Abstract
Seasonal changes in regrowth of Phalaris arundinacea sward in the 2nd harvest year were compared with those of Dactylis glomerata and Festuca arundinacea by means of growth analysis. Dry weight of green material was the highest in Dactylis, followed by Festuca and Phalaris up to the middle stage of each regrowth. But at the late stage in summer, the dry weight was the highest in Phalaris, followed by Dactylis and Festuca, as Phalaris had more stem and less senescence. In spring, the extended sward height, dry weight of the clipped part and top were higher, and LAI was lower than in summer and autumn. At the early stage of regrowth, percentage light penetration at a given time was higher and its value at a given LAI was lower in Phalaris than in the others. Changes in dry weight and LAI with regrowth were fitted well by cubic regression curves. CGR(dw/dt) was obtained by differentiation of a cubic regression equation of the dry weight of green material, and NAR was calculated by CGR (quadratic equation)/LAI (cubic equation). CGR and NAR, at a given time and a given LAI, were higher in spring than in summer and autumn, as the stem weight was high and LAI was maintained at the suitable level even in the late stage of regrowth. Compared with other grasses, CGR and NAR of Phalaris were lower at the early stage of regrowth in any season, and the values were higher from the middle to the late stage in summer and at the late stage in spring.The result suggests that Phalaris needs a longer period of regrowth than Dactylis and Festuca in spring and summer.
