1,721,193 research outputs found
Grapevine in a Changing Environment: A Molecular and Ecophysiological Perspective
No full textOver the last decade, the extent and severity of heat and light stress, often in combination with water scarcity, have caused extensive agricultural losses all over the world. There is consensus that the Vitis vinifera L. displays large variations in terms of tolerance to abiotic summer stresses, i.e. excessive temperature and radiation, water shortage in the soil and high leaf-to-air water vapour pressure deficit (VPD), both when considered alone or in combination. However, a quantification of the effects of such factors on source function and sink strength is crucial to avoid severe imbalances between vine growth and yield, to optimize the use of natural resources, especially water and light, and to develop appropriate management strategies. Therefore, this chapter will provide a brief overview about current knowledge on light and heat stresses with or without a concurrent water stress and how they mutually interact to modify physiology, growth patterns and productivity in the grapevine. Chapter complements this review by summarizing in particular the impact of light, water and heat in berry composition
Chapter 7. Grapevine under light and heat stresses
No full textOver the last decade, the extent and severity of heat and light stress, often in
combination with water scarcity, have caused extensive agricultural losses all over
the world. There is consensus that the Vitis vinifera L. displays large variations in
terms of tolerance to abiotic summer stresses, i.e. excessive temperature and
radiation, water shortage in the soil and high leaf‐to‐air water vapour pressure
deficit (VPD), both when considered alone or in combination. However, a quantification
of the effects of such factors on source function and sink strength is crucial
to avoid severe imbalances between vine growth and yield, to optimize the use of
natural resources, especially water and light, and to develop appropriate management
strategies. Therefore, this chapter will provide a brief overview about current
knowledge on light and heat stresses with or without a concurrent water stress and
how they mutually interact to modify physiology, growth patterns and productivity
in the grapevine. Chapter 10 complements this review by summarizing in particular
the impact of light, water and heat in berry composition
INTERACTIONS OF LEAF AGE, FRUITING, AND EXOGENOUS CYTOKININS IN SANGIOVESE GRAPEVINES UNDER NONIRRIGATED CONDITIONS .2. CHLOROPHYLL AND NITROGEN-CONTENT
No full textThe interactions of leaf age, chlorophyll, and nitrogen content, together with modifications induced by fruiting and kinetin application, were investigated in horizontally trained shoots of field-grown Sangiovese (Vitis vinifera L.) grapevines. Dry weight per unit leaf area (W) increased over a leaf age span of five months and showed a curvilinear relationship with Pn rates reported earlier in the companion paper. Regression of chlorophyll per unit leaf area versus leaf age was curvilinear, maximum chlorophyll content being recorded at 80 to 90 days of age. The correlation of chlorophyll versus Pn was not significant within any shoot zones. Leaf nitrogen content plotted against leaf age exhibited different patterns depending on the unit chosen to express the data. An exponential negative regression was found when leaf N was given as percentage of dry weight. By contrast, a cubic regression fit the data when leaf N content was on a leaf-area basis. Nitrogen accumulated in the leaf up to about 45 to 50 days of age, and then an export pattern set in. Correlation of N versus Pn within each shoot zone was significant only for basal mature leaves when nitrogen data were expressed on a dry-weight basis, whereas the data for median leaves were significant when given on a leaf-area basis. Leaf age effects were not modified by crop level or kinetin. These results indicate that caution is needed when trying to use W, chlorophyll, and nitrogen as indicators of photosynthesis capacity for grapevine leaves of varying age
INTERACTIONS OF LEAF AGE, FRUITING, AND EXOGENOUS CYTOKININS IN SANGIOVESE GRAPEVINES UNDER NONIRRIGATED CONDITIONS .1. GAS-EXCHANGE
No full textThe interactions of leaf age and gas exchange, together with modifications induced by fruiting and exogenous kinetin treatments, were investigated in field-grown Sangiovese (Vitis vinifera L.) grapevines. Analyses carried out both on a seasonal basis and within each sampling date as a function of the natural gradient of age along the shoot showed that maximum Pn occurred at 30 to 35 days of age. A progressive decline started at about 50 days and four-month-old leaves retained 45% of maximum Pn. Very young, rapidly expanding leaves (< 15 days) also showed a consistently lower Pn and water use efficiency (WUE) than recently fully expanded leaves. Differential rates of leaf senescence due to fruiting or kinetin were not observed. These data form a basis for improving the physiological understanding of widely used vineyard management operations (shoot topping, leaf removal) which normally induce variations in canopy leaf age
GAS-EXCHANGE RESPONSE OF GRAPEVINE LEAVES UNDER FLUCTUATING LIGHT
