Agronomic and physiological characteristics of a rice leaf early senescence mutant during its whole growth period

Abstract

Diverse rice (Oryza sativa L.) leaf early senescence mutants have been identified and used for studies on senescence mechanisms. However, the reports are few about the agronomic and physiological characteristics of rice leaf early senescence mutants during the whole growth period. This study used a rice leaf early senescence mutant (osled) and its wild type (WT) to compare their main phenotypic and agronomic traits at different growth stages, as well as some physiological characteristics. The results showed the osled plants exhibited leaf early senescence initiating from the middle seedling stage to maturation, accompanied with dwarf phenotype, prolonged vegetative growth period, decreased green leaf area, reduced aboveground biomass, decreased crop growth rate and net assimilation rate, smaller panicle, an awn of 1.56‐ to 1.58‐cm length, and more panicles. Compared with WT, the osled plants had significantly reduced chlorophyll content, photosynthetic capacity, N content, and activities of nitrate reductase and glutamine synthase in leaves and enhanced activity of glutamate synthase and lowered pre‐anthesis nonstructural carbohydrate accumulation and remobilization in stems. The study revealed some physiological mechanisms underlying leaf senescence of the osled and provided new perspectives for understanding the growth characteristics of rice leaf early senescence mutants.

Effect of nitrogen rates on the growth and grain yield of a leaf early‐senescent rice mutant

“…Leaf early senescence is problematic in crops, leading to a reduction in leaf area, loss of photosynthetic products, and decreases in yield and quality (Liu et al., 2008; Rao, 2011; Wu et al., 2012; Xu et al., 2020). Therefore, studies on how to improve the agronomic and physiological performance of rice plants exhibiting leaf early senescence would be beneficial to increase the yield and optimize the quality.…”

“…The osled , located in the long arm of rice chromosome 3, encoded an LSD1‐related Zn finger protein (Zhao, 2015). The grain yield of the osled plants was distinctly lower than that of the WT plants (Xu et al., 2020; Zhao et al., 2014). The osled plants initiated leaf senescence since the middle seedling stage and showed significantly slender and shorter plant type during the rice whole growth period.…”

“…The osled plants initiated leaf senescence since the middle seedling stage and showed significantly slender and shorter plant type during the rice whole growth period. The upper leaves of the osled plants including the flag leaves had senescence symptoms at heading stage and rust spots were largely shown on the leaves, while the WT plants performed excellently even at the late growth stage (Xu et al., 2020). The ultimate purpose of this study was to make clear whether and how various N rates influenced the agronoimic and physiological traits and grain yield of the leaf early‐senescent rice mutant osled .…”