Fan F, Zhang Q G, Zhang Y L, et al . Fertilization effects on alfalfa nodule. Bulletin of Agricultural Science and Technology, 2006, (7): 96-98.
[2]
Yan J, Han X Z, Wang S Y, et al . Effect of different forms nitrogen on nodule growth and nitrogen fixation in Soybean. Soybean Science, 2009, 28(4): 674-677.
[3]
Liu X J, Liu Y N. Effects of different N levels on productivity and quality of alfalfa varieties. Acta Agrestia Sinica, 2013, 7(4): 702-707.
[4]
Liu X J, Kuai J L, Li W Q, et al . Effects of NH 4 + -N and NO 3 - -N on root growth, nodulation and nitrogen-fixation of alfalfa. Journal of Gansu Agricultural University, 2011, 46(5): 106-110.
[5]
Heidi T, Heuberger J, Kling G, et al . Contribution of N uptake and morphological root characteristics to N efficiency in tropical maize cultivars. Crop Production, 2002, 29: 958-963.
[6]
Xu G W, Li S, Zhao Y F, et al . Effects of straw returning and nitrogen fertilizer application on root secretion and nitrogen utilization of rice. Acta Prataculturae Sinica, 2014, 23(2): 140-146.
[7]
Chen P, Feng K, Wang X L, et al . Effects of pH on uptake of different forms of nitrogen by young core. Journal of Yangzhou University (Agricultural and Life Sciences Edition), 2003, 24(3): 46-50.
[8]
Yang X E, Sun X. Different varieties of NH 4 + -N and NO 3 - -N absorption kinetics. Chinese Journal of Soil Science, 1991, 22(5): 222-224.
[9]
Qiao Y F, Miao S J, Han X Z. Effects of nitrogen forms on the root morphology and proton extrusion in soybean. Soybean Science, 2006, (3): 265-269.
[10]
Sun M, Guo W S, Sun T F, et al . Effects of nitrogen forms on root characteristics in wheat. Journal of Yangzhou University (Agricultural and Life Sciences Edition), 2007, 28(1): 54-57.
[11]
Song H X, Shen S L, Ma S Y, et al . Effects of NH 4 + -N and NO 3 - -N on the nitrogen fixation of soybean nodules. Soybean Science, 1997, 16(4): 283-286.
[12]
Gan Y B, Tu X W, Tian R J. Study on optimum timing of nitrogen application on soybean. Soybean Science, 1998, 17(4): 287-291.
[13]
He J G, Yan H, Jia J C, et al . Effect of nitrogen management on growth and yield of soybean. Soybean Bulletin, 1990, (10): 11-15.
[14]
Zhang Q, Zhang L, Wei S Q, et al . Effects of Ca 2+ on acid tolerance of Medicago sativa and Rhizobium meliloti . Chinese Journal of Applied Ecology, 2007, 18(6): 1231-1236.
[15]
Sun J G, Zhang Y C, Xu J, et al . Isolation and biological characteristic investigation on efficient nitrogen-fixing bacilli. Scientia Agricultura Sinica, 2009, 42(6): 2043-2051.
[16]
Wang F, Liu B, Zhu J W. Effect of magnesium (Mg) on root activity, chlorophyll content and permeability of soybean. Journal of Agro-Environment Science, 2004, 23(2): 235-259.
[17]
Yao T, Zhang D G, Hu Z Z. Associative nitrogen-fixing bacteria in the rhizosphere of Avena sativa in an alpine region I Isolation an identification. Acta Prataculturae Sinica, 2004, 13(2): 106-111.
[18]
Nan L L, Shi S L, Zhang J H. Study on root system development ability of different root-type alfalfa. Acta Prataculturae Sinica, 2014, 23(2): 117-124.
[19]
Zhang C M, Xu Y H, Zhao H J. Effects of different nitrogen forms on nitrogen uptake and root growth of rice at the seedling stage. Journal of Nanjing Agricultural University, 2011, 34(3): 72-76.
[20]
Saravitz C H, Chaillou S, Mussel J, et al . Influence of nitrate on uptake of ammonium by niteogen-depleted soybean: is the dffect located in roots or shoot. Journal of Experimental Botany, 1994, 280(45): 1575-1584.
[21]
Liu Y N, Liu X J, Zhang X L, et al . Effect of clipping and fertilization on production performance of different alfalfa varieties. Grassland and Turf, 2013, 33(3): 69-73.
[22]
Wang S Q, Han X Z, Qiao Y F. Root morphology and nitrogen accumulation in soybean ( Glycine max L.) under different nitrogen application levels. Chinese Journal of Eco-Agriculture, 2009, 17(6): 1069-1073.
[23]
Wang D Y, Wang Z Q. Effect of planting date, plant density and nitrogen application rate on yield and quality of vegetable soybean. Journal of Zhejiang University (Agricultural and Life Sciences Edition), 2001, 27(1): 69-72.
[24]
Dong S K, Liu L J, Sun C Z, et al . Effects of nitrogen levels on nodule growth of soybean using 15 N tracing method. Plant Nutrition and Fertilizer Science, 2011, 17(4): 985-988.
[25]
Li B Z, Xin W J, Sun S B, et al . Physiological and molecular responses of nitrogen starved rice plants to re-supply of different nitrogen sources. Plant and Soil, 2006, 287(1-2): 145-159.
[26]
Jia Y B, Yang X E, Liu J X. Morphological and physiological adaptation of plant root to nutrient defficit and elemental toxicity stress. Chinese Journal of Soil Science, 2005, 36(4): 610-616.
Peng L Q, Li X Y, Qi X, et al . The relationship of root traits with persistence and biomass in 10 alfalfa varieties. Acta Prataculturae Sinica, 2014, 23(2): 147-153.
[49]
Kuai J L, Liu X J, Li W Q. Effects of different nitrogen levels on the growth characteristics of alfalfa inoculated with rhizobium. Grassland and Turf, 2010, 31(3): 56-59.
[50]
Linkohr B I, Williamson L C, Fitter A H, et al . Nitrate and phosphate availability and distribution have different effects on root system architecture of Arabidopsis . The Plant Journal, 2002, 29(6): 751-760.