Early Fruit Research Articles

The Effect of Different Methods and Quantities of Pollination on the Infestation Percentage by two of Early Date Fruit Insect Pests in Date Palm Farms in New Valley Governorate, Egypt

The Effect of Different Methods and Quantities of Pollination on the Infestation Percentage by two of Early Date Fruit Insect Pests in Date Palm Farms in New Valley Governorate, Egypt

Impact of pinching on growth, flowering and early season fruit yield of bottle gourd [Lagenaria siceraria (Mol.) Standl.

A study to assess the “impact of pinching on the growth, flowering, and early season fruit yield of bottle gourd (Lagenaria siceraria (Mol.) Standl.)” was conducted during the kharif season of 2022 at two locations: Punjab Agricultural University - Vegetable Research Farm in Ludhiana (L1) and Regional Research Station in Abohar (L2). The study employed a randomized block design, consisting of three replications, and encompassed nine distinct pinching treatments, which included: no pinching (T1), pinching on a main branch at 2nd node (T2), pinching on main and lateral branches at 2nd node (T3), pinching on the main branch at 4th node (T4), pinching on the main branch and lateral branches at 4th node (T5), pinching on main branch at 6th node (T6), pinching on the main branch and lateral branches at 6th node (T7), pinching on a main branch at 8th node (T8) and pinching on the main branch and lateral branches at 8th node (T9). Pinching treatment was given at the main branch and lateral branches of bottle gourd vines in each plot according to the assigned treatments. The results revealed that pinched plants on the main branch and lateral branches at 6th node (T7) remarkably increased the number of branches (7.36), female flowers (24.35), days taken to first male flower appearance (49.18) and early season fruit yield (188.89 q ha-1) whereas it reduced vine growth (383.17 cm), days taken to first female flower appearance (53.97), number of male flowers (121.69) and narrow sex ratio (5.0). According to the findings from the present study, it was observed that pinching on both the main and lateral branches at the 6th node (T7) demonstrated the most favorable growth, flowering, and early-season fruit yield of bottle gourd.

Variations in phytic acid, phenolic, flavonoid, and mineral-bioavailabilities during pomelo fruit development and their relation to fertilization strategy

Pomelo fruit is naturally rich in health-promoting components. However, few studies have quantified phytic acid (PA), which is both an antioxidant compound and an antinutrient that limits mineral bioavailability. In this study, we analyzed the temporospatial changes in fruit PA, total phenolic, total flavonoid, estimated mineral bioavailabilities, and their response to fertilization strategies. Compared to pulp, pomelo peel contained higher PA, total phenolic, total flavonoid and most minerals concentrations (except for P) but lower estimated mineral bioavailabilities (Mg, Zn and Fe). The concentrations of PA, total flavonoid, and minerals (P, Ca, Mg, Zn) and Fe estimated bioavailability in pulp gradually decreased with ripening. Total phenolic concentrations and the estimated bioavailabilities of Ca, Mg and Zn in pulp decreased in the early fruit expansion stage but subsequently increased markedly until maturity. Reduced chemical fertilization while supplementing Mg simultaneously increased estimated mineral bioavailabilities in pulp through reduced PA as an antinutrient, and increased bioactives concentrations in peel through increased PA as an antioxidant together with total phenolic and total flavonoid. Overall, our results indicate that reducing NPK while supplementing Mg fertilization in pomelo orchards with acidic and Mg-deficient soil is the most beneficial approach for achieving biofortification of the edible pulp parts and integrated fruit quality enhancement.

Morpho-pathological and genomics-based identification of the Aspergillus species infecting pomegranate with nano- driven solution

Pomegranate (Punica granatum L.) is the dominant fruit for the tropical and sub-tropical area that belongs to the family Punicsceae. It has been cultivated throughout the world and drier parts of southern Asia. Good source of carbohydrates and minerals. Among post-harvest fungal pathogens attacked on pomegranate, Aspergillus niger is common store fungus that causes black mold disease. It mainly attacks in the flowering stage and early fruit developing during rainy seasons without any external symptoms. Disease samples were collected from different local markets of Faisalabad. Infection of fungus was done from the infected part of the pomegranate using artificial media. The fungus was identified on a morphological basis then Koch postulates were followed to confirm pathogenicity. The proved pathogen was determined by molecular characterization. DNA extraction and PCR have done of fungus. Antifungal potential of silver nanoparticles against Aspergillus niger were performed in three different concentration 50ppm, 100ppm and 150 ppm and compared with control The data were collected on the 3rd, 5th and 7th day of the fungal growth in which the 150ppm concentration was very affected than other concentrations. Keywords: Pomegranate, postharvest disease Aspergillus niger, nanoparticles.

