Hand Thinning Research Articles

Chemical thinning increasing larger fruits and profit in red guava orchards

The guava is a fruit of strong economic and social relevance, regionally projected and greatly important in some regions of Brazil. The chemical thinning has been adopted in some fruit trees to obtain greater caliber of fruits and better prices. However, some aspects still need to be investigated for the safe and economical viability use of such technique. This research aimed to evaluate the chemical thinning efficiency, production and commercial classification of guava fruits cv. Paluma and provide an economic analysis of this crop system. The ethephon and benzyladenine were applied to fruits with an average size of 18 mm at 0, 150, 300 and 450 mg L-1. The trial was carried out in two crop seasons, and the randomized block design was used as statistical model in a factorial arrangement 2x4. The economic analysis was calculated through total production operational cost, in order to determine gross revenue, net revenue, profitability index, equilibrium price and yield. The benzyladenine and ethephon promoted the highest percentage of thinning fruits at 450 mg L-1, with averages of 67.6% and 70.0%, respectively. However, benzyladenine had a phytotoxic effect when applied at highest concentrations, 300 and 450 mg L-1, respectively. The ethephon enabled greater production of larger caliber fruits in the highest concentration (450 mg L-1). Chemical thinning reduced total operational cost and increased net revenue by 7.57%, as compared to hand thinning. Results also presented that chemical fruit thinning provided equilibrium yield of 4.98 t ha-1 for ‘Paluma’ guava fruit, as fresh fruit.

Effect of some Treatments on Vegetative Growth, Yield and Fruit Quality of Gold Nugget Mandarin Trees

This investigation was conducted during two successive seasons (2019/2020; 2020/2021) on almost 12-year old identical Gold Nugget mandarintrees Citrus reticulata Blanco (Wilking mandarin x Kincy mandarin), grafted on Volkamer Lemon (Citrus volkameriana) (VOL) rootstock cultivated in a private orchard located in Al Qalyubia Governorate, Egypt. The trees were grown at a distance of 2 × 6 m in silt soil under the Immersion irrigation system. To study the effect of hand thinning, chemical thinning using NAA at 400ppm, Potassium nitrate (5gm/L),Spirulina platensis ( algae extract) (2cm/L) and Potassium sulfate (1.25g/L) +Zinc sulfate (2.5g/L) +Salicylic acid (0.11g/L) on vegetative growth, fruit quality and yield of Gold Nuggetmandarin trees. The experiment was designed as a randomized complete block design with five replications. Results illustrate that most of the experimental treatments significantly increased tree canopy volume both hand or chemical thinning was the highest value and Chemical thinning treatment significantly increased leaf area. Potassium nitrate foliar spray significantly increased shoot thickness, number of leaves/ shoot. Spirulina platensis treatment enhancing of the spring growth cycle, number of flowers, fruit-set, number of fruits/tree, tree yield efficiency as the number of fruit / M3 canopy and vitamin C. as for Potassium sulfate + zinc sulfate+ Salicylic acid treatment was superior with statistic differences for tree yield as kg/tree and kg/ M3, fruit physical properties (fruit weight, fruit size, Juice volume, Juice weight and fruit Pulp Weight).

