Determination of Fruit Cracking Rates in Some Pomegranate (Punica granatum L.) Genotypes Growed Non-Irrigated Conditions

Pomegranate (Punica granatum L.) is a tropical and subtropical climate plant with high economic value and nutritional content. Having valuable phytochemicals in terms of health caused an increase in demand for pomegranate consumption and this situation accelerated pomegranate production. However, global warming and climate changes are among the factors limiting the production of pomegranate. Especially abiotic stress factors caused by adverse ecological conditions cause significant economic losses in pomegranate production. Drought stress, which is one of these negativities, causes fruit cracking problem, which is one of the important problems in pomegranate production. Minimizing the fruit cracking problem, which causes economic losses, is possible by breeding varieties that are resistant to under non-irrigated conditions. Determining the resistance of the cultivars to be used in breeding programs against fruit cracking will allow the development of elite cultivars. For this purpose, it was aimed to determine the fruit cracking rates of 30 different pomegranate genotypes in the Pomegranate Genetic Collection of Çukurova University, Faculty of Agriculture, Department of Horticulture, under non-irrigated conditions. A correlation was made between the cracking rates of the genotypes and the amount of soluble solids content (SSC). According to the correlation analysis between the cultivars, there is no statistically significant difference between the SSC and the cracking rate. However, a weak negative correlation was determined between SSC-cracking rate (-0,1132). In the light of the pomological data obtained, it was determined that 8 pomegranate genotypes grown under non-irrigated conditions had a fruit cracking rate of 40 % - 85 %, cracking rates were below 10 % in 8 pomegranate genotypes and no fruit cracking was observed in 6 genotypes. As a result of the analysis, it was observed that drought stress was effective on the fruit cracking rate or the exacerbation of the fruit cracking rate, but the resistance level of some genotypes against the fruit cracking problem was high.

Effects of NIR Reflective Film as a High Tunnel-Covering Material on Fruit Cracking and Biomass Production of Tomatoes

Tomatoes require higher irradiance, although the incidence of physiological disorders in fruit increases at high temperatures. Near-infrared (800–2500 nm) (NIR) reflective materials are effective tools to suppress rising air temperatures in greenhouses. We examined the physiological and morphological changes in tomato growth and fruit quality when grown in a high tunnel covered with NIR reflective film (NR) and in another covered with polyolefin film (PO; control). There was no relationship between the fruit cracking rate and mean daytime temperature under NR. The fruit temperature at the same truss was lower and the increase in air temperature was slow under NR. Fruit dry matter (DM) content under NR was also significantly decreased. These findings suggest that the reduction in fruit cracking under NR results from a decrease in fruit DM content as a consequence of lower fruit temperature and a decrease in total DM (TDM). Total fruit yield did not differ, whereas TDM was significantly decreased under NR. This was considered to result from a lower transmitted photosynthetic photon flux density (400–700 nm) (PPFD) and LAI, and lower photosynthetic capacity in single leaves because of a decrease in both total nitrogen and chlorophyll content. We conclude that NR film reduces fruit cracking in exchange for a slight reduction in TDM.

Comparative Transcriptomic Analyses of Different Jujube Cultivars Reveal the Co-Regulation of Multiple Pathways during Fruit Cracking

Fruit cracking is a common physiological disorder in many fruit species. Jujube (Ziziphus jujuba Mill.) is an economically valuable fruit in which fruit cracking seriously affects fruit yield and quality and causes significant economic losses. To elucidate cracking-related molecular mechanisms, the cracking-susceptible cultivars ‘Cuizaohong’ and ‘Jinsixiaozao’ and the cracking-resistant cultivar ‘Muzao’ were selected, and comparative transcriptome analyses of cracking and non-cracking ‘Cuizaohong’ (CC and NC), cracking and non-cracking ‘Jinsixiaozao’ (CJ and NJ), and non-cracking ‘Muzao’ (NM) were conducted. A total of 131 differentially expressed genes (DEGs) were common to the CC vs. NC and CJ vs. NJ comparisons. To avoid passive processes after fruit cracking, we also mainly focused on the 225 gradually downregulated DEGs in the CJ, NJ, and NM samples. The functional annotation of the candidate DEGs revealed that 61 genes related to calcium, the cell wall, the cuticle structure, hormone metabolism, starch/sucrose metabolism, transcription factors, and water transport were highly expressed in cracking fruits. We propose that expression-level changes in these genes might increase the turgor pressure and weaken mechanical properties, ultimately leading to jujube fruit cracking. These results may serve as a rich genetic resource for future investigations on fruit cracking mechanisms in jujube and in other fruit species.

Impact of Potassium Pre-Harvest Applications on Fruit Quality and Condition of Sweet Cherry (Prunus avium L.) Cultivated under Plastic Covers in Southern Chile Orchards

In rainy locations, sweet cherry is cultivated under plastic covers, which are useful to prevent fruit cracking but decrease cherry quality such as firmness and acidity. Here we evaluate the impact of pre-harvest K foliar applications on harvest and post-harvest fruit quality and condition of sweet cherry cultivated under plastic covers in southern Chile orchards. The study was performed on two commercial orchards (cv. Regina), located in different regions, during two consecutive seasons. In all cases, a conventional K regime (four sprays) was compared to an intensive K regimen (seven sprays). Results showed that cherries from the most southern region revealed lower acidity but higher soluble solids content weight and size. The intensive K regime improved the firmness and acidity of fruits of covered trees at harvest and post-harvest. Moreover, we found that condition defects were higher in fruits from un-covered trees and that trees grown under intensive K regime showed lower levels of cracking at harvest and pitting at post-harvest compared to trees treated with the conventional K regime. Otherwise, pedicel browning was inconsistently affected by K sprays. Our results revealed that an intensive K regime could improve the quality and condition of fruits at harvest and post-harvest in covered orchards of sweet cherry cv. Regina; however, the impacts can significantly vary depending on season and locality.

