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.