Advanced Fruit Maturity Research Articles

Changes of physicochemical parameters, bioactive compounds & antioxidant capacity of four different cultivars of Punica granatum (L.) at four distinct maturity stages

In this comprehensive exploration of Punica granatum, the investigation delves into the alterations of physicochemical parameters, bioactive compounds, and antioxidant capacity across various anatomical segments of four distinct pomegranate cultivars cultivated in Sri Lanka (cv. "Nayana," "Kalpitiya Hybrid," "Nimali," and "Daya") at four discrete stages of maturity, namely one month (immature), two months (semi -mature), three months (mature), and four months (ripen) after fruit set. The Total Antioxidant Capacity (TAC) was measured using a Ferric Reducing Antioxidant Power (FRAP) assay. Concurrently, Total Phenolic Content (TPC) and Total Flavonoid Content (TFC) were analyzed using the modified Folin- Ciocalteu method, and the colourimetric method, respectively. Results revealed that all parts of all tested varieties contain a significant amount of TAC, TPC, and TFC. Among tested cultivars, physicochemical parameters were increased from immature through semi-mature to ripened fruit, being maximum at this stage except for Titratable acidity (TA), and it significantly declined with the advancing fruit maturity. The content of bioactive compounds of four tested cultivars was varied as Nimali>Daya>Nayana>Kalpitiya hybrid, respectively. Since immature fruits of tested pomegranate cultivars contain many bioactive molecules, using immature fruits in traditional medicine has been scientifically validated and could be recommended for value-added nutraceutical production.

Combining the Use of Reflective Groundcovers and Aminoethoxyvinylglycine to Assess Effects on Skin Color, Preharvest Drop, and Quality of ‘Honeycrisp’ Apples in the Mid-Atlantic US

Apples are one of the most valuable fruits worldwide. ‘Honeycrisp’ is the top sales-producing cultivar in the US. Lack of red skin coloration and increased preharvest fruit drop significantly reduce the market value for cultivars such as ‘Honeycrisp’. The use of reflective groundcovers has been shown to enhance apple skin coloration. While the use of plant growth regulator AVG reduces fruit drop, it negatively affects skin coloration. Studies on the impacts of these practices in mid-Atlantic US-grown apples are limited. In this work, for two years, we compared differences in the light environment, fruit drop, internal ethylene concentration (IEC), physicochemical parameters, and skin coloration of ‘Honeycrisp’ apples in the lower third of the canopy. Apples were submitted to four treatment combinations of reflective groundcover (Extenday) and AVG (130 mg L−1). Assessments occurred throughout three ripening stages. Our results demonstrated that Extenday significantly promoted skin coloration (>75% blush) via the increased reflectance of photosynthetic photon flux density and UV radiation, and increased IEC, while also advancing fruit maturity, i.e., overripening. Conversely, AVG significantly minimized fruit drop and decreased EIC, delaying fruit maturity but drastically reducing red coloration (30–48% blush). The combined use of Extenday and AVG had a synergistic effect by decreasing fruit drop while enhancing fruit with >50% blush, without promoting overripening. Combining Extenday and AVG can boost the market value for ‘Honeycrisp’ apples in the mid-Atlantic US.

A Targeted Metabolomics Approach to Study Secondary Metabolites and Antioxidant Activity in 'Kinnow Mandarin' during Advanced Fruit Maturity.

In this study, we investigated the impact of harvest maturity stages and contrasting growing climates on secondary metabolites in Kinnow mandarin. Fruit samples were harvested at six harvest maturity stages (M1–M6) from two distinct growing locations falling under subtropical–arid (STA) and subtropical–humid (STH) climates. A high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) technique was employed to identify and quantify secondary metabolites in the fruit juice. A total of 31 polyphenolics and 4 limonoids, with significant differences (p < 0.05) in their concentration, were determined. With advancing maturity, phenolic acids and antioxidant activity were found to increase, whereas flavonoids and limonoids decreased in concentration. There was a transient increase in the concentration of some polyphenolics such as hesperidin, naringin, narirutin, naringenin, neoeriocitrin, rutin, nobiletin and tangeretin, and limonoid aglycones such as limonin and nomilin at mid-maturity stage (M3) which coincided with prevailing low temperature and frost events at growing locations. A higher concentration of limonin and polyphenolics was observed for fruit grown under STH climates in comparison to those grown under STA climates. The data indicate that fruit metabolism during advanced stages of maturation under distinct climatic conditions is fundamental to the flavor, nutrition and processing quality of Kinnow mandarin. This information can help in understanding the optimum maturity stage and preferable climate to source fruits with maximum functional compounds, less bitterness and high consumer acceptability.

