K. K. Nanda

Abstract

This paper deals with observations on the growth and flowering behaviour of the main shoot and branches of teak (Tectona grandis, L.f.). Trees growing in close stands have very few branches on their lower part and grow quite tall. On the other hand those growing either singly or on the border show profuse branching and rebranching which gives the tree a broad much branched appearance. The flowering of the main shoot as well as branches is terminal. In close stands flowering occurs only in dominant and co-dominant trees and is confined to the upper parts which are exposed to bright sunlight. There are no inflorescences either on the lower parts of these trees or on those which grow under a thick canopy. Flowering is profuse on all sides in trees which are growing singly. As against this in trees growing on the border of thick stands flowering is confined to the lighted side and is more or less completely absent on the shaded side. These differences in growth and flowering are ascribed to the differences in the intensity of light to which these plants are exposed while growing in different situations. It is shown that the curtailment of light delays not only the initiation of flower buds but also their development into flowers as well as in the production and ripening of fruits. The emergence of branches and their flowering appears to be controlled by factors which are related to ageing or completion of the developmental process of the main shoot or the branch on which these are produced. The first branch emerges from the node immediately below the previous year's inflorescence and the second one from the node next below it and so on. The flowering of these branches also follows the same order. This basipetal sequence in the emergency and flowering is exhibited even by secondary, tertiary, quarternary and further branches. The results are discussed in the light of branching and flowering behaviour of other plants and their practical significance is pointed out.

Full Text

     

K. K. Nanda

Abstract

In spite of the paramount importance of plant physiology and the pivotal position that it occupies amongst various disciplines of forestry,its application in scientific forestry remained a much neglected subject till the Expert Committee on Forest Research Institute and Colleges, Dehra Dun (1956) recommended the establishment of a unit for this work in the expanded Botany Branch of this Institute. A section of Plant Physiology was, thus, started in 1960. This paper deals with a survey of the present status of research in forest tree physiology and its future scope in this country. The survey reveals that the scope for research in forest tree physiology is immense. It is more or less a virgin field. Some of the problems in the solution of which tree physiology can play an important role are indicated. These relate to natural and artificial regeneration of forest species; their water and mineral requirements; the germination, viability, storage and dormancy of their seeds; the proper exploitation of their economic products; their growth and development and the use of auxins in the ischolar_maining of cuttings, in parthenocarpic development of fruits, in abscission of leaves, in pre-mature drop of flowers and fruits, in inducing meristematic activity and as weedicides. The programme of research that is proposed to be followed in the newly started Section of Forest Tree Physiology at this Institute is outlined and results of some of the preliminary experiments that have been conducted since the setting up of the Section are briefly summarized. A suggestion is made that the State Forest Departments should establish wings of plant physiology in their own research units so that problems in forest tree physiology relating to their own soil and climatic conditions may be worked out.

Full Text

     

K. K. Nanda

Abstract

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 complete nutrient solution and served as control. Of the remaining six lots each received nutrient solutions deficient in one of the macroelements - N, P, K, Ca, Mg or S. Periodical records were taken of height; number, size and abscission of leaves and the visual symptoms. The rate of stem elongation was higher and extension growth continued for a longer period under LD than under ND condition. Plants under LD, therefore, were taller than those under NO at all stages of growth. The number and size of leaves was also higher under LD than under ND, while during the earlier stages of growth this higher number was due to the higher rate of production of new leaves, during the later stages it was due mainly to the slower rate of their abscission. Macro-nutrient deficiencies retarded stem growth, production of leaves and their size. The retarding effect was most marked in plants deficient for all major elements and decreased in order in those deficient for N. P, K and S. The deficiencies of Ca or Mg did not affect the growth of these parts to any appreciable extent. The abscission of leaves was more in plants deficient for Mg, P and K than in those deficient for N. In plants deficient for S the abscission of leaves was low and compared favourably with the controls. The deficiencies of different macro-elements caused very distinctive visual symptoms and a key is presented on the basis of these results to help in the diagnosis of deficiency diseases in the field. The differentiating symptoms did not show up under low intensity of light. Plants under this light-condition were weak and died after a few weeks. The deficiency symptoms showed up more distinctly under LD than under ND. This was probably because of the prolonged growing period under this light treatment due to delayed onset of dormancy. The significance of interaction of factors in the study of problems in mineral nutrition of tree species is stressed and the results are discussed in the light of investigations by other workers.

Full Text

     

K. K. Nanda

Abstract

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.

