The nutritional and hormonal studies on pineapple

Abstract

Amongst the three varieties of pineapple - Giant Kew, Queen and Jaldhoop which are mostly cul-tivated in Assam, the former is reported to be superior to the other two varieties. The agroclimatic condition of Assam is best suited to the pineapple cultivation but because of the lack of scientific nutritional study the yield potentiality of this crop is not satisfactory. The present investigation was therefore launched with a view to improve this variety of pi-neapple through proper scientific nutritional study. The duration of time required for the investigation was over three years and a half (1971-74). The first aim of this study was to examine the effect of nitrogen, phosphorus, potassium and lime singly; the second aim was followed by the studies of the joint effect of nitrogen, phosphorus and potassium in double combination viz- nitrogen - phosphorus (NxP), nitrogen - potassium (NxK) and phosphorus - potassium (PxK) and in the third attempt, the joint effect of these three major elements in triple combination (NxPxK) was studied. The rate of nitrogen used in all these three cases was 0,6,12 and 18 g/plant. Phosphorus as p2o5 at the rate of 0,3,6 and 9 g/plant and potassium as K2o at 0,8,16 and 24 g/plant were applied. The dose of lime was kept at 0,80,160 and 240 g/plant. The forms of nitrogen, phosphorus, potassium and lime were ammo-nium sulphate, superphosphate, muriate of potash and calcium carbonate respectively. The results of the present investigation indicate that when these fertilizers were used alone, nitrogen significantly promoted the height and leaf number of the plants and weight and size of the fruits. Nitrogen also increased flowering percentage and hastened flowering and fruits ripening. Phosphorus and potassium on these scores were found to be not so much effective. Nitrogen decreased and potassium increased both sugar and acid contents of the fruits without effecting their vitamin C contents. Fruits quality was not altered due to application of phosphorus. Lime application was found not...