Boll distribution in the cotton canopy is affected by nitrogen management and cover crops in a sandy soil under water scarcity

Context or problemA favorable cotton boll distribution within the plant canopy can promote early fruit retention and increase crop yield and fiber quality, particularly in rainfed crops in sandy soils that are subject to periodic water deficits. However, the effects of different cover crop rotation systems combined with different nitrogen (N) rates and sources on boll distribution and cotton earliness are unknown. Objective or research questionThe objective of this study was to evaluate the boll distribution and earliness of cotton as a function of the cover crop rotation system and N sources and rates, in a sandy soil of a tropical region of Brazil prone to drought. MethodsA field study was carried out for two growing seasons (2018–2020) in southeastern Brazil in an area with sandy soil. The treatments consisted of the following crop rotation systems, which were implemented in 2016: Fallow; single grass; grass + grass; grass + legume; and MIX (grass+legume+grass). In addition, N rates of 70, 100, and 130 kg ha−1 (applied as topdressing) and two N sources (urea; and controlled-release urea, CRU) were evaluated. ResultsLow water availability in the 2018/2019 crop season resulted in early plants that reached 95% boll yield below fruiting node 12 when 70 kg ha−1 N (urea) was applied. Satisfactory rainfall in the 2019/2020 crop season resulted in 95% boll yield below fruiting node 14 when 130 kg ha−1 N was applied for all N sources and rotation systems. Applying CRU increased the boll distribution in the top third of the plant. Applying 130 kg ha−1 N increased the boll distribution in the middle and top thirds of the plant, particularly in the treatments with legume cover crops and CRU. In the crop season with higher rainfall and yield potential, the rotation systems without legumes that received 70 kg ha−1 N (urea) had a lower boll distribution in the top third of the plant. ConclusionsCotton boll distribution is affected by cover crop rotation systems, N rates and sources and water availabity throughout the season. The best strategy for improving early boll setting is to apply lower rates of N as CRU in a rotation system with a mixture of grasses and legumes as cover crops. Additionally, there is still a challenge to increase the cotton earliness in years with high water availability. Implications or significanceCover crops and increased efficiency fertilizers are important to improve boll setting throughout the entire cotton canopy. Because these technologies improve the availability of nitrogen and water in the soil, especially in dry years. Improving cotton earliness is still a challenge in low-altitude regions, since plant cycle is naturally short in these environments, due to the greater accumulation of degrees days. Even so, the use of lower N rates associated with cover crops and controlled-release urea may have a small increase in cotton earliness, but mainly help in early fruit retention.

New apple variety – Hrustal’nyj Bashmachok

The domestic apple tree (Malus domestica Borkh.) occupies a leading place among fruit crops, both in terms of area planted and in terms of gross fruit harvest. Currently, apple tree varieties are subject to strict requirements for highly adaptability, winter hardiness, early fruiting, high yield and quality of fruits. The new apple tree variety Hrustal’nyj Bashmachok (breeding number 1-18), meets many of the listed requirements, is the result of breeding work of the Orenburg branch of the Federal State Budgetary Institution Federal Scientific Center for Horticulture, aimed at improving the assortment and meeting the demand of producers and consumers of agricultural products in the Ural region. A variety of autumn ripening, universal use, obtained from open pollination of Antonovki Obyknovennoj and combines in its genotype such valuable qualities as high winter hardiness, productivity, and resistance to scab. The tree is medium in size, with a rounded crown of medium density. Fruits with an average weight of 152 g, conical, regular in shape. The surface of the fruit is smooth, slightly ribbed, the main color at the time of harvest and consumer ripeness is greenish-yellow. The outer color is present on a smaller part of the fruit and is orange. Subcutaneous dots are small, white, barely noticeable. The fruit pulp is creamy, dense, juicy, fine-grained, with a medium aroma. The taste is sweet and sour, pleasant, tasting score 4.4 points, average aroma. The shelf life of fruits is 20-30 days. Chemical composition of the fruit: sugar content 10.8 %, ascorbic acid 19.1 mg/100 g, dry matter 13.4 %; acidity 0.8 %. The Hrustal’nyj Bashmachok variety has average drought and heat resistance, is slightly affected by scab, and begins to bear fruit in the third year after planting. Over a long period of study, the variety showed a high level of economically valuable traits, including yield from 14.8 to 18.8 t/year and stable annual fruiting. The Crystal Shoe variety has been included in the State Register of Breeding Achievements approved for use in the Ural region since 2022 and is recommended for updating the industrial assortment of the region and cultivation in farms of various categories.

