Studies in Mineral Nutrition of Indian Forest Species. II. Effect of Deficiency of Macro-nutrients on Rate of Dry Matter Accumulation in Salmalia malabarica Schott. and Endl. Under Varying Light Conditions

Fifty-five day old seedlings of Salmalia malabarica were transferred under three light conditions; (1) Long Day (LD); (2) Normal day (ND); and (3) Light of low intensity,-and were divided into eight lots each. One lot received solution deficient in all major elements. The second lot received solution complete in all nutrients and served as control. Of the remaining six lots each received nutrient solution deficient in one of the macro-elements-N, P, K, Ca, Mg or S respectively. Periodical samples were taken for fresh and dry weight determinations. The relative rates of growth of the whole plant and individual parts were calculated from dry weight data. Whole plant-, stem-, petiole-and leaf weights are more under LD condition. Stem and petiole weights do not increase under ND but increase progressively under LD condition. The leaf weight rises during early stages land then declines under both the photoperiods. The decline occurs earlier in ND plants. Long days, thus, prolong the period through which dry matter accumulation takes place. The rate of growth of individual plant parts is also higher under LD than under ND condition except in ischolar_main where it is higher under ND during the earliear stages of growth. Macro-nutrient deficiencies lower the fresh and dry weights of the whole plant and individual parts. There is hardly any increase in weight upder N deficiency and only slight under deficiencies of P and K. The weights increase appreciably under deficiencies of Ca, Mg and S, although these remain lower than the controls. The increase in weight under S deficiency takes place during the earlier stags only and then falls rapidly. The differences in the dry weights are due to the effect of the deficiencies of these elements on the rate of accumulation of dry matter in these parts. The results are discussed in the light of few other investigations on forest species, available in literature.