| Abstract: | A field experiment was conducted to study growth characteristics of contrasting varieties of Lolium perenne (early heading: Gremie ; late heading Vigor ) in different growth/regrowth periods during 1984 and 1985. A growth function was fitted to data of weekly measurements of dry matter production (DM) and leaf area index (L) to derive the following parameters according to quantitative analysis of plant growth: crop growth rate (C), relative growth rate (R), leaf area ratio (LAR) and leaf weight ratio (LWR). Furthermore phenological development of the swards was recorded.
The chief differences in the growth potential of the varieties were found in primary growth on the one hand and in both investigated first regrowth periods on the other hand. In second and third regrowth periods no distinct differences were found either in DM nor in L regarding variety effects. In primary growth the early heading variety gained an advantage in DM, which was enhanced with prolonging growth period until the middle of June combined with a rapid reproductive development of the sward. Growth potential in the first regrowth period was determinated by the time of cutting in primary growth according to the development stage of the swards at cutting time. It was evident that highest values of DM and C were corresponding with a high amount of undamaged reproductive tillers in the sward. DM of vegetative summer regrowths were comparable, while in late summer/autumn under worsening environmental conditions a reduction in DM was observed. In opposite to that L developed rather similar in the investigated regrowth periods. According to this force of expression of L is discussed in relation to DM and phenological development of the swards. |
