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Effects of sward type and rest periods from sheep grazing on white clover presence in perennial ryegrass/white clover associations
Author(s) -
GOODING R. F.,
FRAME J.,
THOMAS C.
Publication year - 1996
Publication title -
grass and forage science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.716
H-Index - 56
eISSN - 1365-2494
pISSN - 0142-5242
DOI - 10.1111/j.1365-2494.1996.tb02052.x
Subject(s) - trifolium repens , grazing , perennial plant , biology , agronomy , white (mutation) , red clover , stolon , gene , biochemistry
The effects of the imposition and timing of a rest period from continuous sheep stocking, for a conservation cut, on white clover presence in forty perennial ryegrass/white clover associations were studied over two full grazing seasons. Each association consisted of one grass variety along with one white clover variety, the grasses being diploid and tetraploid ryegrasses from each of five maturity groups and the white clovers from each of four leaf size categories. The presence of white clover within each association was assessed at the beginning and end of both seasons by means of a 0–64‐m 2 quadrat subdivided into 100 squares, each 80 mm × 80 mm, the number of squares in which any part of a white clover plant was visible being recorded. Complementary point quadrat data were also collected. Although continuous sheep stocking did not necessarily have an adverse effect on white clover presence, a July to mid‐August rest period increased white clover proportions in the swards (means: unrested, 48–1; April to late May rest, 32.7; July to mid‐August rest, 67.3 ‐ s.e.d. 7.59; P < 0.05) the benefit increasing with increasing white clover leaf size. The early rest period (April to late May) reduced white clover presence and the late rest period (July to mid‐August) increased white clover presence, these effects being intensified with increasing white clover leaf size (very large‐leaved clover: unrested, 20.6; April to late May rest, 8.3; July to mid‐August rest, 41.1 and small‐leaved clover: unrested, 96.3; April to late May rest, 84.8; July to mid‐August rest, 97 ‐ s.e.d. 9.2; P <0001). Tetraploid ryegrass/white clover associations had consistently and significantly more white clover than diploid ryegrass/white clover associations of similar ryegrass maturity group (tetraploid, 53.4; diploid 44.8 ‐ s.e.d. 2.12; P <0.001) and associations with early maturing ryegrass contained more white clover than those with late maturing ryegrasses, the effect of maturity group being greater than that of ploidy. Overall, white clover presence increased with increasing openness of grass growth habit.