Fruit Growth Pattern Research Articles

Pattern of flower and fruit abscision and fruit growth of hass avocado under tropical conditions

Research elucidating abscission processes in fruits of Hass avocados has been conducted in production areas in the subtropics, but there are few studies under tropical climate conditions that can serve as a starting point to guide suitable management practices. In a seven-year-old commercial orchard of Hass avocados, grafted onto native rootstocks (Antillean rootstocks), 20 trees were evaluated. A weather station installed on-site monitored the climate of the location. The pattern of fruit growth and development, flower and fruit abscission, and yield variables were characterized. More than 145,000 and 270,000 flowers abscised per tree were recorded, with final fruit sets of 0.1 ± 0.009% and 0.19 ± 0.04% in the first and second crop years, respectively. Fruit growth followed a sigmoid curve with no differences in growing degree-days until the time of harvest. Additionally, the alternate bearing behavior of Hass avocado was confirmed with an average yield of 24.3 ± 4.5 kg/tree and 93.3 ± 9.5 kg/tree for the first and second crop years, respectively, finding an average alternate bearing index of 0.74 ± 0.06.

Modelación de crecimiento de frutos de tangor murcott e incidencia de factores medioambientales sobre los parámetros estimados

Fruit production forecasts are a tool to plan the harvest and improve market strategies. To carry it out, it is essential to have information about the behavior of fruit development over time. The objective of this work was to find the mathematical-statistical model that best describes the growth pattern of tangor murcott fruit (Citrus reticulata x C. sinensis 'Murcott') and analyze how it is affected by environmental conditions. For this, in nine orchards, located in four locations in the province of Corrientes, Argentina, the equatorial diameter of 2,053 fruit from 82 days after full flowering to harvest were periodically registered during five seasons. The nonlinear models were compared: Logistic, Gompertz, Brody, Von Bertalanffy, Weibull, Morgan Mercer Flodin (MMF), Richards, and their respective re-parameterizations. The magnitudes of nonlinearity measures, coefficient of determination and estimates of residual deviation were considered as the main goodness-of-fit criteria. The selected model-parameterization combination was the fifth parameterization of the Logistic model with random effects on its three parameters. An Analysis of Variance model on the estimates of these parameters for each fruit showed that orchard and season factors were an important source of variability, mainly in those related to the initial size of the fruit and their growth rate. These results will allow the construction of growth tables, which in addition to making yield predictions, can be used to estimate fruit size distribution at harvest and improve the cultural practice of manual fruit thinning.

The Use of Cubic Smoothing Spline Models for Predicting Early Fruit Size in ‘Keenan’ Valencia (Citrus sinensis L. Osbeck) Oranges

Fruit size is an important factor for the sale of fruit in fresh markets. Fruit size prediction early in the growing season would help with planning harvest operations, administering marketing strategies and an advance determination of the proportion of fruit that will be suitable for certain size classes. Fruit diameter growth of ‘Keenan’ Valencia oranges was measured over five consecutive growing seasons (2014–2018) during Stage II (cell enlargement) and Stage III (maturation) periods between January and October. Fruits were randomly selected and tagged from around the tree canopy to record the fruit diameter at fortnightly intervals until harvest. The data were used to develop a fruit size prediction model using the cubic smoothing splines technique. Results indicated that from the fruit growth patterns, an accurate prediction of the final fruit size and distribution were possible during the early Stage II fruit development phase, 6–7 months ahead of the final harvest. It was concluded that fruit size must be 66 mm in diameter by 30 March to attain a fruit size > 77 mm at harvest. This model was tested in 2019 with an accuracy of 97% in predicting fruit size distribution harvest across three size classes.

Morphometrics and Structural Changes of "Terung Asam" Sarawak (Solanum lasiocarpum Dunal) During Growth and Development.

