Root growth of Lolium Perenne L.

Abstract

The effect of plant age, seed weight, and nutrient concentration on root weight, root length, and number of root apices has been examined in young plants of Lolium perenne L. cv. ‘Grasslands Ruanui’. The size of the root system increased with age. At 12 weeks the root system had an average of 263,000 apices, 1,816 m total length, and weighed 6 g. Length of root, number of apices per unit of root, and shoot dry weight were initially high but dropped sharply and subsequently rose again. The sharp drop coincided with the growth of the first nodal roots. Differences in plant size caused by differences in seed weight, white still present at 8 weeks, were smaller than at 2 weeks, indicating that plants from low-weight seed had a higher growth race. There were no differences in length or number of apices per unit weight of root or in apices per unit length of root. The high-weight seed plants had a lower shoot/root ratio at 2 weeks, but this difference had disappeared by 8 weeks. Root and shoot weights were both highest at the normal nutrient concentration. At the high nutrient concentration both shoot and root weight were depressed to the same extent whereas at low concentrations the effect on shoot weight was more severe. In contrast to weight, root length and apex numbers were not depressed at 0.25 standard nutrient concentration. Length and number of apices per unit weight of root decreased with increasing nutrient concentration. The technique used for estimating root length and apex numbers is described.