Uptake capacity of ammonium and nitrate to several crops
TIAN Xiao hong,LI Sheng xiu,WANG Zhao hui (Department of Resource and Enviromental Sciences,Northwestern Agricultural University,Yangling,Shaanxi 712100,China)
The solution culture experiment was conducted in order to investigate the relatively uptake capacity of lettuce,rape,soybean and wheat to nitrate and ammonium,as well as the influence of 3 different nitrogen sources on growth and development of these four crops.The obtained results showed that:(1) When the distilled water was supplied as the growth medium in the nutrient solution,different nitrogen sources greatly affected on the growth and development of lettuce,rape,soybean and wheat.When nitrate was solely supplied,all of these crops growed very well;when the same amount of nitrate and ammonium was supplied as nitrogen source,to some extent the growth amount of lettuce decreased;While ammonium was solely supplied,the growth amounts of these crops decreased greatly except rape,lettuce and soybean were very sensitive to NH + 4-N,and withering took place at late growing stage.(2) During the water culture,the total nitrogen uptake amount of the tested crops had close relation to the nitrogen source.To lettuce,the nitrogen uptake amount as nitrate supplied was significantly higher than that when the same amount of nitrate and ammonium was supplied,if comparing the same amount of NO - 3+NH + 4 treatment with solely supplying nitrate nitrogen treatment,and the nitrogen uptake amounts of lettuce and wheat were almost same;While supplying the same amount of NO - 3+NH + 4,the nitrogen uptake amount of soybean and rape was the largest,when solely supplying nitrate it greatly decreased.When ammounium was supplied,except rape the nitrogen uptake amount of other crops was the lowerest.(3) The tested crops had apparent preference on the uptake of nitrate and ammonium.When the same amount of ammonium and nitrate was supplied,the uptaked nitrate by rape and wheat was larger than ammonium,but the lettuce was vice verse,and the absorped nitroten of two forms by soybean were almost the same.The preference had characteristics of stage,generally speaking,the crop which prefer to nitrate maybe show property of favours ammonium.