Plant hydraulic conductance adapts to shoot number but limits shoot vigour in grapevines

2015 ◽  
Vol 42 (4) ◽  
pp. 366 ◽  
Author(s):  
Markus Keller ◽  
Laura S. Deyermond ◽  
Bhaskar R. Bondada

The rate of shoot growth (vigour) in grapevines tends to decrease as the number of shoots per plant increases. Because the underlying causes of this relationship remain unclear, they were studied by variable pruning of field-grown, deficit-irrigated Merlot grapevines (Vitis vinifera L.). Shoot number ranged from 11 to 124 per vine and was inversely correlated with shoot growth rate, leaf appearance rate, axillary bud outgrowth, internode length, leaf size, shoot leaf area, carbon partitioned to the fruit (Cfruit) per shoot, average daily maximum photosynthesis (Amax), stomatal conductance (gmax), and leaf-specific hydraulic conductance (Kl). Shoot number was positively correlated with canopy leaf area, whole-vine Cfruit, whole-plant hydraulic conductance (Kv), and canopy conductance (Kc). Higher shoot vigour was associated with higher Amax, gmax, predawn leaf water potential (Ψpd), shoot hydraulic conductance (Ks), Kl, and Kv. Vigorous shoots supported both more vegetative growth and more reproductive growth; thus fruit growth did not compete with shoot growth for photosynthates. These results indicate that the hydraulic capacity of grapevines adapts to varying shoot numbers to support leaf physiology, growth, and carbon partitioning, but adaptation may be limited, putting upper bounds on the growth of individual shoots and fruit.

1994 ◽  
Vol 24 (1) ◽  
pp. 149-154 ◽  
Author(s):  
Brayton F. Wilson ◽  
Matthew J. Kelty

The bud bank in black oak (Quercusvelutina Lam.) trees is composed of four bud types, with the first three occurring on current shoots: (i) large buds in terminal clusters; (ii) large intercluster buds; (iii) small leafless buds; and (iv) preventitious buds on older shoots. Leafless buds may grow and preventitious buds may form epicormic shoots after injuries to large buds. We applied clipping treatments to small trees growing in either shade or light to test for crown recovery of leaf number, leaf area, leaf weight, shoot number, and total shoot length. Removing the terminal bud cluster almost doubled the proportion of intercluster buds that produced shoots and did not affect crown parameters, compared with control trees. Removing all large buds increased epicormic shoot production, but did not affect crown parameters. Removing current shoots reduced only leaf area and leaf number in the shade. The more extreme clipping treatments released primarily 2-year-old preventitious buds, but only a few older buds. Buds of all ages could be forced on isolated stem segments. Mortality of buds from the 1st to 2nd year was more than 90% for buds with leaves and about 50% for leafless buds.


1993 ◽  
Vol 20 (2) ◽  
pp. 143 ◽  
Author(s):  
T Winkel ◽  
S Rambal

A comparative study of soil-plant water relations was conducted on three grapevine cultivars (Vitis vinifera L. cvv. carignane, merlot, shiraz) to investigate their adjustment to short-term and long-term water stress under field conditions. Adjustment was a function of the relative stability of the internal plant water status on diurnal and seasonal scales. On a diurnal scale, stomatal closure in response to water vapour pressure directly contributed to this stability. Indirect evidence suggested an influence of the soil water status on the diurnal stomatal activity. On a seasonal scale, sufficient leaf hydration required high whole-plant hydraulic conductance. This was achieved by either daily stomatal regulation or limitation of leaf area. Physiological adjustment to water stress through stomatal control was well developed in cv. carignane, which originated in a Mediterranean environment. However, cv. shiraz, which was of mesic origin, apparently adjusted to water stress by reducing leaf area. Our study demonstrates the utility of integrating data on stomatal conductance, leaf water potential and whole-plant hydraulic conductance to interpret whole plant adaptation to water stress, and elucidates two mechanisms by which genotypes differentially acclimate to water stress.


2014 ◽  
Vol 1 ◽  
pp. e003 ◽  
Author(s):  
Pierre-Éric Lauri ◽  
Antoine Marceron ◽  
Frédéric Normand ◽  
Anaëlle Dambreville ◽  
Jean-Luc Regnard

It is generally postulated that at the tree scale a drought-related decrease in hydraulic conductance is balanced by a decrease of leaf area. We hypothesized that, at the individual leaf scale, drought affects the allometry between leaf area or mass and hydraulics, leading to a non-linear relationships between these traits. The study was conducted on well-watered and on water-stressed shoots of several apple genotypes covering an extended range of leaf area. Working on dried leaves, we measured leaf lamina area and mass and analyzed their relationships with the maximal xylem hydraulic conductance of the water pathway through the parent shoot and the petiole connected to the leaf lamina. Drought decreased leaf area and mass in absolute values. It also changes the allometric relationships between these two variables: for a same decrease of leaf dry mass the water-stressed shoot had a lower decrease of leaf dry area than the well-watered shoot. Our study also showed that drought affected the stem-to-petiole hydraulics with a higher hydraulic efficiency in the well-watered shoot compared to the water-stressed shoot. We discuss that, compared to the well-watered condition, drought not only decreased leaf size, but also reduced xylem efficiency through the stem-to-petiole pathway with regard to the leaf area and mass supplied.


