Fruit Load Research Articles

Effects of fruit load on growth, photosynthesis, biochemical characteristics, and fruit quality of Camellia oleifera

Camellia oleifera Abel is one of the four major woody oil species that produce edible oil from seeds. Nevertheless, its oil yield is comparably low, due to an imbalance in its source–sink relationship caused by its alternate bearing cycle. In this study, we conducted a pot experiment using 5-year-old C. oleifera ‘Huaxin’ young plants to examine the source–sink relationship and determine the optimal fruit load for oil production that ensures maximum economic value for C. oleifera. From April to October, the C. oleifera young plants were subjected to different leaf:fruit ratios: no fruit (control, CK), low fruit load (FL1, leaf:fruit ratio of 36:1), medium fruit load (FL2, leaf:fruit ratio of 18:1), and high fruit load (FL3, leaf:fruit ratio of 9:1). The results showed that the FL2 and FL3 treatments significantly reduced plant height, stem diameter, and flower bud differentiation from August to October, compared with the control. The net photosynthetic rate (Pn) and stomatal conductivity (Gs) of new leaves on clear days from June to August were decreased in the FL2 and FL3 treatments, compared with the control. Medium and high fruit loads (FL2 and FL3 treatments) and prolonged growth duration led to greater reductions in fruit size, weight, seed kernel oil content, oil production per plant, oil body volume, and distribution area, compared with the FL1 treatment. However, stearic acid and oleic acid contents were significantly higher in camellia oil obtained from the FL1 treatment than in camellia oil obtained from the FL2 and FL3 treatments. Thus, a leaf:fruit ratio of 36:1 is recommended to ensure proper C. oleifera ‘Huaxin’ growth and yield, and higher fruit loads should be avoided.

Detection of on‐tree chestnut fruits using deep learning and RGB unmanned aerial vehicle imagery for estimation of yield and fruit load

AbstractThe on‐tree counting of chestnut fruit (bur) is essential for yield estimation and monitoring of fruit load as well as tree health, which is important in determining the management strategy for orchards, markets, and tree health monitoring. However, the practice is still conducted by manual count or farmers’ intuition. Precise and effective counting method is yet to be established. This study attempted to count chestnut fruits with the object detection algorithm, You Only Look Once (YOLO), using the RGB imagery collected with an unmanned aerial vehicle (UAV). The model trained with 500 images (7866 burs labeled with bounding boxes) in YOLO version 4 (v4) could count the number of burs with a R2 value of 0.98 and a root mean square error of 6.3 (8.3% of the mean) relative to the manual count in the data set for each whole tree (n = 53). The R2 of linear regression between the number of burs obtained with the YOLOv4 model and the total yield was 0.76, with a standard error of 1.08 kg tree−1 (26.4% of coefficient of variation), which was equivalent to the in situ burs count by an expert technician. In addition, the number of burs counted with the YOLOv4 model after the adjustment of trunk circumference was negatively correlated with nut weight. Overall, the study revealed that YOLO algorithm coupled with UAV‐based RGB imagery is a precise and efficient method for on‐tree burs detection, which could be used as an indicator of yield and fruit load.

Fruit Load of ‘Shahi’ Affects Not Only Fruit Size but Many Attributes

Fruit Load of ‘Shahi’ Affects Not Only Fruit Size but Many Attributes

Down-regulation of photosynthesis in apple leaves under elevated CO<sub>2</sub> concentration: a long-term field study with different fruit load

Down-regulation of photosynthesis in apple leaves under elevated CO<sub>2</sub> concentration: a long-term field study with different fruit load

Temporal progress of coffee leaf rust and environmental conditions affecting severity in Veracruz State, Mexico

Coffee is an important crop in Mexico. Unfortunately, coffee production has been affected by coffee leaf rust (CLR). The severity of this infection occurs with variations along the year described before in different coffee-producing regions worldwide. For Veracruz, there are available reports of weekly CLR severity, but this information is only descriptive. We analyzed variations along the year of CLR severity in Veracruz with data from municipal weekly reports provided by Mexico’s federal government phytosanitary epidemiological monitoring coffee program. We selected reports dated in 2018 from nine municipalities and after calculations of mean monthly severity values, we conducted a one-way ANOVA (months as factors) of severity data. We compared this information with other coffee-producing regions. Additionally, we explored the association of temperature, rainfall, and altitude with CLR severity using Principal Component Analysis and multiple linear regressions. Temperature and rainfall data were obtained from Mexican National Meteorological Service. We found that CLR severity in January, October, November, and December (months of harvest period) was significantly higher than values from March-June. During the harvest period, coffee plants allocate resources mainly for fruiting which competes in resources for other tasks such as defense and leaf growth, so this competition of resources can explain the positive relationship found between fruit load and CLR severity. This monthly variation of severity was similar to those reported in Chiapas, Guatemala, Colombia, Uganda, and Ethiopia. Our model (R2 = 0.401) showed a significant and negative effect of altitude and medium temperature on CLR severity, while the effect of rainfall was positive. With our study, we suggest applications of fungicides in March-June when coffee plantations are in leaf phenophase. Key words: Altitude; Coffea arabica; Hemileia vastatrix; phenophase.

