Effects of irrigation management and nitrogen fertilization on the yield and quality of 'Gala' apple
2011
Campi, P. | Garcia, C.
Fertilizers application in irrigation water (Fertigation) is considered to be an efficient method of fertilizing fruit trees, but some information is needed on the relationship between irrigation depth and nitrogen (N). The objective of this work was to know the response of apple tree to different levels of irrigation depth based on maximum crop evapotranspiration (ETc) and N fertilization. The experiment was carried out in 2008-09 summer growing season of apple trees Malus x domestica Borkh ‘Gala’, with a row spacing of 4×1 m (2500 pl. ha-1), seven years old, on the M9 rootstock, in a silt loam soil. The experimental design was split plots with two factors, with four complete randomized blocks. A main plot was irrigation depth according ETc: 0% (only rainfall), 50, 75 and 100% of the ETc, and a submain plot was three N fertilization levels: 0, 110 and 220 kg N ha-1. Soil water content (0-20 cm of soil depth), leaf minerals content (N, P, K, Ca, Mg), trunk section diameter, fruit total number, fruit diameter, weight, colour and firmness were measured. Different leaf mineral contents for N, K and P according irrigation depth were observed at pre-harvest. Nitrogen fertilization, however, only affected the leaf N content. Results indicate that it was a significant differences in yield, fruit diameter and weight response to the supplemental irrigation application. Yield for irrigation at 100% ETc, reached 40 t ha-1 and, for non-irrigation plants 27 t ha-1. Fruit diameters average was 71.53 and 62.69 mm for 100% ETc and non-irrigation treatments, respectively; and there were 70.97 and 67.88 mm for 220 kg N ha-1 and non-nitrogen treatments respectively. The differences in N fertilization on yield and fruit quality variables were not observed. Nitrogen application rates only affected fruit diameter but not yield.
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