Quality and quantity of chemically-thinned and hand-thinned pear fruit ( Pyrus communis L.) cv. 'Conference'

Summary The influence of chemical and hand thinning on the quality and quantity of pear fruit ( Pyrus communis L.) form the cv. 'Conference' was investigated at Pirsenbreg (Slovenia) in 2005, 2006 and 2007. The experiment included these four treatments: chemical thinning with NAA 8 mg l -1 , hand thinning 0.8 fruits cm -2 of trunk cross sectional area (TCSA), hand thinning 0.5 fruits cm -2 of TCSA and control in 2005. Because thinning with NAA 8 mg l -1 was insufficient, an additional treatment with NAA at 16 mg l -1 (NAA 16) was performed in 2006, and NAA at 20 mg l -1 (NAA 20) in 2007. Hand thinning 0.8 or 0.5 fruits cm -2 TCSA had no influence on floral density, yield efficiency or soluble solids content. Hand thinning did produce a statistically significant increase in fruit diameter and fruit weight in 2005 and 2007. Chemical thinning had a minor influence on fruit dimension (diameter, length, and weight), because the differences between control and individual chemical thinning treatments were insignificant. Chemical thinning by NAA of fruit on trees was insufficient. In 2005, we noticed a higher and statistically significant amount of soluble solids in the fruit of trees thinned with NAA 8 mg l -1 . Chemical thinning with NAA 8 mg l -1 had no influence on fruit firmness in 2005, while in 2006 and 2007 fruit firmness was higher than in the control. Chemical thinning had no negative effect on floral density, number of fruit per tree, fruit set, yield per tree, yield efficiency, crop load or total acids content.