Water Absorption of Cucumber Plants Based on Diurnal Variation in Plant Weight with Solar Radiation and Fruit Load

Water Absorption of Cucumber Plants Based on Diurnal Variation in Plant Weight with Solar Radiation and Fruit Load

Aplicações sucessivas de ácido giberélico em tangerineiras em alternância de produção

Abstract Gibberellins can promote the inhibition of floral induction in citrus in order to reduce alternate bearing. However, not much is known about the responsiveness of Citrus deliciosa to exogenous applications of gibberellic acid. Furthermore, the successive application of gibberellins is barely studied. The main objective of this work was to evaluate the effect of successive applications of gibberellic acid (GA3) on the reduction of spring flowering subsequent to low fruit load periods (off-year) in ‘Montenegrina’ and ‘Rainha’ mandarin trees, in southern Brazil. The treatments consisted of one to four successive applications of GA3 (40 mg L-1) with 21-day interval in off-year trees. Applications began in May and ended in July. There was a significant reduction in sprouting and flowering of ‘Montenegrina’ mandarin with more than two GA3 successive applications compared to the control. To ‘Rainha’ mandarin, only two GA3 applications reduced the sprouting and solely one GA3 application was enough to reduce sprouting in relation to the control. GA3 use reduced sprouting and flowering of Montenegrina and Rainha cultivars. The orchard age may be related to its level of alternate bearing and, therefore, to the greater or lesser sensitivity of gibberellin applications.

Dry mass input into fruits can be predicted by fine root morphology of pepper cultivars exposed to varied lighting spectra

Many pepper cultivars can be raised under artificial lighting in a plant factory. An easily measured parameter is needed to fast predict fruit loading in pepper cultivars. In this study, four pepper cultivars with contrasting manners in growth and fruiting were cultured under three light-emitting diode (LED) spectra in comparison with a sunlight control. It was found that the red-light spectrum (71.7% red-, 13.7% green-, 14.6% blue-lights) increased over 40% of dry mass in fruits, while the green-light spectrum (26.2% red-, 56.4% green-, 17.4% blue-lights) induced no fruiting compared to the control. Only two cultivars responded by fine root morphology, which was characterized as smaller surface-area and fewer tip-number in the blue-light spectrum (7.8% red-, 33.7% green-, 48.5% blue-lights) than in red LED light. Tip-number showed a negative correlation with fruit dry-mass in three cultivars, while fine root diameter increased with dry mass in fruits. In conclusion, fine root tip-number can be used as a predictor of fruit dry-mass in pepper cultivars high in fruit quality or yield. The red-colour light was recommended for raising pepper cultivars in a plant factory with the purpose of greater fruit productivity.

Dose-Dependent Potential of Chitosan to Increase Yield or Bioactive Compound Content in Tomatoes

Chitosan is a natural polymer with multiple applications in agriculture due to its ability to stimulate plant growth and resistance to both biotic and abiotic stressors. The impact of chitosan application on fruit production and quality was studied under greenhouse conditions in a summer crop in a semi-arid climate. Treatments consisted of the spray application of this biostimulant to the aerial plant part at different doses (0, 0.1, and 1 g L−1). Treatment with the lowest dose did not produce significant differences in yield (total production, number, and mean weight of the fruit), but increased the concentration of flavanones (trusses 2 and 7) and phloretin-C-diglucoside (truss 2) with regard to the control. On the contrary, the high-dose treatment increased the yield due to the rise in the number of fruits and produced a significant decrease in the concentration of vitamin C, lutein, β-carotene, and hydroxycinnamic acids (trusses 2 and 7); lycopene, phytoene, and phytofluene in truss 2; and flavanols and phloretin-C-diglucoside in truss 7. These results show the ability of chitosan to improve tomato yield or to enhance the accumulation of bioactive compounds (phenolic compounds) in fruit, depending on the dose. Results are explained on the basis of the ability of chitosan to activate yield and secondary metabolite production, the dilution effect due to an increased fruit load, and the interaction of chitosan with changing environmental factors throughout the crop cycle.

