Summary. The effect of plant density on growth,
development, yield and quality of kabocha (buttercup squash)
(Cucurbita maxima) was examined during 1992–93, at
a field site in Cambridge, Tasmania. Plant densities ranged between 0.5 and
4.7 plants/m2. Marketable and total yields were
fitted to a yield–density model. Total yield followed an asymptotic
trend, approaching 33 t/ha at 4.7 plants/m2,
while marketable yield had a parabolic relationship with density. Marketable
yield increased to a maximum of 18 t/ha at 1.1
plants/m2, while declining at higher densities
because of increased numbers of undersized fruit. Yield of vine marked and
callused fruit did not vary with density, but represented a significant
proportion of the total yield at all densities. High plant density reduced
vegetative growth per plant due to competition for limited resources; as shown
by decreased leaf area, number and length of vines, and plant dry weight.
Yield tended to decline at high densities because of fewer female flowers and
increased fruit abortion per plant. Plants at low densities had more
vegetative growth but decreased yields, as increased abortion of fruit
relative to the higher plant densities left only 1–2 large fruit per
plant. Economic returns varied with plant density. At high densities, variable
costs increased (particularly due to high seed cost) while gross income
declined reflecting the relationship between marketable yield and plant
density. The gross margin therefore declined at high densities.
Effects of plant density on yield and quality of watermelon (Citrullus lanatus thunb) under Gezira conditions, Sudan