Influence of Sunn Hemp Biomass Incorporation on Organic Strawberry Production

Sunn hemp (Crotalaria juncea L.), a warm season leguminous cover crop, is commonly used in rotation with organic strawberry production in Florida’s subtropical environment. This study was conducted to explore the impacts of sunn hemp on growth and yield performance of the subsequent organic strawberry crop in sandy soils, taking into consideration the nutrient contribution from soil incorporation of sunn hemp biomass. Sunn hemp was seeded during the summer off-season and terminated before flowering, three weeks prior to the fall planting of two strawberry cultivars (‘Strawberry Festival’ and ‘Camino Real’). With sunn hemp residues incorporated into the soil, two application rates of nitrogen (N) through pre-plant organic fertilization for the strawberry season were used, including N at a rate of 84 kg/ha, without consideration of the N credit from sunn hemp, and N at a rate of 19.8 kg/ha, with consideration of the estimated N credit from sunn hemp. A summer fallow without cover crop and with a pre-plant organic fertilizer application at the N rate of 84 kg/ha was included as the control. Overall, the sunn hemp incorporation at three weeks after termination did not benefit the strawberry plant growth or fruit yield in this study, with rather low levels of soilborne pathogen and nematode infestations. Both sunn hemp treatments exhibited a significantly lower level of total soil N compared to the summer fallow plots at the end of the strawberry season. The reduction in the pre-plant N fertilization resulted in lower above-ground plant dry weight and accumulation of N, phosphorus (P), and potassium (K) at the end of the strawberry season, along with fewer leaves and smaller crowns of the strawberry plants during the early season. Both sunn hemp treatments decreased early fruit yields, while the sunn hemp treatment with the reduced N fertilization also led to a significant reduction in the total fruit number and weight, although no significant differences in the whole-season marketable fruit yield were observed among the nutrient management treatments. Overall, ‘Strawberry Festival’ yielded higher than ‘Camino Real’, but the effects of nutrient management did not vary with the strawberry cultivars. Further studies are needed to enhance organic strawberry nutrient management involving rotational cover crops.

Comprehensive Review on Automated Fruit Disease Detection at Early Stage

Fruits are now cultivated in many different countries, which has increased global fruit output to 2,914.27 thousand tons. Numerous countries want to increase their fruit production in the next years, thus the number of countries producing fruits is expected to keep growing. But despite this, a variety of challenges and problems are still experienced while growing crops. These include problems with the fruit's general quality, the cost of manufacturing, the state of the seed, and the fruit's own illness. The main causes of fruit diseases' detrimental impacts are microbes and fungus. Early fruit disease detection is used to foresee fruit disease, which helps farmers save money by lowering the amount of capital they have to spend. To stop fruit illnesses in their early stages, it is crucial to figure out the best way to identify fruit infections. Many studies on a variety of fruits, including the papaya, apple, mango, olive, kiwifruit, orange, etc., have employed deep learning approaches. This study compares several ways for image capture, pre-processing, and segmentation as well as deep learning techniques. The study discovered that the best deep learning strategy for a particular collection of data may change depending on the system's computational power and the data being used. The results of this study show that a convolution neural network is more accurate and can predict a wide range of fruit diseases.

