Soil Temperature Prior to Veraison Alters Grapevine Carbon Partitioning, Xylem Sap Hormones, and Fruit Set

Abstract

To gain a better understanding of environmental effects on grapevines and the physiological regulation of acclimation, we determined the effects of soil temperature (14 or 24°C) between anthesis and veraison on growth, nonstructural carbohydrates, cytokinins, abscisic acid, and leaf function of potted Vitis vinifera cv. Shiraz. Plants of each regime were selected from two groups that had been grown in a glasshouse from three weeks prior to budbreak at an average soil temperature of either 13 or 23°C. Soil temperature between anthesis and veraison affected utilization and restoration of root and trunk nonstructural carbohydrates and changes in biomass of major plant organs. Soil warming promoted shoot growth via utilization of starch reserves, while soil cooling promoted starch storage in both the root and wood and shifted overall biomass partitioning to the roots. A change in soil temperature from warm to cool through flowering was also associated with reduced fruit set. Diurnal courses of photosynthesis, transpiration, and stomatal conductance after fruit set were significantly affected by soil temperature. Phytohormones (cytokinin and abscisic acid) were measured in the xylem sap and leaves at fruit set and veraison. Differences between these two sample types during grapevine development highlight a phytohormone shift likely involved in postveraison fruit ripening. We conclude that soil temperature significantly affects grapevine growth and that the responses are mediated largely by an influence of temperature on mobilization of nonstructural carbohydrates from the roots.

Application of Fractions of Crop Evapotranspiration Affects Carbon Partitioning of Grapevine Differentially in a Hot Climate

“…Under our experimental conditions, yield per plant was strongly related to shoot, leaf, and root BM. Similarly, Field et al (2020) found that grapevines with the lowest shoot growth rate (elongation or dry biomass) before veraison had significantly less fruit set than the other treatments, attributing these effects to the restoration of root carbohydrate reserves that occurred at the same time.…”

“…However, canopy BM was greatly reduced in both 50% ET c and 25% ET c compared with 100% ET c . Accordingly, Field et al (2020) reported that grapevine grown under warm soil conditions favored shoot and fruit development over carbohydrate reserve accumulation. In contrast, Candolfi-Vasconcelos et al (1994) reported that a lower leaf area to fruit ratio increased the translocation of carbohydrates from permanent structures to reproductive organs to support grape ripening.…”

“…Therefore, to ensure sufficient vegetative growth, yields, and acclimation to environmental stresses, grapevines must efficiently allocate available annual resources to both vegetative and reproductive tissues. Increased soil temperature due to the changing climate, especially before veraison , strongly affects seasonal balance between shoot and root growth, bloom, plant water use, photosynthesis, and the availability of carbohydrate reserves ( Field et al, 2020 ). Water availability is a determining factor for cell growth and photosynthesis ( Medici et al, 2014 ) and for the redistribution of carbohydrates between the source and sink organs ( Lemoine et al, 2013 ).…”

The Hulks and the Deadpools of the Cytokinin Universe: A Dual Strategy for Cytokinin Production, Translocation, and Signal Transduction

“…Over the years, there have been several indirect lines of evidence for CK transport. CKs serve as a long-range signal for nitrogen [ 24 , 286 ], and t Z- and iP-type have been detected in xylem and phloem sap, respectively [ 40 , 148 , 286 , 287 , 288 , 289 ]; experiments with grafted plants have repeatedly shown the ability of WT roots or shoots to complement for a detrimental mutation [ 120 , 290 , 291 ] and overall, the transport of CKs has been shown [ 175 , 178 , 292 ]. Lastly, the expression sites of IPT and LOG genes do not overlap with the CK response domains [ 12 ].…”

Potential Phenotyping Methodologies to Assess Inter- and Intravarietal Variability and to Select Grapevine Genotypes Tolerant to Abiotic Stress

“…Heat stress physiology in turn, at both leaf and berry levels, should be evaluated to better understand the impacts of drought and high soil and air temperatures on grapevine physiology and morphology of leaves, berries, and bunches ( Costa et al, 2019a ; Field et al, 2020 ). This is particularly important because berries tend to ripe earlier in warmer conditions, due to the effect of heat in anticipating phenological events ( Van Leeuwen and Destrac-Irvine, 2017 ).…”