Effects of leaf zeatin and zeatin riboside induced by different clipping heights on the regrowth capacity of ryegrass

Abstract

The effect of clipping height on ryegrass regrowth was investigated by examining the roles of several plant hormones. Our study consisted of three treatment conditions: (1) darkness over whole plants, (2) darkness only over stubble leaf sheaths, and (3) light over whole plants. Results showed that under darkness over whole plant, low stubble height resulted in low leaf regrowth biomass. Similar leaf regrowth biomass was observed under conditions of darkness only over stubble leaf sheaths as well as light over whole plants. Each unit weight of stubble at different clipping heights has relatively similar potential of providing stored organic substance for leaf regrowth. Therefore, regrowth index, calculated as newly grown leaf biomass divided by unit stubble weight, was used to evaluate regrowth capacity at different clipping heights under minimal influence of organic substances stored in stubbles. Under light over whole plants and single clipping, low stubble height and high stubble height with root thinning resulted in low leaf biomass and high regrowth index. On the other hand, under light over whole plants and frequent clipping high leaf biomass and regrowth index were observed in high stubble height. In addition, we found that leaf zeatin and zeatin riboside (Z + ZR) affected ryegrass regrowth and that roots regulated leaf Z + ZR concentration. Thus, our results indicate that root-derived cytokinin concentration in leaves influences ryegrass regrowth at different clipping heights.

Successive Harvests Modulate the Productive and Physiological Behavior of Three Genovese Pesto Basil Cultivars

“…The increased leaf number at the second harvest could be attributable to cut-induced mechanical distress or due to the increased number of stems after the cut. Probably, as outlined by Wang et al [25], the cut would induce higher cytokinin production, which stimulates cell division, regulates leaf primordia number, and reduces stomatal resistance [7,26,27], as supported by our results (Tables 1 and 3).…”

Successive Harvests Affect Yield, Quality and Metabolic Profile of Sweet Basil (Ocimum basilicum L.)

“…Defoliation also enhances the above-ground N yield of grasses [60], because of an increase uptake and preferential allocation of nitrogen to the shoots [61]. In the same way as our results, single clipping reduced leaf biomass in ryegrass and increased cytokinin concentration in leaves [62]. Although the morphogenetic activity of cytokinins in leaves is intricate [63], this hormone regulates leaf primordia number by stimulating cell division [64].…”

Rooting responses of black pepper (Piper nigrum cv. Bragantina) as affected by chemical, physical and microbiological properties of substrates and auxin

“…The development of axillary buds was positively regulated by a signal from the roots (ex. : cytokinin synthesis as zeatin and zeatin riboside) of ryegrass (Wang et al, 2014). Therefore, the root node produced in the stem near the axillary bud establishes a more effective connection system for transporting water, nutrients, organic compounds and plant growth regulators such as cytokinins.…”