Effects of crown height on the compensatory growth of Italian ryegrass based on combined effects of stored organic matter and cytokinin

Abstract

AbstractThe interaction between stored organic matters in crowns and leaf cytokinin induced by roots was determined to investigate the compensatory growth of Italian ryegrass (Lolium multiflorum. Lam). The experiment comprised five treatments: (a) clipping once with 5 cm crown height, (b) clipping once with 2 cm crown height, (c) clipping twice with 5 cm crown height, (d) clipping twice with 2 cm crown height and (e) no clipping. Results showed that low crowns and single clipping promoted regrowth and the sum total of all previously clipping and final harvest of Italian ryegrass. Super compensatory growth and compensatory growth, which were assessed based in total biomasses, respectively, occurred in Italian ryegrasses with high crowns and single defoliation and those with high crowns only. Increased leaf net photosynthetic rates in Italian ryegrasses with high crown were promoted by stored organic matter in crown and leaf cytokinin in the first and later 7‐day regrowth periods, respectively. Compared with single clipping, frequent clipping decreased the stored organic matter in roots; causing decreases in leaf cytokinin concentration and photosynthetic rate. The delivery rate of cytokinin from the roots to the leaves determined the leaf cytokinin concentration in Italian ryegrass during the regrowth period. Thus, organic matters from crowns and leaf cytokinin induced by roots played a combined effect on aboveground compensatory growth in the Italian ryegrasses.