Physiological and transcriptome analyses reveal that mid-fruit load improves the strength of source and sink in grapevine (Vitis Vinifera L.)

• In the present study, the assay for biochemical and molecular mechanism were used by 13 C labeling, full-length RNA-seq and gene transformation. • We make a conclusion that 50%FL significantly improved the source and sink strength. As a prime candidate gene, overexpression of VvPUP1 in grape cells improved its sugar accumulation. • These results demonstrates that the optimal fruit load was about 50%. Appropriately adjusting fruit loads (FL) can promote plant productivity in the field. In the present study, physiological, transcriptomic, and gene function assays were conducted by 13 C labeling, full-length RNA-seq, and gene transformation. A comparative analysis of three different FL treatments (25%FL, 50%FL, and 100% FL) was performed to identify the mechanism that response to different FL. The results showed that 50%FL significantly improved the source strength by enhancing photosynthesis. The sink strength of 50%FL also reached the maximum when considering soluble sugar, weight, 13 C allocation, sugar metabolism-related enzyme activity, and composition in berries, and yield. In addition, full-length transcriptome profiling exploited 1,098 differently expressed genes (DEGs) in 25%FL and 100%FL, and 1,479 DEGs in 50%FL and 100%FL, respectively. Thirty-four genes, including PUP1 and FBA1 , were identified in carbon transport and metabolism-related pathways. As a major candidate gene, VvPUP1 was found to enhance sugar accumulation when overexpressed in grape cells. The transgenic cells had high soluble sugar contents and sucrose synthase (SS), neutral invertase (NI), and sucrose phosphate synthase (SPS) activities. Overexpression of VvPUP1 in tomatoes increased fruit size and weight, soluble sugar concentration, and the expression levels of SlSUS1, SlSPS1 , and SlBGLU13 , suggesting that VvPUP1 can promote berry enlargement and sugar accumulation. These results provide novel insights into the response of grapevine to different FL, demonstrating the differences in the source (leaf) and sink (berry) strength among different FL grapes.

ALTERNATE BEARING IN FRUIT PLANTS

Fruit trees exhibit a characteristic called "alternate bearing," which means that some fruit trees have fewer flowers in years when they have a lot of fruit. Pollination, temperature, carbohydrate concentration, family, cultivator, fruit load, and environmental pressures are physiological and biochemical factors contributing to alternate bearing in trees. Phytohormones are also considered very important for fruit production, both in good years and in bad ones. The alternate bearing index (I) determines how often crops grow in different places. When done right, trimming, thinning, and controlling when flower buds start to grow can lead to normal fruiting. Also, genetics, management practices, and biotic and abiotic stresses can cause a bird to change how it bears its young. To reduce the effects of alternate bearing, it's important to use good management techniques and choose types that are less likely to do this

Effect of Physical Methods on Date Fruits Insects and Microbes

Aims: Siwi dates fruits are infected with many pests, which leads to a high deficiency in the quality and safety of dates. The study aimed to investigate the possibility of three physical methods (freezing, gamma radiation, and ozone) as suitable methods for pest control.
 Study Design: Original research.
 Place and Duration Study: The study was conducted in Giza, Egypt in season 2021.
 Methodology: In the first method, the date fruits were frozen at -18⁰C at different times (15, 30, 60,120,180, 240,300, and 360 min). In the second method, the date fruits were exposed to gamma rays in different doses as 25, 50, 75, 100, 200, 300, 400, 500, 600, and 700 grays. In the third method, the date fruits were exposed to different ozone concentrations of 200, 400, 600, and 800 ppm at different exposure periods (1, 2, 3, and 4 hrs.).
 Results: The data showed that freezing at -18⁰C for 5 hrs, radiation at a dose of 700 grays, and ozone at 800ppm for 4 hrs controlled insect stages and the microbial load of the sample date fruits, respectively.
 Conclusion: The obtained data revealed that freezing or ozone treatments were the suitable methods followed by radiation.

Expression Profiling of Four Mango FT/TFL1-Encoding Genes under Different Fruit Load Conditions, and Their Involvement in Flowering Regulation.

