氮素对菠菜衰老生理指标的影响

田间小区试验研究了氮素与菠菜衰老的关系。结果表明,菠菜生长前期,植株根系活力增强,叶片叶绿素含量、光合速率及SOD、POD、CAT等保护酶活性升高,但生长后期均持续降低;而叶片电解质渗漏及丙二醛(MDA)含量在全生育期内则持续增加。在施氮量低于600.kg/hm2条件下,增施氮素可显著降低菠菜叶片的电解质渗透率及MDA含量,增强SOD、POD和CAT等保护酶活性及根系活力,提高叶绿素含量及光合速率,延缓菠菜衰老,进而提高菠菜产量。菠菜收获时,氮素用量600.kg/hm2处理的叶片电解质渗透率和MDA含量分别比对照(不施氮)降低50.9%、67.2%,SOD、POD和CAT活性及根系活力分别高59.2%、478.4%、290.9%和131.3%;叶绿素含量及光合速率分别高59.6%、131.3%,增产率达88.0%。施氮量达900.kg/hm2时则发生负效应,虽然产量比对照增产75.3%,但比600.kg/hm2施氮量减产6.7%。

Effect of nitrogen nutrition on physiological index of spinach senescence

A field pilot study was carried out to study the effects of nitrogen nutrition on spinach senescence.The results showed that the root vigor,chlorophyll content,photosynthetic rate and superoxide dismutase(SOD),peroxidase(POD),catalase(CAT) activities increased at the early growth period of spinach,but decreased stably later;the electrolyte leakage and malondiadehyde(MDA) content continually increased within the whole growth period.However,when nitrogen applied rate was less than 600 kg/ha,nitrogen fertilization significantly reduced the electrolytic leakage and MDA content,enhanced SOD,POD,CAT and chlorophyll content and photosynthetic rate of spinach leaves,promoted root vigor and delayed the senescence,furthermore,increased the yield of spinach.At the time of spinach harvest,the electrolytic leakage and MDA contents of the treatment,which applied 600 kg/ha nitrogen,were 50.9% and 67.2% lower than that of CK(without N),respectively.Nevertheless,the SOD,POD,CAT and root vigor were 59.2%,478.4%,290.9% and 131.3% higher than that of CK,the photosynthetic rate and chlorophyll content also increased by 59.6%,131.3%,and the yield increased by 88.0%.Applying nitrogen 900 kg/ha resulted in a negative effect.Although it increased the yield by 75.3% compared to CK,it decreased yield by 6.7% compared to the treatment with applying nitrogen 600 kg/ha.