SEASONAL VARIATION IN APPEARANCE AND GROWTH OF GRASS ROOTS

Abstract

Data from two field experiments, and from a root observation trench, suggest an annual cycle of root growth by grass swards. The production of adventitious roots from the tillers of four grass species, and from perennial ryegrass in a grass/clover sward varied greatly during the year. They were produced in increasing numbers through late winter to early spring; this rate fell sharply in April or May, and was low in summer. The differences in this annual cycle between grass species were small. Examination of roots of perennial ryegrass in a glass‐sided trench showed that root elongation was most rapid in summer and was largely confined to the lower soil horizons. Rather more roots were produced in early autumn than during summer, but the rate of elongation was slow from October until spring.Individual roots of grasses appeared to survive for limited periods. Their longevity depended upon the time of year in which they were first formed; those produced in autumn or winter lived longer than those produced in spring or summer.