Impacts of kinetin implementation on leaves, floral and root-related traits during seed production in hybrid rice under water deficiency

Abstract

Background: Water deficit is one of the most significant abiotic factors affecting rice and agricultural production worldwide. In hybrid rice, cytoplasmic male sterility (CMS) is an important technique for creating high-yielding crop based on heterosis. The phytohormone kinetin (Kin) regulates cell division in plant during the early stages of grain formation, as well as flow assimilation and osmotic regulation under water stress. The present study performed to estimate the effects of irrigation intervals (irrigation each six days (I₆), nine days (I₉), twelve days (I₁₂) and fifteen days (I₁₅) against continuous flooding (CF, each three days)) and kinetin exogenously application (control, 15 mg L^-1 and 30 mg L^-1) on hybrid rice (L1, IR69625A; L2, G46A and R, Giza 178 R) seed production.

Results: Leaves traits (Chlorophyll content (CHC), relative water content (RWC), stomatal conductance (SC), Leaf temperature (LT) and transpiration rate (TR)), floral traits such as style length (SL) and total stigma length (TSL), in addition to root traits (i.e., root length (RL), root volume (RV), root: shoot ratio (RSR), root thickness (RT), root xylem vessels number (RXVN) and root xylem vessel area (RXVA) were evaluated and a significant enhancement in most traits was observed. Applying 30 mg L^-1 kinetin significantly and positively enhanced all growth, floral and roots traits (RV and RXVA recorded the most increased values by 14.8% and 23.9%, respectively) under prolonging irrigation intervals, in comparison to non-treated plants.

Conclusions: Subsequently, spraying kinetin exogenously on foliar could be an alternative method to reduce the harmful influences of water deficiency during seed production in hybrid rice.

Keywords: CMS lines; Drought stress; Growth traits; Kinetin; Plant root; Sustainability.