HortScience ◽  
1990 ◽  
Vol 25 (9) ◽  
pp. 1111f-1111
Author(s):  
Curt R. Rom

Shoot growth `Starkspur Supreme Delirious' on 10 different rootstock was measured on 3-, 4- and 6-year-old trees at weekly intervals from budbreak until terminal bud formation. Spur density, spur development, and extension shoot leaf area development were measured in September. Growth rate was analyzed by regression against chronological time and accumulated growing degree days using linear and nonlinear statistics.Rootstock affected shoot length, leaf number, leaf area, leaf size, leaf dry weight/leaf area and internode length. Trees on M.4, M.7 EMLA, P-1 and seedling had the longest shoots and highest shoot growth rate. Trees on P16 had least leaves and leaf area per shoot and smallest shoot leaves. Leaf dry wt./area were negatively correlated to leaf size. Typically, trees with shortest shoot length and smallest internode length had greatest spur density. Rootstock affected both rate and duration of shoot growth. Shoots on trees with P22 and P2 rootstocks grew for the shortest duration while trees on M.4 and M.7 EMLA grew for the longest period.


OENO One ◽  
2021 ◽  
Vol 55 (1) ◽  
pp. 93-103
Author(s):  
Maria Schulze-Sylvester ◽  
José Antonio Corronca ◽  
Carolina Ivon Paris

Vine mealybug Planococcus ficus Signoret (Hemiptera: Pseudococcidae) is an important phloem-feeding pest species in many grapevine producing areas worldwide. The economic damage of P. ficus is thought to be mainly caused by sooty mould on infested grape clusters and transmission of plant viruses. Direct damage caused by mealybug feeding to grapevine plants (Vitis vinifera, L.) has only been vaguely described or otherwise completely discarded. The present study is the first to give an insight into the direct impacts of P. ficus on vegetative growth and biomass dynamics of grapevine plants. In a screenhouse, three-year-old, potted grapevine plants were infested with mealybugs at two different densities, imitating high and low field infestation levels. Mealybug numbers, plant biomass, leaf area, leaf size and leaf number were monitored over six months and compared to a control treatment without mealybugs. High infestation levels reduced leaf and stem biomass by one third, while low levels of P. ficus impacted only stem biomass, indicating a higher sensibility of the perennial parts of the plant or a reallocation of biomass. Leaf area, size and number were not affected by mealybug feeding.In conclusion, grapevine response to P. ficus is gradual and involves different plant parts depending on the severity of the attack.  Contrary to previous assumptions, this study demonstrates considerable direct impacts of mealybug feeding on temporal and perennial parts of grapevine plants.


2013 ◽  
Vol 40 (7) ◽  
pp. 749 ◽  
Author(s):  
Mark Eltom ◽  
Mike Trought ◽  
Chris Winefield

The influence of restricting available carbohydrates (CHOs) on shoot growth was studied by cane girdling field grown Vitis vinifera L. Sauvignon Blanc grapevines before budbreak. Canes were girdled 5, 10 or 20 cm from the terminal bud of the cane, and the shoot growth of the terminal bud was monitored over the course of a single growing season. A linear relationship was found between the initial rate of shoot growth and the amount of cane isolated by the girdle. A decrease in available CHOs during initial shoot growth appeared to inhibit the shoot’s ability to produce new vegetative nodes past the point of discontinuity, resulting in a decrease in total leaf area due to incomplete leaf expansion. The transition from the vine’s dependence on reserve CHOs to a net positive state appeared to occur when shoot growth reached a steady state. In the case of severe CHO restriction, no lateral growth occurred, suggesting the CHO status in the vine may play a role in lateral bud growth. The cross-sectional area of canes or shoots were shown to have a linear relationship to their CHO content, which allows for an estimation of the amount of CHOs required to obtain growth similar to the control treatment. Additionally, main shoot leaf area can be used to predict total CHO content in the shoot at harvest.