Early diagnosis and mechanistic understanding of citrus Huanglongbing via sun-induced chlorophyll fluorescence

Citrus Huanglongbing (HLB) is a serious disease that is devastating the citrus industry worldwide. The infection of HLB causes a significant impact on the photosynthesis and growth of citrus but the early diagnosis of HLB is challenging. This study aims to propose an effective method for early HLB diagnosis and mechanistic understanding via sun-induced chlorophyll fluorescence (SIF) during the whole growth period of citrus. SIF signals and net photosynthetic rate (A) of healthy, asymptomatic HLB (aHLB) and symptomatic HLB (sHLB) citrus leaf samples were acquired throughout the whole citrus growth period. Seasonal variations of the peak SIF yield at 687 nm (SIFY687) and 741 nm (SIFY741) and A were investigated. Leaf chlorophyll a content (Ca), chlorophyll b content (Cb), and carotenoids content (Cxc) were also measured by spectrophotometry in the laboratory. It was found that the A of the aHLB was close to that of sHLB, which was significantly different from the healthy leaves at the physiological fruit dropping (PFD) period. The ratio of chlorophyll content (Chl) to Cxc (Chl/Cxc) was evidently different between aHLB and healthy leaves at the late PFD and early fruit expanding (FE) stage, which could be a potential biomarker to identify HLB in the incubation period. The classification result showed PFD was the optimal stage for HLB diagnosis and the index based on SIFY741 was recommended (overall accuracy > 90 %). Moreover, HLB had a great influence on the relationship between A and SIF at the PFD stage, and the coefficients of determination (R2) of the univariate linear regression model between A and SIFY687 and SIFY741 decreased from 0.81 and 0.72 to 0.21 and 0.17, respectively. These results demonstrate the HLB effect on the relationship between A and SIF, and that the SIF could be a proxy to citrus photosynthesis and further used to diagnose early HLB in situ.

Activation of growth and photosynthetic processes of tomato plants by LED lighting under production conditions

The advantage of FLORA LED lighting in comparison with HPS lamps for cultivation of tall tomato varieties under production conditions is shown. Under LED illumination with well-balanced spectral composition, the main growth and physiological parameters of tomato juvenile plants (such as dry weight and accumulation of dry matter of vegetative organs, content of photosynthetic pigments, rate of oxygen release during photosynthesis, coefficient of photosynthetic efficiency, time of flowering onset) were superior to plants grown under HPS lamp illumination. It is assumed that increased photosynthetic activity, as well as more intensive growth and development processes provided a higher adaptive potential and survival during transplantation, early fruiting. and higher yields to plants grown under LED lighting.

Effect of Foliar Calcium Fertilization on Fruit Quality, Cell Wall Enzyme Activity and Expression of Key Genes in Chinese Cherry

ABSTRACT Chinese cherries are early flowering and early fruiting, with both edible and ornamental values. This study aims to explore the effects of pre-harvest spraying with different concentrations of CaCl2, amino acid calcium, and sugar alcohol calcium on the quality of Chinese cherry and the expression of genes related to cell wall softening. The goal is to identify suitable calcium-based agents for pre-harvest spraying on Chinese cherry. The results of the study demonstrated that all three exogenous calcium treatments significantly increased the mineral content compared to the control group. Moreover, these treatments also led to a significant increase in various fruit quality parameters such as hundred fruit weight, firmness, soluble solid, soluble sugar, titratable, vitamin C, soluble protein, β-Carotene content and superoxide dismutase, peroxidase activities. Additionally, they were found to effectively reduce rot rate, polyphenol oxidase activity, malondialdehyde content and relative conductivity. The activity of pectin methylesterase, polygalacturonase, cellulase and β-galactose was reduced by amino acid calcium and sugar alcohol calcium. All three types of exogenous calcium down-regulated the expression of PME and ChCaBP1. Additionally, amino acid calcium and sugar alcohol calcium decreased the expression of PG, Cx, and BGal. Exogenous calcium reduces the size of stomata in the fruit epidermis, leading to a decrease in both fruit respiration rate and transpiration. Of the three calcium preparations, amino acid calcium and sugar alcohol calcium were more effective than CaCl2, with 0.12 g·L−1sugar alcohol calcium and 0.06 g·L−1 amino acid calcium being the most effective.