Effect of Fruit Thinning on ‘Hosui’ Pear Fruit Quality and Yield

In Bhutan, naturally occurring local type of pears were grown. Asian or Nashi pears are recent introduction which have become quite popular in eastern Bhutan since it was promoted by Agriculture Research and Development Centre (ARDC) Wengkhar. Although, horticulture has been gaining momentum in recent years, many growers in Bhutan follow traditional methods of crop cultivation and thus, majority of farmers still do not adopt important aspects of fruit production like fruit thinning. In commercial fruit farms elsewhere, fruit thinning is an essential management practice. However, in Bhutan, it is rarely practiced and there is no empirical study on its benefits. Fruit thinning is believed to be beneficial in increasing yield efficiency whilst also sustaining or increasing market returns by improving the fruit size and quality. Thus, a study was conducted in 2019 and 2020 at ARDC, Wengkhar. Effect of hand thinning on Hosui pear was assessed by randomly sampling 15-year-old Hosui trees with four replications – each tree treated as an experimental unit. Canopy of these trees were divided into two equal halves so that one half represents thinning and the other half non-thinning treatments. The treatments were randomly assigned to the two halves of each tree. Hand thinning resulted in significant increase in the fruit weight by 39%, fruit diameter by 12% and fruit height by 12 % over the non-thinning treatments; Total Soluble Solids (TSS) content, an indicator of taste, was greater by 9%. However, the overall yield was lower in the thinning treatments but in the second year of the study, the mean fruit yield in thinning treatments increased by 55% while the yield of non-thinning treatments plummeted by 33%. Hence, the study indicates that fruit thinning has significant effect on fruit quality and yield stability.

Effects of Different Crop Loads on Physiological, Yield and Fruit Quality of ‘JoyaTM’ Apple Trees: High Crop Load Decreases Maximum Daily Trunk Diameter and Does Not Affect Stem Water Potential

ABSTRACT This study aimed to evaluate the effects of different crop load levels on apple trees’ yield and physiological characteristics, emphasizing the relationship between stem water potential and crop load and the link between trunk diameter growth and crop load. It was conducted in 2014 at Station Expérimentale Fruits et Légumes (SUDEXPE-CEHM) in Southern France. The ‘JoyaTM’ apple on Pajam-1 rootstock was used as the plant material. Trees were subjected to hand thinning to obtain four final crop load levels as high (100%; 10 fruit/cm2 of branch cross-sectional area (BCSA)), medium-high (75%; 7.5 fruit/cm2 of BCSA), medium-low (50%; 5 fruit/cm2 of BCSA) and low (25%; 2.5 fruit/cm2 of BCSA). The four crop load levels were set up in a randomized block design with four replications, and each plot was formed of five uniform trees. Stem water potential was weakly affected by crop load but was mainly driven by vapor pressure deficit. The maximum daily trunk diameter, by and large, reduced while crop load level increased. The increase in crop load level was negatively related to fruit size, acidity and soluble solids content. Crop load did not affect bitter pit incidence. However, in parallel to the increasing crop load level, cumulative yield, yield efficiency and water productivity increased.

Ethephon - a best alternative for hand thinning to improve fruit set, colour and shelf life of apple

Ethephon - a best alternative for hand thinning to improve fruit set, colour and shelf life of apple

Chemical thinning of apple blossoms in organic production

An experiment on chemical blossom thinning on apple variety 'Summerred'/ M9 was performed in an experimental plantation in Brdo pri Lukovici. Different chemical thinners were applied on apple’s fruitlets in organic production. The experiment was designed in 7 randomized block with 13 treatments: 1. unthinned trees (as a control), 2. hand thinning in June, 3. 1% NaCl, 4. 1,5% NaCl, 5. 1% CH3COOH, 6. 3% CH3COOH, 7. 3% CaSx, 8. 1% rape oil, 9. 3% rape oil, 10. 3% of sunflower oil, 11. 3% soybean oil, 12. 5% dextrin, 13. emulsifier 100 + OCA 30. Chemical thinners were applied in a phenological stage at peak blooming with a manual knapsack sprayer. The best thinning of fruitlets (similar to hand thinned trees) was observed with 3% rape oil, however, relatively strong russeting of fruit skin was detected in this treatment. Statistically significant reduction of final fruit set also occurred when 1,5% NaCl and 3% soybean oil were applied, but with less fruit russeting.

