Effect Of Crop Load Research Articles

Effect of crop load on leaf and fruit nutrient status in apple cv. Gala Redlum

Effect of crop load on leaf and fruit nutrient status in apple cv. Gala Redlum

Rootstock and Crop Load Effects on ‘Honeycrisp’ Photosynthetic Performance and Carbohydrate Accumulation

Rootstock selection and crop load adjustment are key practices in apple orchard management; nevertheless, the effects of rootstocks and crop load levels on important physiological processes of the scions, such as photosynthetic performance and carbohydrate accumulation, are still unclear. To investigate the impact of different rootstocks and crop load levels on scion photosynthesis and carbohydrate buildup, in 2020, ‘Honeycrisp’ trees grafted on rootstocks ‘G.41’, ‘G.935’, and ‘M.9-T337’ were thinned to low and high crop load levels, and photosynthetic performance and carbohydrate accumulation in leaves and fruit were evaluated. Leaves from ‘G.935’ showed the highest net photosynthesis and electron use efficiency of photosynthesis and the lowest activity for non-net carboxylative processes, all together indicative of enhanced photosynthetic performance. High crop load determined an increase in gas exchange, suggesting a positive feedback of high fruit competition on carbon assimilation. While rootstock ‘M.9-T337’ showed a higher accumulation of starch in leaves, no pattern regarding the composition of leaf-soluble sugars among rootstocks could be identified. Conversely, by the end of the harvest season, leaves from low-cropping trees had higher fructose, glucose, and sorbitol than those from high-cropping trees, but differences in starch content were not significant. Fructose and sorbitol concentrations were affected by rootstock and crop load, respectively. Overall, this study showed that high cropping enhanced photosynthesis in ‘Honeycrisp’ apple and determined lower accumulation of some soluble carbohydrates (fructose, glucose, sorbitol) in leaves. This study also provided insights into how rootstocks affect photosynthetic performance of ‘Honeycrisp’, highlighting ‘G.935’ as the rootstock conferring the highest photosynthetic capacity under the present experimental conditions.

Determination of Target Crop Loads for Maximising Fruit Quality and Return Bloom in Several Apple Cultivars

In apple (Malus domestica), the level and timing of crop load have a major impact on the final fruit size and can also play a role in optimising internal fruit quality. Ideal crop loads vary with cultivar, but very few cultivars have recommended crop load targets that consider the effect of crop load on both return bloom and fruit quality. To address this issue, studies examining a range of crop loads and thinning times were undertaken on several apple cultivars. Return bloom and multiple fruit quality parameters were examined. The results of these studies demonstrate positive effects for early thinning, not only on fruit size but also on firmness and soluble solids content. Early-thinned fruit showed higher sugar levels than late-thinned fruit. Previously undemonstrated positive relationships between fruit sugar content and weight and between fruit firmness and weight in both ‘Fuji’ and ‘Delicious’, as well as between fruit sugar content and fruit firmness in ‘Delicious’, indicate that early thinning is a valuable tool in improving fruit quality. The current target crop load recommendations of 4–6 fruit cm−2 trunk cross-sectional area (TCSA) for ‘Fuji’ and 2–4 fruit cm−2 TCSA for ‘Delicious’ are confirmed by this study. New recommendations are proposed for the other cultivars in this study taking into account the impact of crop load on both fruit quality and return bloom. Both ‘Pink Lady’ and ‘Gala’ can support crop loads of up to eight fruit cm−2 TCSA without impacting return bloom, but fruit quality is compromised; hence, lower targets in the range of 4–6 fruit cm−2 TCSA are recommended. Large fruit size and good return bloom can be maintained in ‘Jonagold’ at crop loads of eight fruit cm−2 TCSA, while crop loads of four fruit cm−2 TCSA are suggested for ‘Braeburn’ to sustain regular bearing and good fruit size.

