不同耐盐品种棉花根系主要指标对盐分胁迫的响应

以盐敏感品种‘中棉所45’(CCRI45)、弱耐盐品种‘新陆早17号’(XLZ17)、中等耐盐品种‘新陆早13号’(XLZ13)和耐盐品种‘中棉所35’(CCRI35)为试验材料,利用根系分析系统研究盐分胁迫下棉花根系形态特征及其与棉株耐盐性的关系.结果表明:盐分胁迫显著降低棉花根和叶的干质量以及K^+/Na^+,其中耐盐品种CCRI35和中等耐盐品种XLZ13的根干质量、叶干质量以及根中K^+/Na^+分别比盐敏感品种CCRI45提高了69.3%~104.4%、24.8%~45.3%和25.0%~45.8%;盐分胁迫显著抑制棉花根系生长发育,其中CCRI 35和XLZ13的总根长、根系总表面积、根系总体积以及0~10 cm土层中直径为0~1.2 mm内的根长、根表面积和根体积均显著高于CCRI45,分别增加了15.2%~85.8%、12.0%~68.5%、31.7%~217.8%、27.2%~73.9%、39.6%~74.3%和99.0%~309.7%.主成分分析表明,比根长、浅层根长比例和细根比例受基因型差异的影响较为明显,是区分不同耐盐品种棉花根系形态差异的主要指标.逐步回归分析显示,比根长、0~10 cm土层的粗根根长、细根根表面积、粗根根表面积、粗根体积、中根比例,以及10~20 cm粗根根长、粗根表面积、粗根体积等根系参数对盐分响应敏感.耐盐棉花品种可通过维持表层根长比例、细根比例和比根长的增加来适应盐分胁迫.

Responses of main characters of root system to salt stress among cotton varieties with diffe-rent salt tolerance.

A pot experiment was carried out to test the effects of salt levels on root morphology as well as the relationship between root morphology and salt tolerance with four cotton cultivars (salt-sensitive cultivar CCRI45, weak salt-resistance cultivar XLZ17, moderate salt-resistance cultivar XLZ13 and salt-resistance cultivar CCRI35). Results showed that dry mass and K⁺/Na⁺ ratio of cotton root and leaf were significantly reduced by salt stress. Dry mass of root and leaf and K⁺/Na⁺ ratio of root of cultivars XLZ13 and CCRI35 were 69.3%-104.4%, 24.8%-45.3% and 25.0%-45.8% higher than those of cultivar CCRI45, respectively. Root development was significantly restrained by salt stress. Total root length, total root surface area and total root volume of cultivars XLZ13 and CCRI35 were 15.2%-85.8%, 12.0%-68.5% and 31.7%-217.8% higher than those of cultivar CCRI45, respectively. Furthermore, the length of fine and middle roots, root surface area and root volume of cultivars XLZ13 and CCRI35 in 0-10 cm soil layer were 27.2%-73.9%, 39.6%-74.3% and 99.0%-309.7% higher than those of cultivar CCRI45, respectively. Results from principal component analysis showed that the variations of specific root length, root length ratio at 0-10 cm soil layer and fine root length ratio at 0-10 cm soil layer among cultivars was significant. Specific root length, root length ratio at 0-10 cm soil layer and fine root length ratio at 0-10 cm soil layer were the main root characters to distinguish different salt tolerant cotton cultivars. Results from the stepwise regression analysis showed that specific root length, coarse root length, coarse root area, and coarse root volume at 0-10 cm and 10-20 cm soil layers, as well as fine root area and middle root ratio at 0-10 cm soil layer were sensitive to salt. Salt tolerant cultivar adapted to salt stress through increasing root length ratio, fine length ratio, and specific root length.