Growth and water relations of field-grown ‘Valencia’ orange trees under long-term partial rootzone drying

Climate, soil water potential (SWP), leaf relative water content (RWC), stem water potential (WPstem), stomatal conductance (g s), trunk, shoot and fruit growth of ‘Valencia’ orange trees were monitored during five consecutive seasons (2007–2012) to study water status and growth responses to irrigation placement or volume. 48 adult trees were exposed to conventional irrigation (CI, 100% of crop evapotranspiration on both sides of the rootzone), partial rootzone drying (PRD, 50% of CI water only on one alternated side of the rootzone) and continuous deficit irrigation (DI, 50% of CI water on both sides of the rootzone). Reducing irrigation volumes by 55% (DI) over CI increased leaf water def…

Phloem and xylem flow contributions to nectarine fruit development

This study aimed at determining how source-sink balance and phloem/xylem flows affect nectarine fruit growth during development. Different levels of water and assimilate availability to growing fruits were induced in vivo by varying leaf:fruit ratio (L:F) of fruiting shoots and by interrupting the phloem stream (girdling) at the base of entire fruiting shoots. Two fruiting shoots in each of six ‘Big Top’ adult nectarine trees were selected, labeled and their L:F was adjusted by thinning fruits or removing leaves to two levels: high L:F and low L:F. Stem water potential, stomatal conductance, continuous fruit diameter and leaf turgor pressure were measured before and after girdling at stage …

Monitoraggio in tempo reale dello stress idrico del pesco

La frutticoltura odierna è sempre più caratterizzata dall’utilizzo di nuove tecnologie che si basano sull’utilizzo di molteplici sensori. Una delle grandi sfide della Smart Agriculture (agricoltura intelligente) è quella di integrare le informazioni provenienti da sensori remoti, prossimali e a contatto in modelli informativi in grado di sostenere gli agricoltori, in modo tale da determinare un sostanziale beneficio economico per le aziende. La complessità delle informazioni ottenute scoraggia l’integrazione di dati apparentemente molto diversi, ma allo stesso tempo apre le porte a nuovi modelli d’impresa. In questo lavoro vengono messi in risalto alcuni vantaggi e difficoltà dell’utilizzo …

Preliminary evaluation of sixPrunusrootstocks for peach in Italy

In Italy, the evaluation of rootstocks is supported by the Ministry of Agriculture and carried out in a network of trials along the Country. This study evaluated growth and yield performance of ‘Big Top’ nectarine and ‘Rome Star’ peach grafted on six rootstocks of different origin and vigor, namely GF677 (the most widespread in Italy), Garnem, Adesoto, RootPac®20, RootPac®40, and RootPac®90, in three different locations, Castelvetrano (Sicily), Forlì and Cesena (Emilia-Romagna). Yield, number of fruits, trunk cross-sectional area (TCSA), average fruit weight, flesh firmness, soluble solids content (SSC) and titratable acidity (TA) were determined at the third leaf (2015). In all sites, tree…

Heat requirements for loquat fruit development may be assessed with a Beta model approach

In Mediterranean areas, loquat trees (Eriobotrya japonica Lindl.) typically bloom in fall and fruits develop during the winter period, reaching their ripening in spring. So far, little interest has been driven towards models capable of estimating heat requirements for the accomplishment of fruit development in the winter period. In this work, we verified whether in Mediterranean areas the heat accumulation (GDH) needed for loquat fruit growth, may be precisely described using a Beta model, a flexible mathematical function which, in the past, has been successfully used in peach. BBCH phenological stages of ‘Algerie’ trees were recorded in two experimental sites: Palermo, Italy (38°04’N, 13°2…

Field non-destructive determination of nectarine quality under deficit irrigation

This study investigated the effects of deficit irrigation (DI) at different fruit growth stages and tree orientation on fruit quality of ‘September Bright’ nectarines (Prunus persica L. Batsch). Control trees were fully irrigated throughout the entire fruit development period, whereas deficit irrigation was supplied at fruit growth stage I (cell division, DI-I), II (pit hardening, DI-II), IIIa (cell expansion, DI-IIIa) and IIIb (fruit maturation, DI-IIIb). Non-destructive measurements of fruit maturity and quality were carried out using portable devices based on near-infrared spectrometry and pigment fluorescence on west- and east-oriented trees of an Open Tatura system. Chlorophyll degrada…

