低温胁迫对玉米苗期根系特征及电导率的影响

Effects of low-temperature stress on root system characteristics and electric conductivity of maize seedlings

苗期低温是限制黑龙江省玉米高产稳产主要因素之一。为了探讨苗期低温对玉米幼苗根系的影响,选取耐低温型(郑单958)、中间型(先玉335)、低温敏感型(丰禾1)3个品种,分别设置昼/夜温度为20℃/11℃(CK)、18℃/9℃、16℃/7℃和14℃/5℃温度处理,处理时间为2、4、6、8、10 d,处理后分析根系特征及其电导率的变化。结果表明:随温度胁迫程度加强,各品种的根系干重(RDW)、根长(RL)、根表面积(SA)、根长密度(RLD)、根重密度(DRWD)增长率均降低,电导率均升高,5℃时根系几乎停止生长;低温对根系的抑制作用表现为丰禾1>先玉335>郑单958,低温下根系细胞膜的透性表现为丰禾1>先玉335>郑单958;低温抑制根系生长,增加根系细胞膜的透性;耐冷性品种表现出较好的根系生长状态、较稳定的根系质膜系统和较低的渗透率。

Low temperature during the seedling period is one of the main limiting factors for high and stable yield of maize in Heilongjiang Province. To address the effect of low temperature on the growth of seedling root, three maize cultivars Zhengdan 958 （ cold resistance type）, Xianyu 335 （middle type）, and Fenghe 1 （sensitivity type） were investigated at diurnal temperature of 20 ℃/ll ℃ （CK）, 18 ℃/9 ℃, 16 ℃/7 ℃, 14 ℃/5 ℃ for 2, 4, 6, 8, 10 days. The root characteristics and root electric conductivity after low temperature treatment were studied. The results showed that with increasing the temperature stress, the growth rates of root dry weight, length, surface area, and dry weight density decreased, the electric conductivity increased, and the roots almost stopped growing at 5 ℃. The inhibitory effects of low temperature on the growth and cell membrane permeability of roots of the three cuhivars were in order of Fenghe 1 〉 Xianyu 335 〉 Zhengdan 958. The results indicated that low temperature could inhibit the growth of roots, while increase the cell membrane permeability of roots. Cold resistance cultivars showed better root growth, more stable root plasma membrane system with a lower permeability.