氮素营养水平对黄瓜氮代谢关键酶活性变化及氮化物的影响

探讨黄瓜叶片氮代谢关键酶类活性与果实氮化物含量的相互关系,为黄瓜氮素的高效利用和品质优化提供依据。采用二因素裂区设计,研究了氮肥用量对黄瓜叶片氮代谢酶活性和结果盛期果实氮化物含量的影响。结果表明:在225~375 kg/hm~2施氮情况下,随施氮量增加功能叶片硝酸还原酶(NR)、谷氨酰胺合成酶(GS)、谷氨酸草酰乙酸转氨酶(GOT)和谷氨酸丙酮酸转氨酶(GPT)的活性逐渐升高,处理间差异显著,施氮量超过375 kg/hm~2其酶活性增加不明显且有下降的趋势。不同品种间酶活性大小依次为津优35号、园丰元6号、永昌9618,博特202,其中津优35号与园丰元6号酶活性差异不显著,与永昌9618和博特202差异显著。果实中氮化物的含量随施氮量的增加逐渐提高;施氮量为375 kg/hm~2时游离氨基酸、可溶性蛋白及粗蛋白含量达到最大值;增加到450 kg/hm~2时3种氮化物含量均下降,而硝酸盐含量持续增加;在525 kg/hm~2时含量最高,津优35号硝酸盐和游离氨基酸含量最低,可溶性蛋白和粗蛋白含量最高,博特202与之相反。相关分析表明,果实中硝酸盐含量与NR和GS活性呈显著正相关关系,与GPT和GOT无显著相关关系;可溶性蛋白和粗蛋白含量与4种酶类存在显著或极显著正相关关系。不同品种间果实氮化物的差异是氮素吸收同化综合作用的结果。选择氮素吸收同化能力强的品种,既有利于提高氮素利用,又可改善产品质量。

Effects of Nitrogen Nutrition on Change of Key Enzyme Activity during Nitrogen Metabolism and Nitrogenous Compounds in Cucumber

The relationship between leaf enzyme activity of nitrogen metabolism and fruit nitrogenous compounds was studied to provide evidence for nitrogen efficient utilization of cucumber and optimization of product quality.Four North China cucumber cultivars with yield difference were used to study the effects of nitrogen fertilizer treatment on characters of leaf enzyme activity of nitrogen metabolism and fruit nitrogenous compound content in full fruit period by the split plot design for two factors.The experimental results show that leaf NR,GS,GOT and GPT activities were increased with nitrogen application from 225～ 375 kg/hm2 and the differences among treatments were significant.When application of pure nitrogen was over 375 kg/hm2,activities were not significantly increased and showed a dropping trend.The order of enzyme activity of different cultivars was Jinyou 35＞Yuanfengyuan 6＞Yongchang 9618＞Bote 202.Jinyou 35 enzyme activity was not significantly different from that of Yuanfengyuan6,but the difference was significant compared with Yongchang 9618 and Bote 202.Fruit nitrogenous compound content was increased with nitrogen application.Amino acid,soluble protein and crude protein content were the highest in 375 kg/hm2,and they will drop in 450 kg/hm2.However,nitrate content increased continuously,and with 525 kg/hm2 it was the highest.Nitrate and amino acid had the lowest content and soluble protein and crude protein had the highest content,and Bote 202 was the opposite.The correlation analysis showed that fruit nitrate content was positively correlated with leaf NR and GS activities,but it was not significantly correlated with GPT and GOT;soluble protein and crude protein content was significantly or very significantly positively correlated with the four enzymes.The differences of nitrogenous compound content among different cultivars resulted from synthetic action of absorption and assimilation.The use of cultivars with stronger ability to absorb and assimilate could not only improve nitrogen efficiency,but optimize quality.