plant showed a rising trend, and were highest at 3.29g/strain of relay cropping and 3.25g/strain of solo cropping in the total nitrogen treatment of 17.5 kg / 667 m2. The nitrogen harvest index and nitrogen partial factor productivity showed the increased at first and then decreasesd. The nitrogen harvest index were highest at 0.65 of relay cropping under the total nitrogen treantment of 11.5 kg / 667 m2 and 0.70 of solo cropping under the total nitrogen treantment of 13.5 kg / 667 m2. The nitrogen partial factor productivity were highest at 148.79kg/kg of relay cropping and 157.49 kg/kg of solo cropping under the total nitrogen treantment of 11.5 kg / 667 m2. |
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