Fruitlet Thinning Improves Juice Quality in Seven High-tannin Cider Cultivars

Over 3 years (2016–18), tree productivity, biennial bearing, return bloom, and fruit quality were evaluated for seven high-tannin cider apple (Malus ×domestica Borkh.) cultivars. Five treatments were evaluated on each of the seven cultivars: hand-thinned of all fruit (a zero crop load treatment); hand-thinned to crop densities of three, six, or nine fruit/cm2 trunk cross-sectional area (TCSA); or left unthinned. In this paper, we report on the fruit maturity and juice quality properties that were analyzed for the three nonzero crop load treatments and the unthinned control. The effects of crop load on fruit maturity, as measured by starch pattern index and preharvest drop, were cultivar dependent. Crop density (fruit/cm2 TCSA) had a significant effect on all fruit maturity and juice quality variables, although effects were weakest in the “off” year (2017) for the whole planting when initial fruit set was low. As crop density increased, total poly phenols, titratable acidity, soluble solids, and primary amino nitrogen decreased in the juice of all seven cultivars. A partial budget analysis indicated that the reduced costs of nitrogen supplements due to increased primary amino nitrogen concentration alone would not justify cost of chemical or hand-thinning. By extrapolating the spring flowering density in the fourth year to potential fruit yields at harvest, we found that reducing crop load was projected to increase cumulative total polyphenol yields per tree over the long term. For the cultivars in this experiment, a target crop density of nine fruit/cm2 was found to adequately decrease biennial bearing while also not diminishing juice quality for hard cider production. High-tannin cider apple growers should consider juice quality, particularly tannin production, when making crop load management decisions.

Preliminary Study on Effect of Crop Load on Tree Nutrition in Intensive Apple Orchards

Elma endüstrisinde ürün yükü yönetimine olan ilgi giderek artmaktadır. Nitekim ürün yükü yönetimi özellikle periyodisiteyi hafifletmek ve meyve kalitesini arttırmak açısından oldukça önemlidir. Bununla birlikte ağaç beslenmesi de ürün yükü yönetiminden etkilenmektedir. Bu ön çalışmada (i) ürün yükü ve yaprak besin elementleri arasındaki ilişkiyi ortaya çıkartmak, (ii) dormant dönemde alınan budama artıklarının (odun doku) besin elementi içeriklerini belirlemek ve böylelikle ürün yükünün odun dokusunda depolanan besin elementleri üzerine olan etkisini saptamak ve (iii) yaprak ile odun doku örneklerinin besin elementi içerikleri arasında bir ilişkinin olup olmadığını saptamak amaçlanmıştır. Deneme 2021 yılında Göller Yöresinde (Bayındır Köyü/Yeşilova/Burdur) bulunan Royal Gala/M.9 ağaçlarından oluşan sık dikim bir elma bahçesinde yürütülmüştür. Farklı ürün yüklerini temsil eden toplamda 18 ağaç belirlenerek etiketlenmiş, yaprak analizi, verim ve odun doku analiz örnekleri/verileri aynı ağaçlardan toplanmıştır. Çalışmada ürün yükü arttıkça yaprak-potasyum içeriğinin önemli derecede azaldığı, buna karşın yaprak-kalsiyum ve yaprak-manganez içeriklerinin arttığı belirlenmiştir. Yaprak ve odun dokularında bulunan kalsiyumun pozitif bir korelasyon (0,5418) gösterdiği saptanmıştır.

Integration of a System Dynamics Model and 3D Tree Rendering—VISmaF Part II: Model Development, Results and Potential Agronomic Applications

Biological–mathematical models of trees can be exploited for a wide range of agronomic applications including crop management, visualization of ecosystem changes over time, in-field phenotyping, crop load effects, testing of plant functions, biomechanics, and many others. Some models propose a 3D output of tree that, in addition to having functionality to visualize the result, offers an additional tool for the evaluation of some parameters of the model itself (interception and amount of light, temperature, obstacles, physical competition between multiple trees). The present study introduces a biological–mathematical model of tree growth with a 3D output of its structure in a realtime 3D rendering environment (Unity©). Thanks to the virtual environment created in Unity©, it was possible to obtain variable environmental parameters (amount of light, temperature) used as inputs to the mathematical simulation of growth. The model is based on ordinary differential equations (ODEs) that compute the growth of each single internode in length (primary growth) and width (secondary growth) and the accumulation of growth inhibitors regulating the seasonal cyclicity of the tree. Virtual experiments were conducted varying environmental conditions (amount of light and temperature), and the species-specific characteristics of the simulated tree (number of buds, branching angle). The results have been analyzed showing also how the model can be adapted for the creation of different tree species and discussing the potential agronomic applications of model.