"Terung asam" Sarawak (Solanum lasiocarpum Dunal) is an underutilised fruit vegetable. Information on the fruit growth is very lacking. Thus, this study was conducted to characterise fruit growth pattern based on physical characters and cellular structures. Data were recorded weekly from fruit set until senescence. All the morphological growth of "terung asam" fruit exhibits a single sigmoid growth pattern that fitted well to logistic model. There are three distinct phases of growth, i.e., S1, S2 and S3. At S1, the size of fruit cells was small without intercellular spaces. As fruit grew to S2, cell size increased with distinct vascular tissues. By S3, fruit has achieved its maximum size with green peel turn to yellow and finally golden yellow at late S3. Cuticle and two types of trichomes formed the outer layer of fruit. The thickness of fruit exocarp increased while density of trichomes decreased as fruit developed.

Investigation of Fruit Growth Patterns, Olive Fly Bactrocera oleae (Rossi) Infestation, and Genetic Diversity in Italian Olive Cultivars

The olive fruit fly Bactrocera oleae (Rossi, 1790) poses a significant threat to oliviculture worldwide, despite extensive chemical control measures. The susceptibility of olive (Olea europaea L.) to this pest varies among cultivars, with fruit size being a key factor of interest, as it can be assessed using non-destructive automated technologies. In this study, we investigated the oviposition preferences of the olive fruit fly in six Italian olive cultivars, tracking fertile and sterile punctures in relation to the diametric growth of the drupe. Additionally, we assessed the genetic diversity among cultivars using SSR markers, aiming to uncover a potential correlation between variation in the genetic diversity patterns and infestation levels. The results revealed that the relationship between fruit size and infestation level is non-linear and varies across different cultivars. The co-inertia analysis (COIA) performed on the genetic and infestation datasets revealed possible shared patterns of diversity and relationships between the two datasets. This study emphasizes the complex and diverse nature of the interaction between the olive fruit fly and its host, underscoring the importance of comprehending non-linear relationships to develop accurate genotypic-specific predictions and models.

Neck shrivel in European plum is caused by cuticular microcracks, resulting from rapid lateral expansion of the neck late in development

Main conclusionSusceptibility to neck shrivel in European plum is due to cuticular microcracking resulting from high surface area growth rates in the neck region, late in development.Susceptibility to the commercially important fruit disorder ‘neck shrivel’ differs among European plum cultivars. Radial cuticular microcracking occurs in the neck regions of susceptible cultivars, but not in non-susceptible ones, so would seem to be causal. However, the reason for the microcracking is unknown. The objective was to identify potential relationships between fruit growth pattern and microcracking incidence in the neck (proximal) and stylar (distal) ends of selected shrivel-susceptible and non-susceptible cultivars. Growth analysis revealed two allometric categories: The first category, the ‘narrow-neck’ cultivars, showed hypoallometric growth in the neck region (i.e., slower growth than in the region of maximum diameter) during early development (stages I + II). Later (during stage III) the neck region was ‘filled out’ by hyperallometric growth (i.e., faster than in the region of maximum diameter). The second category, the ‘broad-neck’ cultivars, had more symmetrical, allometric growth (all regions grew equally fast) throughout development. The narrow-neck cultivars exhibited extensive radial cuticular microcracking in the neck region, but little microcracking in the stylar region. In contrast, the broad-neck cultivars exhibited little microcracking overall, with no difference between the neck and stylar regions. Across all cultivars, a positive relationship was obtained for the level of microcracking in the neck region and the difference in allometric growth ratios between stage III and stages I + II. There were no similar relationships for the stylar region. The results demonstrate that accelerated stage III neck growth in the narrow-neck plum cultivars is associated with more microcracking and thus with more shrivel.

