Controlled Water Stress to Improve Fruit and Vegetable Postharvest Quality (original) (raw)
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Water shortage and quality of fleshy fruits--making the most of the unavoidable
Journal of experimental botany, 2014
Extreme climatic events, including drought, are predicted to increase in intensity, frequency, and geographic extent as a consequence of global climate change. In general, to grow crops successfully in the future, growers will need to adapt to less available water and to take better advantage of the positive effects of drought. Fortunately, there are positive effects associated with drought. Drought stimulates the secondary metabolism, thereby potentially increasing plant defences and the concentrations of compounds involved in plant quality, particularly taste and health benefits. The role of drought on the production of secondary metabolites is of paramount importance for fruit crops. However, to manage crops effectively under conditions of limited water supply, for example by applying deficit irrigation, growers must consider not only the impact of drought on productivity but also on how plants manage the primary and secondary metabolisms. This question is obviously complex becau...
Fruits, 2005
Abstract --Introduction. Vegetative and fruit growth in fruit trees are differentially sensitive to water deficit during the season depending on the stage of fruit growth. Attempts have been made to evaluate the possibilities of using regulated deficit irrigation to control vegetative growth and save water in the fruit industry. Materials and methods. Effects of water stress (WS) and crop load (CL) on fruit growth and carbon assimilation rates were evaluated in a 7-year-old 'Elegant Lady' peach orchard. A completely randomized block design with 2 × 3 factors [irrigation with two levels (control and WS) and CL with three levels (light, commercial and heavy)] was used. Results and discussion. Both WS and CL affected fruit growth during the last stages but not early on. CL did not affect trunk water potential which was, however, significantly reduced by WS throughout the day and the season. Trunk water potential of water-stressed trees was lower than that of control trees throughout the day and the season regardless of CL. The magnitude of WS increased as the season progressed. Stomatal conductance, transpiration rate and CO 2 assimilation rate were not affected by CL but were reduced by WS. The trees responded (acclimated) to stress by progressively reducing their transpiration rate as the severity of stress increased. For each irrigation regime, assimilation rates were similar for all three crop levels. This indicated the existence of alternate sinks for assimilates when CL was low, which compensate for the reduction of fruit sink activity resulting from fruit thinning. Conclusion. Water deficit reduced trunk water potential, stomatal conductance, transpiration and photosynthesis in 'Elegant Lady' peach trees. However, CL had a limited effect on these functions. There were good correlations between trunk water potential and either stomatal conductance or assimilation rate in water-stressed trees but not in control trees. This indicates a poor coordination between leaf functions in peach trees under optimal conditions. However, these relationships were stronger under WS conditions. Thus, water use efficiency appeared to increase under water deficit conditions.
Tolerance to water deficit in young trees of jackfruit and sugar apple 1
Revista Ciencia Agronomica, 2010
The predawn leaf water potential (Ψ l ), stomatal conductance (g s ), CO 2 assimilation (A), transpiration (E), chlorophyll a fluorescence and leaf metabolite contents (soluble sugars, proteins and free amino acids) of two tropical fruit species grown in a greenhouse were evaluated to determine the effect of induced water stress on young plants. Six month-old jackfruit (Artocarpus heterophyllus Lam.) and sugar apple (Annona squamosa L.) plants were evaluated in 10.0 L pots after eight days of water withholding, imposed by suspension of irrigation. Jackfruit water status was better than sugar apple. Sugar apple plants showed different daily stomatal behavior when well hydrated, compared to jackfruit plants under the same conditions. The gas exchange of both species showed sensibility to high vapor pressure deficit (VPD). However, under water deficit, photochemical efficiency dropped at midday in both treatments (control and water deficit) and both species showed low tolerance to high VPD and light intensity under greenhouse conditions. In contrast, some chlorophyll fluorescence variables showed good photosystem II stability at highest VPD hour (14:00 h). The present results involving carbohydrate metabolic changes revealed an accumulation of soluble sugars; moreover, protein and free amino acid contents in water stressed leaves also increased. These findings suggest an absence of damage to photosynthetic machinery for water deficit period. Jackfruit revealed greater tolerance to water deficit than sugar apple an important feature for commercial crops in northeastern Brazil.
