Effect of Rootstock, Mulching and Nitrogen Application on Growth, Development, Yield and Fruit Quality of 'Forelle' Pear

Most commercial pear cultivars in South Africa (SA) are established on semi-vigorous BP1 (Pyrus communis L.) rootstocks, but in modern higher density orchards more dwarfing and precocious Quince A (QA) (Cydonia oblonga L.) rootstocks are gaining in importance. Water and fertilization management appropriate for the rootstock induced characteristics is essential especially in the prevailing hot dry summers. Either 60, 120 or 180 g/tree of limestone ammonium nitrate (LAN) were applied in (either) three, six or twelve annual applications to mulched or non-mulched 'Forelle' pear trees on both BP1 or QA rootstocks for five seasons. There was little difference in tree vigour, QA had better shoot development and fruit set, but mulching promoted growth, development and production more in BP1. Mulched BP1 and QA were more vigorous (16 and 6%, respectively) with a better (44 and 26%, respectively) fruit set. Mulched BP1 had a 28% higher yield, but mulching had less effect on QA yield. Mulching both rootstocks tended to result in larger, more blushed fruit with higher total soluble solids (TSS). For BP1 the annual application of 180 g LAN/tree (applied monthly) provided the best response, while for QA the best treatment was 60 g LAN/tree applied monthly.