Influence of on-the-tree fruit bagging on biotic stresses and postharvest quality of rainy-season crop of ‘Allahabad Safeda’ guava (Psidium guajava L.)

In India, guava trees produce two crops per year, one in the rainy-season and another in the winter. The rainy-season crop is severely infested by fruit fly, anthracnose disease and birds. Because of low quality, the rainy-season crop is usually discarded by farmers. In recent years, on-the-tree fruit bagging has emerged as one of the most effective approaches for controlling pests and diseases and quality improvement in fruits. Hence, we attempted to observe the effects of five different types of bags on the rainy-season crop of ‘Allahabad Safeda’ guava. For this, fruits were covered with either of four types of bags (nylon nets, polypropylene (PP) non-woven, butter paper and brown paper) at marble stage of development during the rainy-season crop for two consecutive years. All bags significantly advanced fruit maturity and improved fruit weight, texture, visual appeal, quality, and functional attributes over unbagged (control) fruits. Interestingly, fruit bagging with PP non-woven bags significantly reduced fruit drop and provided complete control of fruit fly, anthracnose and bird damage compared to unbagged fruits that suffered high incidence of fruit fly (56.6 ± 1.08%), anthracnose (6.6 ± 0.27%) and bird damage (14.6 ± 0.23%). Thus, it can be concluded that on-the-tree fruit bagging with PP non-woven bags is useful for controlling major pest and/or disease and improving fruit quality of the rainy-season guava crop.

Effect of exogenous application of amino acids on fruit quality and productivity of peach (Prunus persica)

The present investigations were carried out at Fruit Research Farm, Punjab Agricultural University, Ludhiana during 2016-17 to study the effect of exogenous application of amino acids (Peptone) on fruit quality, maturity and productivity of peach (Prunus persica L. Batsch) in sub-tropics of north India. The 6-year-old peach trees of cv. Florida Prince were sprayed with 0.25% and 0.50% of amino acid (Peptone P1 023), 7 and 14 days after full bloom and the sprays were repeated after 15 and 30 days. The highest yield (53.92 kg/tree) was recorded in T8 treatment (0.50% amino acid applied 14 days after full bloom and repeated after 15 days) while lowest in T12 treatment sprayed with triple spray of amino acids. All the double spray treatments of amino acids advanced fruit maturity by 4 days as compared to control. The mean maximum fruit weight (78.23 g) was recorded in T8 (0.50% amino acid applied 14 days after full bloom and repeated 15 days later) and minimum in the plants sprayed with triple sprays of amino acids (T12). The double spray treatments (T5 to T8) recorded lower fruit firmness indicating early maturity than control and other treatments. Maximum fruit TSS (12.10°Brix), highest total sugars content (5.12%) and lowest mean juice acidity (0.70%) was recorded in T8 treatment. Therefore, the double spray treatments of amino acids advanced fruit maturity, increased yield and improved fruit quality in peach.

Response of “White Robin” Peach Trees Cv. (Prunus persica L.) to Cultivation Under Plastic Covering Conditions and Foliar Application by Hydrogen Cyanamide and Garlic Extract

A field experiment was carried out during 2018 and 2019 seasons on 4 years old ‘White Robin’ peach trees cv. (Prunus persica L.), to investigate the effect of cultivation peach trees under plastic covering conditions (PC) with combination of hydrogen cyanamide (HC at 0.5%) as a Dormex and garlic extract (GE at 1%) on floral and vegetative bud break time, vegetative growth parameters, fruit set, yield and fruit quality of this cultivar. Eight treatments, HC alone, GE alone, HC + GE, PC alone, PC + HC, PC + GE, PC + HC + GE and control were applied. The application of HC and GE under PC, resulted in earlier buds break and harvesting period by 10 and 20 days, respectively. Moreover, it shortened the period between both of flower and vegetative buds break and onset to end fruit harvesting by 10 days. It significantly increased shoot length, diameter and leaf area compared to control and other treatments. Furthermore, it improved fruit physical and chemical properties beside increasing the yield by 30%. All studied parameters gradually improved by other investigated treatments as follow: PC + HC, PC + GE, PC alone, HC and GE, HC alone then GE alone compared by control. Plastic covering might be useful for early peach cultivars for advancing fruit maturity and improving yield and fruit quality, that will be more suitable for exportation and profitable for growers under conditions of Egypt.

