N:Ca ratios in the skin of unripe avocado fruit at harvest may provide one of the best indicators of potential postharvest disease in ripe fruit

Field trials evaluating several parameters of growth, fruit yield and quality of ?Hass? avocado grafted to different rootstocks were established in 2004-2005 in four different growing regions of Australia. Fruit were harvested in three seasons from 2008, ripened and assessed for severity and incidence of anthracnose and stem end rot diseases. Peel samples were collected at harvest and analysed for concentration of major cations, N, K, Ca, and Mg. Rootstock significantly affected anthracnose disease development in 42% of the total number of trials evaluated, with better quality fruit harvested from ?Hass? grafted to A10 or Velvick (at most sites) and Zutarno (at Pemberton, WA). Fruit quality was frequently poor from trees grafted to Duke 7, regardless of growing location. Fruit from rootstocks with superior fruit quality was often associated with lower skin N and higher Ca concentrations. This was supported by correlation analyses. There were significant positive correlations between anthracnose and skin N or N:Ca ratio in 75% of trials evaluated. There was a significant negative correlation between anthracnose and Ca in 42% of trials. The correlations between stem end rot and skin N (positive) or Ca (negative) were each significant in 42% of trials. Based on the results in this project, N:Ca ratios in the skin of unripe avocado fruit at harvest may provide one of the best indicators of potential postharvest disease in ripe fruit, and may have implications for fertiliser regimes. The paper shows a selection of data to demonstrate these trends. SourcesROOTSTOCK SELECTION, NITROGEN AND CALCIUM INFLUENCE POSTHARVEST DISEASE IN AVOCADOCoates, L1, Dann, E2, Whiley, A3, Pegg, K1, Dean, J1, Cooke, T1, Smith, L1, Shuey,L1, Hofman, P4, Marques, R4, Stubbings, B4e.dann@uq.edu.au1Department of Agriculture, Fisheries and Forestry, Brisbane, Australia2University of Queensland, Brisbane, Australia3Sunshine Horticultural Services Pty Ltd, Nambour, Australia4Department of Agriculture, Fisheries and Forestry, Nambour, Australia IHC 2014, International Horticulture Congress, 17-22 August 2014, Brisbane,http://www.ihc2014.org/Picture of?anthracnose by ex-sheffield.orgKey wordsAguacate?? ?palta?? ?avocado?? ?avokado?? ?????????? ????? ??? ?avocat?? ??????????? ?????????? ??? ??? ?awokado?? ?abacate?? ?????????? ??? ?avocado ???? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ?Poscosecha?? ?postcosecha?? ?postharvest?? ?na-oes?? ??? ??? ???????? ????? ??? ?post-r?colte?? ????? ?? ??????????? ??? ?na-oogst?? ?post-raccolta?? ?Obr?bka po?? ?p?s-colheita?? ????????????????? ?hasat sonras??? ??? ?Ernte?? ????????????????? ????? ????????????? ?postcollita?? ?poskliz?ov頠 ????? ??? ??? ??? ?nakon branja?? ?pozberov頠 ??? ?obdelovanje zemlje po?? ?post-colleita?? ?????? ??????? ?pascapanen?? ??il?onn postharvest?? ??????? ?p?c ra?as?? ?derliaus apdirbimas po?? ?lepas tuai?? ??? ?? ???????? ?post-recoltare?? ??????? ??????? ???????????????????? ?????????????? ?????????????????? ?sau thu ho?ch?? ?????????????????? ?zangemva kwenkathi yokuvuna