微根系（细根、根毛）形态和生理特征对棉花早衰的影响和机制

Premature senescence of cotton has an inhibitory effect in its output and quality improvement. It is generally believed that premature senescence of cotton is shown on the “Declining in leaves but sourcing in the roots”. The micro-root (fine roots and root hairs) is the main functional part of the root. However, the growth and development characteristics and physiological mechanism of the micro-root of premature senescence of cotton are still not clear now. This study intends to prepare two cotton populations with different degrees of senescence (premature senescence and robustness) by varieties and nitrogen treatments. Additionally, by using a series of equipments and methods, such as a modified minirhizotron system and a scanning electron microscope to conduct the investigations, which focus on: 1) the physiological activity of the micro-root and the expression of senescence-associated genes; 2) the morphology of the micro-root and the life span and turnover characteristics of root hairs; 3) the relationship between root hair morphology and cell apoptosis in the micro-root system; 4) the senescence characteristics of the root and aboveground plants; 5) the relationship of the senescence characteristics of the micro-root system and the senescence of the root and aboveground plants. This study intends to clarify the morphology, physiological metabolism, apoptosis and senescence-related gene expression and their interactions in the micro-root system of premature senescence of cotton during the process of its senescence, the response characteristics of root length density, life span and turnover to the senescence of the root system, and the physiological mechanism on the effect of senescence in the micro-root system of cotton in the premature senescence of aboveground plants. The results will enrich the knowledge of the development law of the cotton root system, and provide an important theoretical basis for the breeding of anti-senescence cotton varieties and the prevention of its senescence.

早衰是影响棉花产量和品质提高的重要障碍。现普遍认为，棉花早衰“衰在叶片，源在根系”。根系主要功能部位是微根系（细根和根毛），但迄今对早衰棉花微根系的生长发育特征及生理机制尚不明确。本项目拟通过品种和氮素处理创造2种衰老程度（早衰和健壮）的棉花群体，采用改进型微根窗根系系统、扫描电镜等设备及方法，重点研究：1）微根系生理活性及衰老基因的表达研究；2）微根系形态及根毛寿命和周转特征研究；3）微根系中根毛形态与细胞凋亡关系研究；4）根系与地上部植株衰老特征研究；5）微根系衰老特性与根系及地上部植株衰老关系研究。研究拟明确早衰棉花微根系衰老进程中的形态、生理代谢、细胞凋亡及衰老相关基因的表达规律及相互关系；根毛根长密度、寿命及周转对根系衰老的响应特征；探明棉花微根系衰老对地上部植株早衰影响的生理机制。研究结果将丰富对棉花根系发育规律的认识，为抗衰品种选育以及早衰防控提供重要理论依据。

微根系（细根和根毛）是棉花根系的主要功能部位，阐明在不同逆境下微根系形态及衰老特征在根系衰老及棉株早衰过程中的作用及生理机制具有重要意义。本研究基于一种自制的原位根系研究装置（RhizoPot），开展了干旱、养分亏缺和高温等非生物胁迫下微根系的形态、寿命和生理生化特征，以及棉株地上部的发育、光合特性和生理生化的响应。本研究对非生物胁迫导致植株衰老的情况系其微根系衰老和功能特征具有重要关系，研究结果阐明了不同非生物胁迫对棉花微根系的形态和寿命的影响规律，以及微根系形态和寿命发生变化的生理机制，深入的微根系形态和寿命变化与棉株地上部衰老之间的关系。本研究为根系性状的改良、抗衰品种的选育以及早衰防控提供重要理论依据，并丰富对棉花根系发育规律的认识。