Preliminary studies of the effects of reflective mulch, shading, training system and rootstock on red colour development were undertaken by a visiting student from Wageningen University in the Netherlands.

Red colour coverage and intensity is critical for marketing these pear cultivars.

Results showed:

  • the reflected radiation from a white material laid in the inter-row is insufficient to increase colour in 'ANP-0131'
  • red colour can be completely lost when fruit is shaded but for much of the season is recovered when fruit is exposed to sunlight
  • fruit towards the top of the canopy is redder but there were no differences between trees trained vertically and in a V system
Visiting student, Iris Visscher from Wageningen University in the Netherlands.

Video transcript

They're all focusing on the red colour developments that I studied in three different ways. The first project was about the reflective effect of reflective mulch on the red colour development. Second experiment was about artificial shading with the leaves. The third one was about the effects of training system and rootstock on the red colour development.

I just go to orchard floor with its reflective mulch after which I measured the colour of the fruits at different heights in the tree to see if there was an effect of the reflective mulch on the colour of the fruit. Colour in the bottom fruits remains lower compared to the fruits higher in the tree and before you can really sell or market your fruit you need a certain amount of red colour coverage, and we wanted to see if the red, if the reflective mulch has an effect on that as well. So, this should make more profit for a growing. We didn't see the effect of the reflective mulch in the periods we use it. It was short after full bloom and until, I guess the first, just before the end December and I did also some life measurements to measure the amount of light which is reflected by the mulch. So, I compared the, because I of course had a control treatment, I just measured a life with the ceptometer, yeah. Upright, forward and downward to see how much light was reflected by the mulch and that's really showing a difference between the control and the reflective mulch, but you don't see the effect of the amount of light reflected. You don’t see it back in the colour because we didn't find any significant difference, but the light measurements really showed there’s a reflection of light into the canopy. We only saw significant difference, differences among the highest, higher fruits that's a significantly higher colour compared to the fruits in a bottom and in the middle of the canopy.

My second project was about effects of artificial shading of the fruits. I did this by use of umbrellas. In this experiment I had six treatments, of course control treatment and five different treatments of shading. One of those was a long period shading so for 12 weeks, a total of 50 weeks the experimental running and the other four treatments were shorter periods of shading treatments. And we saw a significant effects of red colour in the end, but we expected to see a peak colour, of red colour because it's what it says in the literature. They normally to find a peak colour in the middle of the season so we wanted to see if we could shift those peaks more towards the end by shading.  Finally, it turned up in the ANP-0534. It has the maximum peak in the end of season which is really favourable and made it may be another notifier compared to the others and in the end we saw a significant effect between the fruit which had shading for 12 weeks compared to the other five treatments, so basically if you shard or shade for shorter periods it doesn't matter when you do it, but if you do it for a longer period its colour will be a little bit less in the end. Pretty cool!

The third experiment I was interest in, I investigated the effect of rootstock and training system on red colour development. We did this on two training systems, the Open Tatura training system and the vertical training system, with three different rootstocks - D6, BP1 and Quince A. We did first, I analyzed the effect of rootstock on the separate training systems. Here I found only significant effect of heights, again no effect of rootstock on a red colour development this was the same for both training systems. And after I did a separate analysis, I compared the training systems to see if the colour in the one training system might be higher than the colour in any other training system. But this doesn't make a difference, but this experiment I did between 88 and 160 days, 16 days after full bloom which is starting in half of December and ending the end of January, so late in the season. Maybe there will be a significant effect on Colour caused by rootstock or training system earlier in the season, but that's what I didn't study.

My name is Iris Visscher and I'm from the Wageningen University in the Netherlands. I came here to Agriculture Victoria to do my internship.

See presentation from Iris Visscher

Influence of light exposure on seasonal pattern of red colour development

The degree of red coloration is determined by the content and composition of anthocyanins in the peel of pears. Biosynthesis of anthocyanins in plant tissues either requires, or is enhanced by light.

During this experiment the effect of artificial shading on the red colour development of newly bred ANP-0534 blush pears was investigated. Six different treatments were applied which consist of a control treatment and five artificial shading periods which were differing in duration and timing.

  • Red colour was measured several times during the experiment.
  • Quality measurements, which included weight, firmness and total soluble solids, were investigated at the end.

Effect of reflective mulch on red colour development

The study investigated the use of reflective mulch (Extenday™) to improve fruit colouration in trees under netting and outside netting. The reflective mulch covered approximately 90% of the area between the rows, which maximises the amount of light that can be reflected back into the trees.

Effect of training system and rootstock on red colour development

The study investigated different training systems, Open Tatura and vertical training systems, to see the effect of fruit colouration in trees for new red-blushed pear cultivar ANP-0131 (marketed as Ricō®, previously known as Deliza®). In addition, the effect of rootstock was also investigated for blush pears that were grafted on BP1, QA or D6 within the training experiment.