Fruit thinning in ‘Conference’ pear grown under deficit irrigation to optimise yield and to improve tree water status

Abstract

SUMMARYA fruit thinning strategy is introduced for ‘Conference’ pear to mitigate water stress and to maximise yield. Three irrigation and four thinning treatments were applied. The three irrigation treatments were: full irrigation (FI); deficit irrigation, receiving 50% of the water in FI (DI-50); and deficit irrigation receiving 20% of the water in FI (DI-20). The four fruit thinning treatments were: no thinning (NT); light thinning (LT), leaving more than 80% of the crop load; medium thinning (MT) leaving 50% of the crop load; and heavy thinning (HT) leaving 20% of the crop load. All thinning treatments were combined with DI-20, but only NT and MT were combined with FI and DI-50. Fruit thinning improved fruit size in FI and DI-50, but is not recommended because of the high labour cost and reduction in total fresh-market yield. For DI-20, thinning increased the midday stem water potential ( stem), improved yield (with LT), and increased fruit size (with HT). A three-dimensional regression model was developed to optimise fresh-market yield by fruit thinning, and showed the impact of stem. Using the model, it was also possible to choose, for each value of stem, a suitable crop load to maximise the fresh-market yield.