Fruit morphological and nutritional quality features of goji berry (Lycium barbarum L.) during fruit development

Goji berry (Lycium barbarum L.) is one of the most pivotal economic crops with an exceptional nutritional value. Based on its high global consumption, understanding the fruit growth patterns and nutrient accumulation at each developmental stage is crucial for the field and production management of high-quality goji berry cultivars. In this study, a fruit growth and development model of goji berry was established using a double sigmoid curve, where the entire fruit development period was divided into three phases (phase Ⅰ, Ⅱ, and Ⅲ) with two key time points. Morphological features and nutritional components were measured at four (young, green, coloring, and red) stages of fruit growth in five cultivars. The nutritional constituents, namely galactose, fructose, and total sugar, monotonically increased from young to red stage. The highest polysaccharide content occurred at the young stage, whereas the sucrose, betaine, and flavonoid content were the highest in the green stage. Moreover, corresponding to the fruit growth model, polysaccharide was mainly accumulated during phase I and III, sucrose, betaine, and flavonoid were produced and concentrated during phase Ⅱ, and the galactose, fructose, and total sugar content rapidly increased during phase Ⅲ. The two key time points in the goji berry fruit development and nutrient accumulation range were 10–13 days and 21–26 days after full bloom, where water and fertilizer management should be enhanced. Correlation analyses suggested that morphological features were significantly correlated in all four growth stages, while a strong correlation among specific nutritional components was found in some certain growth stages with p-values smaller than 0.05 and Pearson correlation coefficients greater than 0.5. Principal component analysis indicates that total sugar and polysaccharide contents can be used as the main factors for evaluating the nutritional quality of different cultivars. Among the selected cultivars, ‘Ningqi 7’ was significantly better than other cultivars with respect to the nutritional levels. These findings can support breeding strategies and improve the effective field management of high-quality goji berry cultivars.

The Effect of Electrical Conductivity on Fruit Growth Pattern in Hydroponically Grown Tomatoes

Osmotic stress enhances fruit quality, including the dry matter content, in tomatoes (Solanum lycopersicum L.). This study aimed at providing further insight into the precision control of fruit yield and quality on the long-term moderate osmotic stress conditions in tomato fruit production. We compared the growth pattern between fruits of two cultivars, typical Japanese and Dutch cultivars, under two different nutrient concentrations (2.3 and 5.0 dS·m−1) to understand the effect of electrical conductivity (EC) on dry mass and water content of fruits. The experiment was performed with a rockwool bag culture system in a controlled greenhouse. Increasing EC resulted in an approximately 20% decrease in fruit yield and a 0.5–1% increase in fruit dry matter content in both cultivars. This yield reduction was not caused by the fruit number, but by an approximately 25% decrease in individual fresh fruit weight. Non-linear models were used to describe the changes in dry matter content, water content, and dry weight of tomato fruit as a function of cumulative temperature. The decay rate of dry matter content in the fruit decreased with high EC treatments in the Japanese cultivar. The points at which the rates of changes in water and dry weight increased the in fruit were around 585 and 480 °C-days after anthesis, respectively, under the low EC condition. Rates of water increase in the fruit were changed by high EC treatment, while the shifts were opposite with respect to the cultivars. Dry weight increase in the fruit was not affected by EC treatment. Collectively, our findings clarify the effect of EC on the fruit growth characteristics of Japanese and Dutch tomato cultivars, and provide new insights into the yield of high-Brix tomato cultivation.

Improvement of Fruit Pubescence and Fruiting Pattern among Pure Lines and Landrace of Okra (Abelmoschus spp.) through Interspecific Hybridization

The research study was aimed at improving fruit pubescence and growth pattern in the highly mucilaginous but very spiny local and wild okra variety - ‘Ele Ogwu’ through generic hybridization with selected glabrous conventional and early maturing varieties at the Research Farm of the Department of Crop Science, University of Nigeria, Nsukka. The hybrid seeds generated from their diallel crosses were selfed to generate the F2 seeds. Backcrosses (BC1 and BC2) were also made to the much improved and glabrous varieties. The parents, F1, F2 and BC genotypes were sown in an experimental field in a randomized complete block design and organoleptic assessment was done at harvest. The F2 hybrids from the crosses, ‘UHIE x CLM’ and ‘AGW x CLM’, yielded some smooth fruits; although most of the hybrids generated, exhibited intermediate smoothness, except for ‘OGW x UHIE’ and ‘OGW x LD88’ that exhibited high degree of spineness. Most of the F2 hybrids generated exhibited intermediate growth and fruiting pattern, except for ‘OGW x UHIE’ which showed indeterminate pattern. The Chi-square statistics for the F2 showed that fruit pubescence for the highly spiny landrace and the more glabrous improved ones was monogenically controlled with incomplete dominance, while growth pattern were polygenically controlled. The successful backcrosses obtained showed reduction in the proportion of fruits spininess and increased fruit determinate growth pattern. This hereby indicates the prospect of obtaining okra plants with glabrous, highly appealing and determinate growth pattern with early maturity from the local, wild spiny but mucilaginous, nutritious and high yielding local varieties through sustained hybridization programme.