Apple and Pear Model for Optimal Production and Fruit Grade in a Changing Environment

Apple and pear crops are very important to the rural economy of Portugal. Despite significant improvements in productivity and quality, due to the introduction of new management techniques, model-based decision support may further increase the revenue of the growers. Available simulation models of orchard growth and production are scarce and are often highly empirical. This study presents a mechanistic model for the simulation of productivity and fruit grade of apple and pear orchards under potential and water-limited conditions. The effects of temperature extremes and rain on fruit set are addressed. The model was validated on apple and pear datasets derived from extensive experiments conducted in Central and Southern Portugal. Model performance is high and depicts the effect of crop load on productivity and fruit-size grade and the distribution of both crops. A simulation example shows the relationship between productivity and average fruit size for a hypothetical six-year-olc apple orchard. The model herewith presented is a tool that can be used to estimate optimal crop load for maximum revenue and productivity, fruit size distribution, water use, and other variables relevant for pome fruit production.

Effect of crop load on the yield, fruit quality, and fruit mineral contents of ‘RubyS’ apples

Effect of crop load on the yield, fruit quality, and fruit mineral contents of ‘RubyS’ apples

Effect of crop load on fruit nutritional and nutraceutical traits of greenhouse tomato

ABSTRACT This study aimed to evaluate the effect of crop load on the fruit quality traits especially nutritional and nutraceutical properties of two cultivars of greenhouse tomato (Solanum lycopersicum L.) i.e. ‘Grandella’ and ‘Isabella’. The crop load treatments were: saving one fruit per truss (1F), two fruits per truss (2F), three fruits per truss (3F), and no fruit thinning (control). The results showed that decreasing crop load increased the dry matter content, glucose, fructose, and sucrose concentrations of fruits because of less competition between fruits of each truss and higher relative expression level of tomato hexose transporter genes (LeHTs). Higher transport of sugars toward fruits of 1F resulted in high secondary metabolites concentration. The high secondary metabolites concentration with high fruit load in control that has low soluble sugar availability may result from the opportunity to take advantage of the excess pool of carbon to build cost-free carbon-based secondary metabolites. A reduced crop load would be a recommended management strategy to improve greenhouse tomato quality.

Evaluation of the Concord Crop Load Response for Current Commercial Production in New York

Economic pressures in the New York Concord grape industry over the past 30 years have driven crop management practices toward less severe pruning to achieve larger crops. The purpose of this study was to investigate the effect of crop load on juice soluble solids and the seasonal change in vine pruning weight in New York Concord grapevines. Over a four-year period, vines were balanced pruned at two levels or fixed node pruned at two levels to give four pruning severities. For balanced pruning, vines were pruned to leave 33 or 66 fruiting nodes for the first 500 g pruning weight and an additional 11 nodes for each additional 500 g pruning weight. For fixed node pruning, vines were pruned to 100 or 120 fruiting nodes per vine. The 120-node vines were also manually cluster-thinned at 30 days after bloom to target 0, 25, or 50% crop removal. In a second study, the 120-node pruning with midseason fruit-thinning was repeated over 11 years to assess seasonal differences on the crop load response. Crop load was measured as the yield-to-pruning weight ratio (Y:PW) and ranged from 1 to 40 in this study. On average, the industry standard of 16 Brix was achieved at a Y:PW of 20, and no seasonal pruning weight change was observed at a Y:PW of 17.5. There was a positive linear relationship between seasonal growing degree days and the Y:PW needed to reach 16 Brix, as well as between seasonal precipitation and the Y:PW required to observe no seasonal pruning weight change. The results from this study were used to improve crop load management recommendations for New York Concord vineyards under current practices.

High crop load and low temperature delay the onset of bud initiation in apple

The reproductive cycle of apple (Malus × domestica Borkh.) starts with the induction of floral development, however, first morphological changes within the bud appear during the following period of bud initiation. This study identifies the onset and duration of bud initiation in the apple cultivars ‘Fuji’ and ‘Gala’, characterized by biennial and non-biennial bearing behaviour, respectively, and describes the effect of crop load and heat accumulation on the temporal pattern of floral development. The onset of flower bud initiation in heavy cropping ‘Gala’ trees was delayed for 20 days compared to trees with no crop load, but the rate of initiation was not affected by crop load. Bud initiation on heavy cropping ‘Fuji’ trees was minor, whereas trees with no crop load started initiating buds 19 days earlier than those of ‘Gala’ despite the same cropping status and growing degree hours in a given year. The onset of bud initiation in ‘Fuji’ ‘off’ trees was 5 and 20 days after summer solstice, respectively, in two consecutive growing seasons, suggesting that this process is driven by heat accumulation rather than by daylength. The results indicate, that the genetic make-up of the cultivar determines the onset of bud initiation. This can be delayed by increasing crop loads and low temperatures at the beginning of the flower formation process.

