亚高寒草甸植物叶片生理指标对坡向的响应

研究了甘南亚高寒草甸不同坡向条件下矮嵩草、狼毒和棘豆叶片的叶绿素、游离脯氨酸和可溶性糖含量,以及稳定碳同位素(δ¹³C)的变化,分析干旱胁迫条件下,植物适应干旱胁迫的生理机制.结果表明: 随着坡向由北坡-西北坡-西坡-西南坡到南坡的变化,土壤含水量(北坡0.36 g·g^-1,南坡0.15 g·g^-1)呈降低趋势,土壤温度(北坡14.76 ℃,南坡24.85 ℃)和光照度(北坡540.34 lx,南坡744.12 lx)呈增加趋势;植物物种的组成也随之发生了变化,北坡主要有灌木金露梅及杂类草,而南坡主要有禾草类物种.3种植物叶片的脯氨酸、可溶性糖、叶绿素含量及稳定碳同位素(δ¹³C)随着坡向的变化均有不同程度的变化,且物种不同,各物种的生理指标变化幅度也有差异.在坡向梯度上,3种植物的脯氨酸、可溶性糖含量和稳定碳同位素与土壤含水量均呈显著负相关,与温度和光照强度呈显著正相关;植物叶片叶绿素与土壤含水量呈显著正相关,与温度和光照强度呈显著负相关.其中,土壤含水量是坡向梯度上影响植物生长的关键因子.植物叶片生理指标(脯氨酸、可溶性糖及叶绿素等)可以作为衡量植物抗逆性的因素,3种植物的抗性大小顺序为:矮嵩草>狼毒>棘豆.

Responses of physiological parameters in plants on sub-alpine meadow to slope aspects.

Variations of chlorophyll, free proline, soluble sugar content and stable carbon isotope composition (δ¹³C) of Kobresia humilis, Stelleracha maejasme and Oxytropis ochrocephala were studied on different slope aspects of sub-alpine meadow in Gannan, and the physiological mechanism of plant adaptation to drought stress was discussed as well. The results showed that soil water content (north slope 0.36 g·g^-1, south slope 0.15 g·g^-1) decreased, and soil temperature (north slope 14.76 ℃, south slope 24.85 ℃), light intensity (north slope 540.34 lx, south slope 744.12 lx) increased from north, west north slope, west slope, west south slope and south slope. Plant species composition also changed accordingly. Main species were shrub (Potentilla fruticosa) and forbs on north slope, and grass on south slope. The contents of proline, soluble sugar, chlorophyll and stable carbon isotope of three plant species changed from north to south slope, and the amplitude of variation of physiological parameters also differed among species. The contents of proline, soluble sugar and stable carbon isotope showed a significant negative correlation with soil water content, and correlated significantly positively with soil temperature and light intensity. The chlorophyll content was correlated significantly positively with soil water content, and significantly negatively with soil temperature and light intensity, and soil water content was the key factor influencing plant survival growth at aspect gradient. The results showed that the physiological parameters of plant leaf could be used as an index of plant stress resistance, and the resistance of 3 species was in order of Kobresia humilis > Stellera chamaejasme > Oxytropis ochrocephala.