Investigation of Bunch Cut at Different Times After Pollination and Flower Position in the Spikelet in Date Palm 'Sukkary' Variety

As many studies on other crops showed an acropetal decline of fruit-set and fruit size in the inflorescence, this paper investigates the effect of flower position in spikelets in the '˜Sukkary' variety of date palm on fruit-set and final fruit weight. Also studied was the best time to apply strand-cut (bunch cut) as an alternative to hand thinning, to increase final fruit weight. Hand thinning is a labor cost operation and worker productivity operation is one adult tree per day maximum. To study fruit-set in relation to fruit position, three types of pollen were used to pollinate female trees: new pollen harvested in March 2018, pollen stored for one year at room temperature (25-35° C), and pollen stored for two years at room temperature. Four weeks after pollination, fruits aborted and those non-aborted in every bunch were counted. Recording was done in every spikelet from proximal to distal. To study the effect of fruit position in spikelet on fruit weight, fresh pollen was used to pollinate 'Sukkary' females. Every two days, fruit weight was measured from pollination to harvest, and fruit growth pattern was drawn. An analysis of variance (ANOVA) was carried out for the final fruit weight in every spikelet part. This investigation showed no pattern in fruit-set or in final fruit weight when using new pollen. When pollinated with old pollen that was one and two years old, the proximal '˜Sukkary' flowers of the spikelets showed less fruit-set compared to those of the middle and distal part. This basipetal decline is explained by low viability of old pollen, combined with the basipetal opening of the spathes in date palm...

Flower and fruit development of a low-chill peach, ‘KU-PP2’ in plastic houses with and without heating

Although ‘KU-PP2’, a low-chill peach cultivar, was released for high-quality peach production under forcing culture, the performance of ‘KU-PP2’ trees under forcing conditions has yet to be determined. In this study, we investigated the spring phenology, fruit development, and fruit quality of ‘KU-PP2’ in a heated plastic house compared with the same traits in an unheated plastic house and open field conditions. We found that the forcing conditions accelerated the spring phenology and harvest period of ‘KU-PP2’. Heated conditions shortened the number of days from dormancy release to blooming and the length of the fruit development period, resulting in the blooming of flowers in late February, with fruit begin harvested as early as mid-May, which was notably earlier than blooming and fruit harvest under natural conditions by 4 and 6 weeks, respectively. Similarly, the unheated conditions accelerated the time to blooming and harvest by up to 3 and 4 weeks, respectively compared with the open field conditions. However, although the fruit produced by trees raised in the heated plastic house could be harvested at an earlier date, the amount of fuel used for the heating system was 50 L per tree, which could be prohibitively expensive for commercial production. Although the fruit growth pattern did not differ significantly between the forcing and natural conditions, the rate of fruit growth at stages S1 and S2 was higher in the heated plastic house than that under the other assessed conditions. Furthermore, the size and quality of fruit obtained under forcing conditions were slightly larger and superior, respectively, than those of fruit produced under natural conditions. Moreover, we found no evidence of split-pits under the forcing conditions. The findings of this study accordingly indicate that cultivation of the low-chill peach ‘KU-PP2’ under forcing conditions is conducive to a notably earlier harvest of fresh peaches. These observations advance our current understanding of the flowering, fruit development, and fruit production of low-chill peaches under forcing conditions.

Is There Daily Growth Hysteresis versus Vapor Pressure Deficit in Cherry Fruit?