Plant flowering is antagonistically modulated by similar FLOWERING LOCUS T (FT) and TERMINAL FLOWER 1 (TFL1) proteins. In mango (Mangifera indica L.), flowering is induced by cold temperatures, unless the tree is juvenile or the adult tree had a high fruit load (HFL) in the summer. Here, we studied the effects of juvenility and fruit load on the expression of four MiFT/TFL1 genes cloned from the mango ‘Shelly’ cultivar. Ectopic expression of MiFT1 in Arabidopsis resulted in early flowering, whereas over-expression of MiFT2 and the two cloned MiTFL1 genes repressed flowering. Moreover, juvenility was positively correlated with higher transcript levels of MiFT2 and both MiTFL1s. In trees with a low fruit load, leaf MiFT1 expression increased in winter, whereas HFL delayed its upregulation. MiFT2 expression was upregulated in both leaves and buds under both fruit load conditions. Downregulation of both MITFL1s in buds was associated with a decrease in regional temperatures under both conditions; nevertheless, HFL delayed the decrease in their accumulation. Our results suggest that cold temperature has opposite effects on the expression of MiFT1 and the MiTFL1s, thereby inducing flowering, whereas HFL represses flowering by both suppressing MiFT1 upregulation and delaying MiTFL1s downregulation. The apparent flowering-inhibitory functions of MiFT2 are discussed.

Reproductive tradeoffs in a perennial crop: Exploring the mechanisms of coffee alternate bearing in relation to farm management

Like many perennial crops, coffee exhibits alternate bearing, a pattern of reproduction in which high-yielding years are followed by low-yielding ones. Alternate bearing threatens farmer livelihoods, yet little is known about the underlying mechanisms in coffee or the potential for farm management to mitigate it. The resource budget model, an ecological theory positing endogenous resource tradeoffs as the driver of reproductive variability, could help fill this gap. On three coffee farms in Santa María de Dota, Costa Rica, we manipulated relative fruit load, fertilizer levels, and shade cover to test whether the model’s core assumptions (i.e., that fruiting depletes resources and limits investment in subsequent reproduction) can elucidate patterns of alternate bearing in coffee, and to assess whether these patterns are impacted by farm management practices. Coffee plants exhibited within-year and between-year tradeoffs of a high fruit load that scaled from decreased bean size during the same season to fewer fruited nodes and fruits per node in both old and new cohorts of branches during the subsequent season. Stem nitrogen concentration was also depleted in response to high fruit loads and recovered during the subsequent season of low fruiting. The findings provide novel evidence that tradeoffs of a high fruit load are manifested in several reproductive traits at both the branch- and plant-level and offer initial support for the resource budget model in the system. While both moderate shade and increased fertilizer levels tended to improve reproductive traits, a lack of interactive effects between either management treatment and the relative fruit load treatment suggests that they do little to mitigate the reproductive tradeoffs underlying alternate bearing.

Experience in thinning trial to regulate the fruit load on three apple cultivars

Experience in thinning trial to regulate the fruit load on three apple cultivars

Fruit weight and yield estimation models for five avocado cultivars in Ethiopia

Avocado (Persea Americana Mill.) is an important tree crop and proved to be a very rewarding commercial crop for export and local consumptions. Due to high local and global market demand, avocado plantation and production is considerably increasing in many parts of Ethiopia. Thus, pre-harvest yield estimation is necessary for market planning, monitoring, and tracking long-term productivity. Though there are studies on various characteristics of avocado tree, not much has been documented about its productivity due to lack of easy and non-destructive ways to estimate yield. Hence, this study was conducted to develop cultivar-specific and mixed-cultivar fruit weight estimation models using single and multiple predictors including fruit length and diameter. We harvested and weighted 1800 fruits from five cultivars grown in 30 smallholder farmlands. The highest mean fruit load was recorded for Nabal (281 (±36 Fruit. tree−1) and Hass 249 (±27 Fruit. tree−1). A large proportion of avocado fruits were in the range that are commercially valuable. The correlation between fruit load and crown diameter were positive for each cultivar and it was stronger for Ettinger (r = 0.7, p < 0.01, n = 30), followed by Nabal (r = 0.64, P < 0.01, n = 30). We observed that fruit weight correlates significantly (P < 0.01) with fruit diameter and length. Our best models explained 80% for Ettinger, 78% for Fuerte, 80% for Hass, 63% for Nabal, 72% for Reed and 72% for multiple cultivars. Estimated yield was nearly 45 kg. tree−1 for Ettinger, Fuerte, Hass, Reed and 90 Kg. tree−1 for Nabal. The equations developed in this study are suitable for conducting pre-harvest yield estimation and monitoring changes in avocado productivity. Such information is critical for planned marketing and support government initiatives towards making horticulture sector as a possible engine for poverty alleviation and national economic growth.

