Analytical Studies on the Process of Growth and Production of Mat Rush (Juncus decipiens Nakai) : I. Effect of tip cutting on tillering, stem elongation and dry matter production

Abstract

The process of growth and production of mat rush was analyzed to elucidate the effect of tip cutting on tillering, stem elongation and dry matter production. This experiment was carried out in the southern part of Okayama prefecture. The results are summarized as follows: 1. The increase of the number of stems per hill depended on the tillering of the 1st and 2nd tillering stem groups, and the tillering rate reached a ceiling in the latter part of April. 2. Relative tillering rate reached a maximum in the middle of March, and then fell off. At the early stage of growing season, one stem sprouted two tillers, but after the stage of the maximum tillering rate, the behavior of tillering changed and one stem sprouted only one tiller. 3. Tip cutting markedly promoted the elongation of stems, while it had little effect on the increase of the number of stems. 4. Stem surface area index (SAI), is synonymous with leaf area index (LAI), gradually increased until the later stage of the growing season and reached 22 in the latter part of June in the non-tip cutting plot and 25 just before the harvest time in the tip cutting plot. Net assimilation rate (NAR) decreased after the beginning of May, and crop growth rate (CGR) also decreased after the middle of May. However, in the tip cutting plot, the decrease of these parameters began about 10 days late, and both NAR and CGR were higher than those in the non-tip cutting plot. And the increase of dry matter production in the tip cutting plot was caused through the improvement of productive structure. 5. On the basis of the effect on stem elongation and dry matter production, it was concluded that tip cutting was effective for the long stem production.