关键词: 冬小麦, 晚霜冻胁迫, 发育进程, 株高, 节间和穗长, 籽粒产量

Abstract:

【Objective】 The objective of this study was to explore the effects of late frost stress on plant height and its components in winter wheat, and to clarify the characteristics of plant height reduction and its relationship with internode length, ear length and grain yield, in order to provide a basis for establishing the evaluation index of late frost damage. 【Method】By using two frost simulation means based on the Cold Climate Chamber and the Field Movable Climate Chamber, six pot experiments and three plots experiments were carried out with the developmental progresses (floret primordia differentiation (FPD), pistil and stamen primordia differentiation (PSPD), anther connective tissue formation (ACTF), tetrad formation (TF) and heading phase) of young ear and the subfreezing treatment temperatures (-1 °C, -3 °C, -5 °C, -7 °C, -9 °C and -11 °C) as the gradients. Culm injury was investigated after each frosting treatment, and plant height and its components, and grain yield were measured at maturity. Variance analysis, regression function fitting and test method for sudden change were used to study the rule of plant height reduction, the contribution of each component to plant height, and the regression relationship of plant height and grain yield. 【Result】 (1) In the stages of PSPD to late ACTF, plant height generally showed a decreasing trend with the decrease of treatment temperature. When the treatment temperature was lower than -5℃ or so, a mutation began, and there were certain differences between individual plants and varieties. At the same treatment temperature, the greatest decline in plant height occurred in the late ACTF stage. (2) In the stages of PSPD, early ACTF and late ACTF, fourth internode length from the top (FIL), antepenultimate internode length (AIL), penultimate internode length (PIL) and ear length (EL) all showed shortening trends in different degrees under the frost stress. In these periods, the key two internodes contributing to plant height were FIL and AIL, AIL and PIL, and PIL and FIL, respectively, that showed a strongly significant correlation (P<0.001) with plant height. Correspondingly, plant height significantly decreased. (3) The regression curves between plant height and kernel number per ear, 1 000-kernel weight, and yield per plant were well fitted by the power function models. The reduction in yield per plant showed a trend from the rapid to the slow as plant height decreased. When yield per plant was reduced to 1.5 g or less because of the further frost stress, it became relatively stable as plant height continued to decrease, also, kernel number per ear did not change significantly any more at that time. 【Conclusion】 Under the simulated late frost stress, a significantly shortening trend occurred only in the imminent or elongated internodes and young ear, but not in the end of elongation. When the shortening internodes were consistent with the internodes that mainly contributed to the plant height, plant height significantly decreased. Using the shortening feature of the internodes, and the power function model between plant height and yield per plant, a new approach could be provided for the risk assessment of plant lodging in late growth and yield loss of winter wheat affected by late frost.

Key words: winter wheat, late frost stress, developmental progress, plant height, length of internode and ear, grain yield