Research
Fruit selection
IAD monitoring for harvest prediction date should start at least 4 – 5 weeks prior to harvest and be performed at least weekly . It is important to find the IAD values corresponding to pre-climacteric , on-set of climacteric and post-climacteric fruit development . This will ensure the identification of fruit at high IAD values , corresponding to fruit not producing ethylene ( Pre-climacteric ). Fruit selection should continue as the IAD values decrease with at least 5 fruit for each 0.1 IAD increment ( i . e . 0.80 and 0.89 would be placed in the 0.8 group ) until fruit between IAD values of 1.7 to 0.2 are measured for ethylene production . This should result in a minimum of 75 fruit sampled for ethylene . It is important that fruit are free from any blemish , wounds , disease , pest damage or bruise as it will affect ethylene production rate . The 5 fruit for each 0.1 IAD increment do not have to be collected on the same day but can be spread across sampling times . It is most important that a minimum of 5 fruit are collected for each 0.1 IAD increment .
It is possible to sample more than one cultivar at the same time but the samples must be correctly labelled for each cultivar and IAD value . Sampling more than one cultivar at a time does not increase the overall time commitment by much but it increases the number of
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The DA meter is an innovative instrument for non-destructively determining a fruit maturity index by measuring the decline in chlorophyll content immediately below the skin during ripening .
It is possible to sample more than one cultivar at the same time but the samples must be correctly labelled for each cultivar and IAD value .
" chambers to be used at each single time or it requires multiple samplings with a fixed number of chambers to be able to collect from 5 fruit in each 0.1 IAD group .
Fruit selection can be performed in two ways :
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Harvest minimum of 100 fruit at random into cardboard trays with single fruit liners to separate fruit and minimise bruising ; fruit should be collected at shoulder height and from multiple trees , usually no more that 8 – 10 fruit / tree . Measure and write the IAD value on each fruit with a permanent marker . Segregate the fruit in groups within the same 0.1 of IAD increments with a minimum of 5 fruit for each increment from 1.7 to 0 .
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Measure fruit with the DA-Meter on the tree . Write the IAD value on the fruit with a permanent marker . Select a minimum of 100 random fruit at shoulder height and from multiple trees , usually no more that 8 – 10 fruit / tree . Harvest the fruit that will be needed to segregate the fruit in groups within the same 0.1 of IAD increments with a minimum of 5 fruit in each group ( from 1.7 to 0.2 ) and place them in cardboard trays with single fruit liners to separate fruit and minimise bruising .
Ethylene sampling steps
1 . Print or have sample record sheet on computer / tablet open and ready to edit . 2 . Label the fruit numerically ( e . g . 1 – 20 ). 3 . Record the IAD , the weight of each fruit and the volume of the chamber in which the fruit goes .
4 . Place each fruit into its allocated chamber . Seal all the chambers at once and record the time , in hours and minutes . A chamber with no fruit in it should also be sealed at this time to determine if there are any background ethylene contaminations that will affect the results .
5 . The chambers should be left for 3 to 4 h in the shade
38 Australian Stonefruit Grower | august 2016 summerfruit . com . au