Chemical Thinning Research Articles

IMPACT OF THINNING AND FOLIAR-BORON-ZINC SPRAY ON SOME MORPHOLOGICAL AND PHYSIOLOGICAL INDICATORS IN APPLE TREE (MALUS DOMESTICA CV. GOLDEN DELICIOUS)-"TARTOUS GOVERNORATE"

The research was conducted in Tartous governorate on apple trees cv. Golden Delicious grafted on the rootstock “Malus domestica Borkh”, during two seasons 2019-2020 to study the impact of manual and chemical thinning using foliar boron /zinc spray separately or in combination on some morphological and physiological indicators. The results showed a significant increase in leaf area and its content of total chlorophyll and carotenoids in the second season (low fruit load) compared to the first season (heavy load) due to a rise in vegetative growth and a reduction in fruiting. During the heavy load season, a balance between vegetative and fruiting growth was noted when the manual and chemical thinning applied with no significant differences was found between the two seasons in leaf area, total chlorophyll and carotenoids content. On the other hand, the application of manual thinning, chemical thinning and foliar spraying with boron and zinc separately or together pointed out an increase in the branches content of carbohydrates and nitrogen and C/N ratio in the low load season compared to the control. Consequently, fruit thinning was more effective to obtain a balance between the seasons in term of leaf area, its pigments content, and C/N ratio in branches, which in turn mitigate the alternate bearing phenomenon.

Influence of Mechanical Flower Thinning on Fruit Set and Quality of ‘Arisoo’ and ‘Fuji’ Apples

This study aimed to identify the efficiency of mechanical flower thinning (MFT) and its influence on apple fruit quality. In the first experiment, ‘Arisoo’ apple flowers were subjected to MFT with one hundred sixty-two (half) and three hundred twenty-four (full) strings at the same rotor (300 rpm) and tractor (6 km/h) speeds. Hand thinning was performed as a control. The number of removed flowers in each terminal and lateral flower cluster was slightly higher in MFT with full-strings than that of MFT with half-strings. The fruit set rate was lower in MFT with full-strings than that of MFT with half-strings. However, the use of full-strings during mechanical thinning increased the leaf damage rate compared to half-strings. Except a* value, MFT with full-strings improved flesh firmness, soluble solids content (SSC) and titratable acidity (TA), and reduced starch pattern index of fruits at harvest compared to the control. In the second experiment, ‘Fuji’ apple flowers were subjected to chemical thinning, MFT (300 rpm, 6 km/h), and MFT + chemical thinning treatments and compared with hand thinning (control). The thinning efficiency of MFT was similar to that of chemical thinning and MFT + chemical thinning treatments in terms of the removal of flowers and fruit set rates. Compared to the control, MFT, chemical thinning, and their combined treatments improved flesh firmness and SSC of fruits at harvest. TA was highest in the chemical thinning treatment compared to other thinning treatments. However, fruit size, weight, and a* value were unaffected by any treatment. In conclusion, the use of full-strings during MFT achieved optimal results in ‘Arisoo’ apples. In ‘Fuji’ apples, MFT treatment alone achieved effective results and the addition of chemical thinning after MFT had no supportive role in thinning efficiency and fruit quality.

Green fruit segmentation and orientation estimation for robotic green fruit thinning of apples

Apple is a highly valued specialty crop in the U.S. Green fruit thinning is an important operation of apple production, which is the removal of excess fruitlets in the early summer. The task ensures that remaining fruits at harvest time grow to have good size and quality while reducing the risk of biennial bearing. Current methods of thinning include hand, chemical, and mechanical. However, hand thinning generally requires a large labor force to implement, chemical thinning is non-selective and dependent on timing and weather during application, and mechanical thinning is also non-selective and destructive. A robotic green fruit thinning system could possibly be implemented that does not exhibit the drawbacks of current methods. A vision system is an essential component for a robotic green fruit thinning system that is responsible for green fruit detection and segmentation, decision-making on which fruit to remove, and environment reconstruction for path planning. This study took the first step towards developing a vision system for robotic green fruit thinning. First, green fruit and stem instance segmentation was applied using Mask R-CNN. Then, green fruit and stem orientation estimation was applied using Principal Component Analysis (PCA). Average precision scores for green fruit and stem segmentation on all mask sizes were 83.4% and 38.9%, respectively, whereas these increased to 91.3% and 67.7% if only considering the fruits and stems with mask sizes greater than 322 pixels. Green fruit orientation estimation with correction made 89.3% and 75.5% of estimates accurate within 30° of actual orientations for ground-truth and segmentation-generated masks, respectively. Performances respectively were 97.4% and 84.0% when only unoccluded masks are considered. Orientation correction resulted in considerable improvements in all cases of green fruit orientation estimation, with the greatest improvement seen on unoccluded ground truth masks where estimates accurate within 30° of ground truth orientations increased by 23.9%. Stem orientation estimation achieved very high accuracies with corresponding scores of 99.8% and 99.7%. The outcomes provided guideline information for developing a robust machine vision system for robotic green fruit thinning.

