Water status and gas exchange of pistachio trees under different irrigation levels

The aim of this study was to investigate the physiological responses of pistachio trees to varying water supply in the attempt to identify reliable parameters to manage irrigation. Three different irrigation regimes were applied to 25-year-old pistachio trees of cultivar 'Bianca' on P. terebinthus rootstock. Midday stem water potential (ΨSWP), leaf relative water content (RWC), light-saturated net CO2assimilation (An), stomatal conductance (gs), and ambient conditions were monitored throughout the season, and light response curves of net photosynthesis were constructed. To reflect tree water status, trees were separated into three classes of ΨSWP, no deficit (ΨSWP> -1.5 MPa), mild defici…

Seasonal dynamics of photosynthesis and total carbon gain in bearing and nonbearing pistachio (Pistacia vera L.) shoots

Seasonal changes in leaf gas exchange, assimilation response to light and leaf area were monitored in bearing and nonbearing pistachio shoots. Shoot bearing status did not directly affect leaf photosynthetic rate. However, photosynthetic light-response curves strongly varied during the season demonstrating the dominant effect of the tree’s seasonal phenology on assimilation. Early in the season low photosynthetic rates were associated with high rates of dark respiration indicating limited photosynthesis in the young leaves. As leaves matured, dark respiration decreased and assimilation reached maximum values. Photosynthetic efficiency was strongly reduced late in the season due to leaf ag…

Sustainability of pistachio production (Pistacia vera L.) under supplemental irrigation in a Mediterranean climate

Abstract The objective of this study was to examine the effects of supplemental micro-irrigation, in a commercial rainfed orchard, on tree water status, gas exchange and productivity of Pistacia vera L. (cv Bianca) grafted on P. terebinthus. Irrigating with 10–15% of estimated full evaporative demand significantly increased average annual productivity by increasing yield in the on-crop year of this alternate bearing species. Irrigation increased yield by 30%, resulting in 1600 kg of in-shell product per ha. Irrigation delayed leaf senescence while flower bud abscission was not reduced until the third year of experiment. Irrigation did not improve gas exchange during Stage I (pericarp growth…

Predicting olive flowering phenology with phenoclimatic models

In plants, day length and temperature are the major climatic factors that affect the transition from a phenological phase to the next one. Non-linear models, such as growing degree hours (GDH), have been successfully used to calculate thermal time required for spring bud burst in deciduous fruit trees. In this experiment, temperature records and blooming dates of olive trees in different years and for 10 different sites in the Italian territory were recorded. Olive booming time was correlated to the amount of (GDH) accumulated from the date of bud rest onset, calculated as the day when the maximum negative chilling units accumulation was reached (UTAH Model), to full bloom. The GDH model wa…

Horticultural management of Italian Pistachio orchard systems: current limitations and future prospective

Pistachio production and consumption have strongly increased in the last years due to its capability to grow under limiting conditions, the profitability of this nut in the market and its well claimed healthy properties. The Sicilian pistachio industry is diminutive in comparison to big producing countries such as California and Iran. Its economical profitability is limited by a low productivity per surface area, strong alternate bearing, and long unproductive period, mainly associated with the lack of implementation of innovative management practices. This “traditional” agricultural system is surviving in a highly competitive international market thanks to the unique organoleptic profile o…

Horticultural performance of 23 Sicilian olive genotypes in hedgerow systems: Vegetative growth, productive potential and oil quality

Abstract The super high density (SHD) model is a new olive growing system characterized by earlier and higher yields, fully mechanized harvesting and reduced orchard management costs. Until recently all commercial SHD orchards were planted primarily with three varieties: ‘Arbequina’, ‘Arbosana’ and ‘Koroneiki’. To increase variety diversity, broaden available olive oil chemical and organoleptic profiles, and olive oils for marketing, minor local varieties should be evaluated for adaptability to the SHD system. This study compares multiple Sicilian native genotypes to the three current cultivars ‘Arbequina’, ‘Arbosana’ and ‘Koroneiki’. The cumulative fruit and oil production, trunk-cross sec…

Modeling seasonal branch carbon dynamics in pistachio as a function of crop load

A simplified model for the prediction of carbon balance was developed to elucidate the seasonal trend of sink-source relationships in bearing and non-bearing pistachio (Pistacia vera L.) branches. Seasonal changes in growth rate of vegetative (leaf and shoot) and reproductive (infructescence) organs were monitored in branches of mature rainfed pistachio trees during the entire growing season (April–September). Simulations from the model were used to gain understanding of the implications of crop load on branch carbon (C) depletion and alternate bearing. Results showed that the pistachio branch was energetically able to sustain up to two infructescences (∼28 fruits) having a slightly positiv…

Toward the valorization of olive (Olea europaea var. europaea L.) biodiversity: horticultural performance of seven Sicilian cultivars in a hedgerow planting system

Abstract An intense survey of the Sicilian’s olive growing areas for autochthonous germplasm, mainly represented by centennials olive trees (Olea europaea var. europaea L.) apparently older then III centuries, started at the beginning of the 1980s and resulted in the selection of more than 150 cultivars and accessions. This germplasm was propagated in a nursery, by grafting onto seedlings of Olea europaea L., and planted in an experimental orchard, in an olive district located in the South-west of the Island, where they were evaluated for over 30 years and selected for their early bearing, high and constant productivity, as well as high oil content of the fruits and excellent chemical (olei…

