Nutrient Distribution and Requirement of ‘Forelle’ Pear Trees on Two Rootstocks

Abstract

Accurate water and fertilizer management are essential in modern high intensity orchard systems to enable the manipulation of both reproductive and vegetative development. Studies have been conducted to establish the annual plant fertilization requirements, of several tree crops but there exists little information regarding the requirements of pear trees on rootstocks of differing vigour. Nineyear-old 'Forelle' pear trees in a commercial orchard on either vigorous, BP1 or dwarfing, Quince A (QA) rootstocks were completely removed from the soil and divided into various tree parts (roots, stems, leaves, shoots and fruit), each part massed, milled and a mineral analysis conducted. Annual requirements of the nineyear-old trees for macro-(N, P, K, Ca and Mg) and micro-elements (Mn, Fe, Cu, Zn, B) were determined by calculating losses and fixation and their requirements expressed in g or mg element/kg yield respectively. 'Forelle' on the more vigorous BP1 shows higher requirements than the more dwarfing QA rootstock mainly because of the higher mass of summer and winter wood removed as prunings as well as a higher mass of young shoots. From these results, and with due consideration given to various production differences, annual minimum and maximum fertilization guidelines based on the yield have been determined.

Macro and micro element requirements of young and bearing apple trees under drip fertigation

“…Corresponding maximum losses were 7.8, 32.6, 1.1, 6.5, 7.6 and 0.3 mg kg -1 yield. The S3 tree B requirements of 5.7 mg kg -1 (minimum) and 7.6 mg kg -1 (maximum) in the present study were comparable to the B requirement findings by Stassen & North (2005) of 5.8 mg kg -1 (minimum) and 7.0 mg kg -1 (maximum) in the 9-year-old 'Forelle' pear on Quince A rootstock.…”

“…The present findings of 0.4 (maximum) to 0.2 (minimum) g Mg kg -1 compare favourably with the Mg requirements of 'Forelle' pear on Quince A which, according to Stassen and North (2005) range from 0.37 to 0.33 g kg -1 .…”

“…Amounts of mineral elements present in trees at different stages of the season, and their seasonal uptake patterns are most reliably quantified by sequentially excavating trees and determining the mass and mineral concentrations of their component parts (Weinbaum et al, 2001). Such studies have been conducted with peach (Stassen et al, 1981a;Stassen et al, 1981b;Stassen et al, 1983;Stassen, 1987;Krige & Stassen, 2008), apple (Batjer et al,1952;Terblanche, 1972;Haynes & Goh, 1980), pear (Stassen & North, 2005), pistachio (Rosecrance et al, 1996), mango (Stassen et al, 1997;1999) and grapevines (Conradie, 1980;1981).…”

“…Total nutrient application rates for seasons one (S1, 2003/04), two (S2, 2004/05) and three (S3, 2005/06) (Table 1) were based on pear data (Stassen & North, 2005), adjusted for apples according to apple industry guidelines, leaf and soil analysis and orchard observations. Changing total nutrient application rates over the first three seasons is routinely carried out to promote rapid growth and infilling in S1 and to continue the growth phase through S2, whilst making provision for the first harvest in S3.…”

Photosynthetic capacity and diurnal gas exchange of ‘Brookfield Gala’ apple leaves under three irrigation systems

“…Each rootstock was randomly allocated in each system in each of the eight blocks. Earlier work by Stassen and North (2005) studied the annual nutritional requirements for pear trees. The guidelines developed from this study were adopted with minor amendments and the nutrients were applied in instalments distributed throughout the year based on the phenological stage of the tree.…”