干旱胁迫对甘蔗4个生理指标遗传变异的影响

【目的】研究干旱胁迫对气孔导度(Gs)、PSⅡ原初光能转化效率(Fv/Fm)、叶片伸长速率(leaf elongation,LE)和叶片相对含水量(relative water content,RWC)4个甘蔗生理指标遗传变异的影响,为其在甘蔗育种程序早期阶段的应用提供参考。【方法】采用裂区设计,以自然干旱和人工灌溉为主区,不同甘蔗基因型为副区,在云南省红河州开远市和玉溪市元江县2个试验点先后对22个和18个甘蔗基因型同时开展田间试验,主要在2个生长季甘蔗拔节前期先后13次、18次、15次和10次分别对4个生理指标Gs、Fv/Fm、LE、RWC进行测量。采用软件GenStat计算各指标各次测量的遗传方差分量(σ_g~2)和环境方差分量(σ_e~2),并计算广义遗传力(h_b~2),采用SAS9.1对每次测量干旱和灌溉处理下获得遗传方法分量和广义遗传力进行成对t测验。【结果】四项生理指标受干旱影响极显著,13次Gs、18次Fv/Fm、15次LE和10次RWC处理间差异均为极显著。在干旱和灌溉处理下,13次Gs基因型间分别10次和11次差异显著,广义遗传力范围分别为0.19-0.68和0.19-0.82,13次平均分别为0.49和0.53,灌溉条件下的遗传方差显著高于干旱胁迫下的遗传方差;18次Fv/Fm基因型间分别17次和16次差异显著,广义遗传力范围分别为0.26-0.83和0.16-0.85,平均值分别为0.64和0.58,干旱条件下的遗传方差极显著高于灌溉条件下的遗传方差;15次LE基因型间分别14次和10次差异显著,广义遗传力范围分别为0.09—0.89和0.09—0.81,平均值分别为0.58和0.50,干旱处理下平均遗传方差和遗传力较高;10次RWC基因型间分别8次和6次差异显著,广义遗传力范围分别为0.10-0.76和0.16-0.77,平均值分别为0.57和0.47,干旱条件下平均遗传方差和广义遗传力较高。总之,除Gs,其他3个指标在干旱条件下获得广义遗传力均高于灌溉条件下的广义遗传力。【结论】干旱胁迫影响Gs、Fv/Fm、LE和RWC的遗传变异和广义遗传力,在灌溉条件下测量Gs和在干旱条件下测量其他3个指标更易获得较高的遗传变异和广义遗传力,但所有4个生理指标均能在灌溉条件下获得较高的广义遗传力。

Genetic Variation of Four Physiological Indexes as Impacted by Water Stress in Sugarcane

【Objective】Understanding of the genetic variations in response to drought conditions of four physiological indexes, namely stomatal conductance (Gs), original light energy transformation efficiency of PSII (Fv/Fm), leaf elongation (LE) and leaf relative water content (RWC) could help their adaption to the current breeding program.【Method】The genetic variation (s_g²), broad sense heritability (h_b²) under rainfed and irrigated conditions for four physiological indexes, namely Gs, Fv/Fm, LE and RWC were measured for 13, 18, 15 and 10 times, respectively, from two sets of field trials in 22 and 18 genotypes which were consistently conducted at two locations in Kaiyuan and Yuanjiang counties of Yunnan province in the crop growing periods of 2013 and 2014. In the trials, rainfed and irrigated treatments were set as the main plot, and genotype was used as the sub-plot. The s_g² and error variation (s_e²) for each index at each measurement was determined using software GenStat, and h_b² was calculated. Paired t tests for the differences of s_g² and h_b² between drought and irrigated treatments were processed using software SAS9.1.【Result】The mean differences between drought and irrigated treatments were all significant (P＜0.01) in 13, 18, 15 and 10 measurements of Gs Fv/Fm, LE and RWC, respectively. Under drought and irrigated treatments, the differences in Gs among the genotypes was significant in 10 and 11 out of 13 measurements with the ranges of h_b² at 0.19-0.68 and 0.19-0.82, and grand means of 0.49 and 0.53, respectively, overall significantly higher s_g² and h_b² were found under the irrigated treatment. The differences in Fv/Fm, among the genotypes were significant in 17 and 16 out of 18 measurements with the ranges of h_b² at 0.26-0.83 and 0.16-0.85, and grand means of 0.64 and 0.58, respectively, overall higher s_g² and h_b² were found under the drought treatment. The differences in LE among the genotypes were significant in 14 and 10 out of 15 measurements with the ranges of h_b² at 0.09-0.89 and 0.09-0.81, and grand means of 0.58 and 0.50, respectively, overall higher s_g² and h_b² were found under the drought treatment. The differences in RWC among the genotypes were significant in 8 and 6 out of 10 measurements with the ranges of h_b² at 0.10-0.76 and 0.16-0.77, and grand means of 0.57 and 0.47, respectively, overall higher s_g² and h_b² were found under the drought treatment. 【Conclusion】The s_g² and h_b² of Gs, Fv/Fm, LE and RWC were impacted by water stress, in general, much higher s_g² and h_b² of Gs could be obtained under irrigated conditions and that of Fv/Fm, LE and RWC under drought conditions. However, higher h_b² could be obtained under irrigated conditions for all the four physiological indexes.