Hello! Thank you all for your input!
I did not explain why I was looking at drop and fruit size: it was an experiment on the use of ReTain. In the end I’m not sure I can pinpoint the reason this increased fruit size on trees with more apples (notwithstanding ReTain), but your input underlined that a number of variables can be involved! I liked Duane’s idea. If you’re curious, the report will read: ReTain Treatments significantly increased harvested McIntosh yield as compared to the control (p<0.0001). Average fruit size at harvest was proportional to the total number of fruits on the trees present at the start of the experiment (p=0.01) and fruits treated with ReTain were larger than in the control (p=0.02). The effect of ReTain on harvest was expected (drop prevention) but the effect on fruit size was undetectable if the model was not adjusted to the initial crop load (thus my question) So the next question is now: why are ReTain treated fruits bigger than untreated fruit at harvest? bye for now, Vincent On 14janv., 2014, at 10:06, Duane Greene <dgre...@pssci.umass.edu<mailto:dgre...@pssci.umass.edu>> wrote: Hello Vincent, I usually am not an active participant in post but I thought that I might weigh in on your comment since I have been doing preharvest drop research for a number of years. Jim Krupa our technical assistant has been involved and he expressed an interest in doing an experiment to find out a little more about why fruit drop? The experiment was done on McIntosh and Delicious over two seasons. Briefly, 6 to 10 trees were selected. Half were designated to be drop trees and half were designated to be harvest trees. The experiment was carried out from the time the first fruit dropped until most of the fruit were on the ground. Each morning fruit under the drop tree were picked up and taken to the lab where they were weighed and internal ethylene was determined on each fruit. Red color, flesh firmness, soluble solids and starch rating were determined and seed number counted. This was repeated for fruit that dropped at 3:00 pm. Three times a week 10 fruit were harvested from the harvest trees and similarly processed. Seed number was not associated with fruit weight or drop although this has been documented in the literature. I suspect that this may be an issue when there are 0, 1 or 2 seeds per fruit but that was not the case here. The conclusion that we came to was all fruit that dropped were climacteric and showed signs of ripening (internal ethylene greater than 1 ppm, increased red color and reduced starch content). The appropriate question to ask then may be why did the fruit that drop ripen early? We know from research done here in the 1980s that fruit with very low seed number are also low in calcium. Fruit low in calcium may ripen earlier. I offer another explanation. Many of you know that recent reserach has indicated that a carbohydrate balance deficiency in trees druing June drop is a factor that infouences thinner response as well as the severity of June drop. This is based on the original work of Alan Lakso and taken to the field by Terence Robinson. The model is good and the practical application for thinning is important. However, if one looks at the carbon balance in Alan's model over the growing season you will note two things. First, there is likely to be a deficit during the June drop period and this has been highly publicized. A second period of deficit occurs at harvest time and this has been largely ingnored. It makes perfect sense since as fruit ripen there is a large increase in respiration (climacteric) which fuels the synthesis of enzymes involved with ripening. Vincent mentioned that were might be a shelf shedding mechanism in trees. When trees have a carbohydrate deficit they must respond. In some instances this response is shedding of fruit. Even with fruit it is survival of the fittest. This occurs at June drop, why not at harvest? Drop is frequently controlled by spurs. If spurs are shaded or leaf area is small then the fruit on these spurs are most likely to drop early. Mite damaged trees also show early drop. We have followed drop from McIntosh over the course of the season which often occurs over a 7 week period. Fruit increase in size about 1% per day they are on the tree. Consequently, it is not surprising that average fruit sized will increase over the harvest season. This is one of the attributes of using drop control compounds. I am not sure if I have helped in this discussion but drop can be precipitated by several events (seed number, heat, lack of light, reduced leaf area, damaged leaves, etc) but I do believe it comes right back to any factor that stimulates ripening will lead to increased drop. Duane On 1/13/2014 12:12 PM, Vincent Philion wrote: Hello, I’m analyzing some data and I have seemingly contradictory results. I’m hoping someone can comment and