Reevaluation of the degree day base 60°F concept in US cotton (Gossypium hirsutumL.) production

AbstractCotton (Gossypium hirsutumL.) management decisions to abet early growth, fruit set, boll maturation, and harvest preparation are often facilitated by prediction of the date when critical developmental stages are reached. In the United States, growing degree days calculated with a base 60°F (DD60s) are commonly used to predict cotton development. Observations suggest development of modern cultivars differs from previously established guidelines. The objectives were to (1) reevaluate DD60s required for an early, mid‐maturing and late maturing cultivar to reach key growth stages across the US Cotton Belt; and (2) determine if predictions of growth stages are strengthened by optimizing base temperature or including an upper threshold by growth stage. During 2018 and 2019, 22 field trials were established in 10 states. Plant growth stages were monitored weekly and air temperature was computed from interpolated surface observations weighted by a physical, geographic model. Observed DD60s to reach growth stages varied slightly by cultivar and region (≤85 DD60s and ≤130 DD60s, respectively). Required DD60s to reach growth stages exceeded most published ranges. Optimization of base temperature and inclusion of an upper threshold by growth stage did not substantially decrease errors in predicting date of growth stage occurrence. The DD55 and DD55 with an upper threshold of 86°F calculations resulted in slightly lower errors in predicting date of growth stage occurrence than the DD60 calculation. Although guidelines should be updated, it is unlikely slight modification in base temperature or upper thresholds will drastically increase the predictive ability over the DD60 calculation.

Interaction of VvDELLA2 and VvCEB1 Mediates Expression of Expansion-Related Gene during GA-Induced Enlargement of Grape Fruit.

Exogenous gibberellin treatment can promote early growth of grape fruit, but the underlying regulatory mechanisms are not well understood. Here, we show that VvDELLA2 directly regulates the activity of the VvCEB1 transcription factor, a key regulator in the control of cell expansion in grape fruit. Our results show that VvCEB1 binds directly to the promoters of cell expansion-related genes in grape fruit and acts as a transcriptional activator, while VvDELLA2 blocks VvCEB1 function by binding to its activating structural domain. The exogenous gibberellin treatment relieved this inhibition by promoting the degradation of VvDELLA2 protein, thus, allowing VvCEB1 to transcriptionally activate the expression of cell expansion-related genes. In conclusion, we conclude that exogenous GA3 treatment regulates early fruit expansion by affecting the VvDELLA-VvCEB1 interaction in grape fruit development.

Delayed rooting hormone application and stem cutting collection time improved Flacourtia indica rooting ability and root growth

Flacourtia indica (Burm.f.) Merr. is an important fruit and medicinal tree in Southern Africa. Efforts to achieve early fruiting have failed with juvenile propagules (planting materials) such as seed. Assessing rooting ability of mature (fruit bearing) F. indica stem cuttings is vital to attaining early fruiting, or precocious fruiting, which reduces the long juvenile phase experienced by many woody fruit trees when propagated from seeds (juvenile planting materials). The objectives of this study were to assess responses of mature stem cuttings to different application times of rooting hormone (Seradix® No. 2) and collection times of stem cuttings, and also to identify important pheno-phases in the yearly tree growth cycle of F. indica. A significantly higher rooting percentage (p < 0.001) was obtained with delayed Seradix® No. 2 application than with immediate application. Stem cuttings collected at flowering and leaf fall seasons were responsive to Seradix® No. 2 application, but all stem cuttings collected at fruiting time failed to produce roots. For stem cuttings collected during flowering time, immediate Seradix® application resulted in significantly (p = 0.0482) more roots than in stem cuttings subjected to delayed Seradix® application. The failure to produce roots of cuttings collected at fruiting time could be due to low sugars (carbohydrates) in the stem cuttings. The study concluded that the best time to collect stem cuttings from mature F. indica trees for rooting is either at flowering or leaf fall stages and that delayed Seradix® No. 2 application improves rooting of stem cuttings from mature F. indica trees.