The growth of cherry fruit is generally described using a double sigmoid model, divided into four growth stages. Abiotic factors are considered to be significant components in modifying fruit growth, and among these, the vapor pressure deficit (VPD) is deemed the most effective. In this study, we investigated sweet cherry fruit growth through the continuous, hourly monitoring of fruit transversal diameter over two consecutive years (2019 and 2020), from the beginning of the third stage to maturation (forth stage). Extensometers were used in the field and VPD was calculated from weather data. The fruit growth pattern up to the end of the third stage demonstrated three critical steps during non-rainy days: shrinkage, stabilization and expansion. In the third stage of fruit growth, a partial clockwise hysteresis curve of circadian growth, as a response to VPD, appeared on random days. The pattern of fruit growth during rainy days was not distinctive, but the amount and duration of rain caused a consequent decrease in the VPD and indirectly boosted fruit growth. At the beginning of the fourth stage, the circadian growth changed and the daily transversal diameter vs VPD formed fully clockwise hysteresis curves for most of this stage. Our findings indicate that hysteresis can be employed to evaluate the initial phenological phase of fruit maturation, as a fully clockwise hysteresis curve was observable only in the fourth stage of fruit growth. There are additional opportunities for its use in the management of fruit production, such as in precision fruit farming.

Impact of foliar spray with 24-epibrassinolide on yield, quality, ripening physiology and productivity of the strawberry

Increasing the productivity, yield and quality and modulating the ripening physiology of the fruit is considered as a main concern for the fruit growers. Brassinosteroids (BRs), as natural phytochemicals, are produced endogenously during fruit development and play a vital role in regulating its developmental, ripening and quality formation processes. In this study, the effects of different concentrations of exogenous 24-epibrassinolide (EBL), a common brassinosteroid, on ripening physiology, quality parameters and yield of strawberry fruit was studied. Foliar spray of strawberry plants and developing fruits with EBL significantly modulated the pattern and rate of fruit growth, decreased the fruit growth duration and enhanced the precocity rate. Visual indices such as size, shape and color of the fruits were significantly affected by EBL treatment. EBL at 1 μmol/L enhanced fruit growth rate and had no significant effect on the shape, but at 4 μmol/L significantly decreased the length/diameter ratio and resulted in the production of more spherical fruits with a very short growing period. However, a decrease in flesh firmness was observed in fruit treated with higher EBL concentration. EBL treatment significantly enhanced fruit weight, water content, total phenolics and anthocyanin contents and carbohydrate metabolism. The results indicate that the use of brassinosteroids can be considered as a novel method for modulating the growth pattern, yield and different quality parameters in strawberry fruits.

Evaluation of Tinda Gourd (Praecitrullus fistulosus) Germplams’s Yield

Tinda Gourd is the most important summer vegetable widely grown in Pakistan. It contains a high amount of iron and other vitamins and minerals. Hence, its medicinal value is also high due to its ingredient profile. This field experiment was conducted in the vegetable area, Institute of Horticultural Sciences in the University of Agriculture, Faisalabad in order to recognize the morphological characteristics of Tinda gourd, fruit growth pattern, and the yield of Tinda (Praecitrullus fistulosus) gourd germplasm lines. Sixteen germplasm lines, in which one line was used as control, were sown and grown on flat beds in the field. The field experiment was arranged as Randomized Complete Block Design (RCBD) with three replications. Data related to the maturity time of fruit, fruit per vine, fruit weight in grams, fruit diameter and total yield obtained were recorded. The fruit texture was marked as phenotypic parameter. All parameters were collected and then analyzed statistically. All lines and replications showed different results from each other according to the chosen parameter. The variety L1 took 56 days to mature, closely followed by line L4 (56.66 days) and line L8 (56.33 days). There was not much difference in fruit per plant among Tinda gourd lines. Among them, 198 g fruits were found in line L0, followed by line L1 (224 g) and line L15(225.00 g). Line L9 showed fruit diameter of 7 cm closely followed by line L1 (7.23 cm) and line L2 (7.23 cm). The maximum yield was observed in line L0 (599.33 grams) as compared to other lines. There was a significant difference in the yield of lines. Among them, line L4 showed 421 grams of yield closely.

