GROWTH OF ANANAS COMOSUS (L.) MERR. AT DIFFERENT LEVELS OF MINERAL NUTRITION UNDER GREENHOUSE AND FIELD CONDITIONS. I. PLANT AND FRUIT WEIGHTS AND ABSORPTION OF NITRATE AND POTASSIUM AT DIFFERENT GROWTH INTERVALS

Abstract

Increasing N in association with K or Ca increased the wts. of the leaves and stem. K increased stem wts. more than Ca. Root growth, especially length rather than number of roots, increased more with low N. Also, root wts. as % of total plant wts. were higher in low N cultures. Plants supplied with high N and Ca produced fruits at the regular season. Many plants with high'' NO3 and K, failing to undergo floral differentiation, continued in the vegetative stage from 3 to 6 mos. thereafter. K and NO3 intakes by plants was correlated with the concns. of same in the nutrient soln. Equi-ionic rations of K to NO3 absorbed by the different cultures ranged from 2.63 to 0.73. High Ca concns. interfered less with the absorption of K than high K concns. with Ca. NO3 concns. in the stem and in the non-chlorophyllous basal tissues of the leaves increased in proportion to the concns. in the substratum. Root wts. (as % of total plant wts.) and NO3 concns. showing descending gradients with advancing plant age, suggest that the decline in the NO3 concns. might have resulted from dilution in larger volumes of aerial plant tissues due to the decreasing root to plant wt. ratios.