Effect of N and K levels and planting density on pineapple fruit yield and quality

Abstract

A pineapple [Ananas comosus (L) Merr.] field experiment was established in which planting densities and levels of foliarly applied N and K2O  were evaluated. No significant treatment interactions were detected for fruit yield and quality and production of slips and crowns. Increasing plant population from 39,174 to 52,240 and to 67,925 plants/ha resulted in a significant fruit yield increase in the ratoon crop, but had no significant effect on the plant crop. Treatment combinations of N at 336, 560 and 784 kg/ha and K2O at 246, 470 and 694 kg/ha had no significant effect on fruit yield and quality or slip and crown production in the plant crop. A significant reduction in fruit yield was obtained in the ratoon crop at the higher N-K2O levels. The reduction in yield was attributed to salt accumulation on pineapple leaves as a result of foliar spraying, especially from urea. Nitrogen and K2O levels did not significantly affect the production of slips and crowns in the plant crop. The combination of 470 and 417 kg/ha of N and K2O, respectively, produced significantly larger slips and crowns in the ratoon crop. The concentration of N, P, Ca and Mg in the D-leaf was adequate for 4-month-old plants but N and K concentration was below adequate levels in 9-month-old plants, especially at the lower treatment application. In the ratoon crop all plant nutrients were low even at the higher application rates of N and K.