Full Text

     

K. K. Nanda

Abstract

Fifty-five d.y old seedling. of Salmalia malcharica were transferred under three light cOllditions- Long Day (LD); Normal Day (ND) and light of low intensity (LI) - 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-elementsN-, P, K, Ca, Mg, or S respectively. Periodic. I samples were taken for fresh and dry weight determinations. From the data of fresh and dry weights calculations were made of the water content of different plant parts and the net assimilation rates at different stages in the growth of the plant. But for per hour of illumination it is slightly higher in ND plants compared to L.D. plants probably due to low intensity of light used to supplement the normal day. The net assimilation ratc is the highest in plants receiving complete nutrient solution and the lowest in those deficient for all macro-elements. It is slightly higher in those deficient for N, P and K but fairly high in p lants deficient for Ca, mg and S during the earlier stages. Top/ischolar_main dry weight ratio remains higher in LD than ND plants throughout the period of growth. The ratio decreases with Macro-nutrient deficiencies. The decrease is more marked in plants deficient for N than in those d eficient for P and K. In plants deficient for Ca, Mg and S the ratio is bigher than the control as their deficiency results in greater reduction in the dry weight of the ischolar_main than shoot. The accumulation of dry m atter in the ischolar_main is more after the growth of the top slows down. The water content of ischolar_main, stem, petiole and leaf is higher in LD than in ND plants during the earlier stages. Later on, however, it becomes higher in the latter. The water content of roct, stem and petiole shows a fall after 87 days in plants deficient for N, P and K. In the control and in plants deficient for Ca, Mg and S the water content increases and the fall is delayed to 118 days. The water content of leaf does not differ with the nutrient treatments. It ;s considered that the deficiency of either regulatory substance(s) or nutrients limits the production of nucleic acids, as a consequence of which the meristematic activity of the growing apex is arrested. This causes a change in the balance of demand and consequently an alteration in the distribution of metabolites and accumulation of dry matter in different parts of the plant and the mistake of water. The ecological significance of these findings and their application in forestry is discussed.

Full Text

     

K. K. Nanda , A. N. Purohit , Adarsh Bala , V. K. Anand

Abstract

Rooting response of stem cuttings of 35 tree species to different auxins during different seasons was investigated. The results show that (i) Plant species vary markedly in their ability to ischolar_main. Some ischolar_main easily, others with difficulty and still others do not ischolar_main even with auxin application; (ii) Planting season has a pronounced effect on ischolar_maining of cuttings and the effect appears to be correlated with seasonal changes in cambial activity during the annual cycle; and (iii) The effectiveness of auxins on ischolar_maining of cuttings varies with the season. An auxin may stimulate ischolar_maining of a plant species in one season but may inhibit it in other season. Again maximum ischolar_maining of the same plant species may be caused by two different auxins in two different seasons. The results are discussed in the light of available literature on the subject.

Full Text

     

K. K. Nanda , V. K. Anand , Parshotam Kumar

Abstract

This paper deals with the effect of 10 and 100 mg/l each of IAA, IBA, 2,4-D and NAA on seasonal changes in the ischolar_maining response of stem cuttings of forest plants. Anatomical structure of stem and seasonal changes in the mobilization of reserve food materials in a few cases were also studied. Experiment 1 deals with ischolar_maining trials on 102 broad-leaved species at 3-month intervals; experiment 2 on 9 species at 1-month intervals and experiment 3 with stem anatomy of some representative species. It was found that ischolar_maining occurred in 49 species only; on 26 without and 23 with auxin application. Of these 6 ischolar_mained throughout the year; 7 in 3 out of 4 plantings; 12 in two and 21 in one planting only. Stem cuttings of 53 species did not ischolar_main at all. The easy-ischolar_maining species possessed multi-seriate vascular rays opening directly in the cortical region, while shy-ischolar_maining ones possessed a continuous ring of sclerenchyma surrounding the vascular bundles and which probably acted as a barrier to the penetration of water and emergence of ischolar_mains. Stem cuttings of Populus nigra, Hibiscus rosa-sinensis and Ficus infutoria exhibited seasonal changes in ischolar_maining response closely corresponding with changes in starch content; low ischolar_maining corresponding with high and high ischolar_maining with low content of starch. Auxin effects on ischolar_maining are considered to be mediated through their effect on mobilization of starch caused by enhanced activity of hydrolyzing enzymes and is determined by the morpho-physiological status of the branches that govern the production of endogenous auxin.

Full Text