HortScience ◽  
1998 ◽  
Vol 33 (3) ◽  
pp. 468b-468
Author(s):  
Stephen F. Klauer ◽  
J. Scott Cameron ◽  
Chuhe Chen

After promising results were obtained with an open-style split trellis (two top wires) in its initial year, two new trials were established in 1997 in northwest (Lynden) and southwest (Woodland) Washington. For the split trellis, actual yields were 33% (machine-picked 1/2 season) and 17% (hand-picked) greater, respectively, for the two locations compared to the conventional trellis (one top wire). In Woodland, canes from the split trellis had 33% more berries, 55% more laterals, 69% more leaves, and 25% greater leaf area compared with the conventional trellis. Greatest enhancement of these components was in the upper third of the canopy. Laterals were also shorter in this area of the split canopy, but there was no difference in average total length of lateral/cane between trellis types. Total dry weight/cane was 22% greater in the split trellis, but component partitioning/cane was consistent between the two systems with fruit + laterals (43%) having the greatest above-ground biomass, followed by the stem (30% to 33%) and the leaves (21% to 22%). Measurement of canopy width, circumference, and light interception showed that the split-trellis canopy filled in more quickly, and was larger from preanthesis through postharvest. Light interception near the top of the split canopy was 30% greater 1 month before harvest with 98% interception near the top and middle of that canopy. There was no difference between the trellis types in leaf CO2 assimilation, spectra, or fluorescence through the fruiting season, or in total nitrogen of postharvest primocane leaves.


Water ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 252
Author(s):  
Muhammad Shahinur Alam ◽  
David William Lamb ◽  
Nigel W. M. Warwick

Estimating transpiration as an individual component of canopy evapotranspiration using a theoretical approach is extremely useful as it eliminates the complexity involved in partitioning evapotranspiration. A model to predict transpiration based on radiation intercepted at various levels of canopy leaf area index (LAI) was developed in a controlled environment using a pasture species, tall fescue (Festuca arundinacea var. Demeter). The canopy was assumed to be a composite of two indistinct layers defined as sunlit and shaded; the proportion of which was calculated by utilizing a weighted model (W model). The radiation energy utilized by each layer was calculated from the PAR at the top of the canopy and the fraction of absorbed photosynthetically active radiation (fAPAR) corresponding to the LAI of the sunlit and shaded layers. A relationship between LAI and fAPAR was also established for this specific canopy to aid the calculation of energy interception. Canopy conductance was estimated from scaling up of stomatal conductance measured at the individual leaf level. Other environmental factors that drive transpiration were monitored accordingly for each individual layer. The Penman–Monteith and Jarvis evapotranspiration models were used as the basis to construct a modified transpiration model suitable for controlled environment conditions. Specially, constructed self-watering tubs were used to measure actual transpiration to validate the model output. The model provided good agreement of measured transpiration (actual transpiration = 0.96 × calculated transpiration, R2 = 0.98; p < 0.001) with the predicted values. This was particularly so at lower LAIs. Probable reasons for the discrepancy at higher LAI are explained. Both the predicted and experimental transpiration varied from 0.21 to 0.56 mm h−1 for the range of available LAIs. The physical proportion of the shaded layer exceeded that of the sunlit layer near LAI of 3.0, however, the contribution of the sunlit layer to the total transpiration remains higher throughout the entire growing season.


2016 ◽  
Vol 61 (1) ◽  
pp. 45-55
Author(s):  
Dragan Vujovic ◽  
Dragoljub Zunic ◽  
Boris Pejin ◽  
Jelena Popovic-Djordjevic

During a four-year period, ampelographic experiments focusing on the berry cluster (average length of grape cluster, number of grape clusters per shoot, number of berries per grape cluster and length of peduncle), berry (length of berry and berry juice yield), length of pedicel and seed (length of berry seed) of Merlot cultivar (used as a relevant standard) and 11 clones (Nos. 022, 023, 025, 026, 027, 028, 029, 030, 031, 033 and 034) were performed in order to establish the differences among them. These experiments were actually conducted in the third phase of individual clonal selection of Merlot cultivar carried out in Serbia. The lengths of grape cluster and pedicel as well as berry must yields differed significantly among the examined clones. The cluster and principal component analyses classified 12 samples into three divergent clusters/groups, respectively. The clones belonging to the cluster II /the second group/ had significantly higher values of numbers of grape clusters per shoot and berries per grape cluster; lengths of peduncle and berry; berry must yield and length of pedicel, compared both to standard Merlot /the cluster I, the first group/ and the clones of the cluster III /the third group/. The phenological observations showed no significant differences in the beginnings and durations of phenological stages and vegetation period of the examined clones. The obtained results indicate the real need for further research work focused both on the agrobiological and technological properties of the grapes and wines aiming to better describe the selected clones.


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