Relationship between canopy architecture and fruit quality on 'Rich May' peach grafted onto 'Penta' and 'GF677' rootstocks

Observations on crop efficiency and fruit quality of peach trees of ‘Rich May’ grafted onto ‘GF677’ (peach x almond) and ‘Penta’ (Prunus domestica L.) rootstocks are reported. Results were related to canopy architecture parameters, particularly to scaffold branches, shoot and leaf blade inclination angles, to the pattern of light distribution, and to the area of sunflecks projected at midday on the ground. Trees grafted onto ‘GF677’ were more vigorous, in terms of trunk cross-sectional area, summer pruning weight and leaf area. Within canopy light distribution profiles were in agreement with foliage density, with a higher light interception observed in trees grafted on ‘GF677’. Within canop…

Rootstock Effect on Stem Water Potential Gradients in cv. 'Armking' Nectarine Trees

The effects of rootstock vigour on scion xylem hydraulic conductivity were studied on potted trees of cv. ‘Armking’ nectarine grafted onto GF677 (vigorous) and MrS 2/5 (low-vigour) rootstocks. Water potential gradients of non-transpiring leaves were measured at three levels of the stem starting at 10 cm above the graft-point. Transpiration rates were estimated by weighing. Two sets of measurements were taken on the same trees, at two different transpiration-rate levels obtained by imposing a different level of evaporative demand. Measurements were taken after allowing transpiration to reach a steady-state (20 minutes after any environmental perturbation). Trees grafted onto the low-vigour r…

Annual and monthly carbon balance in an intensively managed Mediterranean olive orchard

At present, research activities on the role of orchard systems in sequestering atmospheric CO2 remain scarce. This paper aimed to contribute to assessing the carbon balance of a Mediterranean olive (Olea europea) orchard. The net ecosystem exchange, the ecosystem respiration and the gross primary production were computed for two consecutive years through eddy covariance, and the different biomass accumulation terms were also inferred in the same period through an inventorial method. The net carbon exchange ranged from 13. 45 t(C) ha-1 year-1 to 11. 60 t(C) ha-1 year-1. Very similar values [12. 2 and 11. 5 t(C) ha-1 year-1] were found with the direct carbon accumulation inventory. The intens…

Ecophysiological Characterization of the Canopy of Peach (P. persica L. Batsch) in Two Planting Systems

Micrometeorological and sap flow measurement of water vapour exchanges in olive: Scaling up from canopy to orchard

A comparison of water consumption evaluated at tree and orchard level was carried out in a commercial olive orchard located in Sicily using up-scaled sap-flow evapotranspiration estimations and eddy covariance measurements. Sap flow probes were installed on olive trees placed in one of the four plots characterizing a heterogeneous orchard. Trees were chosen, from a preliminary footprint analysis, in correspondence to the peak of the “relative normalized contribution” to flux for the prevailing wind conditions measured by an eddy covariance station localized in the central part of the orchard. Tree-age and planting density as well as main tree and orchard characteristics (Leaf Area per tree,…

CO2 FLUXES OF OPUNTIA FICUS-INDICA MILL. TREES IN RELATION TO WATER STATUS

Gas exchange pattern in O. ficus-indica(OFI), refers to the Crassulacean Acid Metabolism (CAM); trees have nocturnal stomata opening, so net CO2 uptake and water loss occur during the cooler part ofthe 24-hour cycle. Succulent cladodes skip severe periods of drought through their water storer tissue (parenchyma). To study carbon fluxes in stress and no stress conditions, an experiment was carried out on 3-year-old irrigated and non-irrigated OFI potted trees; whole tree gas exchange was measured continuously with a balloon system made up by a portable Infrared Gas Analyzer. Continuous measurements(nighttime) during the summer season were useful to assess differences in carbon uptake under s…

Comparison of growth potentials of epicormic shoots of nectarine trees grown on size-controlling and vigorous rootstocks

SummaryThe vegetative performance of four nectarine tree scion/rootstock combinations, with varying growth capacities, were analysed in the Spring after the canopy:root ratio was dramatically reduced by severe pruning in the dormant season. We anticipated that severe pruning and reduction of the shoot:root ratio would mitigate known root water supply limitations related to the various rootstocks and determine if other factors associated with the rootstocks would control the rates of epicormic shoot growth. The trees used in this field experiment were 3 years-old, with ‘May Fire’ nectarine grafted onto four different rootstocks: ‘Nemaguard’ (a vigorous seed-propagated control, P. persica P. …

Canopy Architecture Appraisal by Fractal Dimension of 'Flordastar' Peach Trees Grafted onto Different Rootstocks