Effect of crop load on fruit size and nutrients in fruit parts of mango ‘Num Dok Mai Sithong’

Effect of crop load on fruit size and nutrients in fruit parts of mango ‘Num Dok Mai Sithong’

Water stress for a long period before harvest and crop load effects on marketable yield and consumer acceptance of nectarine

Under water shortage growers may need to adjust horticultural practices to optimize yield and fruit quality. This study explores the reduction of crop load as a technique to mitigate water stress considering marketable yield and consumer acceptance as the most relevant traits. Commercial irrigation (CI) and deficit irrigation (DI) for a long period before harvest was applied to a late-maturing nectarine (‘Nectalady’) in 2011 and 2012. In both years, midday stem water potential (midday SWP) in CI trees was around −0.85 MPa while in DI trees the values ranged between −1.50 and −1.80 MPa. In the experiment, CI and DI were combined with three crop loads: low crop load (LCL, 85 fruits/tree) in 2011, and medium crop load (MCL, 150 fruits/tree) and commercial crop load (CCL, 230 fruits/tree) in 2012. Under CCL and MCL conditions, DI reduced marketable yield due to a significant reduction of the number of fruits that can be commercialize (fruit size higher than 65 mm). DI combined with LCL slightly reduced fruit size but not marketable yield. Reducing crop load by 60% (from 230 to 85 fruits/tree) maintained fruit size to the standard of marketable yield despite the water stress. Fruit thinning did not affect consumer acceptance of fruit, but it was slightly increased under DI in the first pick each year. The benefit of DI on consumer acceptance may have been observed because trees did not experienced midday SWP below −1.80 MPa for the extended period of water shortage (35 and 53 days in 2011 and 2012, respectively). For the levels of midday SWP experienced in this study (1.50 to −1.80 MPa), marketable yield was more sensitive to water stress than consumer acceptance. Consequently, growers do not need to worry about fruit quality, but crop load adjustments should be done to maintain marketable yield.

Effect of crop load, fruit position and shoot vigour on yield and quality of Annona atemoya × Annona squamosa in India

ABSTRACT The effect of crop load, position of the fruit on the shoots and vigour of the shoots on yield and quality of Annona atemoya × A. squamosa hybrid ‘Arka Sahan’ was investigated in India over two years. The trees were hand-pollinated and thinned to 20, 40, 60, 80 or 100 fruit after fruit set. Information was collected on total and marketable yield, yield efficiency, average fruit fresh weight, peel weight, the number of seeds per 100 g of pulp, pulp content in the fruit, total soluble solids (TSS) and total titratable acidity. In other experiments, fruit were harvested from weak, medium or vigrous shoots, or from basal, middle or apical nodes. Total yield increased up to 60 or 80 fruit per tree and marketable yield increased up to 60 fruit per tree. Average fruit weight and peel weight increased as cropping increased. These results suggest that optimum productivity and quality is associated with 60 fruit per tree or 0.17 to 0.19 kg cm2 trunk-cross sectional area. The quality of the fruit in different positions on the shoots or on the different types of shoots was highly variable and generally not affected by the various treatments.

Optimizing Crop Load for New Apple Cultivar: “WA38”

Crop load management is growing increasingly important as a factor related to biennial tendencies, post-harvest disorders, and inconsistent fruit quality in apples like “Honeycrisp”. Washington State University released a new apple cultivar, called “WA38”, in 2017. Limited literature is available about the productive characteristics of this new cultivar. An experimental trial evaluating the effect of crop load on leaf area, fruit quality, mineral composition, and return bloom of “WA38” was conducted for two consecutive years (2017 and 2018) to determine an optimal crop load. Trees were trained as a spindle and grafted on Malling-9 Nic29 (Nic29) rootstocks. Crop loads were adjusted to 2, 4, 6, and 8 fruits/cm2 of trunk cross-sectional area (TCSA). Crop load had a significant effect on production, with yields ranging from 28 to 83 MT/ha in 2017. Fruit quality was impacted by increasing crop load, with a reduction in fruit weight, soluble solid content, firmness, dry matter, titratable acidity, and a delay in maturity. Leaf-to-fruit ratios were higher in lower crop loads. Relatively consistent flower bud formation was seen at the 6 and 8 fruits/cm2 categories. A possible threshold for optimal fruit quality and consistent bloom was identified around 6 fruits/cm2 TCSA.

