The Effects of Plant Spacing on The Yield of Bulb Onions (Allium Cep AL.) Grown from Seed

Abstract

The yield results of six field experiments with bulb onions are presented and it is concluded that : (1) The total yield of ripe bulbs increased with increasing number of plants per sq. ft. until an optimum was reached and thereafter the yield declined.(2) At the optimum plant densities for total yield the bulbs were too small for normal market purposes but were of a suitable size for pickling whole.(3) Some varieties of onion would not produce large bulbs even when grown at low plant densities; thus the choice of varieties for ware bulb production is of paramount importance.(4) The fitting of a mathematic model to the density/yield data showed that if varieties were ranked for yield at anyone plant density this ranking would remain the same at all other plant densities. Absolute yield differences between varieties were, however, greatest at low plant densities.(5) Decreasing the distance between rows at a given plant density increased the total yield of bulbs. At 7 plants per sq. ft., a density suitable for commercial dry bulb production, reducing the row spacing from 18 in. to 9-12 in. increased yield by 10 to 30%.