Assessing Preharvest Field Temperature and At-harvest Fruit Quality for Prediction of Soft Scald Risk of ‘Honeycrisp’ Apple Fruit during Cold Storage

‘Honeycrisp’ apple is susceptible to the postharvest chilling disorder soft scald that renders fruit unmarketable. Reducing or preventing this disorder is an important component of ‘Honeycrisp’ postharvest management. In commercial settings, advanced fruit maturity and orchard history contribute to an estimation of soft scald susceptibility, but additional at-harvest information indicative of soft scald risk would enable better management decisions. In this study, we obtained fruit from commercial orchards for 3 successive years, and assessed field growing degree days (GDD), field chilling hours (CH), and fruit quality metrics at harvest, followed by soft scald incidence assessment at 12 weeks of cold storage. The analyses indicated starch index, soluble solids content (SSC), internal ethylene concentration, titratable acidity (TA), peel background color, firmness, GDD, or CH do not reliably indicate fruit susceptibility to soft scald. However, SSC and TA were elevated in fruit that later developed soft scald, and a higher number of GDD also sometimes preceded soft scald, which is consistent with advanced fruit maturity that can enhance soft scald risk. Overall, results suggest that other tools may be required to accurately predict postharvest soft scald on a quality control laboratory scale. The statistical analyses applied to the present study would have utility for assessing other soft scald prediction tools or markers.

High Humidity and Age-Dependent Fruit Susceptibility Promote Development of Trichothecium Black Spot on Apple.

Fruit bagging is a widely used orchard practice in China. Trichothecium black spot (TBS) is a disease highly associated with the fruit bagging. In this study, we characterized in vitro factors affecting the causal agent, Trichothecium roseum, and TBS development and infection histology on field-bagged apple fruit in situ. Under in vitro conditions, conidial germination required exogenous nutrients, and the germination rate was significantly promoted by high humidity, a condition mimicking the bag microenvironment. Germ tubes penetrated fruit via natural openings including stomata, lenticels, and surface cracks. To determine the chronology of infection by T. roseum, 'Fuji' fruit were inoculated in the field at different developmental stages. The earliest infection occurred 60 days after full bloom (dafb), and disease incidence increased as fruit maturity advanced. At harvest time (165 dafb), lesions on more recently inoculated fruit (105 dafb, 150 dafb) were larger than lesions from fruit inoculated on earlier dates. Histological observation showed that infection of younger fruit elicited stronger host lignification responses restricting lesion development. Taken together, our results support the hypothesis that high humidity in sealed bags and increased susceptibility associated with advancing fruit maturity are key factors promoting T. roseum infection and TBS symptom development on bagged apple fruit.

Effect of harvest date on off-flavor development in mandarins following postharvest wax application

Mandarins (Citrus reticulata Blanco) are very prone to off-flavor formation following the postharvest application of wax and it had been previously observed that off-flavor also increases with advanced fruit maturity. To more fully evaluate the maturity effect on off-flavor and to determine potential causal mechanisms for it, ‘Owari’ and ‘China S-9’, two Satsuma varieties, were harvested at three to four dates within the harvest season, waxed and placed into storage for either 2 weeks at 5 °C or 1 week at 5 °C + 1 week 20 °C, the latter treatment being expected to develop off-flavor. The testing was conducted over three seasons with ‘W. Murcott’, a non-Satsuma variety, being included in the third season. In all three seasons analyses were conducted for various parameters related to fruit internal atmosphere composition. At the end of the storage period, in the first two seasons, the fruit were evaluated for flavor using a semi-expert sensory panel. Consistently, in seasons 1 and 2 where flavor was evaluated, both Satsuma varieties did not develop off-flavor or a loss in acceptability in the initial harvest. In subsequent harvests, however, off-flavor became increasingly noticeable and was correlated with the decline in flavor acceptability. There were occasional impacts on other flavor attributes, but the results were inconsistent. Advancing maturity in all three seasons was associated with a decrease in internal oxygen and an increase in internal carbon dioxide, except in the case of ‘W. Murcott’ where there was little or no change in internal oxygen and an increase in carbon dioxide. Enhanced fermentative metabolism was indicated in the later harvests in the form of higher ethanol in the Satsuma varieties. Peel gas permeance measurements performed in season 3 showed no meaningful relationship with the internal gas concentrations measured during the season. Respiration rate, however, strongly increased during the season in the Satsuma varieties and decreased in ‘W. Murcott, both changes being associated with the internal gas composition. It is concluded that maturity influences the propensity for off-flavor development in mandarins, but it does not occur in every instance and is influenced by year, storage and temperature. The potential mechanism modulating the change in the three varieties examined in this study appeared to be changes in the rate of respiration, since when respiration is sufficiently high, oxygen levels decline to a level where fermentation occurs, and off-flavor becomes apparent.

