Use of water by six grass species. 2. Root distribution and use of soil water

Abstract

The use of soil water by six grasses (perennial ryegrass, cocksfoot, timothy, rough stalked meadow grass (RSMG), tall fescue and Italian ryegrass) was measured over 2 years. The swards were cut either at 3-week (C 3 ) or 6-week (C 8 ) intervals. In both years the maximum soil water deficit attained under C 6 was greater than under C 3 . Following several of the cuts from C 6 there was a marked, although temporary, reduction in the rate of water uptake.An extended dry period in the second harvest year revealed substantial differences in the total water used and in the patterns of uptake from the soil profile by the grasses. Effective depths of utilization of water under treatment C 6 were: RSMG, 40 cm; timothy, 70 cm; cocksfoot, 70 cm; perennial ryegrass, 80 cm; tall fescue > 100 cm. This order of depth of utilization corresponded with the order of yields obtained during drought conditions. An examination of the root systems of four grasses also showed that, particularly under treatment C 6 , roots of tall fescue were more numerous at depth than those of timothy, cocksfoot or perennial ryegrass, and under this treatment it showed its greatest tolerance to dry conditions. Drought tolerance in these grasses appears largely determined by the volume of soil exploited by the roots for water.

Vertical distribution of organic amendment influences the rooting depth of revegetation species on barren, subgrade serpentine substrate

“…While the roots of the granite A. millefolium ecotype and the annual grasses V. microstachys and B. madritensis were restricted to compost amended layers, the root distribution of the serpentine A. millefolium ecotype and the perennial grasses B. laevipes and E. elymoides was not restricted. Distribution of soil resources including nutrients (Robinson, 1994) and water (Garwood et al, 1979), and soil physical properties including spatial textural differences and rocks which present obstacles to rooting (Weaver and Darland, 1949), are known to have a substantial influence on plant root distribution. Classic root mapping studies of numerous grass species native to the US have demonstrated that most perennial, tillering bunch grasses have a relatively even horizontal distribution of roots throughout the soil profile with a steady vertical decline in root biomass with increasing soil depth (Weaver and Darland, 1949).…”

Plant drought survival under climate change and strategies to improve perennial grasses. A review

“…In phalaris, the early onset and high level of senescence of herbage were observed to reduce transpiration (McWilliam 1968) while the development of an extensive root system and/or superior hydraulic conductance to maximise soil water uptake was noted as being important for ongoing production under drying conditions in tall fescue (Garwood and Sinclair 1979). Dehydration-avoiding plants are able to survive extended dry spells but can only do so if able to maintain high tissue water status.…”

Improving the adaptation of perennial ryegrass, tall fescue, phalaris, and cocksfoot for Australia

“…Thinopyron and Bromus continue to be cultivated while several other genera remain under evaluation. Apart from their adaptability, part of the popularity of the main four introduced perennial grasses would appear to be their deep root system, relative to annuals (Garwood & Sinclair 1979) which helps to prolong the period of active growth by utilising subsoil moisture (e.g., Donald 1970), their herbage and seed yield potentials, their nutritive value, and ease of establishment.…”