Effects of fertilization and density on soluble sugar and protein and nitrate reductase of hybrid foxtail millet

【Objectives】 This paper investigated the effects of fertilization and density on nitrate reductase, and soluble protein, soluble sugar of Zhangzagu 5 to provide a theoretical basis for the high-yield and high-quality cultivation of foxtail millet.【Methods】 An experiment based on the quadratic general rotary unitized design was carried out to study effects of nitrogen, phosphate and potassium, plant spacing and row spacing on nitrate reductase, and soluble protein and sugar of foxtail millet. The experiment was done in 2011 and 2012. The quadratic general rotary unitized design included 5 factors, 5 levels of each factor, a total of 32 experimental treatment combinations in 2011. In 2012 the verification test was performed of optimal combination and zero level combination selected in 2011. SAS9.0 was used to analysis the correlation between various physiological indices. Interactions between factors and extreme values were studied through an iterative successive approximation method by Lingo software.【Results】 The results show that the levels of nitrogen and phosphate and row spacing have significant effects on soluble protein, soluble sugar and activity of nitrate reductase, and the level of potassium has also significant effect on soluble sugar. Soluble protein and sugar and activity of nitrate reductase have a similar trend from rising to declining with nitrogen and phosphate increasing and row spacing narrowing. The interaction between the potassium level and plant spacing has significant effect on soluble protein and activity of nitrate reductase of leaves. The interaction effects of the 5 factors on soluble sugar are not obvious.【Conclusions】 Comprehensive survey of three physiological indicators, the fertilization and cultivation pattern improve the levels of nitrate reductase, and soluble protein, soluble sugar, 187-198 kg/hm2 for nitrogen level, 90-97 kg/hm2 for P2O5, 55-59 kg/hm2 for K2O, 23-24 cm for row spacing, 9-10 cm for plant spacing. In order to enhance millet soluble protein content, soluble sugar content and nitrate reductase activity, the cultivation style of narrow row spacing and middle density combination and increase of nitrogen and phosphate fertilization should be adopted in the actual production. So the production and quality are increased.