ISSN: 0041-3216 (Online), 0041-3216 (Print)
Volume 52 Number 2
Effect of N, P and K rates on response of cabbage and tomato grown on a coastal clay soil of Guyana*
During the 1972 summer rainy season and 1972-73 winter rainy sea on, experiments were conducted to evaluate effects of P and K rate on cabbage and tomato. In both seasons and for both crops increments in rate of N caused linear yield increases, 'OS -cross' cabbage being more responsive than 'KK-cross' cabbage. In the summer season, yields of 'OS-cross' increased from 13·1 to 26·8t/ha when was increased from 56 to 224kg/ha while the 'KK-cross yield increased from 21·9 to 32·0t/ha. Head size of both cabbage cultivars was also increased by rate. The percentage of plants which formed marketable heads was greater for 'KK-cross' cabbage and was not affected by treatments, but 'OS -cross' formed more marketable heads at the higher rates of N. Yields of 'OS-cross' were also increased by increased rates of K from zero to 112kg/ha. For both cabbage cultivars, interactions between and K rates on yield were significant. Responses to increased rates of applied K were not significant at N rates of 56kg/ha, but were so at higher rates of applied N. Yield and size of tomato fruits were increased by higher rates of N. Although K rate had no effect on fruit size, yield were higher at the highest K rate in both seasons. Interactions between the rates of N and K, and N and P on tomato yields occurred in both seasons. The incidence of blossom-end rot (BER) was 24·3 per cent in the summer and 26·5 per cent in the winter season. In both seasons, losses from BER increased linearly with rate increments. N, P and K contents of the foliage increased with the application rate of the respective elements. In general, the concentration of P and Ca in tomato foliage was less than adequate for normal growth. Foliar contents of Ca were reduced at higher rates of and were negatively correlated with the severity of BER. Foliar concentrations of N, K, Mg, Cu Fe, Mn and Zn were adequate for the normal growth of tomato plants.