Long-term effects of irrigation regime on fruit development pattern of the late-maturing ‘Angeleno’ Japanese plum

Abstract A regulated deficit irrigation (RDI) strategy can be used to ensure efficient water use in fruit orchards under different agro-ecological conditions. However, adapting RDI to specific crop conditions is essential for its successful implementation. To date, very few studies have provided information on its long-term effects. This paper presents an 8 year study assessing the fruit development pattern of Japanese plum cv. ‘Angeleno’ under two different water regimes: a control (C) treatment with crop evapotranspiration (ETc) replacement, and an RDI treatment which had no irrigation in the middle of the fruit growth stage. This unirrigated period was executed for 60 days from 2009 to 2012 and for 30 days from 2013 to 2016; a 30% reduction in ETc was also applied during the post-harvest period in both cases. The results obtained in this study allowed characterisation of the fruit growth pattern of this cultivar under non-water stress conditions and an assessment of the effects of the duration and severity of water stress on the fruit. The swiftness and intensity of the water stress were crucial factors in terms of final fruit size, whereas precise determination of the initiation of RDI played only a secondary role. After eight years applying these RDI strategies, no carry-over effects on orchard yield were observed. Based on these results, RDI appears to be a sustainable practice for this cultivar and growing conditions.

A detailed description of morphological and anatomical characters of olive (Olea europaea) fruits in relation to phenological growth stages

This paper describes both morphological and anatomical changes of olive (Olea europaea) fruits of “Nevadillo” variety, growing under rainfed conditions, in relation to the phenological stages of fruit formation and development described by the Biologische, Bundesantalt, Bundessortenamt and Chemische Industrie (BBCH) scale. Mesocarp transverse area (TA m), total number of cells and TA per cell were measured in mesocarp equatorial transverse sections of the fruits. Changes in cell dimensions and shape along the mesocarp radial longitudinal section and endocarp sclerification were also analysed. The pattern of fruit growth showed linear increases in TA m, coupled with the whole fruit TA (TA f) increases throughout its whole developmental period. This observation disagrees with the classical growth model which suggested that the growth of a drupe adjusts to a double sigmoid curve. A strong correlation between TA m and TA f and a weak correlation between endocarp TA and TA f were observed. The tissue organisation in the cross‐sectional area of the fruit agrees with previous histological descriptions. Cell organisation in the longitudinal radial plane of the olive fruit was established for the first time: a single‐layered epidermis; a hypodermis: first four layers of subepidermal parenchyma cells; an outer mesocarp: from the layer 5 to layer 24 to 27 and an internal mesocarp: following layers of parenchyma cells up to the vascular bundles. Until now, comparative anatomical studies on olive fruit have been carried out only in the cross section, that is, in two dimensions. The anatomy of longitudinal section described here, together with the cell organisation in the transverse plane, will allow designing a tridimensional model of the fruit anatomy. This model will be useful to interpret the cell processes (division and expansion) involved in fruit growth, morphogenesis and oil storage, and to explore how climate and agricultural management practices could impact on olive fruit development on “Nevadillo” and other cultivars under different growing conditions (e.g., water status and temperature variations).

Altered development, quality and sink strength in asynchronous maturing fruits produced from the two-sequence female flowers inflorescence/cluster of ‘Yu Her Pau’ litchi