CARATTERIZZAZIONE CLIMATICA E COMPORTAMENTO FENOLOGICO DI GENOTIPI LOCALI DI PESCO NELL’ALTOPIANO DI UDZUNGWA IN TANZANIA

La coltivazione del pesco nell’altopiano di Udzungwa in Tanzania risale agli inizi del XX secolo e ancora oggi rappresenta un'opportunità per aumentare l’apporto nutritivo alla popolazione locale. Questo studio preliminare mira a caratterizzare la climatologia del luogo in rapporto al comportamento fenologico di genotipi locali derivati da vecchie cultivar di pesco europee. Le osservazioni fenologiche sono state condotte nel settembre 2010 e a luglio-agosto 2011 su alberi di pesco appartenenti a un genotipo precoce e a uno tardivo. I dati di temperatura sono stati ricostruiti e utilizzati per stimare l’accumulo di freddo mediante tre modelli fenoclimatici: Utah, Mean Temperature e Dinamico.…

Water relations and carbohydrate partitioning of four greenhouse-grown olive genotypes under long-term drought

The four olive genotypes exhibited different responses to drought involving leaf drop and g s reductions (broad-leaved genotypes, good leaf hydration); or growth reductions (narrow-leaved genotypes, dehydration tolerance). There was minor effect on carbohydrate levels. Olive plants of broad-leaved ‘Minuta’ (MN) and ‘Nocellara del Belice’ (NB) and narrow-leaved ‘Passulunara’ (PA) and ‘Biancolilla Siracusana’ (BS) were studied to evaluate their responses to drought. In a greenhouse, 2-year-old rooted cuttings were irrigated to field capacity (WW) or with 20% of WW evapotranspiration (DS) for over 3 months. Subsequently, all pots were rewatered to field capacity for 20 days. Gravimetric soil w…

Physiological and Structural Responses to Prolonged Water Deficit in Young Trees of Two Olive Cultivars

This study aimed to characterize the physiological and structural responses of potted one-year-old olive trees belonging to two olive cultivars—‘Nocellara del Belice’ and ‘Cerasuola’—exposed to prolonged drought under greenhouse conditions. Two irrigation treatments based on evapotranspiration (ET) were imposed for 69 days, i.e., well-watered (WW, 100% ET) and drought-stressed (DS, 10–30% ET). Leaf stomatal conductance (gs), stem water potential (Ψstem), transpiration (E), photosynthetic capacity (Amax), water use efficiency (WUE), stem (Kstem) and root (Kroot) hydraulic conductance, trunk diameter variations (TDV), and leaf patch attenuated pre…

Diurnal irrigation timing affects fruit growth in late-ripening nectarines

Little is known about the best diurnal irrigation timing for maximum fruit growth in stone fruit, despite fruit size being the most important focus for growers to achieve maximum marketable yield. This study investigated the effects of morning and afternoon irrigation on nectarine fruit growth in stage I (cell division) and stage III (cell expansion). In the 2017/18 season, ‘September Bright’ trees were subjected to morning (Iam) and afternoon (Ipm) irrigations. Fruit diameter was monitored continuously (15-min intervals) using fruit gauges and converted into fruit weight, relative growth rate (RGR) and fruit growth efficiency (FGE), with the latter representing RGR per unit of crop water s…

Detecting Mild Water Stress in Olive with Multiple Plant-Based Continuous Sensors.

A comprehensive characterization of water stress is needed for the development of automated irrigation protocols aiming to increase olive orchard environmental and economical sustainability. The main aim of this study is to determine whether a combination of continuous leaf turgor, fruit growth, and sap flow responses improves the detection of mild water stress in two olive cultivars characterized by different responses to water stress. The sensitivity of the tested indicators to mild stress depended on the main mechanisms that each cultivar uses to cope with water deficit. One cultivar showed pronounced day to day changes in leaf turgor and fruit relative growth rate in response to water w…

Transpiration rates and hydraulic conductance of two olive genotypes with different sensitivity to drought