Effect of Plant Growth Regulators on Growth and Yield of Sweet Pepper

A field experiment was carried out to study the effect of plant growth regulators on growth and yield of sweet pepper (cv Indra) in Rayagada district of Southern Odisha during September-January of 2019-20 and 2020-21. The experiment was laid out in Randomized Block Design with three replications and seven treatments. From the present study it was revealed that the maximum plant height (43.3 cm) was obtained with IAA (100 ppm) whereas maximum fruiting branches (8.20), maximum fruit weight (106.80 g) was obtained with 2,4-D (10 ppm). Maximum polar diameter (6.6 cm), shoulder diameter (5.2 cm) and single fruit weight (82.3 g) was obtained with BA (5 ppm). Maximum fruit yield (13.8 t/ha) was recorded with BA (5 ppm). Early fruit fetches higher market price than late harvested fruit and gives higher return to farmer which was obtained by application of BA (5 ppm) i.e., 28.1 days for first flowering and 60.2 days for first harvesting.

Elucidating the effect of plant growth regulators on embryo maturation for shortening the breeding cycle in papaya

Papaya (Carica papaya L.) is a tropical fruit crop with commercial importance due to its nutritional andmedicinal value. The long generation time required by papaya plants during the breeding process significantly slows crop improvement, and developing a variety takes 15-16 years (7-8 generations). As a solution in this direction, using plant bioregulators (PGR) to improve seed maturity in conjunction with the embryo culture technique may aid in reducing the time between fruit set and seedling establishment. We investigated the effect of ethrel, abscisic acid (ABA), and methyl jasmonate (MeJa) in different concentrations during early fruit development on hastening embryo maturity followed by embryo culture for shortening the breeding cycle of dioecious papaya var. Pusa Nanha. Fruits after 60 and 75-days old fruit (DOF) were treated with ethrel (100, 120 ppm), abscisic acid (10-6, 10-4 M), and MeJA (10-5, 10-3 M); the effect of treatments was observed after 15 days of PGR application. Among the treatments, ethrel 120 and 100 ppm at 75 DOF were found to be effective fo hastening seed maturity, as measured by seed colour (light brown), embryo formation (85%), and embryo size (2.93 mm), maximum in vitro germination (85%), rapid shoot emergence (5.67 days), earliest radicle emergence(2.67 days), resulting in maximum plantlet regeneration (86.67%). The embryos isolated from the fruits treated with MeJA (10-5 M) showed the maximum number of roots (5.13), with 75.50 % plantlet regeneration. As a result, using the above method, the breeding cycle of papaya could be reduced to as low as 3 months, compared to the standard period of 6-9 months (from pollination to seedling establishment).

A Data Ecosystem for Orchard Research and Early Fruit Traceability

Advances in measurement systems and technologies are being avidly taken up in perennial tree crop research and industry applications. However, there is a lack of a standard model to support streamlined management and integration of the data generated from advanced measurement systems used in tree crop research. Furthermore, the rapid expansion in the diversity and volumes of data is increasingly highlighting the requirement for a comprehensive data model and an ecosystem for efficient orchard management and decision-making. This research focuses on the design and implementation of a novel proof-of-concept data ecosystem that enables improved data storage, management, integration, processing, analysis, and usage. Contemporary technologies proliferating in other sectors but that have had limited adoption in agricultural research have been incorporated into the model. The core of the proposed solution is a service-oriented API-driven system coupled with a standard-based digital orchard model. Applying this solution in Agriculture Victoria’s Tatura tree crop research farm (the Tatura SmartFarm) has significantly reduced overheads in research data management, enhanced analysis, and improved data resolution. This is demonstrated by the preliminary results presented for in-orchard and postharvest data collection applications. The data ecosystem developed as part of this research also establishes a foundation for early fruit traceability across industry and research.

Microtubule-associated protein SlMAP70 interacts with IQ67-domain protein SlIQD21a to regulate fruit shape in tomato.