Long‐term fuel and understorey vegetation response to fuel treatments in oak and chaparral stands of northern California

AbstractAimsFuel reduction treatments are broadly implemented to reduce the risk of extreme wildfire, but research on the long‐term effectiveness and impacts of these treatments is lacking. In this study, we examined short‐ and long‐term (two and 15 years) changes in fuels and understorey vegetation after treatment in chaparral and oak‐dominated stands.LocationWhiskeytown National Recreation Area, California, USA.MethodsTreatments, including hand thinning, mastication only, burn only, and mastication + burning, were applied randomly to one or two units within each of 10 blocks across two vegetation types (chaparral and oak‐dominated). Vegetation data were initially measured two years after treatment and remeasured 15 years later with additional sampling of dead surface fuels and shrubs. Fuel and vegetation data were analyzed to examine the effect of treatment, time, and vegetation type.ResultsIn chaparral stands, shrub height and cover in the hand‐thinning, mastication, and mastication + burning treatments were still lower than in the control after 15 years. However, only the hand‐thinning treatment reduced fine woody fuels. Hand thinning and mastication + burning increased native species richness after two years, but this was also associated with an increase in exotic species richness and cover that persisted after 15 years. In oak‐dominated stands, treatments had varied and relatively fewer changes to fuels and vegetation. Shrub height was reduced in both the hand‐thinning and Burn‐only treatments, but only mastication reduced shrub cover. Species richness and vegetative cover were largely unaffected by treatment in oak‐dominated stands, except for lower native plant cover in mastication and mastication + burning treatments.ConclusionTreatments varied in their level of effectiveness and most involved trade‐offs between their impacts on fuels and vegetation responses that differed by vegetation type and time. Our findings provide insights for managers interested in balancing these trade‐offs when making fuel treatment decisions and emphasize the importance of examining longer‐term effectiveness of fuels treatments.

Cluster and Berry Characteristics of Grapevine (Vitis vinifera L.) as Influenced by Thinning Agents and Gibberrelic Acid Applications

Some cultivars of grapevine have very compact cluster which adversely affect its quality and marketability. ‘Yaghouti’ is a commercial early table grape cultivar that has very compact clusters. The present study was conducted to assess the effects of mechanical and chemical thinning as well as GA3 application on cluster morphology and berry size of grapevine cv. ‘Yaghouti’. Treatments were chemical thinning agents including: NAA (7.5 and 15 mg/L), Ethephon (75 and 150 mg/L), Sevin (750 and 1500 mg/L) and mechanical thinning by a comb (comb thinning), applied a week after fruit set and unthinned clusters as control with 3 replications, 10 days after thinning, clusters were immersed in GA3 solution at 60 mg/L. Results indicated that berry numbers were reduced in all thinning treatments. Length, width and weight of berries increased significantly when treated with hand or chemical thinning. GA3 alone and Sevin at 750 mg/L in combination with GA3 treatment improved yield and the quality of berries. Total phenolics compounds, TSS and berries colour were improved in all thinning treatments. In general, application of Sevin at 750 mg/L combined with GA3 and hand thinning along with GA3 are proposed to improve quality of grapevine berries.

Hand-held mechanical device improves thinning efficiency of peach trees

The objective of this study was to evaluate the effect of mechanical-manual thinning (MmT) at different developmental stages in the thinning efficiency and productive performance of ‘Sensação’ peach trees. The experiment was performed during the 2013 and 2014 growing seasons, in a commercial orchard located in Morro Redondo (RS), Brazil. Plant material consisted of 7-year-old peach trees grafted on Capdeboscq rootstock and trained as an open-vase system. The experiment was arranged as a randomized block design, with five three-trees replications. In order to reduce the effect of personal experience, the treatments and measurements were applied by the same person in a set of replications throughout the experiment. Treatments consisted of: control I [without thinning (WT)]; control II [hand thinning (HT) 40 days after full bloom (40 DAFB)]; MmT at full bloom (FB): 50% of open flowers; MmT at the end of bloom (EB): 80-100% of open flowers; MmT at petal fall (PF); and MmT at the green fruit (GF) stage (fruit with ~1 cm of diameter). The MmT was performed using a hand-held portable device. The parameters assessed were: percentage of thinning, fruit set, thinning time, work economy, production per tree, fruit mass, estimated yield and fruit size distribution. The use of the MmT at the stages tested reduces thinning time of ‘Sensação’ peach trees, resulting in labor saving, as well as increases the percentage of fruit in category (CAT) 1. The MmT when performed at GF results in a higher percentage of thinning. The treatment MmT at FB increases the average fruit mass.

