Nutrient management strategies for nectarine orchards

[摘要] ENGLISH ABSTRACT: The macro-element uptake and distribution by higher density central leader'Donnarine' nectarine trees was studied through the sequential excavation of trees. Alarge portion, 41.5%, of the nitrogen manifested in the new growth from dormancy upto pit-hardening, originated from nitrogen reserves in the permanent structure. Thepermanent structure was also an important source of phosphorous reserves. Of thephosphorous in the fruit, leaves and new shoots at pit-hardening, 35.0% came fromreserves in the permanent structure. Potassium did not act as an important reserve inthe nectarine trees and was taken up throughout the season. From pit hardening toharvest the fruit represented the most important sink for potassium. Calcium andmagnesium, like potassium, did not play significant roles as reserves in the nectarinetree and must be available for uptake from the beginning of the season for new growthand development as well as fruit quality.The micro-element uptake and distribution was also studied through the sequentialexcavation of the same 'Donnarine' nectarine trees. Little scientific data is availableon this topic. Manganese and iron was found to act as important reserves in the treewith 46.2% of manganese and 59.5% of the iron found in the new growth at pithardeningcoming from reserves translocated from the permanent structure. Zinc andboron reserves also play a role in nectarine trees, but to a lesser extent thanmanganese and iron.The seasonal mineral nutrient demand of the same 'Donnarine' nectarine trees wasdetermined through the sequential excavation of trees and losses and fixation wascalculated. Guidelines regarding nutritional requirements per ton of fruit produced perhectare by higher density nectarine orchards are respectively 3.82kg nitrogen, 0.35kgphosphorous, 4.43kg potassium, 1.53kg calcium, 0.52kg magnesium, 32.45g sodium,9.44g manganese, 37.46g iron, 3.24g copper, 13.95g zinc and 10.52g boron. Sodiumis not commonly considered to be essential to higher plants, but was included in thetrial.Nutrient solutions with four different EC (electrical conductivity) levels were appliedto 'Donnarine' nectarine trees under pulsating drip fertigation for three periods of different lengths, before harvest. Raising the nutrient solution EC to positively affectfruit quality is a technique widely utilised in the vegetable industry. This techniquedid, however, not have similar positive effects on nectarine fruit grown under apulsating drip fertigation system. Good production practices such as accurate nutritionand irrigation as well as the correct horticultural inputs should be the primary focus ofproducers who wish to alter or improve the fruit quality of their crop.

[发布机构] Stellenbosch University