Gill, Mandeep SinghShubhkiran Kaur2019-11-162019-11-162019http://krishikosh.egranth.ac.in/handle/1/5810135475The present investigation entitled “Effect of plant bio-regulators on growth, yield and quality of pear cvs. „Patharnakh‟ and „Punjab Beauty‟” was conducted at Fruit Research Farm, Punjab Agricultural University, Ludhiana during the year 2018-19. Eight years old pear cvs. „Patharnakh‟ and „Punjab Beauty‟ plants trained on the Y-trellis training system were treated with three plant bio-regulators of varying concentrations viz. Pro-Ca (prohexadione calcium)@ 100 mg Lˉ¹ (T1), 200 mg Lˉ¹ (T2), 400 mg Lˉ¹(T3); CCC (chlomequat chloride)@ 250 mg Lˉ¹ (T4), 500 mg Lˉ¹ (T5), 1000 mg Lˉ¹ (T6); PBZ (paclobutrazol) @ 100 mg Lˉ¹ (T7), 250 mg Lˉ¹ (T8), 500 mg Lˉ¹ (T9) and water spray (T10) after 10 days of full bloom through foliar application. Evaluation of data recorded for growth, ecophysiology, fruit yield and quality parameters was done. All the treatments significantly reduced the vegetative growth of pear plants. TCSA (trunk cross-sectional area) of pear plants was significantly reduced by T9 and T3 treatments in „Patharnakh‟ and „Punjab Beauty‟ pear, respectively. Shoot length was reduced by 31.11 % and 17.63 % by treatments T3 and T2 in cvs.. „Patharnakh‟ and Punjab Beauty‟, respectively, along with the significant increase in shoot diameter. T3 treatment significantly reduced the internodal length and spur length was significantly decreased by the T9 and T3 treatments in „Patharnakh‟ and „Punjab Beauty‟ pear, respectively. Plant bio-regulator treatments reduced the leaf area of „Patharnakh‟ and „Punjab Beauty‟ pear by 17.15 % and 23.73 %. Pruning wood weight (PWW) was decreased as a result of reduced shoot length and number of shoots. Ecophysiological parameters viz. PAR (photosynthetic active radiation) and net photosynthesis rate were improved significantly throughout the season. Deduction in canopy size led to improved light penetration and hence, higher photosynthesis. Leaf total chlorophyll (FW) and spur carbohydrate content were enhanced by T3 treatment in both the cultivars. The plant bio-regulator treatment T3 increased fruit number, size and weight contributing to improved yield (up to 36.56 % in „Patharnakh‟ and 33.84 % in „Punjab Beauty‟ pear) and production efficiency. Pedicels of pear fruits were shortened and thickened by T3 treatment in „Patharnakh‟ and by T2 treatment in „Punjab Beauty‟ pear. Fruit firmness, TSS and reducing sugars were significantly improved while the effect on fruit titratable acidity was insignificant. Lowest leaf nitrogen content and highest leaf phosphorus and potassium were recorded in T3 treatment. Pro-Ca@400 mg Lˉ¹ could be considered as best in terms of growth control and improvement in yield, PAR and net photosynthesis rate as well as fruit quality.ennullThesis