Influence of leaf ageing, leaf area and crop load on photosynthesis, stomatal conductance and senescence of grapevine (Vitis vinifera L. cv. Pinot noir) leaves

Treatments varying the leaf area (source) to crop load (sink) balance of pot-grown Pinot noir vines caused differences in the photosynthesis (Pn) rates of the fourth leaf, 48 h after they were applied. Stomatal conductance was only affected by leaf removal, not by the presence or absence of crop. The vines with and without crop were subject to a range of leaf removal treatments. All treatments retained leaves at nodes 1-4 from the shoot base and then had 100%(control), 66 %, 33 %, or 0 % leaves retained from node 5 to the apex of the shoot. Leaf removal elevated the Pn rate of the fourth leaf, but there was no difference in Pn rate between vines with or without crop pre-veraison. From veraison on the photosynthetic rate of vines with crop and 100 % leaves retained increased. Similar, high Pn rate was also observed for vines without crop and 0 % leaves retained. The lower Pn rate of vines with crop pre-veraison suggests that there is potential to increase vine productivity in this period. The Pn rate of vines without crop, 100 % and 66 % leaves retained declined from 15 d after treatment. Average Pn of all treatments over the 4 measurements prior to harvest was positively correlated with the vine leaf area (source) to total vine dry weight (sink) ratio. Leaves of vines with a high source:sink ratio (without crop, 100, 66 or 33%leaves retained) senesced i.e. decreased in chlorophyll content more rapidly than leaves of the low source to sink ratio treatments. Results indicate that the decline in grapevine leaf Pn, previously associated with advanced leaf age is actually caused by a progressive increase in leaf area to fruit weight (source:sink) ratio, as leaves emerge on the developing vine

Variability in flowering, fruit set and yield in response to vineyard topography and pruning type in Pinot noir

Aim: This study investigates the effects of site aspect and pruning management on flowering, fruit set and yield in Pinot noir vines. Methods: Two rows of 19-year-old Pinot noir vines were selected within a commercial vineyard with south, hilltop, and north-facing aspects. Vines were either cane- or spur-pruned, retaining 20 nodes per vine. One monitoring vine was selected at each sub-plot (consisting of four vines) and used to assess days to 50% flowering, fruit set (%) and days to 50% veraison. Total soluble solids samples were taken from each sub-plot and vines were harvested separately for yield. Results/Findings: Days to 50% flowering was affected by the topographical position. Vines from south-facing plots reached 50% flowering three days earlier during 2018-19 and eight days earlier 2020-21 compared to other plots. Cane pruning advanced the flowering date by one day compared with spur pruned vines (2019-20). Fruit set (%) was affected by topography. Vines from the hilltop plots had less than 50% fruit set during 2018-19 and 2020-21 compared to south and north plots (>70% fruit set). The lower fruit set was reflected in reduced yields. Despite the delayed flowering, vines from the hilltop position reached 50% veraison four days earlier than vines from the south and north plots during 2020–21. While there were initial differences in total soluble solids (at 7 to 8 oBrix) at six topographical positions, these variations disappeared by the time the vines were ready for a commercial harvest (>20 oBrix). The type of pruning generally had little effect on fruit set, the date of véraison or soluble solids at harvest, although cane pruning resulted in a 40% increase in yield in 2019–20 when compared to spur pruning. Conclusions: Flowering, fruit set, veraison, and vine yield were affected by topography (site aspect) and pruning type had little to no effect. Vine yield was a reflection of the fruit set (%) with differences between topographical positions. Positions with delayed veraison showed delayed soluble solids accumulation but reached a similar harvest soluble solids and yield

Reduced grapevine canopy size post-flowering via mechanical trimming alters ripening and yield of 'Pinot noir'

