Effect of seed crop management on the potential seed yield of contrasting white clover varieties.

Abstract

Three contrasting white dover varieties, Olwen (large-leaved), Menna (medium-leaved) and SI 84 (small-leaved) were sown with and without a grass companion in 30 cm drills. Two grazing and one mechanical spring defoliation managements were imposed. Counts of the total number of inflorescences and of the percentage in various ripeness categories were made throughout the period of seed crop development to determine the pattern of inflorescence development and optimum harvest date. Inflorescence numbers were greatest in cv, SI 84 and least in cv, Olwen and, in general, varieties produced both more inflorescences and a greater proportion of ripe inflorescences when grown under spring defoliation managements similar to those for which they were bred. Thus, cv. Olwen produced more ripe inflorescences, and a lower proportion of brown inflorescences (semi-ripe), after mechanical defoliation while cv, Menna produced more ripe inflorescences following mechanical defoliation and rotational grazing. However, cv. S184 produced more ripe inflorescences under both grazing managements than under mechanical defoliation. Optimum harvest date was not affected by management or variety, total inflorescence number and maximum ripe inflorescences having reached a peak on 11 September. However, varieties Correspondence lo: Dr A. H. Marsiiiiii. Instiiuie for Crassland and Animal Produclion, Welsh Plant Breeding Station, Abcrysiwyih. Dyfed, SY23 3EB, U.K.differed in the proportion of ripe and brown (semi-ripe) inflorescences on this date, with cv. Menna and cv. S184 containing a significantly higher proportion of brown inflorescences than cv. Olwen, The implications of these differences in inflorescence development, the proportions of inflorescences in the various ripteness categories and their contribution to seed yield are discussed in relation to the management of white clover seed crops and harvesting method under UK climatic conditions. IntroduetionWhite clover seed production in the United Kingdom is limited because of the difliculty of obtaining consistent economic seed yields (Hides et ai, 1984) despite the higher seed yield potential of recently bred UK varieties (Evans and Davies, 1978; Evans ei al., 1986). This can be attributed partly to variable weather conditions during critical periods of crop growth (Hides et al.., 1984) and also to the lack of suitable seed crop management practices for optimising seed yield. Clearly, if UK seed production is to be increased then it is essential that management systems are developed which improve the reliability of seed yield of these varieties within the constraints of the variable UK climate, Deflning optimum seed crop management practices is also complicated by the fact that varieties have been bred for the demands of different agricultural systems and are classified into leaf size categories, each exhibiting different growth patterns and stolon morphologies. Smallleaved varieties, which have a dense mat of small, branched stolons, have been bred for persistency under continuous heav...

Review: World checklist of white clover varieties II

“…Had greatest number of inflorescences/m 2 and seed set values of 15 cultivars in Wales (Evans et al 1986) but did not flower in eastern Canada (Christie 1991). Had lower seed yield, floret number, and seeds/ head than OLWEN in United Kingdom (Hollington & Marshall 1988;Marshall et al 1989;. High seed yield in Czech Republic (Zapletalova 1991) and in Victoria, Australia (Clark 1991b).…”

Effect of seed crop management on potential seed yield of contrasting white clover varieties

“…The eflect of spring management on the inflorescence development of these three cultivars has t)een described previously (Marshall et al., 1989). The present paper has reported the efl'ects of crop managements in the same experiment on their potential seed yield and seed yield components.…”

“…The possible extent of this contribution has been mentioned elsewhere (Marshall et al., 1989), and the rate at which inflorescences ripen in the swath after desiccation and cutting is an important area which requires further study.…”

“…A previous paper has described the problems associated with producing white clover seed in the United Kingdom, and shown the efl'ect of the system of spring management on inflorescence development {Marshall et al, 1989).…”

Centrosema pubescens(centro) andManihot esculenta(cassava) intercropping: The effect of spacing and time of planting centro on seed yield

“…1985) or live plants with erect growth habits (Ferguson et al 1987). Unlike plants, these man-made systems pose no competition for environmental growth factors (Marshall et al 1989). However, the construction of such systems is costly and returns from the sale of seed attributed to these systems often do not offset the construction costs (Castillo & Siota 1978).…”