Tolerance to water deficit in young trees of jackfruit and sugar apple
Revista Ciência Agronômica, 2010
The predawn leaf water potential (Ψ l ), stomatal conductance (g s ), CO 2 assimilation (A), transpiration (E), chlorophyll a fluorescence and leaf metabolite contents (soluble sugars, proteins and free amino acids) of two tropical fruit species grown in a greenhouse were evaluated to determine the effect of induced water stress on young plants. Six month-old jackfruit (Artocarpus heterophyllus Lam.) and sugar apple (Annona squamosa L.) plants were evaluated in 10.0 L pots after eight days of water withholding, imposed by suspension of irrigation. Jackfruit water status was better than sugar apple. Sugar apple plants showed different daily stomatal behavior when well hydrated, compared to jackfruit plants under the same conditions. The gas exchange of both species showed sensibility to high vapor pressure deficit (VPD). However, under water deficit, photochemical efficiency dropped at midday in both treatments (control and water deficit) and both species showed low tolerance to high VPD and light intensity under greenhouse conditions. In contrast, some chlorophyll fluorescence variables showed good photosystem II stability at highest VPD hour (14:00 h). The present results involving carbohydrate metabolic changes revealed an accumulation of soluble sugars; moreover, protein and free amino acid contents in water stressed leaves also increased. These findings suggest an absence of damage to photosynthetic machinery for water deficit period. Jackfruit revealed greater tolerance to water deficit than sugar apple an important feature for commercial crops in northeastern Brazil.
Physiological response of two apple genotypes to different water regimes under semiarid conditions
The effect of five irrigation regimes (20%, 40%, 60%, 80%, and 100% of "Class A" pan evaporation rate) were studied under field conditions in the main fruit growth phase of two apples genotypes, 'Red Ace Golden Delicious' and 'Red Edna', grafted on MM106 rootstock. The crop was harvested on 15 September 2008 and fruit size and weight were determined. Biochemical (chlorophylls a and b, proline) and physiological [net photosynthesis (A), stomatal resistance (Rs), transpiration rate (E) and intercellular CO 2 concentration (Ci)] parameters already known as stress indicators in apple trees were measured in leaves of trees subjected to different irrigation regimes. Fruit number and yield per tree were determined in the field; fruit flesh firmness, total soluble solids (TSS), and titratable acidity were measured subsequently. Transpiration rate did not differ significantly among the treatments at all sampling dates for both cultivars.
American Journal of Plant Sciences, 2013
Water restrictions management for fruit rosaceous during slowdown periods of fruit growth can increase water use efficiency and improve fruit quality without reducing significantly their yield. In this context, two water restriction levels were tested during four consecutive seasons (2007-2011) in peach, plum and almond trees during slowdown periods of fruit growth corresponding to stage II for peach and plum and to stages II and III for almond. Water was applied by drip irrigation to produce different water-application treatments of 50% ETc (T 50) and 75% ETc (T 75) of non-stressed trees irrigated at 100% ETc (T 100). The response of trees is presented only for the last season of the experiment (2010-2011) where the effect of the applied water stress is more pronounced. Results show that the effect of water restrictions varied depending on the species. Yield and fruit size were reduced significantly for peach only under treatment T 50. Fruit quality was improved for this species with an increase of brix refractometric index and a decrease of acidity. These parameters were evolved in the same manner for plum but the observed differences were not significant. For almond, kernel quality remained unaffected by water restriction at T 75. However, the epidermal wrinkles of kernels were more embossed, in response to treatment T 50 , which affected their appearance. Except leaf area, the evolution of shoots growth, chlorophyll content and leaf temperature showed that the physiology of all species was affected by water stress created by the application of the two irrigation treatments but without profound influence, particularly in plum. In conclusion, irrigation-water may be economized during slowdown periods of fruit growth without major negative effect up to 25% ETc for peach and almond and up to 50% ETc for plum.
The Effect of Reduced Soil Water Status on 'Golden Delicious' Apple Trees
X International Symposium on Integrating Canopy, Rootstock and Environmental Physiology in Orchard Systems, 2014
In the Western Cape, South Africa, uncertainty exists regarding effects of global warming-induced climatological changes on limited water resources, as well as the future incidence and extent of droughts. A need to employ appropriate irrigation strategies timeously during drought periods, instigated research concerning the possibility to maintain optimum fruit yield and quality by means of deficit irrigation (DI) in the Koue Bokkeveld production region. 'Golden Delicious' apple trees on M793 rootstock were subjected to 15 treatments, which consisted of irrigation at combinations of 50%, 75% or 90% plant available water (PAW) depletion or no irrigation during four phenological phases viz. vegetative growth and cell division (Phase 1), cell enlargement (Phase 2), fruit ripening (Phase 3) and post-harvest (Phase 4). The vegetative growth, yield and fruit quality response of the trees to these treatments were evaluated during 2005/06, 2006/07 and 2007/08. Plant physiological data were collated in 2005/06 at the end of Phases 1, 2 and 3. In 2005/06, leaf (Ψ l) and stem (Ψ s) water potential correlated well at predawn and midday. Cloudy conditions interfered with midday photosynthesis measurements of Phase 2. Water deficits during Phases 2 and 3 decreased predawn Ψ s at the end thereof from ca.-0.43 MPa to ca.-1.67 MPa and ca.-1.41 MPa, respectively. At the end of Phases 1, 2 and 3, midday Ψ s decreased from ca.-1.1 MPa to ca.-1.8 MPa,-2.4 MPa and-2.2 MPa, respectively. At the end of Phase 1, leaf photosynthesis, stomatal conductance and transpiration tended to decrease with decreased midday Ψ s. During Phase 3, increased leaf temperatures tended to exacerbate water deficit effects on photosynthesis. Under the prevailing conditions, DI during Phases 1 and 3, respectively, may be partially accountable for decreased shoot and/or fruit growth rates, and eventually lower yield and fruit quality.