Effect of fruit thinning on fruit yield and quality of cactus pear Opuntia ficus-indica (L.) Mill. in a semi-arid area

The aim of this work was to study the effect of fruit thinning on fruit yield and quality of cactus pear. To meet this objective, trials on fruit thinning were conducted on an adult plantation of cactus pear in a semi-arid region in southern Morocco. The fruit thinning consisted of reducing the fruit load of overcharged cladodes by reducing the number of fruits to 6 or 12 per cladode. It was practiced in early May on three types of one-year old cladodes (small cladodes, the medium ones and large cladodes), by removing some floral buds or young fruits at the flowering stage. The control cladodes had an average number of 18 fruits per cladode. Obtained results showed that the reduction in the load of cladodes improved fruit size and quality. In thinned plants to 6 fruits per cladode and for the three types of cladodes, average fruit weight was 160.44 g and average fruit length and diameter was 8.64 and 6.38 cm respectively. While in not thinned plants and for the three types of cladodes, average fruit weight was only 74.53 g and average fruit length and diameter was 6.40 and 4.46 cm respectively. Fruit thinning increased the content of sugar in the fruits and decreased the number of seeds in the fruits and the fruit peel thickness, but did not affect the juice content in the fruits and the pH and titratable acidity of the juice. Fruit thinning also improved the economic income of the yield and the gain in the yield of thinned plants to 6 fruits per cladode was 33912 DH per hectare compared to not thinned plants.

The Best Fruit Loads for the Cold Resistance of Wine Grape (Vitis Vinifera L.) In the Eastern Foothills Of Helan Mountain, China

Wine grape cannot grow well in cold areas. The cold resistance abilities of grape have become a very important problem to be solved. Effects of different fruit loads on the physiological and biochemical indexes of wine grape cultivar were studied through experiments. Results showed that different fruit loads had significant effects on the conductivity, soluble sugar content, Malondialdehyde (MDA), superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) of grape branches. Factor analysis and principal component analysis were used to analyze the physiological and biochemical indexes of cold resistance of wine grapes with different loads. Results showed that combined with the physical microstructure, physiological and biochemical data of branches, the best fruit load of wine grape was 5 kg in eastern foot of Helan Mountain, China. Bangladesh J. Bot. 51(2): 263-270, 2022 (June)

Brown Rot Disease in Stored Nectarines: Modeling the Combined Effects of Preharvest and Storage Conditions.

Brown rot in stored stone fruits, caused by Monilinia spp., may be due to preharvest and storage factors, but the combined effect of these factors has yet to be investigated. We set up two experiments to monitor the progression of brown rot during the storage of nectarines subjected to various preharvest and storage conditions. We assessed the effects of different agricultural practices (irrigation regimen × fruit load) and harvest dates on brown rot progress during storage in 2018 and the effect of different storage temperatures in 2019. We found that the cumulative incidence of brown rot during storage increased with individual fruit mass, which was influenced by agricultural practices, and for later harvest dates. It also increased with storage temperature. We observed that during storage no secondary infections developed in nectarines not in direct contact with fruits infected with Monilinia laxa. These findings led to the identification of candidate variables describing the brown rot risk on nectarines during storage, such as individual fruit mass, meteorological conditions before fruit harvest, prevalence of brown rot at harvest, and storage temperature. We used these variables to build a mathematical model for estimating the time-to-appearance of brown rot symptoms in stored nectarines. This model fitted the experimental data well, highlighting the need to pay greater attention to the interaction between preharvest and storage conditions. This model could be used to evaluate management strategies for reducing the impact of brown rot in nectarines during storage.

Modelling the Impact of Water Stress during Post-Veraison on Berry Quality of Table Grapes

The aims of this work were modelling the effect of water stress intensity during post-veraison on table grape quality and yield, as well as predicting berry quality at harvest using a machine learning algorithm. The dataset was obtained by applying different irrigation regimes in two commercial table grape vineyards during seven growing seasons. From these data, it was possible to train and validate the predictive models over a wide range of values for the independent (water stress intensity and fruit load) and dependent (firmness and berry color) variables. The supervised learning algorithm Gaussian Process Regression allowed us to predict the variables with high accuracy. It was also determined that a reduction in irrigation of up to 40% during post-veraison, compared to vines without water limitations, and the accumulation of the water stress integral of up to 30 MPa per day, linearly increase the irrigation water use efficiency (IWUE) and promote higher berry color and firmness. The severe water scarcity and the increasing uncertainty about the irrigation water availability for the season that farmers are facing highlight the advantage of incorporating these validated techniques into agricultural decision making, as they allow for the planning of cultural practices and criteria to increase the IWUE and crop sustainability.