This paper reports the findings of a five-year study on the growth patterns, production and means of persistence of white clover in a cool temperate environment with summer dominant rainfall, on the Northern Tablelands of New South Wales. White clover essentially persisted as a perennial, but large and rapid declines in plant frequency occurred during late summer if soil moisture levels became depleted. The critical combination of conditions at which plant frequency was adversely affected occurred when available soil moisture levels declined below 35 mm and mean weekly maximum temperatures exceeded 20�C; conditions which often occur in late summer in this environment. During one prolonged period of moisture stress in the second spring and summer period of the study, all plants died. Regeneration was due to germination of seeds and seedling establishment, but plants subsequently persisted as perennials. Relationships were developed to predict the probability of survival of white clover over the range of temperatures and soil moistures recorded in these experiments. Germination occurred to a variable extent each year, but was observed only during winter and spring. Seedling establishment was effective in only one year, which followed the death of white clover in summer, 1980-81. The sward was slow to recover after seedling regeneration owing to low winter temperatures and competition from established temperate perennial grasses in spring. Seedlings contributed little to dry matter production in spring. These results indicate that white clover is unlikely to be of value as an annual in temperate pastures. Strategies aimed at improving white clover in cool temperate environments, either by management or selection/breeding programs, should therefore focus upon improving the ability of white clover to persist as a perennial.
1. Vogel's (1920) assertion that the labral canal is closed ventrally by apposition of the edges of the labral groove is fully confirmed. The hypopharynx plays no part in the ventral closure of the food canal except at its base. The somewhat popular term “labrum-epipharynx” is dispensed with in favour of “labrum”.2. The mandibular teeth vary in number round about 40. The mandibular suspension is fully described.3. Evidence from musculature is put forward for the existence of a small maxillary palpifer not present in other Diptera.4. Snodgrass (1935) criticizes Crampton's (1925) homologizing of the labella with labial palps because “the lobes of the fly labium have usually each only one muscle inserted directly upon it”, whereas palpi usually have antagonistic muscles. Vogel for Culex and this paper for Anopheles maculipennis show that the labial lobes of these insects have antagonistic muscles like typical palpi.
Three major pasture types probably occurred on the Northern Tablelands prior to European settlement. The dominants were probably Poa sieberana Spreng. and Themeda australis (R.Br.1 Stapf. at the higher elevations, T. australis, P. Sieberana and Sorghum leiocladum (Hack.) C.E. Hubbard on fine textured soils at lower elevations and T. australis, Aristida ramosa (R.Br.) and Cymbopogon refractus (R.Br.1 A. Camus. on coarse textured soils. The subsidiary species composition of these pasture types is also suggested, derived from fragmentary early accounts, earlier published work and observations on the behaviour under grazing of the different species involved. The characteristics of the important native and naturalised grass species are described. These species are classified into warm season perennials, warm season annuals, cool season perennials and cool season annuals. The native warm season perennials is the largest group of species at present on the Tablelands. The effects of grazing on the species composition of natural pastures is described. The grazing behaviour of merino sheep leads to a striking zonation of herbaceous species resulting from uneven grazing intensity and distribution of dung and urine. Data from an unreplicated stocking rate by superphosphate application rate trial at Shannon Vale are presented. This trial indicated that the proportion of white clover in the pasture depended on both stocking rate and superphosphate rate and that the proportion of Danthonia spp. increased when white clover decreased. Wool production data are also presented which show that high levels of pro- ductivity per hectare can be obtained from topdressed natural pastures. A number of different natural pasture types occur on the Tablelands. A schemeis presented showing the interrelationship$ between the original and the present pasture types as affected by grazing intensity and the addition or depletion of plant nutrients.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.