Management of water and nutrient through fertigation and the impact of rootstock to optimize yield and maximize quality in apples

Water usage, tree growth, leaf mineral nutrients, yield, and fruit quality attributes in ‘Autumn Rose Fuji’ apple (Malus × domestica Borkh) under five irrigation systems (full sprinkler (FS), 50% full sprinkler (50% FS), full drip (FD), 65% full drip (65% FD), and 50% full drip (50% FD)) between 2008 and 2011 and effects of four rootstocks (Bud 9, RN 29, Supporter 4, and G30) and two irrigation systems (FS and FD) on tree trunk cross sectional area (TCSA) in 2006, cumulative yield in 2006 and 2007, fruit quality between 2004 and 2007, and leaf size and leaf mineral nutrient between 2002 and 2007 in ‘Pacific Gala’ were studied. On average, each tree with an FS system received 5927 L and each tree with FD received 3609 L water per season. ‘Autumn Rose Fuji’ trees receiving FS and FD had higher yield tree-1 and larger fruit than those with other treatments. ‘Autumn Rose Fuji’ trees with 65% FD and 50% FD received much lower volumes of water while they had significantly larger fruit compared to the trees with 50% FS. ‘Autumn Rose Fuji’ fruit soluble solids concentrations (SSC) increased in all trees that received any water-deficit treatment, leading to a significantly higher SSC in trees with 50% FS. In ‘Autumn Rose Fuji’, concentrations of leaf N, Ca, and Mn were higher than those in any drip irrigation, and leaves from trees with FS and FD treatments had higher K. ‘Pacific Gala’ trees on Bud 9 rootstock were smaller and had higher leaf N (as expressed on mg cm-2 of leaf area), Ca, Zn, and Mn, but lower K than those on other rootstocks. Bud 9 and G30 rootstocks enhanced the fruit maturity of ‘Pacific Gala’ by increasing fruit SSC and reducing fruit firmness. In ‘Pacific Gala’, drip irrigation increased fruit size and advanced fruit maturity by increasing SDP and reducing firmness as compared to sprinklers system. Overall, drip systems are recommended for both ‘Autumn Rose Fuji’ and ‘Pacific Gala’ production.

Fruit maturity and associated changes in Khasi mandarin (Citrus reticulata) at different altitudes in humid tropical climate

Fruit maturity and associated changes in terms of physicochemical and sensorial qualities of Khasi mandarin (Citrus reticulat Blanco) grown at different altitudes, viz. 500-600 m, 700-800 m, 900-1 000 m and 1 300-1 400 m were studied under humid tropical climate of Meghalaya. Rapid increase in fruit growth was recorded from fruit development to colour break stage, however it was slow thereafter at all the altitudes. At 500-600m and 700-800m, juice yield was recorded highest at fruit maturity stage (46.64% and 49.11%) while, it was highest in advanced fruit maturity stage (50.90% and 51.15%) at 900-1 000 m and 1 300-1 400 m. Diurnal variation in climate stimulated drop in chlorophyll (‘a’, ‘b’ and total) and promoted development of yellowish orange colouration on fruit peel at altitude of 500-600 m and 700-800 m while deep orange colouration at 900-1 000 m and 1 300-1 400 m. Significant rise in TSS and TSS: acid ratio with drop in titratable acidity were recorded during maturation. Ascorbic acid content was recorded maximum at 1 300-1 400 m (44.13 mg/100 g) and 900-1 000 m (41.05 mg/100 g) compared with 700-800 m (37.56 mg/ 100 g) and 500-600 m (35.66 mg/100 g) at advanced maturity stage. Duration of 1 and 1 ½ month (fruit development to colour break stage) represents maturation at 500-600 m and 700-800 m considering TSS (10.23 °B and 10.13 °B), TSS: acid ratio (13.22 and 12.60), sweetness (3.93 and 3.67), flavour (8.00 and 7.93) and appearance (8.07 and 7.87) score. While duration of 2 and 2 ½ months (fruit development to fruit maturity stage) required at 900-1 000 m and 1 300-1 400 m considering TSS (10.07 °B and 10.16 °B), TSS: acid ratio (12.40 and 12.02), sweetness (4.07 and 3.93), flavour (7.87 and 7.93) and appearance (7.93 and 8.00) score.

