Recovery Processes after Leaf Cutting in Cereals and Forage Grasses : II. Regrowth of organs of rice plant for a short period after defoliation and concomitant change of reserve starch content during recovery

[摘要] Rice seedlings of 35 cm height with 6 tillers were differently defoliated in 1959 when the main stem reached 9.8 leaf-stage, and the regrowth processes of each organ during 15 days after the treatment were observed. In 1962, a root-box mehod was used to record the daily elongation following defoliatiation directly on the acryl resin fronts of the box. Moreover in 1964, the rooting process after clipping at paddy field was studied. 1) The more severely being removed of foliage, the more reduction of dry matter production followed with shorter plant height, less tillers and less roots. The rate of regrowth of leaf-blades was higher than other organs, and at the 15th bay after defoliation the ratio of green leaf-blades to the whole plant by dry weight reached about 40% in all plots differently defoliated, the value being the same as that of the untreated plant (fig. 1). All the defoliated plants recovered well 2 weeks after the treatment as far as the balance of each organ is concerned (fig. 2). The recovery of root numbers was earlier than that of tiller numbers (fig. 1) 2) Severe defoliation induced less photosynthetic contribution to the plant reducing the starch content in the leaf-sheath (fig. 3). Defoliated leaf may expand consuming carbohydrates stored in the base of the leaf, but elongating uncut leaves may use preferentially the carbohydrates stored in the sheaths of other leaves (fig. 10), resulting in shortage of the resources for the elongation of new tiller buds (fig. 4; 8, 9 buds) and roots (fig. 4-8, table 1). 3) Removal of whole leaf-blades caused root growth to stop for a time, although it began to recover with the regrowth of leaf-blades 4 days after clipping. The higher rate as compared, to the control of root growth occurred with the recovery of leaf-growth, and the root number in the treated plants equalled to the control 2 weeks or 3 weeks after clipping at higher or lower density of planting, respectively. Although the defoliated plants formed new roots smaller in diameter than the control even 10 days after treatment (table 2), the successively formed new roots became progressively thicker until they surpassed the control.

[学科分类] 农业科学（综合）