The effect of plant density, harvest date and method on the yield of seed and components of yield of parsnip (Pastinaca sativa)

Abstract

SUMMARYExperiments conducted over four years (1980–1983) with parsnip cv. Avonre‐sister examined the effects of plant density, harvest date and method on seed yield and the components of yield. In 1980, using the root‐to‐seed method, the yield of seed increased by 50% for an increase in plant density from 5.6 to 35 plants m‐2; the maximum yield at the optimum harvest date was 3015 kg h‐1. In the other three years, using the seed‐to‐seed method, seed yield increased to a maximum with an increase in plant density from c. 1 to 10 plants m‐2 but at higher densities yields were lower. At c. 10 plants m‐2, seed yields were 1567, 4029 and 1040 kg ha‐1, in 1981, 1982 and 1983, respectively, when harvested at the optimum time. An increase in plant density increased the number of non‐seeding plants in the population, reduced the number of umbels per plant and reduced the number of seeds per umbel. Mean seed weight was, in general, unaffected by plant density and so effects of density on yield reflected changes in seed numbers. Increasing the plant density increased the proportion of primary‐umbel seed. Maximum yields of seed were obtained from crops harvested at a seed‐moisture content of 50 to 70%, which occurred 46 ± 2·4 days after flowering. Delay in harvesting after this date led to a loss of yield of 33, 35, 139 and 32 kg ha‐1wk‐1 in 1980, 1981, 1982 and 1983, respectively. Plants cut, placed in the windrow to dry and then threshed gave similar yields to those harvested at the same time but dried in bins.