Effect of exogenous plant hormones on agronomic and physiological performance of a leaf early-senescent rice mutant osled

Abstract

Plant hormones play an essential role in the regulation of leaf senescence in crops. However, limited information is known about the effects of plant hormones on the growth and development of rice plants with leaf early senescence. This study used a leaf early-senescent rice mutant (osled) and its wild type as materials and chiefly investigated how exogenous plant hormones, including indole-3-acetic acid (IAA), trans-zeatin (Z), gibberellic acid (GA3), and 24-epicastasterone (24-epiCS), influenced the main agronomic and physiological performance of the osled. The results showed, compared with the control (CK, spraying deionized water), IAA, Z, and 24-epiCS treatments respectively increased the grain yield of the osled plants by 9.73%, 28.1% and 10.3%, while GA3 treatment significantly reduced that of the osled plants. The IAA, Z, and 24-epiCS treatments obviously delayed leaf senescence and reduced the yield loss of the osled plants by improving crop growth rate, leaf function, and root activity and enhancing the remobilization and contribution of non-structural carbohydrates from stems to grains. Additionally, Z treatment had the best effect in delaying leaf senescence and decreasing yield loss of the osled plants, GA3 treatment promoted a faster growth of rice plants at the early stage, and 24-epiCS treatment inhibited tiller occurrence of the osled plants. The results verify that exogenous plant hormones are applicable to regulate leaf senescence and grain yield of the osled plants, and simultaneously enrich their responses to various hormones in the aspects of agronomic and physiological performance.