Interactive Impacts of Plant Growth Regulators And Fertigation on Quality of Pomegranate (Punica Granatum L.) In Sub-Humid Agro Ecological Zone of Rajasthan

Individual and interaction effects of plant growth regulators and fertigation on quality of pomegranate were investigated. Maximum mean polar diameter (9.59 cm), equatorial diameter (8.10 cm), fruit weight (206.06 g),fruit volume (190.86 cc), number of arils per fruit (416.81), aril weight per fruit (146.35 g), weight of 100 arils (35.86 g) and aril per cent (70.92 %) along with minimum specific gravity (1.090), rind thickness (5.15 mm), rind per cent (29.09%) and fruit cracking (5.58%) were recorded in F2 (100 per cent RDF through fertigation). Similarly, spray of 100 ppm NAA (N2) and 250 ppm ethrel (E2) significantly influenced the above characteristics of fruit. Treatment combination of 100 ppm NAA + 150 ppm ethrel + 100% RDF through fertigation (N2E1F2) gave better quality fruit over other treatments including control. Bangladesh J. Bot. 50(3): 623-631, 2021 (September)

Genetic variation in melon (Cucumis melo L.) landraces and wild relatives of Karnataka state of southern India

Melon (Cucumis melo L.) is an economically important vegetable crop worldwide. Karnataka state of southern India is rich in melon landraces and wild relatives, which are potential sources of genetic diversity for crop improvement. Here we report on the collection, characterization and documentation of previously unexplored landrace and wild material to broaden the availability of this genetic diversity for use in melon improvement. Accessions of botanical groups, momordica, kachri, chandalak, reticulatus, acidulus and indicus, intermediate forms of acidulus and momordica, and three melons of an unknown group were sourced directly from farmers of eight agro-ecological regions. Twenty-three representative melon landraces and wild relatives, along with four reference varieties of different botanical groups, were evaluated for agronomic traits during the year 2016. Very wide and distinctive genetic variations were observed among the melon accessions for ovary characters, sex expression, days taken to first fruit maturity, external and internal fruit traits, and fruit cracking (splitting). The remarkable variability displayed among the melon accessions as observed from the study demonstrates the importance of them as a valuable genetic reservoir for melon improvement.

Effect of Plant Growth Regulators and Micro-nutrients on Vegetative Growth, Flowering and Yield Attributes of Litchi (Litchi chinensis Sonn.)

The experiment was conducted to observe the effect of plant growth regulators (GA3 and NAA) and micro-nutrients (ZnSO4 and Borax) on vegetative growth, flowering and yield attributes of litchi (Litchi chinensis Sonn.). ZnSO4 applied @ 0.4% resulted in maximum per cent increase in plant height and canopy spread, i.e. 5.78% and 6.65% respectively. Whereas, application of Borax @ 0.4% exhibited maximum per cent increase in plant girth (8.72%). NAA @ 2.5 ppm was effective in improving the flowering parameters of litchi. With respect to physical parameters of fruit and yield component, application of borax @ 0.4% resulted in maximum fruit set (43.76%), number of fruits per tree (1128.67), fruit yield (25.11 kg/tree), fruit weight (22.24 g), aril weight (15.65 g) and minimum fruit cracking (5.08%). Lowest fruit drop percentage (60.91%) was however caused by application of ZnSO4 @ 0.4%.

Brassinosteroids Application Responses in Fruit Crops – A Review

Brassinsteroids (BRs) are a class of novel plant hormones gaining importance as potential allies of agricultural development worldwide. Research findings on influences of exogenous BRs application on various aspects of growth and development like vegetative growth, flowering, fruit set, fruit growth, ripening, storage, and tolerance to various biotic and abiotic stresses in fruit plants’ have been reviewed and discussed. The molecular or biochemical aspects of BRs responses to modulate growth and productivity by activating or withholding enzymatic reaction of different biochemical pathways of fruit plants have been elaborated. BRs are involved in ripening and fruit quality development of climacteric and non-climacteric fruits; as per reports of many researchers, they improve fruit color, phenolics, anti-oxidant activities and post-harvest life of many fruits. Fruit cracking in litchi has been found to be significantly reduced due to BRs application. This group of plant hormones possess the capacity to negate genetoxicity and pesticidal residues in many horticultural crops; it reflects the extension of their uses in producing consumer-friendly fruits through BRs application. One of the biggest advantages of BRs application is controlling favorable plant responses under abiotic and biotic stresses; plants have been reported to manage these stresses through modifications in various gene expressions and physiological processes under the influence of the BRs. The need for in-depth studies has been speculated for optimizing the concentration of BRs application together with the standardization of critical stages for harnessing the benefit of quality orchard productivity under varied growing conditions.