Effects of Polyamines Synthesis Inhibitors Sprayed after Heading on Contents and Components of Polyamines in Rice Grains at the Ripening Stage

With a higher polyamine rice （indica variety Jinlingxiang） as experimental material, the changes in contents and components of polyamines （PAs） in rice grains after harvesting were investigated under the treatments by spraying the panicles and flag leaves of rice with PAs synthesis inhibitors, D-Arg （0.5, 1.0, 1.5 and 2.0 mmol/L）, methylglyoxal bis-guanylhydrazone （MGBG） （0.1, 0.5, 1.0 and 1.5 mmol/L） and cyclohexylamine （CHA） （1.0, 5.0, 10.0, 15.0 and 20.0 mmol/L）, at the heading, flowering and grain filling stages. The inhibition of D-Arg on the contents of free and bound PAs and its total amounts in rice grains was significant, especially treated at the flowering and grain filling stages. Treatments with MGBG and CHA affected mainly the components of PAs, and their effects on the total amounts of PAs were not significant except MGBG at the flowering stage and CHA at both heading and flowering stages.