The degree and time of canopy trimming can alter phenology, rates of increase or decrease in berry components during grape ripening, and may influence yield and its components. The objective of this study was to investigate the extent to which reducing canopy size, by mechanical trimming post-flowering, changed Vitis vinifera L. 'Pinot noir' fruit yield and composition. Vines were mechanically trimmed to three different canopy heights at fruitset: 1000 mm (100 % canopy height), 600 mm (60 % canopy height relative to the control treatment) and 300 mm (30 % canopy height relative to the control treatment). Total soluble solids concentration and content, titratable acidity, pH and fresh berry mass were measured throughout ripening, and yield and leaf area were measured at harvest.Reduced canopy size via trimming to 30 and 60 % of the control treatment height slowed total soluble solids accumulation and in some cases increased titratable acidity and increased pH. The total soluble solids-titratable acidity ratio was therefore reduced throughout ripening by these trimming treatments relative to the full canopy height. Trimming to reduce canopy size had two effects on the source-sink ratio; it reduced the source (canopy) but increased fruit yield, an important sink. Therefore, the time of trimming is an important management consideration because it can delay and slow ripening due to reduced source leaves but could potentially accentuate the delay via increasing yield (sink). This technique may represent a way to offset the acceleration of phenology and grape ripening that has been observed to occur as a result of warmer seasons

Effects of cane-and spur-retained node numbers on the pre-flowering vegetative growth of cane-pruned Sauvignon blanc

In established vineyards, node number retention at winter pruning is the first step to achieving and maintaining vine balance. Balanced vines exhibit timely and quasi-uniform 100 percent budburst. To understand how vine capacity and balance are expressed before flowering, mature Sauvignon blanc vines were pruned according to a 5 [total node numbers on canes: 10, 20, 30, 40, 50] x 3 [total node numbers on spurs: 1, 2, 3] factorial design in one site, and in two other sites according to a 5 [total node numbers on canes: 10, 20, 30, 40, 50] x 2 [total node numbers on spurs: 1, 2] factorial design. Two spurs of one, two or three nodes each were retained on either side of the vine. The number of canes laid down per vine was one, two, three and four canes each of 10 nodes for the 10-, 20-, 30-and 40-node treatments, and four canes averaging 12.5 nodes for the 50-node treatment. The budburst percentage was calculated on the whole vine, canes, and spurs. Blind nodes, count shoots, non-count shoots and double shoots were counted and mapped along canes and spurs. Many non-count shoots were measured on the vine head of 10-node vines (29.5 ± 3.0 shoots, p < 0.001), compared to 50-node vines (2.8 ± 1.9 shoots, p < 0.001). 50-node vines had an overall budburst of 100 %, despite having the highest number of blind nodes (7.6 ± 0.3 nodes, p < 0.001). These were mainly located at the canes’ proximal sections relative to the vine head and were likely caused by correlative inhibition and primary bud necrosis. Cane budburst provided a more accurate assessment of the vine response to node loading than vine budburst. The number of double shoots was not associated with the vine node load, as they appeared on both low-node and high-node vines. Three-node spurs developed more blind nodes than one-node and two-node spurs (p < 0.001). Based on the findings of this research, we recommend a composite metric (cane percent budburst, cane blind node count and head shoot count) to assess vine capacity and balance between budburst and flowering, and the practice of retaining one-or two-node spurs at cane pruning is also justified

Antibacterial properties of mussel-inspired polydopamine coatings prepared by a simple two-step shaking-assisted method

A simple two-step, shaking-assisted polydopamine (PDA) coating technique was used to impart polypropylene (PP) mesh with antimicrobial properties. In this modified method, a relatively large concentration of dopamine (20 mg ml−1) was first used to create a stable PDA primer layer, while the second step utilized a significantly lower concentration of dopamine (2 mg ml−1) to promote the formation and deposition of large aggregates of PDA nanoparticles. Gentle shaking (70 rpm) was employed to increase the deposition of PDA nanoparticle aggregates and the formation of a thicker PDA coating with nano-scaled surface roughness (RMS = 110 nm and Ra = 82 nm). Cyclic voltammetry experiment confirmed that the PDA coating remained redox active, despite extensive oxidative cross-linking. When the PDA-coated mesh was hydrated in phosphate saline buffer (pH 7.4), it was activated to generate 200 μM hydrogen peroxide (H2O2) for over 48 h. The sustained release of low doses of H2O2 was antibacterial against both gram-positive (Staphylococcus epidermidis) and gram-negative (Escherichia coli) bacteria. PDA coating achieved 100% reduction (LRV ~3.15) when incubated against E. coli and 98.9% reduction (LRV ~1.97) against S. epi in 24 h