make sense of this: For a number of randomly selected trees, fruit drop was recorded starting late summer until harvest. For each tree, we recorded total fruit drop (and weight), harvested fruit (and weight) and the total (drop + harvest). As I was looking at the data, I noticed average harvested fruit size (weight/number) was related to Total fruits per tree… Nothing strange, until I realized harvested fruit size INCREASED with Total fruit number on tree. As if the fruit dropping left more energy for the remaining fruits to grow? I was expecting harvested fruit size to be smaller on trees that had more total fruit, not the other way around. I’m not sure this late natural fruit drop can be compared to very late hand thinning, but does anyone know if fruit size increase can be linked to late thinning (notwithstanding total yield that can go down)? Maybe this is “normal”? Any comment welcome! Vincent <http://www.irda.qc.ca/assets/client/img/logo.png> Vincent Philion,M.Sc. agr. Microbiologiste Phytopathologiste pomiculture Institut de recherche et de développement en agro-environnement Research and Development Institute for the Agri-Environment www.irda.qc.ca<http://www.irda.qc.ca/> Centre de recherche 335, Rang des Vingt-Cinq Est Saint-Bruno-de-Montarville (Québec) J3V 0G7 vincent.phil...@irda.qc.ca<mailto:vincent.phil...@irda.qc.ca> Bureau: 450 653-7368 poste 350 Cellulaire: 514-623-8275 Skype: VENTURIA Télécopie: 450 653-1927 Verger expérimental 330, Rang des vingt-cinq Est Saint-Bruno-de-Montarville (Québec) J3V 4P6 Téléphone et télécopieur : 450 653-8375 Local pesticide: 450-653-7608 Pour nous trouver, cliquer sur le lien: Laboratoire<https://plus.google.com/113874173074370918274/about?gl=CA&hl=fr-CA> Verger<https://www.google.ca/maps/preview#%21q=verger+irda&data=%214m15%212m14%211m13%211s0x4cc9016b3e604b3d:0x9e4816f2e6bea640%213m8%211m3%211d212357%212d-71.3416925%213d46.8563685%213m2%211i1324%212i934%214f13.1%214m2%213d45.543389%214d-73.341551> Fiers héritiers du travail des frères Saint-Gabri : http://arboretum8gabrielis.wordpress.com<http://arboretum8gabrielis.wordpress.com/> Like most of the data I deal with, I'm best described as either "zero inflated Poisson", or "zero inflated negative binomial". Anything but "Normal". Un expert est une personne qui a fait toutes les erreurs qui peuvent être faites dans un domaine très étroit. ~ Niels Bohr C'est pas parce qu'ils sont nombreux à avoir tort qu'ils ont raison… ~ Coluche To call in the statistician after the experiment is done may be no more than asking him to perform a post-mortem examination: he may be able to say what the experiment died of. ~ Sir Ronald Aylmer Fisher The plural of anecdote is not data. ~ Roger Brinner The combination of some data and an aching desire for an answer does not ensure that a reasonable answer can be extracted from a given body of data. ~ John Tukey Prediction is difficult, especially of the future. ~ Mark Twain (also attributed to Niels Bohr and Yogi Berra) There are three kinds of lies: lies, damned lies, and statistics. ~ Mark Twain or Disraeli Without deviation from the norm, Progress is not possible. ~ Frank Zappa If you don’t know where you are going, you will wind up somewhere else. ~ Yogi Berra You can see a lot just by looking. ~ Yogi Berra Poor, but proudly at the highest step I'm qualified for. http://en.wikipedia.org/wiki/Peter_Principle Inhibiteur de rodomontades depuis 1992. Ce que l'on conçoit bien s'énonce clairement, et les mots pour le dire arrivent aisément. ~ Nicolas Boileau-Despréaux Vingt fois sur le métier remettez votre ouvrage ~ Nicolas Boileau-Despréaux Keep your stick on the ice ~ The Red & Green show Quid quid latine dictum sit, altim videtur. ~ Stéphane Laporte Audi alteram partem Qui potest capere capiat AVIS DE CONFIDENTIALITÉ Ce message peut contenir de l'information de nature privilégiée et confidentielle. Si vous n'êtes pas le destinataire visé ou croyez l'avoir reçu par erreur, nous vous saurions gré d'en aviser l'émetteur. Si ce message vous a été transmis par erreur, veuillez le détruire sans en communiquer le contenu à d'autres personnes ou le reproduire _______________________________________________ apple-crop mailing list apple-crop@virtualorchard.net<mailto:apple-crop@virtualorchard.net> http://virtualorchard.net/mailman/listinfo/apple-crop -- Duane W. Greene Stockbridge School of Agriculture Bowditch Hall University of Massachusetts Amherst, MA 01003 Phone- 413-545-5219 FAX- 413-545-0260 Email- dgre...@umass.edu<mailto:dgre...@umass.edu> _______________________________________________ apple-crop mailing list apple-crop@virtualorchard.net<mailto:apple-crop@virtualorchard.net> http://virtualorchard.net/mailman/listinfo/apple-crop
_______________________________________________ apple-crop mailing list apple-crop@virtualorchard.net http://virtualorchard.net/mailman/listinfo/apple-crop