EFFECT OF FLOWER THINNING ON YIELD AND QUALITY OF ‘`STANLEY`’ PLUM (PRUNUS DOMESTICA L.)

Plum is the most important fruit crop for cultivation in Serbia. However, a small amount of plum fruit is sold as fresh fruit due to its poor quality. In order to improve fruit quality and obtain regular and high yield chemical blossom thinning agents were applied. The experiment was conducted on seven-year-old plum trees of cultivar `Stanley` which were planted on distance 5x5 m. Ammonium thiosulphate and ethephon were applied in the next treatments: 1) ammonium thiosulphate 1.5% (ATS); 2) ethephon 0.015% (E); 3) ammonium thiosulphate 1.5% + ethephon 0.015% (ATS + E); 4) hand thinning (HT); 5) untreated control treatment (UTC). Chemical thinning treatments were performed once during the phase of full bloom, while hand thinning treatment was performed after the fall of unfertilized fruitlets at the end of May. Parameters analyzed were yield, fruit size, fruit weight, pit weight, fruit firmness, fruit shape index, soluble solids content, total acid content and the amount of harvested fruits per time unit. The obtained results have shown that ATS + E, ATS and HT treatments significantly reduced the number of fruits on the trees compared to the control treatment. However, yield per tree was reduced significantly only in the ATS + E treatment. Other treatments compensated for the smaller number of fruits per tree with a significantly larger fruit size. Since the fruit size was larger on treated trees, the amount of harvested fruits per time unit was significant compared to control treatment. There were no significant differences among the applied treatments in terms of fruit firmness, soluble solids and total acid content.

An Advanced Robotic System for Precision Chemical Thinning of Apple Blossoms

Highlights A cartesian robotic spraying system was developed for precision apple blossom thinning. Flower clusters were detected and localized with deep learning model for target spraying. A communication algorithm was developed for positioning the spray end-effector to the target flowers. The cartesian robotic system greatly reduced chemical usage while maintaining thinning effectiveness in the final green fruit set. Abstract. Crop thinning, including blossom thinning, is one of the critical management strategies that determines the annual profitability of apple orchards. Challenges still remain for applying appropriate amounts of chemical thinner; if thinning is inadequate and too many fruits remain on the tree, fruit size will be small, fruit quality will be poor, and flower bud initiation for the following year’s crop may be either reduced or eliminated. Over-thinning also carries economic perils since yield and crop value in the year of application will be reduced. In addition, chemical thinning with excessive spray volume may cause leaf damage and fruit russeting. Thus, a robotic apple blossom thinning system was proposed, aiming to reduce the usage of chemical thinner while maintaining good thinning performance. The robotic system consisted of three major components: (1) a machine vision system that can identify and localize the apple flower clusters in tree canopies, (2) a cartesian robotic system with the guidance of a machine vision system to reach target flower clusters, and (3) a flat-shaped spraying nozzle connected with a solenoid valve as a spraying end-effector to deposit chemical thinner to the targeted flower clusters. A set of field tests was conducted to evaluate the performance of the robotic thinning system by comparing it to conventional air-blast and boom-type sprayers. In the test, the flower cluster detection reached a precision of 93.82%. The integrated robotic system used 2.3 L of chemical thinner to finish the chemical thinning for 18 apple trees, followed by the boom sprayer and air blast sprayer with 4.2 and 6.8 L usage, respectively. The robotic system also obtained an average fruit set of 2.4 per cluster after thinning, which was comparable to that of the air blast sprayer. The results showed that the robotic thinning system saved 66.7% and 45.5% of chemicals compared to the air-blast sprayer and boom-typed sprayers, respectively, while achieving a similar fruit set per cluster. The outcomes of the study provided guidance for developing a full-scale robotic chemical thinning system for modern apple orchards. Keywords: Apple orchard, Blossom thinning, Cartesian robot, Chemical thinning, Machine vision.