Young apple tree responses to crop load

Biennial bearing is a common and important issue facing apple growers that can result in losses in production of up to 30%, depending on cultivar. To study this issue, a collaborative project focusing on molecular, biochemical and whole tree physiological responses to variable crop loads was established between German research institutions and Agriculture Victoria, Australia. The whole tree physiological component of the project was performed in the Yarra Valley in Victoria, Australia. In spring 2015, a series of crop loads, ranging from almost no fruit on the trees to double normal grower practice, were applied to the biennial bearing cultivar ‘Nicoter’ (Kanzi®) and to the non-biennial bearing cultivar ‘Rosy Glow’ (Pink Lady®). Trees were three years old, grafted on M9 EMLA rootstock and trained as Open Tatura. Several tree growth (shoot length and winter wood pruning) and productivity (fruit maturity, size, soluble solids concentration and firmness, and return bloom) factors were measured to understand the effect of crop load. Strength of the response varied depending on the cultivar and factor investigated. In general, all the measured characteristics responded to crop load with the trend inversely proportional to the number of fruit remaining on the trees. Particularly interesting was the return bloom that showed a stronger response in the non-biennial bearing Cripps Pink cultivar than the biennial bearing ‘Nicoter’. This could imply that the response of young trees to thinning may be more important than the inherent tendency of the cultivar to biennial bearing.

Effects of alternate bearing and 2,4-D application on fruit growth pattern, abscission enzymes activity, ACC content of calyx and carbohydrates partitioning of fruits in Satsuma mandarin ( Citrus unshiu Marc.) cv. Miyagawa

Abstract Considerable fluctuations in annual yield (alternate bearing) is one of the noticeable characteristics of some citrus cultivars. Application of chemical thinners at high yield (On) years is an efficient way for ameliorating this problem. The aim of this work was to evaluate the effects of crop load and 2,4-D foliar application at full bloom on Satsuma mandarin (Citrus unshiu Marc.) cv. Miyagawa fruits at On year under rainfed farming. The 24-year-old Miyagawa mandarin trees grafted on Poncirus (Poncirus trifoliata Raf.) rootstock grown at North Iran were examined for ethylene precursor (ACC) content of calyx, activity of cellulase and polygalacturonase in abscission zone of fruitlets, and also the growth pattern and carbohydrates partitioning in fruits. Results showed that 2,4-D was effective in intensifying the activity of abscission enzymes and ACC synthesis during fruitlet abscission and increased fruitlets drop. In addition, 2,4-D significantly increased fruit growth rate from 73 days after anthesis (DAA), resulting to significantly heavier fruits than those of On (check) trees. The other consequence of 2,4-D treatment was the increase in the fruits’ sucrose, fructose, and glucose levels, resulting in fruit quality improvement. As a result, 2,4-D spray of On Miyagawa trees during full bloom period can be a suitable solution to control alternate bearing and to enhance fruit quality.

Vineyard Floor Management and Cluster Thinning Inconsistently Affect ‘Pinot noir’ Crop Load, Berry Composition, and Wine Quality