The objective of this research was to evaluate the modification of canopy architecture of ''Flordastar'' peach (Prunus persica L. Batsch) grafted onto rootstocks with different vigour, by the use of fractal dimension (D). The hypothesis was that different vigour rootstocks are able to modify the complexity of the branching pattern and that this effect can be assessed by a geometric parameter such as the fractal dimension (D) of the 2D projection of tree branching structure. The observations were carried out in a four-year-old experimental orchard of cv. ''Flordastar'' peach trees grafted onto Ishtara, Barrier, GF677 and MrS 2/5 rootstocks. On digital pictures of leafless, dormant peach tree…

Development of a Sensor for Continuous and Accurate Monitoring of Air Flow for Open-System Whole Canopy Gas-Exchange Measurements

The research describes the development and set-up of a simple and accurate solid-state device for continuous monitoring of airflow forced into an open-flow gas-exchange chamber for whole-canopy transpiration and photosynthesis measurements. The ventilation system was formed by a centrifugal fan powered by an electric motor and a PVC pipe (0.193 m inner diameter). To damp airflow turbulence, 50 cm of the main pipe was filled with a bundle of smaller PVC pipes (3 cm inner diameter). The measurement principle of the sensor is the thermal balance of an electrically heated copper plate compared to an unheated one. Calibration of the sensor was performed by two independent methods: gas dilution (…

The relationship of hydraulic conductance to root system characteristics of peach (Prunus persica) rootstocks

Specific rootstocks can differentially influence the vegetative growth and development of fruit trees. However, the physiological mechanism involved in this phenomenon has been elusive. Recent research comparing different peach (Prunus persica L. Batsch) rootstocks suggests that the rootstock effect on vegetative growth in peach trees is associated to water relations and more specifically to differences in rootstock hydraulic conductance. This study was intended to confirm differences in hydraulic characteristics of similar size peach trees grafted on different rootstocks and to examine root system characteristics that could be associated with rootstock hydraulic limitations. Trees on roots…

Validation of an online system for the continuous monitoring of tree water status for sustainable irrigation managements in olive (Olea europaea L.)

Abstract As a result of climate change a large reduction of agricultural water through improved irrigation management is a major need for agriculture sustainability. To this aim, always more sensitive sensors to monitor plant water status have been developed in recent years. Among them, the leaf patch clamp pressure probes are very promising for water management of olive but until now have been tested only in few environmental and management conditions. In this work these sensors have been tested for two consecutive years on two completely different management systems: a traditional rainfed orchard and a super high density (SHD) drip irrigated orchard. Within the SHD orchard the probes have…

CO2 uptake of Opuntia ficus-indica (L.) Mill. whole trees and single cladodes, in relation to plant water status and cladode age

Most of net photosynthesis determinations in Opuntia ficus-indica come from measurements on individual cladodes. However, they have limitations when used to scale up to whole canopy gas exchange, because a large variability of carbon assimilation may occur within the canopy, due to, among others, differences in cladode age and intercepted radiation or individual cladode response to abiotic stresses. The aim of this work was to evaluate the application of open gas exchange chambers, simultaneously applied around the whole canopy, to measure net CO 2 uptake, continuously over a 24 h period, in single Opuntia ficus-indica (L.) Mill. potted trees and in relation with their water status. Net CO2…

Climatic Characterization and Phenology of Local Peach Genotypes in the Udzungwa Uplands of Tanzania

The phenology of two local peach genotypes was studied to verify whether peaches can be produced in the Tanzanian uplands. Observations were conducted on trees of one early- and one late-ripening peach genotype in 2010 and 2011. Temperature trends were reconstructed and three chilling estimation models were tested. The two peach genotypes differed for timing of flower and leaf bud-break. Common symptoms of insufficient chilling (presence of numerous stages at a specific date and about 20% of undeveloped flower buds) were observed in the late genotype. Both Utah and Dynamic models indicated low chilling accumulation, lower than the Mean Temperature model in most cases. This is inconsistent w…

Recurrent deficit irrigation and fruit harvest affect tree water relations and fruitlet growth in ‘valencia’ orange

Background – Partial rootzone drying is an irrigation strategy known for increasing water use efficiency without significantly affecting tree water status. ‘Valencia’ oranges have a very long development period and nearly mature fruit and new fruitlets may be present at the same time on the tree, competing for water and assimilates. Objectives – The present study investigates the effect of recurrent deficit irrigation and fruit harvest on tree water status and fruitlet growth of ‘Valencia’ orange. Methods – Forty-eight adult trees were exposed to three irrigation treatments for seven years (2007–2013): irrigation with 100% of ETc (CI), continuous deficit irrigation (DI, 50% of CI) and parti…