Programas de raleio químico para macieira 'Fuji Mishima' sob tela antigranizo preta

Abstract The objective of this work was to evaluate chemical thinning programs containing mixtures of different plant growth regulators, at low concentrations, applied to 'Fuji Mishima' apple trees at post-blossom, as well as to identify the most effective in reducing fruit set, decreasing the need of manual thinning, and improving fruit quality. Under a black anti-hail net, the apple trees were sprayed with the six following chemical thinning protocols (treatments): benzyladenine (BA) + gibberellin4+7 (GA) at full bloom (FB) and BA + carbaryl (CB) on fruitlets with a 15 mm diameter; BA + GA at FB and naphthaleneacetic acid (NAA) + CB on fruitlets with a 7 mm diameter; BA + GA at FB and BA + CB on fruitlets with a 15 mm diameter; ethephon (ETH) + CB on fruitlets with a 15 mm diameter and metamitron (MM) + ETH on fruitlets with a 20 mm diameter; and MM on fruitlets with a 7 mm diameter and MM on fruitlets with a 20 mm diameter. The treatments were compared with an untreated and a manual thinning control. The black net reduced photosynthetically active radiation in 22%. For 'Fuji Mishima' apples under a black anti-hail net, the chemical thinning program consisting of BA + GA (47 + 47 g a.i. ha-1) at FB, followed by BA + CB (80 + 288 g a.i. ha-1) on fruitlets with a 15 mm diameter, consistently reduces fruit set, requires less manual thinning, and improves fruit weight and size.

Alternative Approaches to Chemical Thinning for Regulating Crop Load and Alternate Bearing in Apple

In the past, chemical thinning dominated in fruit orchards. This paper for the special issue outlines alternatives to chemical thinning for crop load management (CLM) and its effect on fruit size, firmness, sugar, starch, and weight, indicating ripeness and fruit quality, yield, and alternate bearing. A total of 450 apple trees (Malus domestica Borkh., cv. ‘Roter Boskoop’; six years old) on M9 rootstock were used at the Klein-Altendorf experimental station (50° N) of the University of Bonn, Germany. As the first alternatives, trees were mechanically blossom-thinned at the balloon stage (BBCH 59) with a rotor speed of 320 rpm or 380 rpm at 5 km/h tractor speed or were chemically thinned at the full bloom stage (BBCH 65) with ammonium thiosulfate (ATS), ethephon (ETH), and/or 6-benzyladenine (BA) at 10–12 mm fruit size (BBCH 71) after applying ATS/ETH. Flower clusters and/or cluster leaves (source) were manually removed to determine the optimum sink-source ratio to achieve different ratios of fruitlets (sink) relative to the leaves (source) at fruit set (BBCH 67–69). Un-thinned, adjacent trees served as the control. The majority of CLM methods improved fruit size and weight. Removing cluster leaves at fruit set increased fruit size and weight of the remaining fruit, which has not been observed before. The most effective treatment for fruit size and weight and return bloom was the 75% flower cluster and complete cluster leaf removal. Removal of more than 50% of flower clusters successfully improved return bloom, indicative of alternate bearing. The mechanical blossom thinning had a positive effect on fruit size and weight with a return bloom similar to that of removal of 50% flower clusters.

Current forest management intensity and cost associated with major forestry practices in Arkansas, USA

Arkansas’ forestlands are largely owned by private landowners: family, industrial or corporate forest landowners (5.1 million hectares; 67%). Family forest landowners own 4.4 million hectares of forestland (58%). The costs of forestry practices influence landowners’ decisions in forest management. However, state-specific costs for forestry activities are not readily available. The study aims to compare the forest management objectives between family and industrial or corporate forest landowners and also provide robust information about forest management intensity and the unit cost associated with those activities. We employed an online survey to 318 consulting foresters working in the state. In addition, we used Forest Inventory and Analysis dataset in ArcMap (10.8.1) to validate the survey result. Among various forestry practices, landowners requested various services from consulting foresters, including chemical site preparation, thinning, timber cruising and marking, and timber inventory. The unit cost for mechanical site preparation was the highest among several forestry practices, and these costs varied based on forest types. Various stakeholders can utilize the study findings from landowners, forest industries, and policymakers in forest investment decision-making, which can improve sustainable forest management.

