BHARDWAJ, D RKAUR, AMANPREET2022-01-072022-01-072021-12https://krishikosh.egranth.ac.in/handle/1/5810180481ABSTRACT The present study entitled “Reproductive behaviour of Pinus wallichiana (A.B. Jacks) along an altitudinal gradient in the North Western Himalaya” was carried out in the Department of Silviculture and agroforestry, Dr.YSP University of Horticulture and Forestry, Nauni Soaln (HP) during 2019-2021 with the objectives to determine morphological, physiological and reproductive traits of Pinus wallichiana on the germination and growth behavior of the seedlings. The samples were collected from different altitude ranges: 1800-2100 m a.s.l. (A1), 2100-2400 m a.s.l. (A2), 2400-2700 m a.s.l. (A3) and >2700 m a.s.l. (A4) and three aspects: southern (As1), eastern (As2) and south-eastern (As3) aspect from the representative population of the P. wallichiana. On the basis of outer appearances, the higher proportion of leaf shedding (49.6 %), dead branches (51.8 %) and the foliage discoloration (21.4 %) recorded in the uppermost altitudinal range. Apical shoot of Pinus wallichiana were more severe at higher altitudinal ranges and declined towards the decreasing altitudinal ranges. Where, the minimum leaf shedding (33.7 %) and dead branches (37.4 %) and foliage discoloration (17.1%) showed at lower range of P. wallichiana. However, among aspects minimum leaf shedding (39.6 %) and dead branches (40.8 %) were in south-eastern aspect and foliage discoloration (17.3 %) in southern aspect where the stress condition index (SCI) values were low. The biochemical attributes in needles and seedlings of Pinus wallichiana, the total nitrogen, carbon, chlorophyll, sugar and starch content were found higher in both needles and seedlings at lowermost elevation range on southern aspect. Whereas, total phenol content increased along with increasing altitudinal ranges and recorded maximum in value at uppermost altitude. The total nitrogen, total carbon, chlorophyll and sugar or starch content decreased with increasing altitudinal ranges in both tree needles and seedlings. The sugar and starch content in seeds recorded maximum at lowermost altitudinal range on southern aspect whereas, the maximum total phenol content and moisture percent was found maximum at uppermost distribution range in seeds were collected from southern aspect. In the reproductive traits the highest cone weight (105.8 gm), cone length (18.2 cm), number of scales/cone (139), 100 seeds weight (7.37 gm), number of seeds cone-1 (78.4) and seed weight cone-1 (2.16 gm), seed length (9.67 cm), seed width (5.29 mm), seed thickness (3.29 mm) at A2 while cone width (4.36 cm) at A1, and the minimum at A4 at higher altitudinal range. Among three aspects, all the cone, seed and needle parameter showed maximum value in southern and/or south-eastern aspect. The trees growing at the altitudinal range of 1800-2100 m a.s.l. and 2100- 2400 m a.s.l. which is under least stress displayed better cone development, seed characteristics, increased germinability and seedlings growth characters than those from altitudinal ranges. This study concluded that for better success of P. wallichiana afforestation and reforestation programs, the seeds/cones should be collected from the respective altitude and aspect should be tried at immediately their upper distributional range so as to counter the warming impact and facilitate adaptation processes.EnglishThesis