Evaluating sources of variability in inflorescence number, flower number and the progression of flowering in Sauvignon blanc using a Bayesian modelling framework

The time of flowering is key to understanding the development of grapevines. Flowering coincides with inflorescence initiation and fruit set, important determinants of yield. This research aimed to determine between and within-vine variability in 4-cane-pruned Sauvignon blanc inflorescence number per shoot, number of flowers per inflorescence and flowering progression using an objective method of assessing flowering via image capture and statistical analysis using a Bayesian modelling framework. The inflorescence number and number of flowers per inflorescence were measured by taking images over the flowering period. Flowering progression was assessed by counting open and closed flowers for each image over two seasons. An ordinal multinomial generalised linear mixed-effects model (GLMM) was fitted for inflorescence number, a Poisson GLMM for flower counts and a binomial GLMM for flowering progression. All the models were fitted and interpreted within a Bayesian modelling framework. Shoots arising from cane node one had lower numbers of inflorescences compared to those at nodes 3, 5 and 7, which were similar. The number of flowers per inflorescence was greater for basal inflorescences on a shoot than apical ones. Flowering was earlier, by two weeks, and faster in 2017/18 when compared to 2018/19 reflecting seasonal temperature differences. The time and duration of flowering varied at each inflorescence position along the cane. While basal inflorescences flowered later and apical earlier at lower insertion points on the shoot, the variability in flowering at each position on the vine dominated the date and duration of flowering. This is the first study using a Bayesian modelling framework to assess variability inflorescence presence and flower number, as well as flowering progression via objective quantification of open and closed flower counts rather than the more subjective method of visual estimation in the field or via cuttings. Although flower number differed for apical and basal bunches, little difference in timing and progression of flowering by these categories was observed. The node insertion point along a shoot was more important. Overall, the results indicate individual inflorescence variation and season are the key factors driving flowering variability and are most likely to impact fruit set and yield

The influence of site aspect and pruning types on Pinot noir phenology and shoot growth

Aim: Managing the influence that terroir in vineyards has on vine development depends on improving our understanding the effect of the interaction of within-site variability, within-vine variability, and management practices (such as pruning types) on phenology and vine development. This study evaluates the consequence of site aspect and pruning management on budburst, leaf appearance rate, and shoot growth in Pinot noir vines. Methods and results: Two rows of 19-year-old Pinot noir vines were selected within a commercial vineyard with south, hilltop, and north-facing aspects (note: the north-facing slope is sun-facing in the Southern Hemisphere). Vines were either cane- or spur-pruned, retaining 20 nodes per vine. Budburst, shoot development, and leaf appearance were assessed, and vine trunk circumference was measured to quantify the accumulated differences in vine vigour. Hilltop plots had smaller trunk circumferences when compared to the south- and north-facing plots. Irrespective of topographical positions, budburst was earlier in cane-pruned vines compared to spur-pruned vines, but no differences were observed by the time of 12-leaf stage. The rate of shoot growth reflected the variations in topographical positions and trunk circumference. Cane-pruning exhibited more significant within-vine variation in budburst, budburst duration, and shoot growth when compared with spur-pruning. Shoots from hilltop vines were shorter relative to the vines at other plots for both pruning systems. Conclusions: The rate of shoot growth and development was associated more with site and vine vigour as determined by trunk circumference than pruning type. Spur-pruned vines had a later but more uniform budburst when compared to cane-pruned vines. Significance and impact of the study: Pruning type and within-site variability may lead to differences in canopy density and vine vigour, which can ultimately impact subsequent growth and development of the grapevine. Determining the influence of terroir within the vineyard on budburst, leaf appearance, and shoot growth variability will enable the development of improved phenology and growth models to describe within vineyard variability