No full textGas exchange responses to lightflecks of different frequency and duration were studied in mature grapevine leaves. Light-response curves under intermittent light showed lower carbon exchange rate (CER) than continuous light at non-saturating PFD levels (10-500 μ mol m-2s-1). White-dark and white-green alternating light of equal bright and shade periods at 0.33-5.33 Hz systematically resulted in improved light utilization as compared to high continuous light. Transpiration (T) was slightly more limited than the CER under intermittent light, resulting in higher water use efficiency. No differences in carboxylation efficiency were found by comparing the high continuous light treatment to white-dark lightflecks at 0.33 and 2.67 Hz. Our results show that, under short-term alternating light, CER of the grapevine leaf fully responds to the mean PFD level resulting from light oscillations
Performance of Croatina under short-cane mechanical hedging: A successful case of adaptation
No full textThe hypothesis that short mechanical hedging can be successfully applied even on cultivars with low fruitfulness of basal buds was tested over four years (2000 to 2003) on Vitis vinifera L. cv. Croatina. Yield per vine increased from 23 to 49% on hedged vines as compared to short-cane hand-pruned vines; up to a 30% increase (equivalent to ∼60 nodes per vine) there was no detriment to grape quality, and labor demand was cut by 55 to 60%. Yield compensation in the hedged vines mostly occurred as reduced budbreak; weak or no compensation effects were seen for cluster weight and bud fruitfulness, respectively. A tendency for impaired quality was seen only at the highest node number per vine (∼75), while the linear relationship found between yield and node number per vine suggests that short-cane hand-pruning can also be feasible provided that at least 30 nodes per meter of row are retained. These findings indicate that mechanical pruning can be an excellent tool for converting traditionally long-cane pruned cultivars into short-cane pruned with related advantages in terms of more balanced growth and ripening and adaptability to full mechanization
INTERACTIONS OF CROP LEVEL AND LATE-SEASON WATER-STRESS ON GROWTH AND PHYSIOLOGY OF FIELD-GROWN CONCORD GRAPEVINES
No full textThe effects and interactions of late season soil water deficit and crop level on the growth, yield, fruit quality, and physiology of four-year-old Concord own-rooted grapevines in a loam soil in New York were examined. Soil moisture stress was induced in half of the vines by rain-shielding beginning after bloom, while natural and supplemental drip irrigation were used to maintain high water status of the other half. Within each stress plot crop levels were adjusted to give unthinned vines with a mean of 130 clusters/kg pruning weight versus 67 clusters/kg pruning weight giving about 18 and 9 t/ha, respectively. Thinning of the crop significantly decreased cluster number and yield, but increased shoot growth, juice °Brix, and pruning weights as expected. Since significant soil water stress did not developed until about 10 to 20 days after veraison, the stress only significantly reduced net photosynthesis (Pn) and leaf conductance (gl) after veraison at leaf and pre-dawn soil water potential below -1.1 and -0.25 MPa. A significant water stress x crop level interaction occurred at harvest for juice °Brix and total soluble solids (TSS) per berry, indicating that reduction of sugar accumulation due to water stress was aggravated in heavier cropping vines. No significant effects of crop level on leaf gas exchange or vine water use (i.e., soil water reduction in shielded plots) were observed. The reduction of leaf function and earlier leaf senescence in the unthinned stressed vines were not severe enough to cause carry-over effects the following season
INFLUENCE OF ROOT PRUNING AND WATER-STRESS ON GROWTH AND PHYSIOLOGICAL FACTORS OF POTTED APPLE, GRAPE, PEACH AND PEAR TREES
No full textApple, grape, peach and pear trees were grown with roots divided between two pots for 2 months and then assigned to the following treatments: (1) control, receiving 100% of total plant transpiration (TPT) distributed equally between both pots; (2) pruned, receiving 100% of TPT in one pot with removal of roots in the second pot; (3) stressed, receiving 100% of TPT in one pot with water withheld from the other. Shoot growth of all species except peach was reduced only by root pruning (20%, 30% and 40% less than control in grape, pear and apple, respectively). New root growth of pruned and stressed plants was generally less than control (25% on average). During the first 15 days after treatment, both root pruning and water stress depressed transpiration and net photosynthesis. Thereafter, stressed plants did not differ from control; transpiration and net photosynthesis of pruned plants approached those of control only after 50 days. At the end of the experiment unchanged shoot:root ratios were found in stressed trees of each crop compared with control, while root pruning caused a variable shoot:root ratio depending on the degree of canopy reduction. The findings indicate the ability of the examined crops to adapt to drastic manipulations of the root system. © 1992
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