In-Situ Chemical Thinning and Surface Doping of Layered Bi2Se3.

As a promising topological insulator, two-dimensional (2D) bismuth selenide (Bi2Se3) attracts extensive research interest. Controllable surface doping of layered Bi2Se3 becomes a crucial issue for the relevant applications. Here, we propose an efficient method for the chemical thinning and surface doping of layered Bi2Se3, forming Se/Bi2Se3 heterostructures with tunable thickness ranging from a few nanometers to hundreds of nanometers. The thickness can be regulated by varying the reaction time and large-size few-layer Bi2Se3 sheets can be obtained. Different from previous liquid-exfoliation methods that require complex reaction process, in-situ and thickness-controllable exfoliation of large-size layered Bi2Se3 can be realized via the developed method. Additionally, the formation of Se nanomeshes coated on the Bi2Se3 sheets remarkably enhance the intensity of Raman vibration peaks, indicating that this method can be used for surface-enhanced Raman scattering. The proposed chemical thinning and surface-doping method is expected to be extended to other bulk-layered materials for high-efficient preparation of 2D heterostructures.

Crop Load Management in Nashi Pear—A Review

Most nashi cultivars require heavy thinning, and this has traditionally been performed by the time and labour-intensive practice of hand thinning. Crop load management is a key cost driver for nashi production, but there are limited cost-effective options available for nashi growers compared to other pome fruit, especially apples and, to a lesser extent, European pears. There is, however, potential to adapt some of the thinning tools and techniques used in apples and European pears to reduce the labour requirements and high cost of thinning in nashi, thus improving industry profitability. Several chemical thinning agents have potential for nashi, and an understanding of the optimal application rates, times and weather conditions for each chemical, as well as the conditions/factors that impact the tree carbon balance, will improve the predictability of chemical thinning. However, it is difficult to target specific flowers/fruitlets within a cluster with chemicals, and the flowers that produce the preferred fruit shape and size are in the middle of the flower cluster. Mechanical thinning during the flowering period with either Darwin or BAUM-style string thinners has potential, particularly as these devices can be used as early as flower emergence. As for chemical thinning, the issue of non-selectivity needs to be addressed; however, the development of mechatronic systems should overcome most problems that occur with the currently available mechanical thinners. Shading at critical times is an avenue that could be explored further to ascertain the critical stage when developing fruit are susceptible to enable the determination of the optimal timing and duration of shading. Targeted pruning and bud thinning during the dormant winter period to reduce the floral bud numbers is a valuable option for the precise placement of fruit in optimal positions and to set up the required number of clusters. This review highlighted several tools/techniques that, with further work, can be incorporated into a systematic approach to crop load management in nashi while reducing the risk and cost.

Thick Film Ultrasonic Micromotor Based on Chemical Mechanical Thinning and Polishing Process

In this letter, a millimeter scale thick film rotating traveling wave ultrasonic motor based on chemical mechanical thinning and polishing process was proposed. The 30 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{m}$ </tex-math></inline-formula> thick piezoelectric functional layer is fabricated to realize good compactness and high piezoelectric properties. The thickness and diameter of the stator are about 240 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{m}$ </tex-math></inline-formula> and 4 mm, respectively. The vibration mode of the motor is B02 mode under the resonant frequency of 26.2 kHz. The motor can achieve stable bidirectional rotation under the excitation of four sinusoidal voltages. Moreover, when the excitation voltage is 50 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{V}_{\text {pp}}$ </tex-math></inline-formula> , the maximum speed can reach 766 rpm under the preload force of 686 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{N}$ </tex-math></inline-formula> .

Chemical thinning of ‘Nicoter’

Chemical thinning of ‘Nicoter’

Metamitron application could replace carbaryl treatment for chemical thinning in ‘Red Delicious’ apple

Metamitron application could replace carbaryl treatment for chemical thinning in ‘Red Delicious’ apple

Different chemical thinning strategies and their effect on apple production in southern Brazil

Different chemical thinning strategies and their effect on apple production in southern Brazil

Crop Load and Thinning Methods Impact Yield, Nutrient Content, Fruit Quality, and Physiological Disorders in ‘Scilate’ Apples