‘Yu Her Pau’ is one of the most dominant litchi (Litchi chinensis Sonn.) cultivars grown in Taiwan and China. However, the extremely large inflorescences often result in the production of early- and late- flowering female flowers (“two-sequence inflorescence”), thereby leading to the production of late-maturing fruit within the same cluster. This asynchronous maturity, often being regarded as a nuisance by growers and the impact of this trait requires further clarity. To document the alteration of growth and characteristics of fruits that mature asynchronously inside a cluster, 10-year-old field grown plants were used in the present study. Four categories of fruit: early- or late-maturing fruit in the presence of single cluster; and early- or late-maturing fruit in the presence of two-sequence cluster on trees were selected. The fruit growth curves and patterns, liquid endosperm retention in the embryo sac, primary (apparent) sink strength quantity and harvested quality were analyzed. The accumulated heat unit from fruit set to maturity was estimated. Flowering dates were noted to be three weeks apart, whereas harvest dates were noted to be only one week apart between the early- and late-maturing fruit because of the two-week longer maturity period of the early-maturing fruit. All categories of fruit exhibited single sigmoid curve and have commercial value at harvest. Early-maturing fruit from the early-maturing two-sequence inflorescence were approximately 50% heavier and matured two weeks earlier than the late-maturing fruit and exhibited significantly higher quality. The larger fruit from the early-maturing two-sequence clusters was associated with smaller seeds, higher absolute and relative fruit growth rates, longer fruit development periods in response to lower air temperatures pertaining at that time, greater primary sink strength quantity, longer retention of liquid endosperm, and higher accumulated heat units that were amassed during the pulp growth stage. In the meantime, the earlier dissipating of liquid endosperm in late-maturing fruit and in early-maturing two-sequence fruit was associated with decreased seed size. Late-maturing fruit in two-sequence clusters increased the primary sink strength quantity of early-maturing fruit in the same cluster. The results from our research should prompt a re-assessment of the physiological significance of the second-sequence of female flowers in litchi cultivars with extremely large inflorescence.

HEAT REQUIREMENT OF POMEGRANATE FRUIT: A CASE STUDY ON SHISHE-KAB CULTIVAR

The aim of this study was to determine growing degree day (GDD) for pomegranate fruit Shishe-Kab cultivar and study the phonological stages of fruit from bloom to harvest. A completely randomized block design was carried out on the research orchard of the Faculty of Agriculture, University of Birjand, 2017. During the May to October, the diameter and length of the fruits and calyx were recorded using the non-destructive method by a digital caliper on the tree. Next fruit samples were randomly taken from the trees to determine fresh and dry weight. Furthermore, by using the metrological data, the thermal requirement based on the growth degree day (GDD) has been determined from April until harvest day. The effective heat requirement for Shishe-Kab cultivar that was calculated from blooming to reach maturity was 2560.95. The highest cumulative temperature was recorded in the commercial harvest date. By receiving this degree day, fruit reached the highest fresh and dry weight, length and also diameter at the end of growing season. The results indicated that all fruit characteristics significantly increased from the first recording day till the end, except the ratio of fruit length to diameter. A slight decrease in growth rate was presented in fruit diameter and length, which was concomitant with their seed hardening. Results showed that calyx diameter and length of pomegranate fruit has a slow continues liner growth pattern, fruit length and diameter exhibited a double sigmoid growth curve, while the fresh and dry weight followed a single sigmoidal curve. By determining the fruit growth pattern under climatic conditions, it is possible to determine the length of growing season and the critical stages of growth for proper management in the garden.

Characterization of a Potential Ripening Regulator, SlNAC3, from Solanum Lycopersicum.

NAC (for NAM, ATAF1-2, and CUC2) proteins are one of the largest transcription factor families in plants. They have various functions and are closely related to developmental processes of fruits. Tomato (Solanum lycopersicum) is a model plant for studies of fruit growth patterns. In this study, the functional characteristics and action mechanisms of a new NAC-type transcription factor, SlNAC3 (SGN-U568609), were examined to determine its role in tomato development and ripening. The SlNAC3 protein was produced by prokaryotic expression and used to immunize New Zealand white rabbits to obtain a specific polyclonal antibody against SlNAC3. By co-immunoprecipitation and MALDI-TOF-MS assays, we showed that there was an interaction between the SlNAC3 protein and Polygalacturonase-2 (PG-2), which is related to the ripening and softening of fruit. Chromatin immunoprecipitation assays revealed the genome of the highly stress-tolerant Solanum pennellii chromosome 10 (sequence ID, HG975449.1), further demonstrating that SlNAC3 is a negative regulator of drought and salinity stress resistance in tomato, consistent with previous reports. These results indicate that SlNAC3 is not only involved in abiotic stress, but also plays a necessary role in mediating tomato ripening.

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

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