INTRODUCTION Pinus roxburghii Sargent (Chir pine or long needle pine), is one of the most important conifers of north-western Himalayas and is an important timber and resin yielding species (Rawat et al., 2014). The genus Pinus contains 110 to 120 species that are found in the Northern Hemisphere's temperate regions (Price et al., 1998), Pinus roxburghii Sargent, Pinus wallichiana Jackson, Pinus gerardiana Wall., Pinus kesiya Royleex Gord, and Pinus armandi French are the five pines native to India. Pinus roxburghii Sargent, for example, is one of the Himalayan region's most principal conifers, is commercially harvested for resin (CSIR, 1969) and influences the lives of various ethnic and other groups in the region. (Tiwari, 1994). Pinus roxburghii Sargent, also known as ‘Chir-pine; Chir; Chil,' belongs to the Pinaceae. Chir pine covers 14,356 km2 in the country's forests, where it is the most common species and accounts for more than 25 per cent of the total of the order Coniferales. It is distributed in the monsoon belt of the outer Himalaya from Arunachal Pradesh in India to north-western parts of Pakistan (Bhat et al., 2016). Its bark is red-brown in colour and grows thick, deeply and longitudinally fissured andit reaches up to height of 55 m and over 100 cm diameter at breast height (Ghildiyal et al., 2010). Among the many uses of Chir pine, one of the most common non-wood products is oleoresin, which is primarily obtained from it. Oleoresin is the mixture of two components i.e. volatile turpentine oil and solid transparent material (Chauhan et al., 2022). The process of acquiring of resin is called as resin tapping (Hadiyane et al., 2015). Earlier, India used to export resin, but now consumes all its production internally through its small- and large-scale industries. With the increase in day by demand of oleoresin, the dependency on the clones has increased significantly because the oleoresin production from natural stands is insufficient to meet the basic requirement of the resin-based industries (Dutt et al., 2019). To reduce the gap between the demand and supply it has now become necessary to identify superior progenies or clones through breeding programmes such as half-sib progeny evaluation. Therefore, this research was conducted at Shilli conservation reserve to evaluate the high resin yielding half sib families of chir pine for oleo-resin yield traits. MATERIALS AND METHODS The experiment was conducted at Shilli conservation reserve, Solan, Himachal Pradesh during 2020-2021 season where a block plantation of high resin yielders from19 seed source of Himachal Pradesh having high oleo resin properties, was established in 1982. Statistical design employed was Randomized Block Design (RBD). The method employed for oleoresin collection was bore hole method as described by Lekha (2002a); Kumar and Sharma (2007) (Plate 1). The Girmit of 1.0-inch diameter was used for drilling holes as described by Lekha (2002b); Kumar and Sharma (2005). The holes were drilled with slight slope towards opening, so that oleoresin drains freely. The chemical stimulants (10% ethephon and 20% H2SO4) were sprayed with the help of spray bottle (Plate 1). The spouts were fixed in the holes tightly. The plastic-bags made of high-density polyethylene (HDPE) were attached to the spout of each hole with the help of tie for collection of oleoresins and replaced only when filled with oleoresin during the period of tapping (Plate 2). Analysis of oleoresin was done by recording various parameters like oleoresin color, turpentine content, rosin content and rosin color. Turpentine is semi fluid substances obtained by distillation of resin while rosin is solid form of resin obtained from pines mostly conifers. Oleoresin yield was also calculated from different half sib families of chir pine. On the basis of color, oleoresin and rosin was categorized into three colors i.e. yellow, yellowish white and white. Twenty-five gram of oleoresin sample was taken in 1000 ml round bottom flask and 250 ml of water was added to it. The flask was fixed to Clevenger's apparatus and was heated with frequent agitation, until abolition commenced, heating was continued for about an hour and after cooling for at least 5 minutes the volumes of turpentine in the graduated portion of tube was noted. The distillation was continued until successive readings of the volume of turpentine did not differ (Persad, 1983). Turpentine content was extracted from oleoresin by using Clevenger’s apparatus and calculated by the formula given below: Turpentine per cent (ml/g) = X /25 ×100 X = volume of turpentine in ml Rosin content was calculated by using the formula given by Sharma (1987): Rosin per cent = Y/25 ×100 Where Y = Weight of rosin in g 25 = Weight of sample in g The data were statistically analyzed using software OPSTAT (Sheoran et al., 1998). RESULTS AND DISCUSSION Oleoresin Yield. The data on oleoresin yield from various families is shown in Table 1 and Fig. 1. The average oleoresin yield was found to be 430.97 g. The highest oleoresin yield, 780.8 g, was found in the Hamirpur (T14) family. The Jassi (T5) family had the lowest oleoresin yield of 251 g. Oleoresin yield is hereditary and it depends upon the genetics of tree species (Papajiannopoulos, 2002). Environmental factors like light, temperature and moisture status of tree (Dudareva et al., 2004). Highest oleoresin is reported in Hamirpur family because of their greater diameter. Trees having dark green needle colour have highest oleoresin yield. Similar results were reported by Chaudhari et al. (1992); Murtem (1998). Turpentine Content. Table 1 shows the data for the turpentine content of 19 half sib families. The turpentine content of oleoresin ranged from 19.45 (%) to 25.4 (%). Hamirpur (T14) family 25.4 (%) had the greatest proportion of turpentine content. For the Mahasu (T18) family, a minimum value of 19.10(%) was obtained. Turpentine content is related with oleoresin yield, it means if oleoresin yield of a tree species in high its turpentine content is automatically high. Similar result is reported by Sukarno et al. (2015a); Sukarno et al. (2020b) in Pinus merkusii. Rosin Content. Rosin content of oleoresin of different half sib families was shown in Table 1. The Mahasu (T18) family had the highest rosin content 78.60(%), while the Hamirpur (T14) family had the lowest 72.68(%). Mahasu family have higher rosin content because of its greater needle length. Similar result was reported by Bhatt (2015); Sharma et al. (2015) in Pinus roxburghii. Oleoresin Content. The data related to oleoresin colour are presented in Table 2. It was observed that 38 genotype possessed yellow (13 B) coloured oleoresin, 29 genotype possessed yellowish white (10B) coloured oleoresin and 28 genotype possessed only white (155 A & B) coloured oleoresin. The trees with yellow (13 B) colour oleoresin are found to be higher yielder, followed by trees with white (155A& B) colour oleoresin have been observed to be low yielder. The low oleoresin yield of white coloured oleoresin families may be attributable to genetic constitution of families and can operate as an oleoresin yield indicator. Similar work has been reported by Sikarwar (2011) in Pinus roxburghii Sargent. Maximum percentage of rosin was observed in Mahasu (T18) family (78.6%) while the Hamirpur (T14) origin had the minimum rosin content. Hamirpur (T14) family 25.4 (%) had the greatest proportion of turpentine content. For the Mahasu (T18) family, a minimum value of 19.10(%) was obtained.