Intra specific variation in needle colour morphotypes and resin yield determination in Pinus roxburghii Sargent

Abstract

newline xii newlineABSTRACT newlinePinus roxburghii Sargent is a dominant species of mid to high Himalayas, withstands harsh and xeric conditions because of its phenotypic plasticity. The crown of this species displays two morphotypes i.e. dark green and light green which may be attributed either because of environment or genetic cause or both. This species is of great economic importance due to its multipurpose uses especially resin and timber. Hence, the present investigation is carried out on its two morphotypes for identifying the superior natural stands yielding quality timber and high resin yield. newlineHimachal Pradesh constitutes the study area for sampling, which was divided into three provenances according to latitude (30°-31°N, 31°-32°N, 32°-33°N) representing three sample sites. Each provenance was further divided into three altitudinal clines i.e. (upto1000 m, 1000 -1500 m, 1500-2000 m). From each altitudinal cline the research material (needles, cones and seeds) was collected from three trees representing two morphotypes (dark green and light green). The morphological, anatomical and physiological traits were studied. For evaluation of genetic diversity RAPD technique was used. Seeds collected were sown (in the university nursery) for evaluation of juvenile studies. newlineAnalysis reflected statistically significant differences with altitudinal and latitudinal clines and needle colour. Morphological characters like needles, cones and seeds were observed to be maximum in higher (1500-2000m) and mid hills (1000-1500m). The anatomical (stomatal number, number of resin ducts), physiological characters (chlorophyll content) and oleoresin were found to be higher in high hills (1500-2000m). Chlorophyll content was recorded maximum in dark-green needle colour trees inferring the reason for dark colour of needles. Significant results were found for juvenile parameters with respect to all the three factors. Highly significant and positive genotypic and phenotypic correlation coefficients, heritability were observed for different characteristics. Genetic diversity at molecular level using RAPD assay showed close relationship and low differentiation. newlineThe results revealed that mid and high Himalayas are the natural abode of this pine and its phenotypic diversity is maintained through its genetic plasticity. The species shows luxuriant growth in high hills indicating the descent of species from upper to newlinexiii newlinelow hills from the cold Central Asian and Eurasian habitats immediately after the emergence of Himalayas but before the appearance of flowering plants. newlineKeywords: Altitude, latitude, needle colour, needles, cones, seeds, DNA, oleoresin, seedling, P. roxburghii.