Most apple cultivars produce too many flowers to enable consistent yields of high-quality fruit, thus, crop load management (thinning) is an integral part of orchard management in modern apple cultivation. Crop load is managed by thinning excess flowers and/or fruit from a tree, however ideal targets vary between cultivars. In this two-year study, the effect of thinning methods at different levels of crop load on fruit quality and production, post-harvest storability and physiological disorders, and fruit and leaf nutrient content in ‘Scilate’ apples were investigated in southern Tasmania, Australia. Two thinning methods, artificial bud extinction (ABE) and hand thinning (HT), were compared at three levels of crop load: 3, 6, or 12 fruit cm−2 limb cross-sectional area (LCSA), described as low, medium, and high, respectively. During the second season, all the ABE and HT treatments received additional chemical thinning (CT). The results demonstrated that ABE consistently outperformed HT in terms of improved fruit set, return bloom, and fruit weight. The fruit quality parameters, such as flesh firmness, total soluble solids, dry matter content, malic acid content, and fruit shape, were also improved under the ABE regime, with these positive effects being the clearest in the second season. In general, high-quality fruits were obtained from the low and medium crop loads, while the fruit quality was poor for the high crop load trees, but the low crop load fruit had a slightly higher incidence of internal flesh browning (predominantly radial) and fruit softening after regular atmosphere storage. The crop load also impacted on the fruit and leaf mineral nutrient content, where fruit N, Ca, Mn, and Zn, and leaf N, Fe, Zn, and Cu content increased while fruit and leaf K declined with a higher crop load. High crop load, irrespective of the thinning regime, and HT with a medium crop load, induced severe biennial bearing, whereas, the fruit yield was relatively consistent with ABE, even with a medium crop load. We conclude that ABE with a medium crop load (around six fruit cm−2 LCSA) is an effective method of managing crop load and optimizing the fruit quality in ‘Scilate’ apples.

A Review on Crop Regulation Techniques in Guava (Psidium guajava L.) through Hi-Tech Practices

Guava (Psidum guajava L.) is one of the most favorable fruit crops in India and is considered to be a well-executed, nutritionally valuable and profitable crop. Recently, guava has secured higher demand within the global trade because of its nutritional value and processed products. It is a hardy, prolific bearer and produces a fairly remunerative fruit crop. It is mainly cultivated on a large commercial scale. Guava fruit bears three bahar seasons, viz., Ambe bahar, Mrig bahar, and Hasth bahar. The continual bearing habit ends up in the reduction of yield with the inferiority of small-sized fruits. So as to overcome this problem, bahar treatment is practiced. Among the three bahar seasons, the heaviest flowering is observed in the Ambe Bahar season, but the fruit quality of this season is rough, watery, insipid in taste, poor in quality, less nutritive and is heavily attacked by many insects, pests and diseases. The fruit quality of winter season crops is excellent, nutritive, and escaped from the attack of fruit flies. Therefore, the crop regulation practice is to force the tree for rest and produce profuse blossoms and fruits throughout any one of the two or three flushes. It is necessary to reduce the fruit set during the rainy season and subsequently increase the fruit set during the winter season through the use of various chemicals like NAA, ethereal and urea etc to regulate the guava crop. This method aims at regulating uniform and good quality fruit and also maximizing produce as well as profit. This regulation method depends on climatic factors, cropping pattern, extend of the damage by the disease and pests, market and industry demand, cultivar, etc. Crop regulation is accomplished by the various strategies like water management to induce stress, training and pruning of shoots and roots at different levels as well as at different times and manual or chemical thinning of flowers.

Mechanical Thinning Improves the Consistency of Flowering and Yield in Apple Production

Abstract Most apple cultivars tend to bear biennially, i.e. produce many fruits in one and few fruits in the next year, or do not have a nature of self-thinning. The effectiveness of chemical thinning depends on conditions, particularly temperature, at the time of application. In some other fruit-growing regions, the mechanical thinning of flowers is adapted to some cultivars by changing the speed of moving and rotation of the mechanisms to conduct partial thinning — removing of flowers. The investigation aimed to evaluate the effectiveness of total flower removal mechanically on one side of the tree row, and on the other side the next year, during the full production period (8th to 12th year after planting) to obtain regular yields. Seven cultivars on dwarfing rootstocks M.9 and B.396 were compared. Apple trees on the dwarfing rootstock B.396 were less affected by biennial yielding. Cultivars had a strong relation to yield — ‘Gita’ (Vf), ‘Konfetnoye’ and ‘Kovalenkovskoye’ had less fluctuation yearly, while ‘White Transparent’, ‘Rubin’ (Kazah.), ‘Antei’, and ‘Ligol’ performed opposite. There was a positive influence observed on reduction of periodicity by mechanical flower thinning, however, there is a discussion on cumulative yield reduction.