Irrigation Science, 2008
We evaluated the effects of a deficit-irrigation (DI) strategy in mature 'Lane late' sweet orange (Citrus sinensis (L.) Osb.) trees grafted on two different droughttolerant rootstocks, 'Cleopatra' mandarin (Citrus reshni Hort. ex Tanaka) and 'Carrizo' citrange (Citrus sinensis (L.) Osbeck x Poncirus trifoliata L.). Two treatments were applied: a control treatment, irrigated at 100% of crop evapotranspiration (ETc) during the entire season, and a DI treatment, irrigated at 100% ETc, except during phases I (initial fruit-growth period,) and phase III (final fruitgrowth period, ripening, harvest), when no irrigation was applied. Flowering, fruit abscission and fruit growth of trees on 'Carrizo' were more affected by DI than on 'Cleopatra'. Deficit irrigation reduced yield in both rootstocks due mainly to a decrease in the number of fruits. The phase most sensitive to drought stress was phase I. Moreover, DI altered fruit quality depending on the period when drought stress was applied. Fruit quality was modified by DI: total soluble sugars and titratable acidity increased when a severe drought stress occurred only in phase III but only increased the peel/pulp ratio if it occurred only in phase I. The quality of fruits from trees on 'Carrizo' under DI was affected more than that of fruits from trees on 'Cleopatra'. Under DI in semi-arid regions 'Cleopatra' mandarin can mitigate more the negative effects of drought stress on yield and fruit quality than 'Carrizo' citrange.
Factors involved in alleviating water stress by partial crop removal in pear trees
Tree Physiology, 2008
We studied the relief of water stress associated with fruit thinning in pear (Pyrus communis L.) trees during drought to determine what mechanisms, other than stomatal adjustment, were involved. Combinations of control irrigation (equal to crop water use less effective rainfall) and deficit irrigation (equal to 20% of control irrigation), fruit load (unthinned and thinned to 40 fruits per tree) and root pruning (pruned and unpruned) treatments were applied to pear (cv. 'Conference') trees during Stage II of fruit development. Daily patterns of midday stem water potential (Ψ stem ) and leaf conductance to water vapor (g l ) of deficit-irrigated trees differed after fruit thinning. In response to fruit thinning, g l progressively declined with water stress until 30 days after fruit thinning and then leveled off, whereas the effects of decreased fruit load on Ψ stem peaked 30-40 days after fruit thinning and then tended to decline. Soil water depletion was significantly correlated with fruit load during drought. Our results indicate that stomatal adjustment and the resulting soil water conservation were the factors determining the Ψ stem response to fruit thinning. However, these factors could not explain differences in daily patterns between g l and Ψ stem after fruit thinning. In all cases, effects of root pruning treatments on Ψ stem in deficit-irrigated trees were transitory (Ψ stem recovered from root pruning in less than 30 days), but the recovery of Ψ stem after root pruning was faster in trees with low fruit loads. This behavior is compatible with the concept that the water balance (reflected by Ψ stem values) was better in trees with low fruit loads compared with unthinned trees, perhaps because more carbon was available for root growth. Thus, a root growth component is hypothesized as a mechanism to explain the bimodal Ψ stem response to fruit thinning during drought.
Plant Water Status as an Index of Irrigation Need in Deciduous Fruit Trees
HortTechnology, 1997
To be useful for indicating plant water needs, any measure of plant stress should be closely related to some of the known short- and medium-term plant stress responses, such as stomatal closure and reduced rates of expansive growth. Midday stem water potential has proven to be a useful index of stress in a number of fruit tree species. Day-to-day fluctuations in stem water potential under well-irrigated conditions are well correlated with midday vapor-pressure deficit, and, hence, a nonstressed baseline can be predicted. Measuring stem water potential helped explain the results of a 3-year deficit irrigation study in mature prunes, which showed that deficit irrigation could have either positive or negative impacts on tree productivity, depending on soil conditions. Mild to moderate water stress was economically beneficial. In almond, stem water potential was closely related to overall tree growth as measured by increases in trunk cross-sectional area. In cherry, stem water potential...