Effects of different irrigation regimes on a super-high-density olive grove cv. “Arbequina”: vegetative growth, productivity and polyphenol content of the oil

The effects of multiple irrigation regimes on the relationships among tree water status, vegetative growth and productivity within a super-high-density (SHD) “Arbequina” olive grove (1950 tree/ha) were studied for three seasons (2008–2010). Five different irrigation levels calculated as percentage of crop irrigation requirement using FAO procedures (Allen et al. in Crop evapotranspiration. Guidelines for computing crop water requirements. Irrigation and drainage paper 56. FAO, Rome, 1998) were imposed during the growing season. Periodically during the growing season, daytime stem water potential (Ψ STEM), inflorescences per branch, fruits per inflorescence and shoot absolute growth rate wer…

Effect of water stress on dry matter accumulation and partitioning in pot-grown olive trees (cv Leccino and Racioppella)

Abstract Three different water regimes were applied on young pot-grown olive trees of the cultivars Leccino and Racioppella, amounting to 100% (treatment T100), 50% (treatment T50) and 25% (treatment T25) of water transpiration as determined by pot weight. During the two-year trial the following parameters were measured: midday stem water potential, shoots growth, total leaf area per tree, dry matter accumulation and partitioning in different parts of the plant (root, wood, leaves and fruits). Dry matter was affected by the water regime and cultivar. The cv Leccino, for T100, displayed a greater accumulation of total dry matter and fruit dry matter, while these two parameters were greatly r…

Relationship between tree water status and physiology, yield, and fruit quality in the table olive (Olea europaea sativa L.) cultivar ‘Nocellara del Belice’

Although the olive (Olea europaea sativa l.) is considered a xerophytic species, long periods of water stress and high temperatures during summer months can greatly affect plant physiology and productivity. In recent years, the use of plant-based water status indicators have become popular in the study of plant-water relationships and in the design of irrigation programs, particularly midday stem water potential (ψstem). The current trend in the irrigation of olive trees is in the development of Deficit Irrigation (DI) systems whereby the water is applied at a rate which is lower than evapotranspiration needs, resulting in only very small reductions in yield. Rather than working towards min…

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…

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…

Gas Exchanges and Stem Water Potential Define Stress Thresholds for Efficient Irrigation Management in Olive (Olea europea L.)

With climate change and decreased water supplies, interest in irrigation scheduling based on plant water status is increasing. Stem water potential (ΨSWP) thresholds for irrigation scheduling in olive have been proposed, however, a physiologically-based evaluation of their reliability is needed. A large dataset collected at variable environmental conditions, growing systems, and genotypes was used to characterize the relation between ΨSWP and gas exchanges for olive. Based on the effect of drought stress on the ecophysiological parameters monitored, we described three levels of stress: no stress (ΨSWP above about −2 MPa), where the high variability of stomatal conductance (gs) suggests a ti…

Seasonal changes in starch content in pistachio organs as related to crop load

The alternate bearing in pistachio (Pistacia vera L.) results from inflorescence buds abscission differentiated on current season growth during the year of heavy crop. Inflorescence bud drop has been directly correlated with the presence of fruits on 1-year shoot, and in particular with the kernel grow that acts as the major sink of nutrients. Experimental evidences suggest the involvement of competition between reproductive organs for the available resources. The annual carbohydrates storage was analysed in mature pistachio trees characterized by low, medium and high crop load (about 1, 7 and 11 kg tree(-1) of dry in-shell nuts). The experiment was carried out in 2013 in a commercial pista…

A carbon budget model to predict branch carbohydrate deficiencies as a function of water stress and crop load in pistachio (Pistacia veraL.)

The effect of irrigation and crop load on alternate bearing was studied in pistachio tree using a “branch carbon budget model” developed to calculate branch carbohydrate balance. Experiences were conducted in Sicily (37°26’N, 14°03’E, 360 m a.s.l.) on female trees of ‘Bianca’. Two treatments were applied: rainfed (T0) and 100 mm of irrigation (T100). At 29, 44, 65, 86, 103 and 121 DAFB, on one fully expanded leaf selected on three trees per treatment, were monitored leaf gas exchanges. At 15 days interval, three branches treatment-1 were excised and, in the lab, the following parameters were measured: total photosynthetically active leaf surface; number of leaves, fruits, shoot fresh weight…

The Effect of Plant Water Status on the Chemical Composition of Pistachio Nuts (Pistacia vera L. Cultivar Bianca)

Pistachio nuts are worldwide appreciated for their chemical and organoleptic profiles. There are several studies on the influence of irrigation on pistachio productivity, whereas there are little available data on the influence on nut quality. In this study we characterized some qualitative traits of pistachio nuts cultivar Bianca in Mediterranean environment and how plant water status affected them. Water status had a positive and significant influence on the chlorophylls content, nuts from less stressed trees showed higher values of chlorophyll a (14.7 mg/100 g) and b (21.1 mg/100 g) compared than more stressed trees (9.3 and 11.5 mg/100 g for a and b, respectively). Solid phase microextr…

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…

Establishing a Reference Baseline for Midday Stem Water Potential in Olive and Its Use for Plant-Based Irrigation Management

12 páginas.- 7 figuras.- 4 tablas.- 55 referencias.-

Ricerche su aspetti della fisiologia del pistacchio (pistacia vera l.): alternanza di produzione e propagazione vegetativa.

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…