Abstract
AbstractThe 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.
Highlights
Regrowth is one of the most fundamental defense mechanisms of forage grass against herbivorous animals
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
Our results indicate that root-derived cytokinin concentration in leaves influences ryegrass regrowth at different clipping heights
Summary
Regrowth is one of the most fundamental defense mechanisms of forage grass against herbivorous animals. It is a very important process for continuous grassland production and hay yield (Guevara et al 2002; Schiborra et al 2009). Clipping height is an important factor that influences forage grass regrowth. Other studies have reported that clipping height is an important influencing factor for grass regrowth (Conn and Seefeldt 2009; Gastal et al 2010; Regmi and Devkota 2009; Zhang et al 2011). The mechanism by which clipping height affects forage grass regrowth remains unknown
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