Improving of Cherry Fruit Quality and Bearing Regularity by Chemical Thinning with Fertilizer

The study’s objective was to evaluate the influence of thinning on the quality and regularity of yield of ‘Regina’ cherries grown on a dwarf Gisela 5 rootstock. The experiments were conducted in the years 2009–2012 in Western Poland. Trees were thinned using a chemical agent, ammonium thiosulphate (ATS), at doses of 20 g ATS L−1, 30 g ATS L−1 and 40 g ATS L−1, and by hand, and the results of chemical and hand thinning were compared with those obtained for unthinned trees. The course of weather conditions in winter and during flowering had a significant impact on yield. Chemical thinning is known to be an effective method to regulate fruiting of pome trees, but it can also be successful if applied to cherry trees, as reflected by the alternate bearing index, which was the lowest after applying ATS at a dose of 40 g. ATS treatment improved fruit quality in full crop years. Thinning resulted in, among other things, larger and darker fruit and higher content of total soluble solids and titratable acidity. Treatment with 40 g ATS L−1 significantly stimulated the vegetative growth of trees.

Metamitron in the chemical thinning of ‘PS 10711’ peach trees

Chemical thinning of fruits may be an alternative practice to hand thinning. Hand thinning must be performed in a short time during the fruiting stage, but lack of manpower and the onerous costs of the operation make it increasingly difficult to employ it at the right time and at the ideal intensity. The objective of this study was to examine the effect of different concentrations of metamitron as a chemical thinner on ‘PS 10711’ peach trees. The experiment was carried out during two harvests in an orchard in the municipality of Eldorado do Sul, in the Central Depression region of the state of Rio Grande do Sul, Brazil. Treatments consisted of the application of metamitron at the concentrations of 100, 200, 300 and 400 mg L-1; hand thinning; and no thinning. The fruits were thinned chemically and by hand 40 days after the peach trees were in full bloom. Fruit abscission, fruit set, number of fruits, production per tree and fruit quality were evaluated. Metamitron has a thinning effect on the peaches of cultivar PS 10711. The metamitron concentrations of 100 and 200 mg L-1 result in less fruit abscission as compared with hand thinning. The thinning effect of metamitron alters production per tree, but does not interfere with fruit quality.

Morphological changes of tissues after the implantation of the biodegradable threads for the correction of the involution of the hand’s back side skin

The aging process of the skin of the hand continuously progresses from mature to advanced age. With age, the skin of the hand becomes pigmented, dry, wrinkled with an emphasized skin pattern, the tone of the skin of the hand decreases, thinning and atrophy of adipose tissue are noted, skin elasticity is lost with the formation of an excess of hypoelastic thinned dermis. In recent years, smooth thread implants have been used to correct involutional changes in the skin of the back of the hand. The aim of the study was a morphological evaluation of the effectiveness of the correction of involutional changes in the skin of the back surface of the hand with thread implants based on polycaprolactone and poly-L-lactic acid (PCL-PLLA) with notches. Using light and electron microscopy, we studied the reaction of cells and intercellular substance to the introduction of biodegradable filaments into the subcutaneous space. It was found that implantation of PCL-PLLA filaments increases the reparative potential of tissues. 3 months after implantation, stimulation of neocollagenesis and angiogenesis in the dermis and hypodermis was noted. The functional and proliferative activity of cells increased. Mitotic activity of cells in the basal layer of the epidermis led to an increase in its thickness. A clinically confirmed effect was noted after 3 months and persisted for 18 months after implantation. Long biodegradation of the threads (1.5-2 years) helps to slow down the aging process of the skin of the back surface of the hand, prolonging the processes of tissue revitalization.

