增施氮素对甘薯叶片光合作用和CO_2的响应

Response of sweet potato leaves to light intensity and CO_2 concentration under increased N-fertilizer level

甘薯因具高产稳产、抗旱耐瘠的特点而适合在新开垦山地中推广。为明确其合理的氮肥用量,本试验选用3个甘薯品种,研究低浓度(124 mg·kg-1)和高浓度(180 mg·kg-1)2个施肥量对叶片光合生理特性的影响。结果表明,在两种浓度下不同品种甘薯叶片的比叶面积无显著差异;叶绿素b含量、叶绿素(a+b),以及叶片氮含量则均以高浓度处理下较高(P<0.05);光响应曲线参数中的初始量子效率(α)、最大光合速率(Pnmax)、饱和光强(PARsat)、光补偿点(Ic)及暗呼吸速率(Rn)等整体上均无显著差异(P>0.05);CO2响应曲线中的最大羧化速率(Amax)和CO2补偿点(Γ)无显著变化(P>0.05),高浓度处理的初始羧化效率显著高于低浓度处理(P<0.05),高浓度处理饱和胞间CO2浓度则明显降低(P<0.05)。综上所述,甘薯种植过程中建议适当减少氮肥的施用量。

Due to the relatively high and stable yield,and high tolerance to drought,sweet potato is suitable to be cultivated in the newly reclaimed mountain land. In order to determine the suitable application amount of N-fertilizer,three sweet potato cultivars and two N-fertilizer application levels were used to study the influence on photosynthetic characteristics of sweet potato leaves. The results showed that the difference of specific leaf weight was not significant between two N-fertilizer levels. The contents of chlorophyll b,chlorophyll（a ＋ b） and leaf nitrogen were dramatically increased under high N level. The related parameters of light response curve,such as the initial quantum efficiency（α）,maximum photosynthetic rate（Pnmax）,saturation light intensity（PARsat）,light compensation point（Ic） and dark respiration rate（Rn） showed no significant differences（P〉0.05） in general. And,the relevant parameter curve in response to CO2,namely,the maximum rate of carboxylation（Amax） and CO2 compensation point（Γ）,also showed no significant changes（P〉0. 05）. But,the initial carboxylation efficiency and saturation intercellular CO2 concentration varied significantly（P〈0. 05）. In general,photosynthetic characteristics of sweet potato leaves were not significantly influenced by N application level. Thus,N-fertilizer amount was suggested to be appropriately reduced for sweet potato production.