Growers of high-end ‘Pinot noir’ wine grapes (Vitis vinifera L.) commonly reduce yield by cluster thinning with the goal of increasing fruit quality; however, there are no objectively defined yield targets to achieve optimum fruit composition. Canopy leaf area relative to fruit yield can affect total soluble solids (TSS), and recommendations have been established for warm wine grape production regions. However, the relationship between leaf area and photoassimilation differs among climates and training systems. Leaf area to yield (LA:Y) ratios developed in warm, arid regions may not be suitable for cool, wet regions such as western Oregon. A 3-year field study was conducted to elucidate relationships between canopy to yield ratios and berry composition for ‘Pinot noir’. Vegetative growth and fruit yield were manipulated through competitive cover cropping and cluster thinning. Growth was manipulated in three ways: perennial red fescue (Festuca rubra L.) was grown in 1) both (Grass), 2) one (Alternate), or 3) neither (Tilled) of the alleyways flanking the vine row. Within each vineyard floor treatment, fruit clusters were thinned to one per shoot (Half Crop) or vines were left unthinned (Full Crop). Floor management influenced both canopy size and yield because of altered vine nitrogen (N) status. Effects of crop load on berry components were not always consistent between the crop load metrics used [yield to pruning weight (Y:PW) ratio or LA:Y]. In 2 years, TSS reached a maximum at similar LA:Y; however, this did not necessarily produce optimum TSS. Yield had the greatest influence on pH and total anthocyanins (ACY) in the highest yielding, coolest year. Crop load metrics were not reliable predictors of TSS because of the dominant effect of seasonal variation. Relationships between canopy to yield metrics and other berry components were partially explained by tissue N, photosynthetic photon flux (PPF) through the cluster zone, and/or yield. Cluster thinning to adjust yields may not alter source to sink relationships or canopy to yield ratios enough to overcome ripening limitations in cool climates. Only one wine vintage had sensory differences with Alternate-Half Crop and Alternate-Full Crop wines ranked high quality and Tilled-Half Crop and Tilled-Full Crop wines ranked low quality by both consumer and winemaker panels. Therefore, cluster thinning may have limited impact on wine sensory properties.

Evaluation of timing for spraying Metamitron or NAA plus BA for thinning ‘Brookfield Gala’ apple fruitlets

In Chile, apple chemical thinning uses primarily carbaryl, which is expected to be banned in the future. New thinning chemicals are needed. During the 2013-14 season, two trials were conducted in a 'Brookfield Gala'/Pajam 2 orchard. Metamitron (Goltix Compact(MR) 90% WG, 450 g ai ha-1) or BA (Exilis®, 180 g ai ha-1) plus NAA (NAA 800®, 18 g ai ha-1) were evaluated at different timings beginning at 4 mm up to 28 mm fruit diameter at 3 to 8 day intervals. Control treatments included, one without any spray and a sprayed control that included NAA at full bloom, carbaryl (Carbaryl 85 WP, 1368 g ai ha-1) at petal fall and BA (180 g ai ha-1) plus carbaryl (1368 g ai ha-1) at 12 mm fruit. All sprays were done when no carbohydrate deficit was predicted by Malusim Model (Cornell University). Thinning was evaluated on two branches tree-1, fifty days after full bloom, as fruits per cluster (F/C). All treatments differed from the control (2.3 F/C). Metamitron treatments were more effective when applied between 8 and 16 mm fruit (1.0 F/C). NAA+BA treatments were more effective when applied right after petal fall (4 mm fruit; 1.3 F/C). After removing the effect of crop load, average fruit weight was increased with BA+NAA spray at 4 and 12 mm fruit. All treatments of metamitron were different from the control.

Effects of crop load on distribution and utilization of 13C and 15N and fruit quality for dwarf apple trees

In order to define the effects of fruit crop load on the distribution and utilization of carbon and nitrogen in dwarf apple trees, we conducted three crop load levels (High-crop load, 6 fruits per trunk cross-sectional area (cm2, TCA)), Medium-crop load (4 fruits cm−2 TCA), Low-crop load (2 fruits cm−2 TCA)) in 2014 and 2015. The results indicated that the 15N derived from fertilizer (Ndff) values of fruits decreased with the reduction of crop load, but the Ndff values of annual branches, leaves and roots increased. The plant 15N-urea utilization rates on Medium and Low-crop load were 1.12–1.35 times higher than the High-crop load. With the reduction of crop load, the distribution rate of 13C and 15N in fruits was gradually reduced, but in contrast, the distribution of 13C and 15N gradually increased in annual branches, leaves and roots. Compared with High-crop load, the Medium and Low-crop load significantly improved fruit quality p < 0.05. Hence, controlling fruit load effectively regulated the distribution of carbon and nitrogen in plants, improved the nitrogen utilization rate and fruit quality. The appropriate crop load level for mature M.26 interstocks apple orchards was deemed to be 4.0 fruits cm−2 TCA.