Although some mechanisms of leaf dehydration tolerance are known in olive (Olea europaea L.), insights on adjustments in stem and root hydraulic conductance (K) in response to drought are yet to be explored. This work investigated transpiration mechanisms and K regulations in two olive genotypes showing different sensitivity to drought stress. In 2017, one-year-old potted ‘Nocellara del Belice’ (NB) and ‘Cerasuola’ (CE) plants were set in a greenhouse and double-bagged to avoid evaporation from soil surface. Half of the plants were drought-stressed (DS, no irrigation) for more than 30 days and the remaining plants were well-watered (WW). At the end of the drought period, stem and root porti…

Continuous determination of fruit tree water-status by plant-based sensors

Recently, climate change has caused shortages of water worldwide, especially in semi-arid and arid regions. Several irrigation strategies have been studied with the aim of saving water overuse in agriculture. In the past most of the attention was directed towards soil water content, but recently the focus has moved to plant responses to water deficit. In recent years, crop evapotranspiration (ETc) obtained from reference evapotranspiration (ET0) and crop coefficients (Kc), has become common for irrigation scheduling in several crops, but it does not provide precise insights on the tree water status. Today an increasing focus is being given to plant-based sensors for the continuous monitorin…

FRUIT AND LEAF SENSING FOR THE CONTINUOUS MONITORING OF TREE WATER STATUS IN HIGH-DENSITY ORCHARD SYSTEMS

Fruit Growth Stage Transitions in Two Mango Cultivars Grown in a Mediterranean Environment

Studying mango (Mangifera&nbsp

Cladode growth dynamics in Opuntia ficus-indica under drought

Abstract Cactus pear (Opuntia ficus-indica L. Miller) is a CAM plant with an extraordinary capacity to store water in its succulent stems (cladodes). However, the daily variations of cladode thickness is unknown. Studying cladode thickness fluctuations may be useful for the early prediction of plant dehydration stress. The objective of this study was to determine if age, water availability and temperature influence diel cladode shrinkage and enlargement dynamics in cactus pear. The experiment was conducted in a greenhouse from April to July 2014, using cactus pear plants, equally split into irrigated and unirrigated treatments, and unrooted cladodes detached from mother plants. Soil moistur…

Fruit and Leaf Sensing for Continuous Detection of Nectarine Water Status

Continuous assessment of plant water status indicators provides the most precise information for irrigation management and automation, as plants represent an interface between soil and atmosphere. This study investigated the relationship of plant water status to continuous fruit diameter (FD) and inverse leaf turgor pressure rates (pp) in nectarine trees [Prunus persica (L.) Batsch] throughout fruit development. The influence of deficit irrigation treatments on stem (Ψstem) and leaf water potential, leaf relative water content, leaf stomatal conductance, and fruit growth was studied across the stages of double-sigmoidal fruit development in ‘September Bright’ nectarines. Fruit relative grow…

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…

Continuous detection of new plant water status indicators in stage I of nectarine fruit growth

Conventional irrigation management is often inefficient in responding to seasonal changes of tree water needs. The use of leaf- and fruit-based sensors might provide helpful insights on tree water status, although they have been poorly investigated so far. Fruit gauges and leaf patch clamp pressure (LPCP) probes were tested during stage I of nectarine fruit growth to evaluate if leaf turgor pressure and fruit size may serve as indicators of water deficit. This experiment was carried out in the 2017/18 season. Four irrigation levels were applied to ‘September Bright’ nectarine trees (100, 40, 20 and 0% of crop evapotranspiration, ETc) and data were collected during stage I of fruit growth. T…

A Cultivar-Sensitive Approach for the Continuous Monitoring of Olive (Olea europaea L.) Tree Water Status by Fruit and Leaf Sensing

Sustainable irrigation is crucial to reduce water use and management costs in modern orchard systems. Continuous plant-based sensing is an innovative approach for the continuous monitoring of plant water status. Olive (Olea europaea L.) genotypes can respond to drought using different leaf and fruit physiological and morphological mechanisms. This study aimed to identify whether fruit and leaf water dynamics of two different olive cultivars were differently affected by water deficit and their response to changes of midday stem water potential (Ψstem), the most common indicator of plant water status. Plant water status indicators such as leaf stomatal conductance (gs) and Ψstem were measured…