Aerodynamic separation and cleaning of pomegranate arils from rind and white segments (locular septa)

In the process of pomegranate arils pneumatic separation, the aerodynamic characteristics of pomegranate aril, rind and locular septa are essential. The main aim of this study was to measure and compare the aerodynamic characteristics of these materials to provide the data and to facilitate the design and adjustment of machines that perform separation of pomegranate arils from rind and locular septa based on aerodynamic characteristics (terminal velocity, drag coefficient and Reynolds number). To achieve this objective, Ashraf variety pomegranate fruit during its maturity stages was studied. The obtained results showed that the variation in maturity stage significantly influenced the terminal velocity, drag coefficient and Reynolds number (P<0.05). During the fruit maturity, the terminal velocity of locular septa, rind and pomegranate aril increased from 1.05 to 1.16, 3.16 to 3.73 and 5.89 to 6.70ms−1, respectively. The corresponding value of drag coefficient of the three studied materials decreased from 0.92 to 0.79, 0.75 to 0.59 and 0.53 to 0.36, respectively with advancing fruit maturity. Also these ranges for Reynolds number were 403.24–617.75, 1213.44–1986.37 and 2261.76–3568.02, respectively. Consequently, aerodynamic separation of pomegranate aril from locular septa and rind is theoretically possible if the air velocity value is adjusted according to the terminal velocity of pomegranate aril. Also the obtained equations can be used for calculating the parameters of pomegranate aril movement in pneumatic tunnels or in the design and development of air conveyor and pneumatic separator of pomegranate aril.

Pre-harvest foliar application of ethephon strengthens gibberellins-induced fruit expansion in Pyrus pyrifolia.

To identify the roles of ethylene in fruit development in Japanese pear Pyrus pyrifolia 'Niitaka', one of the non-climacteric genotypes, source-sink strength and fruit development during fruit expansion were investigated when ethephon was applied after a conventional gibberellic acid (GA) lanolin paste treatment on the pedicel. The results demonstrate that the conventional GA treatment during the early stage of fruit expansion resulted in larger fruit size and advanced fruit maturation, but pre-harvest foliar application of ethephon only advanced fruit maturation. However, pre-harvest foliar application of ethephon with a preceding conventional GA treatment during the early stage of fruit expansion dramatically improved fruit size and advanced fruit maturation over GA or ethephon alone. Moreover, the early foliar application of ethephon showed a better efficacy in increasing fruit size than the late spraying. A further study revealed that when ethephon was applied after the conventional GA treatment, it improved source-sink strength associated with leaf photosynthesis and the specific rate of [13C] accumulation in fruit, and also strengthened cell expansion more than did GA or ethephon alone.

Quantitative changes in proteins responsible for flavonoid and anthocyanin biosynthesis in strawberry fruit at different ripening stages: A targeted quantitative proteomic investigation employing multiple reaction monitoring.

To gain insight into the molecular mechanisms contributing to flavonoids and anthocyanin biosynthesis and regulation of strawberry fruit during ripening is challenging due to limited molecular biology tools and established hypothesis. Our targeted proteomic approach employing LC-MS/MS analysis and MRM technique to quantify proteins in relation to flavonoids and anthocyanin biosynthesis and regulation in strawberry fruit during fruit ripening is novel. The identification of peptides and proteins provided reliable design and validation of quantitative approaches using SRM on targeted proteins proposed involved in strawberry fruit. Our data revealed the identifying candidate proteins and their quantitative changes in relation to fruit ripening and flavonoids and anthocyanin biosynthesis and regulation. More importantly, this quantitative proteomic data is also compared with chemical analysis to reveal possible control levels of this important quality trait. Although, MRM approach is not new in plant biology research, the application has been very rare. This is the first systematic multi-targeted interrogation of the possible regulation of entire pathway of flavonoids and anthocyanin biosynthesis in strawberry fruit at different ripening stages using quantitative MRM technique on mass spectrometry. Our results demonstrate the power of targeted quantitative mass spectrometry data for analysis of proteins in biological regulation. These results indicate that distinct and diverse control of flavonoids and anthocyanin biosynthesis mechanisms at metabolism and proteins levels. This important and complementary knowledge will be useful for systematically characterizing the flavonoids and anthocyanin biosynthesis pathway of any fruit/plant species.

