FERTILIZER STUDIES WITH PINEAPPLES IN PUERTO RICO

Abstract

1. If pineapple plants become even slightly chlorotic during the growing period or the early part of the fruiting period a reduced yield results. 2. The plants in areas where there is a tendency for chlorosis to occur should be sprayed with iron sulphate sprays as diligently and regularly as applications of fertilizers are made. 3. The phosphates as used at the present time can be reduced to 50 lbs. P₂O₅ or less per acre without affecting the yield greatly. 4. Ammonia nitrogen seemed to be better than the nitrate form to prevent the chlorotic condition in the Manatí field. 5. Slip production and yield of fruit aie both favored by vigorous plants so that if one is increased the other will be increased also. 6. There was no observable effect of fertilizer treatment on "macho" production. 7. Forcing strong plants to early maturity with carbide treatments is a profitable procedure. 8. The relative sizes of pineapples can be predicted fairly accurately by measuring the sizes of the flower stalks only if all the plants in question had the same treatments and growing conditions. 9. If potash is omitted from the fertilizer the quality of the pineapples is poorer judged by acidity, sugar concentration and taste. 10. The keeping qualities of the fruits were not affected by high or low applications of any of the nutrients tried. 11. A favorable fertilizer treatment caused increases in the sizes of both the smaller and the larger fruits proportionally. 13. Applications of lime to raise the pH values of the soil to approximately 5.0 seemed to favor increased yields of pineapples in both experimental fields. 13. If pineapples are allowed to mature naturally those yielding the largest fruits tend to mature the earliest. 14. Applications of small amounts of magnesium tended to favor increased production in both experimental fields. 15. Gum formation on the fruits was not obviously affected by any of the fertilizer treatments used. 16. Nitrogen and potash applications as used gave significant increases in 11 out of 14 cases above those not receiving these fertilizers.