Sink priority on ‘Hayward’ kiwifruit vines

Abstract

An experimental system based on girdled shoots was used to assess how vegetative competition alters the growth of 'Hayward' kiwifruit. Each shoot was pruned to length so that it contained four source leaves and a sink consisting of either a single fruit, a vegetative regrowth, or one fruit and a vegetative regrowth. Vegetative competition had the greatest effect on fruit growth when it occurred about five weeks after flowering, when fruit growth is maximal. When a single fruit was in competition with a defoliated vegetative shoot, fruit size at harvest was reduced by 50%, whereas competition 20 days later reduced the fruit size by only 28%. Our results show that vegetative growth has a higher sink priority than fruit for both fresh weight and dry weight (DW) for the first 120 days after flowering, the time when most fruit growth occurs. Furthermore, during this period vegetative growth had a higher sink strength for DW than fruit. As a consequence of sink priority, when there is competition for limited resources, shoot growth continues at the expense of fruit growth.

Possible Role of High Temperature and Soil Biological Fertility on Kiwifruit Early Decline Syndrome

“…However, it has been postulated that shoots have a stronger sink strength (ability to attract carbohydrate when supply is not limited) and sink priority (ability to compete when carbohydrate supply is limited) over fruits during the first 120 DAMB (Lacointe and Minchin, 2008). Afterwards, in case of competition for limited resources, vegetative growth continues at the expenses of fruit growth (Snelgar et al, 2012). Moreover, high temperatures strongly influence the photosynthates allocation between fruits and shoots, with increased vegetative vigor stimulated by high temperatures at the expenses of sugars accumulation in fruits, whose dry matter at harvest is lowered (Hall and Snelgar, 2008).…”

Modifying Carbohydrate Supply to Fruit during Development Changes the Composition and Flavour of Actinidia chinensis var. chinensis ‘Zesy002’ Kiwifruit

“…Studies of kiwifruit have shown that factors that affect carbohydrate source supply to fruit sinks can influence their final growth and composition. These factors can include crop load [ 3 ], leaf-to-fruit (L:F) ratio [ 31 , 32 ], girdling [ 33 ], application of growth regulators [ 8 , 34 ], pollination [ 35 ], application of nitrogen fertiliser [ 36 ], light [ 37 ] and temperature [ 38 ]. Girdling (to prevent carbohydrate moving to nonfruit sinks e.g., roots) and thinning studies (to increase the leaf:fruit ratio) of ‘Hayward’ vines have shown that effects of changing carbohydrate source supply on fruit size generally occur during rapid fruit growth while effects on fruit dry matter accumulation are seen during the second stage of fruit growth [ 39 , 40 ].…”