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J Exp Bot. 2015 Jul;66(13):3945-58. doi: 10.1093/jxb/erv194. Epub 2015 May 6.
Stomatal conductance (g(s)) and canopy temperature have been used to estimate plant water status in many crops. The behaviour of g(s) in sugarcane indicates that the internal leaf water status is controlled by regular opening and closing of stomata. A large number of g(s) measurements obtained across varying moisture regimes, locations, and crop cycles with a diverse sugarcane germplasm composed of introgression, and commercial clones indicated that there is a high genetic variation for g(s) that can be exploited in a breeding programme. Regardless of the environmental influences on the expression of this trait, moderate heritability was observed across 51 sets of individual measurements made on replicated trials over 3 years. The clone×water status interaction (G×E) variation was smaller than the clone (G) variation on many occasions. A wide range of genetic correlations (r(g)= -0.29 to 0.94) between g(s) and yield were observed across test environments in all three different production regions used. Canopy conductance (g(c)) based on g(s) and leaf area index (LAI) showed a stronger genetic correlation than the g(s) with cane yield (tonnes of cane per hectare; TCH) at 12 months (mature crop). The regression analysis of input weather data for the duration of measurements showed that the predicted values of r(g) correlated with the maximum temperature (r=0.47) during the measurements and less with other environmental variables. These results confirm that the g(c) could have potential as a criterion for early-stage selection of clones in sugarcane breeding programmes.
气孔导度（g(s)）和冠层温度已被用于许多作物中估计植物水分状况。甘蔗中 g(s) 的行为表明，内部叶片水分状况受气孔的定期开闭控制。在不同的水分条件下，在不同的地点和作物周期内，通过对由渐渗和商业克隆组成的多样化甘蔗种质资源进行大量的 g(s) 测量，表明 g(s) 具有很高的遗传变异，可以在育种计划中加以利用。无论环境对该性状表达的影响如何，在 3 年的重复试验中对 51 组个体测量进行的中度遗传力观察表明，在许多情况下，克隆×水分状况互作（G×E）的变异小于克隆（G）的变异。在所有三个不同生产地区的测试环境中，观察到 g(s) 与产量之间存在广泛的遗传相关系数（r(g)=-0.29 至 0.94）。在 12 个月（成熟作物）时，基于 g(s) 和叶面积指数（LAI）的冠层导度（g(c)）与 cane 产量（每公顷吨数；TCH）的遗传相关性强于 g(s)。对测量期间输入气象数据的回归分析表明，预测的 r(g) 值与测量期间的最高温度（r=0.47）相关，与其他环境变量的相关性较小。这些结果证实，g(c) 有可能成为甘蔗育种计划中克隆早期选择的标准。
