Growth and competition studies with snap beans (Phaseolus vulgaris L.) : a thesis presented in partial fulfilment of the requirements for a Master of Horticultural Science at Massey University

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Massey University
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Overseas work suggests that substantial yield increases can occur when the density is increased and the rectangularity is changed to unity. Two trials were carried out to examine some effects of growing snap beans at four densities. The R.G.R. fell with time until pod swell where it showed a slight increase and then fell again. The N.A.R. followed a similar pattern whereas the L.A.R. increased and then fell earlier than either the N.A.R. or the R.G.R., indicating the dependence of the R.G.R. on the N.A.R. The L.A.R. appears to be dependent on the L.W.R. component rather than the S.L.A. component. Fertilizer had no effect on the R.G.R. or the N.A.R. As the level of fertilizer increases, the S.L.A. decreases and the L.W.R. increases, indicating that more leaves are produced and the leaves are 'thicker'. Both the L.W.R. and the L.A.R. are maintained at a higher level with increasing amounts of fertilizer. As density increases, the R.G.R., N.A.R. and L.W.R. fall whereas the L.A.R., S.L.A. and L.A.I. all increase. This shows that at the higher densities, more leaves are produced but they are less efficient at producing and/or utilizing assimilates. As density increases, the maturity of the beans tend to be delayed, yield/plant at high density is decreased through fewer flowers/plant, higher flower and pod abortion rate and a lower bean weight, all probably due to the lower N.A.R. There is also a negative correlation between the number of pods and pod size. The recipricol yield density relationships showed fertilizer to have no effect on the A and B parameters for either total plant dry matter or bean dry matter. The allometric log plant weight to log bean weight showed the ratio of beans to total plant weight decreases with increasing density. Fertilizer had no effect on the yield of beans. Density was also shown to have no effect on the yield of beans when the yields were compared at the same seed length. When yields were compared at the same chronological time, density did have an effect. The mean mature bean yield was 13.95 tonnes/ha but the mean harvestable yield was 18.6 tonnes/ha.
Kidney bean, Growth