The Nitrogen, Phosphorus and Potassium Requirements of Tomatoes Grown in Pots and in the Soil in Unheated Plastic Greenhouses in Cyprus

Abstract

SummaryTomatoes were grown in unheated plastic greenhouses in the soil or in 10–1 pots filled with two soils. Plants grown in pots had 18% lower yields than those grown direct in the soil. Soil-grown plants barely responded to N and K fertilizer because of residual soil N and K. The K requirement was less than the amount of K removed in the fruit. The fertilizer requirement of pot-grown plants producing 7 kg of tomatoes was 17 g थ, 4 g ऩ and 10 g ढ per plant. Maximum yields of pot-grown plants were associated with 4% N, 0.27% ऩ and 2.8% K in the leaves. Despite the low K status, fruit quality was acceptable, possibly due to the salinity of the irrigation water. In one experiment pot-grown plants received all their N as ammonium sulphate without obvious damage. The lower yield of pot-grown plants was attributed to water stress, since there was no response to increased application of N, P and K, but growing in pots filled with a sandy-loam soil appears to be commercially feasible.