Effect of Fruit Crop Load on Peach Root Growth

Abstract

Field experiments were conducted on mature, late-maturing peach trees ('O' Henry') to study the influence of assimilate availability on root growth. Crop load was used to vary assimilate availability by imposing three different fruit thinning treatments: thinned to commercial fruit loads, unthinned and completely defruited. Seven trees were used for each treatment, and four ingrowth root bags were buried per tree during four different periods of the growing season (corresponding to the three fruit growth stages and after fruit harvest). The bags were collected one month after burial and the root growth into each bag was determined from dry weight of all newly developed roots in a bag. Root growth values varied depending on crop load and fruit growth stage. During the first stage of fruit growth there was no effect of crop load on root growth. Root growth in all thinning treatments increased compared to the first stage and was significantly higher for the defruited trees. The root growth was minimal during the third stage of fruit growth in all the treatments. After harvest, root growth increased again in all the treatments. These experiments clearly demonstrated that there are seasonal patterns to root growth activity in peach trees and that crop load clearly influences the extent of that activity primarily during the late spring when the fruits are in the second stage of fruit growth.

Changes in fine-root production, phenology and spatial distribution in response to N application in irrigated sweet cherry trees

“…Indeed, decreases in daily fruit growth rate, e.g., during pit hardening and after fruit harvest, coincided with increases in the daily root production rate and daily shoot growth rate in trees with an ample N supply (Figure 7). Therefore, the effect of source-sink relationships on root production in sweet cherry trees is particularly strong during fruit development, as has been extensively reported for peach trees ( Williamson and Coston 1989, Glenn and Welker 1993, Grossman and DeJong 1995, Inglese et al 2002, Mimoun and DeJong 2006, Basile et al 2007, Abrisqueta et al 2008. In trees without N, the alternating growth pattern of fruit and roots was not clearly observed (Figure 7).…”

“…This should be particularly true in fruit-bearing trees due to the presence of fruits, which are considered to be stronger sinks for carbohydrates in comparison with shoots and roots ( Grossman and DeJong 1995, Flore and Layne 1999, Génard et al 2008. Indeed, several studies have shown that fruiting reduces root growth, especially during the final stage of fruit growth when fruit has maximum sink strength ( Williamson and Coston 1989, Glenn and Welker 1993, Grossman and DeJong 1995, Inglese et al 2002, Morinaga et al 2003, Mimoun and DeJong 2006, Basile et al 2007, Abrisqueta et al 2008. Further evidence of the effect of source-sink relationships on root phenology might be the decoupling frequently registered between root and shoot growth in woody species ( Steinaker et al 2010, Abramoff andFinzi 2015).…”

Root and aerial growth in early-maturing peach trees under two crop load treatments

“…High cropping peach trees generally have reduced vegetative growth (Berman & DeJong, 2003) and root growth (Chalmers & Van den Ende, 1975). Results in support of this were found in experiments with late-maturing peach trees in both potted (López et al, 2008) and field grown (Ben Mimoun & DeJong, 2006) conditions, in which root growth was significantly higher in defruited than in commercial crop load treatments. Nii (1993) reported that the total root volume of non-bearing peach trees was larger and the starch content per root dry weight higher than in bearing trees.…”

Effects of crop load on distribution and utilization of 13C and 15N and fruit quality for dwarf apple trees

“…The reason is that the competition for the photosynthetic nutrient in the late development stage of fruit exists between shoots and roots, and the photosynthetic products are mainly transported to the “sink” organ (fruit) with the increasing crop load. Thus, the roots will appear “hunger” due to the insufficient organic nutrient 43 , inhibiting the absorption of mineral nutrition and water. This phenomenon will lead to the decrease of the nutrient level in the leaves that might be the main cause of decrease of photosynthetic rate 44 .…”