Effects of Fruit/Leaf Ratios on Fruit Characteristics in Kiwifruit

The present study was carried out in order to determine effects of hand thinning on fruit quality and yield. The branch based fruit thinnings were applied at six different rates of fruit/leaf (F/L) (1/1, 1/2, 1/3, 1/4, 1/5, 1/6). The study conducted two years and pomological analysis were performed in collected fruits from the branches. According to the results, the highest values in terms of fruit/leaf ratio were obtained from 1/1 F/L application for yield, total soluble solids (HM-TSS) and titratable acidity at harvest maturity (HM-TA) period; 1/2 F/L application for TSS at ripening period (RP-TSS) and fruit peel colour both at harvest maturity (HM-FPC) and ripening period (RP-FPC); 1/3 F/L application for vitamin C content; 1/5 F/L application for fruit weight and fruit flesh colour at the ripening period; 1/6 F/L application for fruit firmness, fruit lenght, fruit diameter, titratable acidity at ripening period (RP-TA) and titratable acidity at harvest maturity period (HM-TA). It can be concluded that the better results obtained from the applications of 1/5 and 1/6 F/L thinning ratio in view of yield and quality, and so these applications may suggested to be applied in practice.

Hand Thinning Influence on Fruit Quality Attributes of Pomegranate (Punica granatum L. cv. ‘Malase Yazdi’)

ABSTRACT Pomegranate (Punica granatum L.) is one of the oldest fruit trees that is native to Iran and resistant to hot warm and dry climate. Excessive fruit on the tree reduces fruit size and produces fruit with low quality. Hand thinning of flowers and fruits is a management tool to reduce the crop load and increase the quantitative and qualitative attributes of the fruit before harvest. The main objective of this study was to investigate the impact of different hand thinning levels (control, and removal of 10%, 15%, 20%, and 25% of fruit) on the physic-chemical attributes of pomegranate fruit ‘Malase Yazdi’. These results revealed that removing 20% of fruit gave the highest yield and trees thinned at 15%, 20%, and 25% levels produced heavier fruits at harvest. The highest fruit length and diameter were observed in 20% thinning treatment. Fruits from trees thinned at 20% and 25% had significantly higher volume, juice content, total weight of aril, peel fresh weight and soluble solids concentration than fruits from non-thinned trees. Also, a better red of fruits from trees thinned at 20% and 25% was observed. Thinning had a positive effect on studied quality attributes and thinning at 20% seems to be the optimal treatment for a better yield and fruit quality.

Understory responses to restoration in aspen‐conifer forests around the Lake Tahoe Basin: residual stand attributes predict recovery

The removal of conifers from aspen (Populus tremuloides) stands is being undertaken throughout the western United States to restore aspen for local‐ and landscape‐level biodiversity. Current practices include mechanically removing conifers or hand thinning, piling, and burning cut conifers in and adjacent to aspen‐conifer stands. To evaluate the effectiveness of restoration treatments, we examined tree regeneration and herbaceous vegetation cover in thinned, thinned and pile burned, and non‐thinned control stands. Growth rates of small conifer saplings threatening to outcompete and replace aspen were also measured. Two to four years after pile burning, herbaceous vegetation cover within the footprint of burned piles (i.e. burn scars) was 35–73% of that in adjacent areas. Aspen was more likely to regenerate inside burn scars where fewer surrounding trees were true firs. Conifer seedlings were more likely to regenerate in burn scars where more of the surrounding trees were conifers (pine or fir) as opposed to aspen. Fir saplings had much slower growth than did aspen saplings. Overall, our findings show that restoration treatments are promoting desirable outcomes such as enhancing aspen regeneration but that follow‐up treatments will be needed to remove numerous conifer seedlings becoming established after restoration activities. Eliminating conifers, while they are small, growing slowly, and contributing little to fuel loads may be an economical way to prolong restoration treatment effectiveness.

