Jean-Gérard Huguet

Response of peach tree growth and cropping to soil water deficit at various phenological stages of fruit development

SummaryFour- and five-year-old ‘Merrill Sundance’ peach trees, protected from rainfall by polyethylene film covers, were fully irrigated using micro-sprinkler (irrigation scheduling based on a tensiometer technique), or subjected to water stress at different phenological stages of fruit growth. Water deficit imposed during the first phase of rapid growth significantly increased fruit size at harvest during two experimental years when compared with the control full-irrigation treatment, while smaller fruits were produced from trees receiving an imposed water deficit during the final accelerated fruit growth, or throughout the fruit development period. When water deficit was applied to the trees during the pit hardening phase and the first two phases of fruit development, fruit size was not affected. However, shoot extension growth and limb diameter increases were limited whenever water supply was restricted. After-effects on limb expansion growth and benefits of water stress on fruit growth were obvious du...

Irrigation scheduling in a mature peach orchard using tensiometers and dendrometers

Three trickle irrigation schedules, two of which were scheduled according to soil water potential (ψ soil) (tensiometer method) and daily stem contraction (DSC) (dendrometer method) respectively and the other one was a schedule of restricted water supply, were applied to a mature peach orchard.The annual water application based on ψsoil was greater than that based on DSC. However, tree growth, fruit size and leaf water potential (ψleaf) on the trees in the dendrometer scheduling plot did not differ from those in the tensiometer scheduling plot while the premature fruit drop and fruit bud initiation were greatly different. The restricted water supply treatment limited significantly both tree and fruit growth. In addition, the lower ψleaf was observed on the trees in this plot.Further study shows that use of the dendrometer method for scheduling irrigation satisfies the water needs of the plant and that the tensiometer method is less accurate.

Fruit quality and leaf photosynthesis in response to microenvironment modification around individual fruit by covering the fruit with plastic in nectarine and peach trees

Summary The effects of covering fruit with clear plastic film during the final stage of rapid fruit growth were investigated on ‘Big Top’ nectarine and ‘Opal’ peach over three years. Covering fruit with plastic film modified the microenvironment around the fruit, particularly by increasing relative humidity and temperature during the day. These modifications influenced fruit development, fruit quality and leaf photosynthesis. Covering fruit with plastic film significantly reduced the dry matter content, either for fruit flesh or for total fruit, the content of total soluble solids in fruit fresh, and leaf photosynthesis under high light intensities (photosynthetically active radiation in excess of 1000.m.mol.m–2.s–1) as compared with uncovered control fruit. The relationship between photosynthetic rate and other leaf physiological responses showed that the depression of photosynthetic CO2 assimilation was related to reduced stomatal aperture and increased leaf temperature. It is suggested that the stomatal aperture may be considered as the trigger or promoter and leaf temperature as the regulator of photosynthesis under a lower sink-source ratio.

The consequences of cultural practices on growth and cropping of peach trees subjected to localized irrigation: Effects of soil management, nitrogen fertilization and tree density

SUMMARYCultural practices were studied in peach tree orchards irrigated with microsprinklers, herbicide strips being maintained along the tree rows. Differences in fruit cropping between treatments varied in the same way as tree vigour, the most vigorous trees having the highest production capacities. Concerning soil management, ground cover vegetation (permanent or temporary) improved fruit production compared with soil cultivation. According to leaf analysis, ground cover vegetation appeared to ameliorate the conditions of trees nutrition. This effect was probably mainly due to increasing soil resistance to compaction; applying organic matter was not effective in improving the performance of trees grown with soil cultivation compared with those grown with ground cover vegetation. Increasing fruit tree density also contributed to increased fruit production. Nevertheless, more than 600 trees per hectare did not allow further increase in fruit yield for the experimental cultivar. Lastly, nitrogen fertiliza...