Automatic flower cluster estimation in apple orchards using aerial and ground based point clouds

Chemical and mechanical thinning processes have long been used in stone and pome fruit production. During the thinning of apple flowers, growers use chemicals to regulate the tree load. Hand thinning is applied after the June drop to prune trees with excess crop load. The process of thinning can be unpredictable especially in biennial bearing cultivars. Thus, incentives to optimise chemical usage and to reduce expensive manual labour is ever increasing. Ground based machine vision systems have grown in popularity in orchard management due to the level of detail as well as plant coverage they can inspect with. Additionally, unmanned aerial vehicles (UAV) -based remote sensing technology is becoming a popular non-invasive quality inspection solution. This work proposes a framework for combining UAV and ground based RGB image data to detect flowering intensity in a Dutch Elstar apple orchard. The framework, based on point cloud reconstruction, presents automatic point cloud handling techniques as well as automated unsupervised flowering intensity estimation methods. Two linear regression models based on unsupervised machine learning methods were trained and validated from the framework that estimate flowering intensity in the orchard with both models having R 2 > 0.65, RRMSE < 20% and p-stat < 0.005 for the correlation between the image derived flower index and the flower cluster number counted in field. The proposed methods provide a novel strategy for guiding flower thinning using simple RGB images and location data only. Moreover, the proposed methods also reveal the flexibility of intra-tree inspection by checking its sub-volumes. • Automatic flower cluster estimation at the tree level with a R 2 = 0.7, RMSE < 20. • Ground and aerial point clouds have better performance when combined. • Novel strategy developed for guiding flower thinning in orchard management. • Dataset with aerial and ground images, and field sampling data released.

Techniques to Achieve Stretchable Photovoltaic Devices from Physically Non‐Stretchable Devices through Chemical Thinning and Stress‐Releasing Adhesive

AbstractIntegration of photovoltaic devices on the deformable surfaces of plants and animals is challenging, as most of the photovoltaic devices possess no stretchability which severely restricts the underneath deformable substrates and causes potential delamination of the devices from the substrates due to large shear stress. Here, techniques to achieve stretchable photovoltaic devices through chemically thinning flexible solar cells and intermediate hard–soft transition layers are proposed. The resulting photovoltaic devices are only 25 µm in thickness with a radius of curvature of 1 mm, offering excellent adaptability to leaves and many curved surfaces. The intermediate layer that is based on silicone adhesive with low modulus provides an interface between non‐stretchable photovoltaic devices and deformable substrates, resulting in a stretchability of the overall structures larger than 140%. Key parameters of the photovoltaic device such as open‐circuit voltage, short circuit current, fill factor, and conversion efficiency indicate the excellent performance of thinned devices. Potential applications of ultra‐thin photovoltaic devices in energy harvesting and light intensity sensing on stretchable substrates are demonstrated, suggesting the practical use of the devices in constructing stretchable self‐powered wearable systems for agriculture and healthcare monitoring.

Chemical thinning of peach trees

Peach tree thinning is essential to harvest quality fruits and to keep balanced production for several years. Manual thinning of peach trees demands much work force and increases production costs. Chemical thinning may be an alternative solution, but efficiency depends on doses and species. This study aimed at evaluating the effect of metamitron – applied at different concentrations – on chemical thinning of peach trees in the south of Brazil. The experiment was carried out in a commercial peach tree orchard where ‘Sensação’ cultivars, in Morro Redondo, Rio Grande do Sul (RS) state, Brazil. The following metamitron concentrations were applied at concentrations of 100 mg L-1, 200 mg L-1, 300 mg L-1, 400 mg L-1, manual thinning was carried out 40 days after full bloom (DAFB) and to the treatment where the plants have no thinning. Fruit abscission, effective fructification, total number of plants per plant, production per plant, mean mass and fruit diameter were evaluated. Concentrations of 300 and 400 mg L-1 metamitron 40 DAFB provides promoted high fruit abscission, besides decreasing the number of fruits and production. Therefore, concentrations of 100 and 200 mg L-1 of metamitron 40 DAFB provides results in an efficient thinning practice similar to manual thinning for production, mass and fruit diameter.