MM106 Anacı Üzerine Aşılı Bazı Elma Çeşitlerinde Benziladenin ve Naftalen Asetik Asit Uygulamalarının Meyve Seyreltmesi ve Kalitesi Üzerine Etkisi

Fruit thinning is an essential practice to improve fruit size and quality, control alternate bearing and increase return bloom in the next season. Fruit thinning is performed by hand or by using some chemicals. In this study, the effect of chemical thinning, namely two doses of 5 and 10 ppm of Naphthalene Acetic Acid (NAA) or of 100 and 150 ppm of Benzyladenine (BA) on fruit thinning and some fruit quality traits Golden Delicious, Red Chief and Granny Smith apple cultivars grafted on MM 106 clone rootstock in 2015 was tested and compared with the effect of hand thinning. Chemical treatment was applied after three weeks of full bloom, while the hand thinning was made to be released a fruit per cluster on each branch in small fruit period after June-drops. The results showed that the highest fruit thinning ratio was found in the Granny Smith cultivars, with 5 ppm (93.80%) and 10 ppm (91.65%) of NAA, 100 ppm (89.88%) and 150 ppm 88.98%) of BA. It can be concluded that the applications of 10 ppm of NAA and 100 and 150 ppm of BA were found effective for fruit thinning and fruit quality. Furthermore, the hand thinning application increased the fruit weights more than all the chemical applications.

Application of some bloom thinning techniques to overcome alternate bearing in pistachio (Pistaciavera L.)

Biennial bearing is a frequent problem in pistachio (Pistaciavera L.) production and gets worse with age. Abscission of floral buds is due to competition between growing seeds on 1-year-old shoots and developing buds on current season growth. To avoid it, thinning could be a common cultural practice in orchard management. Three chemical thinners including gibberellic acid (GA3; 50, 100 and 150 mg/L), naphthalene acetic acid (NAA; 40, 80 and 120 mg/L) and ethephon (75, 150 and 200 mg/L), and hand thinning (20%) were applied in a commercial homogenous orchard of pistachio cv.‘Akbari’ 2 weeks after full bloom during 2017–2018 in Rafsanjan, Iran. Thinning rate and quantitative and qualitative traits were investigated in comparison to the control in the split plot arrangement in a randomized complete block design. Ethephone at 200 mg/L and NAA at 120 mg/L caused the highest fruit abscission. Hand thinning, NAA (120 mg/L) and all ehtephone treatments decreased flower bud abscission by about 30% in the “on” year. Vegetative traits such as shoot length and leaf area showed significant increase under the treatments. Chemical thinning remarkably enhanced total non-structural carbohydrate, especially in “on” year. All of the treatments except GA3 increased tree yield in the “off” year. Qualitative fruit characteristics such as nuts per ounce, blank and split nuts percentage improved. Alternate bearing in pistachio tree was adequately controlled and chemical thinning was more effective than hand thinning.

Revisiting the role of carbohydrate reserves in fruit set and early-season growth of apple