INTRAVARIETAL VARIABILITY OF 'CRLJENAK KASTELANSKI' AND ITS RELATIONSHIP WITH 'ZINFANDEL' AND 'PRIMITIVO' SELECTIONS

Six ?Crljenak kastelanski? (CK), two ?Primitivo? and one selection of ?Zinfandel? were evaluated in Split, southern Croatia. Vine yield components and fruit composition were measured over two growing seasons, 2008 and 2009. Significant differences were obtained among nine selections for all viticultural traits, with the exception of the number of clusters per vine and Ravaz index. CK selections seem to be not uniform and perform some unique characters in comparison to ?Zinfandel? and ?Primitivo? selections. The certified selection of ?Zinfandel? (ZIN01) showed better vegetative growth having higher yield, cluster length, width and weight, berries per cluster and berry weight than other selections. The ?Primitivo? and CK selections had similar fruit composition and had advanced fruit maturity compared to ?Zinfandel?. The genetic differences were investigated using SSR, IRAP, REMAP and AFLP markers. SSR, IRAP and REMAP markers were not polymorphic, while the level of AFLP polymorphism was comparable with similar studies, however, not sufficient to discriminate clones according to geographical origin or basic viticultural characters. The obtained results indicate a significant genetic variability between the investigated selections and they justify further efforts in clonal selection for CK.

