| Popis: |
The low temperature disaster in spring is one of the main agro-meteorological disasters affecting the yield and quality of winter wheat by affecting the development process and physiological function, resulting in yield reduction. In order to clarify the quantitative relationship between spring low temperature stress and winter wheat yield and its components in Huang-Huai-Hai Region, an indicator is constructed based on yield reduction rate. Based on 1924 sets of experimental data and control data in 34 retrieved literatures, effects of low temperature stress on wheat yield and its components at green-up stage, jointing stage, booting stage and heading-flowering stage are analyzed by Meta-analysis. Using the minimum temperature and accumulated cold of the process as identification factors, the critical thresholds of 0, 10% and 30% of yield reduction rate are determined by using the Youden's Index to establish and verify the low temperature disaster grade indicator. Results show that the yield and its components of winter wheat are jointly affected by the intensity and duration of low temperature to different extent in different developmental stages. The yield and all its components decrease significantly under low temperature stress, and the sensitivity of panicle number per plant and grain number per panicle to low temperature stress is greater than that of thousand kernel weight. The low temperature disaster grade indicators are constructed according to the yield reduction rate of (0, 10%], (10%, 30%], (30%, 100%]. Taking the minimum temperature (unit: ℃) of the process as identification factor, ranges for low temperature disaster grade (Ⅰ, Ⅱ, Ⅲ) during the green-up stage are [-5.0, -2.0), [-8.5, -5.0), |