In apple (Malus x domestica Borkh.), carbohydrate reserves are considered essential for maintaining tree functions during dormancy and for supporting spring growth. The contribution of carbohydrate reserves to fruit set and early-season tree development is unclear. In ‘Royal Gala’/‘M9’ trees, we used artificial spur extinction (ASE) to remove buds in late dormancy and reduce sink numbers. Final fruit numbers were set using hand thinning after final fruit drop. These trees were compared with trees where bud numbers where unmodified and fruit numbers were only modified using post fruit drop hand thinning (PDHT). On both these treatments, either early or natural defoliation was used to manipulate carbohydrate reserve replenishment and alter carbohydrate reserve concentration the following spring. This treatment combination allowed investigation of the interaction of early-season sink demand and altered carbohydrate reserve supply on fruit set. Early defoliation reduced total non-structural carbohydrate concentration in roots the following winter by 44 % and concentration of starch in spurs by 60 % compared with natural defoliation. However, neither defoliation treatment affected fruit set the following spring, implying that at these concentrations, stored carbohydrates in these tissues played little role in fruit set. This conclusion was supported by increase in total non-structural carbohydrate concentration in roots and spurs during the period 2–4 weeks after bloom, when limitations in carbohydrate resources are most likely to affect fruit set. ASE reduced the number of developing floral sinks in spring by 50 % and increased within-bud fruit set compared with PDHT trees, without affecting concentration of total non-structural and soluble carbohydrates in root or spur tissues sampled before final fruit set. In ASE, improved irradiance of spurs may increase fruit set through increased availability of photosynthates to developing fruit. Therefore, supply of newly synthesised carbohydrates probably plays a greater role in determining fruit set than remobilised, carbohydrates. The increase in soluble carbohydrates in roots during fruit set, challenged that concept that storage sinks only accumulate carbohydrates during periods of low carbohydrate demand from other sinks.

IMPROVEMENTS OF YIELD AND FRUIT QUALITY OF ZAGHLOOL DATE PALM BY USING THE DIFFERENT THINNING TREATMENTS

Different hand thinning treatments were conducted on Zaghloul date palm cultivar to study their effects on bunch yield and fruit quality. Seven thinning treatments; (1) control (no thinning), (2) Thinning by removing 25% the bunches number/ palm in Hababouk stage, (3) Thinning by removing 25% the strands number/ palm in Hababouk stage (4) Thinning by removing 25% of strands length per bunch in Hababouk stage, (5) Thinning by removing 25% the bunches number/ palm in Kemri stage, (6) Thinning by removing 25 the strands number/ palm in kemri stage, (7) Thinning by removing 25% of strands length per bunch in kemri stage, at a private farm under the conditions of the Ismailia Governorate, Egypt. Fruit thinning significantly decreased yield per palm. Fruit thinning by treatments (2,5) significantly increased the bunch/weight, however the other thinning treatments decreased the bunch weight. Fruit thinning significantly increased the average fruit weight, fruit size, flesh weight, flesh thick, fruit dimensions, seed weight and color index as compared to the control in both seasons. Fruit thinning had significant effect on the total soluble solids, fruit acidity, vitamin C, reducing sugars, non-reducing sugars, total sugars and total soluble tannins in both seasons. Thinning by removing 25% of strands length bunch in Hababouk stage significantly improved fruit quality compared with the other treatments. Conclusively, it is concerning mentioned that the thinning treatments occurred in Hababouk stage gave good results than in kemri stage.

Different Methods of Thinning Influenced by Variety and Hail Nets in Apple Orchards

Looking at the effects of thinning on apple quality, the purpose of this study was to investigate the fallouts of thinning methods in different varieties and under hail nets. The experiment was developed in Bavendorf, South Germany. The ‘Pinova’and ‘Braeburn’ apple trees were covered with two types of hail net: white, black and without nets. The following thinners were tested: Mechanical thinning (MT) with the ‘Darwin machine’; chemical thinning with Metamitron (CT-Metamitron) or 6-benzyladenine (CT-BA) and hand thinning (HT). The evaluations were: fruit set, time taken for HT, photosynthesis measurements, fruit retention, yield, fruit quality, and thinning efficacy value. The CT-BA treatment required the highest number of hours to perform HT for both varieties and hail nets. Comparing the varieties, the Pinova demonstrated less efficiency for thinning treatments, hence more hours were needed to thin by hand. Photosynthesis measurements were clearly different between CT-Metamitron versus CT-BA and MT curves, where CT-Metamitron remained in effect for 11 days after the treatment. The HT treatment had the highest value for thinning efficacy with 93% and the MT treatment achieved 74% followed by CT-Metamitron with 64% and CT-BA with 54%. Overall the Braeburn variety is easier to thin than the Pinova variety and the black hail nets showed negative effects on color value.