GA3와 Thidiazuron 처리가 '거봉' 포도의 무핵화와 과실품질에 미치는 영향

본 실험은 <TEX>$GA_3$</TEX>와 thidiazuron(TDZ)이 '거봉' 포도의 무핵과율, 수확시기, 열과 및 과실품질에 미치는 영향을 알아보고자 2008년에서 2009년까지 2년간 수행되었다. 2008년에는 <TEX>$GA_3$</TEX> <TEX>$25.0mg{\cdot}L^{-1}$</TEX>에 TDZ <TEX>$2.5mg{\cdot}L^{-1}$</TEX>를 혼용한 것과 혼용하지 않은 것을 만개기와 만개 후 14일에 침지 처리하였다. 과실의 무핵과율과 과실비대는 <TEX>$GA_3$</TEX> <TEX>$25.0mg{\cdot}L^{-1}$</TEX>에 TDZ <TEX>$2.5mg{\cdot}L^{-1}$</TEX>를 2차에만 혼용처리 한 경우 TDZ를 1, 2차 모두 혼용처리한 것에 비하여 약간 증가하였다. 반면에 열과발생률은 모든 생장조절제 처리에서 무처리구에 비해 높게 조사되었다. 2009년에는 <TEX>$GA_3$</TEX> <TEX>$12.5mg{\cdot}L^{-1}$</TEX>과 <TEX>$GA_3$</TEX> <TEX>$25.0mg{\cdot}L^{-1}$</TEX>를 만개기와 만개 후 14일에 두 번 침지 처리하였으며 TDZ <TEX>$2.5mg{\cdot}L^{-1}$</TEX>를 만개 후 14일에만 혼용 처리하였다. 열과발생율은 <TEX>$GA_3$</TEX>의 농도에 영향을 받았다. <TEX>$GA_3$</TEX> <TEX>$25.0mg{\cdot}L^{-1}$</TEX>의 고농도에서는 열과발생율이 유의하게 증가하였으나 <TEX>$GA_3$</TEX> 농도를 <TEX>$12.5mg{\cdot}L^{-1}$</TEX>으로 낮출 경우 열과발생율에 영향이 없었다. 또한 <TEX>$GA_3$</TEX> <TEX>$25.0mg{\cdot}L^{-1}$</TEX> 처리 시에도 만개 14일 후 2차 처리 시 TDZ를 혼용할 경우 열과발생율이 무처리 수준까지 감소하였다. 모든 생장조절제 처리는 과일의 숙기를 촉진하였으며, <TEX>$GA_3$</TEX> <TEX>$12.5mg{\cdot}L^{-1}$</TEX>에 2차에만 TDZ를 추가하였을 경우 가장 효과가 좋았다. 따라서 과실의 숙기와 품종 등 모든 관점을 고려하였을 때 35-40개의 과립수를 가진 400-500g 정도의 '거봉' 무핵과를 생산하기 위해서는 <TEX>$GA_3$</TEX> <TEX>$12.5mg{\cdot}L^{-1}$</TEX>을 만개기와 만개 후 14일에 처리하며 TDZ를 만개 후 14일에만 혼용 처리하는 것이 가장 좋은 결과를 얻을 수 있는 것으로 조사되었다. This experiment was conducted to find the effects of a <TEX>$GA_3$</TEX> and thidiazuron (TDZ) on seedless rate, harvest time, fruit cracking and fruit quality in 'Kyoho' grapes over two years from 2008 to 2009. In 2008, fruit clusters were dip treated with <TEX>$GA_3$</TEX> <TEX>$25.0mg{\cdot}L^{-1}$</TEX> twice at full bloom (FB) and 14 days after full bloom (DAFB) in a combination with TDZ 0 or <TEX>$2.5mg{\cdot}L^{-1}$</TEX>. Berry seedless rate and berry enlargement were slightly improved only when TDZ was added to the second <TEX>$GA_3$</TEX> treatment at 14 DAFB, compared to <TEX>$GA_3$</TEX> + TDZ treatments at both FB and 14 DAFB. However, berry cracking rate was significantly increased by any plant growth regulator (PGR) treatments compared to non treatment. In 2009, <TEX>$GA_3$</TEX> at <TEX>$12.5mg{\cdot}L^{-1}$</TEX> and <TEX>$25.0mg{\cdot}L^{-1}$</TEX> was dip treated twice at FB and 14 DAFB while TDZ <TEX>$2.5mg{\cdot}L^{-1}$</TEX> was treated only at 14 DAFB. Berry cracking rate was depended on the concentration of <TEX>$GA_3$</TEX> applied. The higher concentration at <TEX>$25.0mg{\cdot}L^{-1}$</TEX> significantly increased berry cracking rate while the lower concentration at <TEX>$12.5mg{\cdot}L^{-1}$</TEX> had no effect. Also, the addition of TDZ to <TEX>$GA_3$</TEX> <TEX>$25.0mg{\cdot}L^{-1}$</TEX> at 14 DAFB, substantially decreased the cracking rate to the level of untreated control. Although all PGR treatments advanced fruit maturity, the most significant advance occurred when TDZ was added to <TEX>$GA_3$</TEX> <TEX>$12.5mg{\cdot}L^{-1}$</TEX> only at the second dip. Considering the overall aspects related to fruit maturity and quality, we concluded that the double applications of <TEX>$12.5mg{\cdot}L^{-1}$</TEX> <TEX>$GA_3$</TEX> at FB and 14 DAFB with addition of <TEX>$2.5mg{\cdot}L^{-1}$</TEX> TDZ only at 14 DAFB was appropriate to produce about 400-500 g size of seedless 'Kyoho' grape cluster having 35-40 berries.

Maturity‐dependent chilling tolerance regulated by the antioxidative capacity in postharvest cucumber (Cucumis sativus L.) fruits

The aim of the present study was to reveal the effect of fruit maturity on the chilling tolerance of cucumber (Cucumis sativus L.) fruit and the oxidative and antioxidative mechanisms involved. Chinese mini-cucumber (cv. Hangcui-1) fruits were harvested at four developmental stages: Immature (3-8 days after anthesis (DAA)), Mature (9-16 DAA), Breaker (17-22 DAA) and Yellow (35-40 DAA). All fruits were stored at 2 °C for 9 days and rewarmed at 20 °C for 2 days. The chilling injury index declined with advancing fruit maturity. High superoxide anion radical production rate and hydrogen peroxide content were observed in Immature fruits after cold storage and rewarming. Under chilling stress, superoxide dismutase showed an early response. Fruits at earlier maturity stages exhibited higher catalase, ascorbate peroxidase and monodehydroascorbate reductase activities and glutathione content as well as its redox state, and lower peroxidase, dehydroascorbate reductase and glutathione reductase activities and ascorbate content as well as its redox state. Fruits at the earlier developmental stage are more susceptible to chilling injury, which is related to increased oxidative stress. High peroxidase activity and ascorbate content and maintenance of the latter's redox state appear critical to the chilling tolerance of cucumber fruits at later developmental stages.

