Effects of Plant and Canopy Density on Seed Yield and Oil Content in White Lupin (Lupinus albus)

Abstract

High plant populations caused a reduction in pod set and consequently in seed yield. Removal of axillary branches reduced the average weight of seed and percentage seed oil on primary racemes, indicating transport of photosynthate from branch leaves to storage sites in pods on primary racemes. Debranching at low densities was also associated with premature senescence of leaves and desiccation of immature pods, suggesting that branch removal need not have an exclusively simple nutritional basis. High canopy density reduced oil content, and seeds borne on primary racemes had lower oil levels than those on axillary branches.Reports on several crops indicate that spacing affects the percentage of oil in harvested seed (Dillman and Brinsmade, 1938;Hinson and Hanson, 1962;Donovan et al., 1963). In preliminary experiments forming part of the present study it was also observed that seed borne on secondary racemes could develop a higher oil content than those on the primaries, though the increased oil levels were generally found only when plants were grown in dense stands. Furthermore it has been established (McGibbon, 1978) that a reduction in light intensity reduced seed oil content. The present experiments were planned to study further the relation between plant population, canopy density and pod shading on yield of seed and on oil content. MATERIALS AND METHODSThe work was conducted at the experimental field unit of the Plant Science Laboratories, University of Reading. Experiments 1 and 2 were established in field plots, Expt 3 was conducted on pot-grown plants in the open and Expt 4 on pot-grown plants in an unheated glasshouse. The material was grown and recorded during the 1976 and 1977 growing seasons. The techniques used for determining oil content in seeds have already been described by McGibbon (1978). Experiment 1. Three populations were sown at 6, 25 and 100 seeds per m 2 according to a randomized block design in the field. Plots at the highest densities were divided on day 45, after anthesis of the first flower on the primary raceme, into two sub-plots in which plants (a) were allowed to develop normally to maturity, or (b) had the axillary branches held away from the plant 28.

Genotypic variation of seed yield and architectural traits in dwarf autumn-sown white lupin

“…McGibbon and Williams (1980) (Huyghe, 1993). Dwarfism did not modify this relationship (Huyghe, personal communication).…”

“…In white lupins, relationships between characters related to plant architecture and growth, have been observed by McGibbon and Williams (1980) and Huyghe et al (1994b). McGibbon and Williams (1980) (Huyghe, 1993).…”

An analysis of yield components of Lupinus albus L.

“…A number of authors have already noted in the lupin genus the existence of intraplant competition between the first order and subsequent higher order laterals (McGibbon & Williams, 1980;Porter, 1982;Downes & Gladstones, 1984). It is recognized that in some cases the pod set in the first order is restricted by the emergence of the higher order laterals.…”

“…This is followed by the formation of lateral branches in successive orders, with each lateral branch arising from a vegetative node situated below the terminal raceme. This type of architecture provides the lupin genus with an enormous adaptability to constraints placed on plants by climate and population density (Perry & Poole, 1975;McGibbon & Williams, 1980). Whithers (1984) considers plant components which contribute most to yield to be the number of pods per plant and the number of plants or fertile branches per unit area.…”