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Responses of Wheat Seedlings Growth to Water Stresses and Its Physiological Mechanism

Author: MaFuJu
Tutor: DaiTingBo
School: Nanjing Agricultural College
Course: Crop Cultivation and Farming System
Keywords: Wheat Seedling stage Water stress Growing Physiological Drought tolerance
CLC: S512.1
Type: Master's thesis
Year: 2011
Downloads: 62
Quote: 0
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Abstract

Wheat is one of major grain crops in China, there are less precipitation in most area in which wheat planted, and the spatial and temporal distribution of the rainfall is too uneven, resulting in drought at different growth stages of wheat. Wheat seedling growth was mainly in autumn and winter, so it usually suffering from drought in developing organs and thus yield was reduced. Therefore, understanding the effect of drought stress on morphology and physiology of wheat seedling not only provided a theoretical basis for further research on drought resistant, but also could improve managements on wheat production. In this study, hydroponics experiments were conducted using two wheat cultivars with differential tolerances to drought stress, drought-sensitive cultivar Wangshuibai and drought-tolerance cultivar Luohan7. Hoagland nutrient solutions contained 20% PEG6000 was designed as water stress treatment with no PEG6000 as control. Effects of water stress on growth and physiological performance of wheat seedlings at different leaf ages, effects of water stress on carbon and nitrogen metabolism, photosynthesis and growth of wheat seedlings were investigated. The main results are as follows:1. Effects of water stress on growth, physiological performance of wheat seedlings at different leaf ages.The seedling at 3-leaf age had the most sensitivity to drought and the differences were significant between wheat cultivars at 4-leaf age.2. Effects of short-term water stress on carbon and nitrogen metabolism of wheat seedlings. Water stress reduced the photosynthesis and the assimilation of nitrogen, which reduced the accumulation of dry weight, but Luohan7 could keep steady Pn after 24 hours’ treatment, reduced the inhabition of nitrogen assimilation in leaves. thus contributed absorbency of NO3-N and accumulation of nutrients in root, so the root was able to grow normally under water stress.3. Effects of water stress on photosynthesis of wheat seedlings. During continual drought stress, seedling of drought-resistance cultivar Luohan7 could maintain lower production of O2 in roots to delay the senescence, making stronger water uptake ability, which could keep stronger photosynthetic capacity to maintain seedling growth with more stable leaf area expansion to made enough dry matter accumulation.4. Effects of water stress on growth of Wheat seedlings. Roots of drought-resistant cultivars could made higher sugar content and stability nitrogen compound content to increase ratio of root to shoot, thereby increasing the adaptability to water stress.In summary, the wheat seedlings at different leaf ages had different sensitivity to drought, which provided a theoretical basis for further research on drought resistant. Water stress promoted the nitrogen metabolism in root of drought-resistance cultivar Luohan7, so the root was able to grow normally under water stress; Luohan7 also could maintain lower production of O2- to delay the senescence, maintain stronger water uptake ability, which could keep stronger photosynthetic capacity to maintain seedling growth with more stable leaf area expansion to made enough dry matter accumulation; roots of drought-resistant cultivars Luohan7 could made higher sugar content and stability nitrogen compound content to increase ratio of root to shoot, thereby increasing the adaptability to water stress.

Responses of Wheat Seedlings Growth to Water Stresses and Its Physiological Mechanism

Abstract

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