Effects of Converting from Sprinkler to Drip Irrigation on Water Conservation and the Performance of Merlot Grown on a Loamy Sand

Effects of converting from overhead sprinkler to drip irrigation on the growth, leaf gas exchange, and fruit production of Merlot grapevines with and without cluster thinning were determined over four years. Drip or sprinkler irrigation was applied to the loamy sand soil when in-row soil moisture was depleted to &lt;8%. Irrigation frequency averaged 50% higher (27 compared with 18 times per year) under drip than sprinkler irrigation, but 64% less water (574 compared with 1580 L per vine per yr) was applied on average under drip. Maps of moisture in the soil profile revealed differences in moisture distribution and dry-down dynamics in response to irrigation method. Increasing soil dry-down rates over years indicated that roots proliferated within the drip-irrigated soil volume. Converting to drip reduced the growth and survival of floor vegetation. Vine vigor, leaf gas exchange, and crop yield were reduced but crop yield recovered in the second year and vigor recovered by the fourth year. Stomatal conductance and leaf gas exchange remained lower under drip irrigation. Transpirational water-use efficiency was higher under drip than sprinkler irrigation in the first three years. Input water use efficiency averaged 2.5 times higher under drip irrigation over the four years. Fruit maturation was advanced by drip compared with sprinkler irrigation each year and was associated with increased cluster exposure and higher ambient temperatures. Cluster thinning also advanced fruit maturation but reduced crop yield substantially each year and had only minor interactions with irrigation method.

Efeito do ensacamento dos frutos no controle de pragas e doenças e na qualidade e maturação de maçãs 'Fuji Suprema'

O objetivo deste trabalho foi avaliar a eficiência de embalagens de diferentes materiais para a proteção contra pragas e doenças e seu efeito sobre a qualidade físico-química, maturação e teor de cálcio (Ca) em maçãs 'Fuji Suprema'. O experimento foi desenvolvido nas safras de 2007/2008 e 2008/2009, em pomar manejado sob o sistema orgânico, localizado na região de São Joaquim (SC). O pomar era composto por plantas de dez anos de idade da cultivar Fuji Suprema, sobre porta-enxerto 'Marubakaido', com interenxerto 'EM-9'. Depois do raleio manual, aproximadamente 40 dias após a plena floração, os frutos foram ensacados com embalagens plásticas transparentes microperfuradas ou de tecido não texturizado (TNT). Os frutos foram mantidos ensacados até a colheita. A testemunha foi constituída por frutos não ensacados. Na colheita, os frutos foram avaliados quanto aos danos provocados por mosca-das-frutas (Anastrepha fraterculus), mariposa oriental (Grapholita molesta) e lagarta enroladeira (Bonagota salubricola). As doenças foram avaliadas pela incidência de sarna da macieira (Venturia inaequalis), podridão amarga (Colletotrichum gloeosporioides) e podridão carpelar (Alternaria sp., Fusarium sp.). Também foi avaliada a incidência de distúrbios fisiológicos "russeting" e "bitter pit", atributos físico-químicos de maturação e qualidade e o teor de Ca nos frutos. Independentemente do tipo de embalagem verificou-se que o ensacamento é prática eficaz na proteção contra o ataque de insetos, mas não reduz a incidência e o desenvolvimento de doenças nos frutos. Na safra de 2008/2009, o ensacamento dos frutos aumentou o teor de Ca e reduziu a incidência de "bitter pit", e aumentou a incidência do "russeting". O ensacamento dos frutos antecipou a maturação, especialmente com embalagem plástica transparente microperfurada, e reduziu a coloração vermelha, especialmente com embalagem TNT.

Effects of moderate and severe iron deficiency chlorosis on fruit yield, appearance and composition in pear (Pyrus communis L.) and peach (Prunus persica (L.) Batsch)

The effects of different levels of Fe-deficiency chlorosis on the fruit yield, appearance and composition of pear and peach trees grown in field orchards have been studied. The major effect of Fe deficiency in both species was a large yield reduction, even when chlorosis was moderate, associated to decreases in fruit tree load. Fruit size increased with moderate chlorosis in both species and decreased with severe chlorosis in peach. In peach, moderate or severe chlorosis affected uniformly all branches, leading to firmer fruits with higher acidity, total phenolics and carboxylates. This indicates a delayed maturity that can be attributed to a low C-availability for fruits. In Fe-deficient pear trees, the majority of fruits (98%) were on non-chlorotic or moderately chlorotic branches, and fruits were less green and firm with an increased sugars/acids ratio. This indicates an advanced fruit maturity that can be attributed to an increased C-availability for fruits. All chlorosis levels increased within-tree variation in fruit appearance.