【摘要】 钾缺乏(即低钾)是制约我国甘薯产量和品质的重要因素.采用营养液培养法,设置低钾(0mmol/L)和正常钾(20mmol/L)2个处理,研究了甘薯幼苗期(0~28d)低钾胁迫对叶片光合特性和根系特征的影响,旨在明确不同耐低钾能力品种对低钾胁迫的生物学和生理响应差异.结果表明:1)低钾胁迫处理28d后,钾敏感型品种宁紫薯1号的叶绿素含量显著降低59.8%,净光合速率(P_n)、气孔导度(G_s)和蒸腾速率(T_r)分别显著下降了59.7%,62.3%和66.0%;相比之下,耐低钾型品种徐薯32的叶绿素含量仅降低27.4%,P_n,G_s和T_r的下降率均明显低于宁紫薯1号.2)宁紫薯1号根系的总根长、总表面积、总体积和平均直径在低钾胁迫下均显著降低;徐薯32也有降低趋势,但除总根长外均未达显著差异水平.低钾胁迫下徐薯32的细根(0~0.5mm)比例显著增加10.1%,有利于提高其耐低钾能力.3)2个品种根系活力受低钾胁迫显著抑制,徐薯32的根系活力下降24.4%,远低于宁紫薯1号.宁紫薯1号根系丙二醛(MDA)含量显著增加,诱导了SOD、POD和CAT等抗氧化酶活性的显著提高,而徐薯32的MDA水平和抗氧化酶活性显著低于宁紫薯1号,保持了相对稳定的生理功能.研究表明,不同品种耐低钾能力的差异可能与其光合作用能力、根系的形态和功能有关.更多还原

【Abstract】 Potassium(K~+)deficiency is one key abiotic stress factor limiting the production and quality of sweetpotato in China.The research was carried out by using a hydroponic experiment at different K levels(LK:0mmol/L and control:20mmol/L)to study the effects of K~+deficiency on sweetpotato photosynthetic characteristics and root traits during early growth stage.The aim was to investigate the differences in biological and physiological responses of different sweetpotato cultivars to K~+deficiency.The main findings were as follows:1)after 28 days of K~+deficiency(LK)treatment,the chlorophyll content of Ningzishu 1(sensitive to K~+deficiency)significantly decreased about 59.8%;significant decreases also showed in the net photosynthetic rate(P_n),stomatal conductance(Gs)and transpiration rate(T_r)at 59.7%,62.3% and 66.0% respectively.The decreases of these parameters in Xushu 32(tolerance to K~+deficiency)were all lower than those of Ningzishu 1.2)The root length,surface area,volume,and average diameter of Ningzishu 1 were significantly decreased under LK treatment by comparison with Xushu 32,whose corresponding decreases of Xushu 32 were lower and not significant(except for root length).In addition,the fine roots(diameter,0~0.5 mm)proportion of Xushu 32 significantly increased about10.1% under LK condition,which indicates a higher potassium absorption ability.3)Root activity of these two sweetpotatoes was significantly inhibited by K~+deficiency,but that of Xushu 32 was only 24.4%,much lower than that of Ningzishu 1.The malondialdehyde(MDA)content in the root of Ningzishu 1was significantly increased under K~+deficiency,which induced the significant increases of superoxide dismutase(SOD),peroxidase(POD),and catalase(CAT)activities.However,those variations of Xushu 32 were significantly lower than those of Ningzishu1.These results indicate that the tolerance of different cultivars to K~+deficiency may mainly relate to their photosynthetic capacity,as well as the root morphology and physiological function.更多还原