Leaf Chlorophyll and Grain Yield of Low-gluten Wheat as Affected by Waterlogging at Grain-filling Stage

  Objective  Effects of waterlogging, a serious natural disaster commonly occurring in the middle and late stages of growing season in one of the major production areas in China of middle and lower reaches of the Yangtze River, on the growth, physiology and yield of the low-gluten wheat were studied.

  Method  SPADs of top 3 leaves and yield at grain-filling stage of 4 low-gluten wheat cultivars(i.e., Yangmai 13, Yangmai 15, Yangmai 22 and Waxy wheat)were used in a pot experimentation for the study.

  Result  (1) Waterlogging occurred at the wheat grain-filling stage exerted little effect on the height of a plant. (2) The SPADs of the top leaves on a plant decreased after waterlogging and continued to decline with the condition prolonged. The leaves on lower part of a plant were more sensitive to the stress than those on the upper sections. The SPAD difference between control and treatment (D_SPAD) further widened in 7 days of a natural recovery. Waterlogging caused damages firstly on the lower leaves, then, spread to the upper leaves. (3) D_SPAD of leaves differed significantly according to their location on a plant. The SPAD of the top third leaf and the grain yield significantly correlated, with a correlation coefficient of 0.989 5, suggesting it be used as an indicator to estimate waterlogging damage at grain-filling stage. (4) After 7 d of waterlogging, the yields of all varieties declined significantly. Yangmai 22 was most sensitive to waterlogging with a decrease on yield of 3.6 g/plant or a 39.4% loss over the untreated. The tolerance threshold for Yangmai 22 and Yangmai 15 was 5 d under waterlogging, while Yangmai 13 and waxy wheat 7 d. (5) The effects brought about by waterlogging were variety-specific on yield traits at the grain-filling stage. For Yangmai 13, the reduction was mainly on the 1000-grain weight, while waxy wheat on the number of grains per spike, Yangmai 15 on both 1000-grain weight and grains per spike, and Yangmai 22 on the effective panicle, grain number per panicle as well as the 1000-grain weight.

  Conclusion  Waterlogging at wheat grain-filling stage did not significantly affect the plant height. The SPAD of the top third leaf could be used to estimate the degree of waterlogging damage on the grain yield of a wheat plant. Yangmai 22 was the variety most susceptible to waterlogging, with a significant loss after 7 d under the stress. The tolerance of Yangmai 22 and Yangmai 15 to waterlogging had a threshold of 5 d, whereas Yangmai 13 and waxy wheat 7 d.