Tomato (Solanum lycopersicum) fruit shape is related to microtubule organization and the activity of microtubule-associated proteins (MAPs). However, insights into the mechanism of fruit shape formation from a cell biology perspective remain limited. Analysis of the tissue expression profiles of different microtubule regulators revealed that functionally distinct classes of MAPs, including members of the plant-specific MICROTUBULE-ASSOCIATED PROTEIN 70 (MAP70) and IQ67 DOMAIN (IQD, also named SUN in tomato) families, are differentially expressed during fruit development. SlMAP70-1-3 and SlIQD21a are highly expressed during fruit initiation, which relates to the dramatic microtubule pattern rearrangements throughout this developmental stage of tomato fruits. Transgenic tomato lines overexpressing SlMAP70-1 or SlIQD21a produced elongated fruits with reduced cell circularity and microtubule anisotropy, while their loss-of-function mutants showed the opposite phenotype, harboring flatter fruits. Fruits were further elongated in plants coexpressing both SlMAP70-1 and SlIQD21a. We demonstrated that SlMAP70s and SlIQD21a physically interact and that the elongated fruit phenotype is likely due to microtubule stabilization induced by the SlMAP70-SlIQD21a interaction. Together, our results identify SlMAP70 proteins and SlIQD21a as important regulators of fruit elongation and demonstrate that manipulating microtubule function during early fruit development provides an effective approach to alter fruit shape.

Crop Regulation Studies in guava (Psidium guajava L.) cv. L 49 under Ultra High Density Planting

A field experiment was carried out on 8 years old guava cv L 49 trees to assess the effect of pruning level and growth regulators with different combinations on vegetative growth and fruiting attributes in Ultra High Density Planting. The experiment consisted of 2 factors with 36 combinations viz., factor -1 (pruning level) P1- pruning of 25 cm of the shoot from the tip, P2- pruning of 50 cm of the shoot from the tip, P3- pruning of 75 cm of the shoot from the tip, P4 – control (without pruning). Factor -2(growth regulators) G1, G2- Potassium nitrate (1 ,2%), G3, G4- Thiourea (0.1 ,0.2%), G5, G6- Ethephon (250, 500 ppm), G7, G8- Cycocel (250, 500 ppm) and G9 – Control. Results showed that among different levels of pruning, 50cm pruning from the tip with potassium nitrate spray at 2 different concentrations was found to be the best for promoting early vegetative bud burst, fruit set and fruit yield. The increment in plant height and canopy spread in East-West and North-South were recorded more in 25 cm pruning from the tip. A greater number of shoots are visible in the P3G5 combination. When compared to other treatments, the P3G2 combination significantly increased the average index number of bud bursts and shoot length under Ultra High Density Planting.

Apple Fruitlet Abscission Prediction. I. Development and Evaluation of Reflectance Spectroscopy Models

Chemical thinning, the most common and cost-effective thinning method, is conducted during early apple fruit development over a 3- to 4-week period using multiple applications of plant growth regulators. It is critical to provide apple growers with tools to assess the efficacy of chemical thinners quickly and accurately because visible responses are not apparent for up to 2 weeks after application. The objective of this study was to build a model to predict apple fruitlet abscission following a chemical thinner application with in situ reflectance data obtained with a portable visible and near infrared (Vis/NIR) spectrophotometer. Developed models were compared with the currently available fruitlet growth model (FGM). ‘Honeycrisp’ fruitlet diameter and reflectance were measured on dates around a chemical thinner application across a 2-year period. After June drop, measured fruitlets were determined to have either persisted or abscised. Random forest, partial least squares regression, and XGBoost classification models were used to predict fruitlet abscission from reflectance data. Each classification model was developed with 2021, 2022, and combined 2021 + 2022 data. For each dataset, 5-fold cross validation was used to assess three model performance metrics: 1) overall accuracy, 2) recall, and 3) specificity. Datasets tested were either unbalanced, majority class down-sampled, or minority class up-sampled with synthetic minority oversampling technique. In both years, the FGM reliably estimated chemical thinner efficacy 9 days after application. Before this time point, the FGM had low prediction accuracy of the minority class in both years—persisting fruitlets in 2021 and abscising fruitlets in 2022. For reflectance spectroscopy, the developed random forest models that were balanced with synthetic minority over-sampling technique were found to be the best combination in predicting chemical thinner efficacy. The combined 2021 + 2022 dataset overall model accuracy ranged from 84% the day before to 93% at 9 days after thinner application. These results show that Vis/NIR is a promising tool to predict chemical thinner efficacy. This technology had high prediction accuracies over a range of fruitlet abscission potential and two growing seasons. Further development and testing of the model over cultivars, chemical thinner timings, and growing regions would facilitate commercialization of the technology.