Improved Fruit Color Research Articles

Methyl jasmonate advances fruit ripening, colour development, and improves antioxidant quality of ‘Yoho’ and ‘Jiro’ persimmon

Methyl jasmonate (MJ) has potential to regulate fruit ripening and quality. ‘Yoho’ and ‘Jiro’ persimmons were sprayed with MJ (0, 2, 4, and 6 mM), four weeks before anticipated harvest to evaluate its effects on fruit colour and bioactive compounds. Preharvest MJ application significantly improved fruit colour with increased a*, b*, chroma, and colour index. The MJ 6 mM application had significantly enhanced soluble solids content (SSC), reduced total chlorophyll content in peel and pulp, and soluble and total tannins in persimmons. MJ treatments exhibited higher contents of total phenolics, flavonoids, carotenoids, and antioxidant activities. Additionally, MJ treatments enhanced the activities of shikimate dehydrogenase (SKDH), phenylalanine ammonia-lyase (PAL), catalase (CAT), superoxide dismutase (SOD), peroxidase (POD) and lipoxygenase (LOX) enzymes. Overall, pre-harvest MJ application at 6 mM four weeks before anticipated harvest could be useful for advancing colour and improving bioactive compounds in ‘Yoho’ and ‘Jiro’ persimmons.

Effects of Different Pre-Harvest Bagging Times on Fruit Quality of Apple.

Pre-harvest bagging can improve fruit color and protects against diseases. However, it was discovered that improper bagging times could lead to peel browning in production. Using the Ruixue apple variety as the research model, a study was conducted to compare the external and internal quality of fruits bagged at seven different timings between 50 and 115 days after full bloom (DAFB). Our findings indicate that delaying the bagging time can reduce the occurrence of peel browning in Ruixue apples. Compared to the control, the special bag reduced the browning index by 22.95%. However, the fruit point index of Ruixue fruits increased by 65.05% at 115 DAFB compared to 50 DAFB when bagging was delayed. The chlorophyll content of Ruixue fruits in special bags generally increased and then decreased, with the highest chlorophyll content of Ruixue fruits in special bags at 90 DAFB, which was 26.02 mg·kg-1. When the bagging process was delayed, the soluble solids, total phenols, and flavonoids content in the fruits increased, while the number of control volatiles decreased by 10. After two years of testing, results show that using special fruit bags at 90 DAFB bagging can significantly improve the fruit quality of Ruixue apple.

Enhancing nutritional status, growth, and fruit quality of dried figs using organic fertilizers in rain-fed orchards: A case study in Estahban, Iran.

The majority of Iranian fig production is exported, making it one of the world's most well-known healthy crops. Therefore, the main objective of the current experiment was to investigate the effects of various types of organic fertilizers, such as animal manure (cow and sheep), bird manure (partridge, turkey, quail, and chicken), and vermicompost, on the nutritional status of trees, vegetative and reproductive tree characteristics, fruit yield, and fruit quality traits in dried fig cultivar ("Sabz"). According to the findings, applying organic fertilizers, particularly turkey and quail, significantly improves vegetative and reproductive characteristics. However, other manures such as sheep, chicken, and vermicompost had a similar effect on the growth parameters of fig trees. Additionally, the findings indicated that except for potassium, use of all organic fertilizers had an impact on macro and microelements such as phosphorus, nitrogen, and sodium amount in fig tree leaves. Also, based on fruit color analysis in dried figs, the use of all organic fertilizers improved fruit color. Moreover, the analyses fruit biochemical showed that the use of some organic fertilizers improved that TSS and polyphenol compounds such as coumarin, vanillin, hesperidin gallic acid and trans frolic acid. In general, the results indicated that the addition of organic fertilizers, especially turkey manure, led to increased vegetative productivity and improvement in the fruit quality of the rain-fed fig orchard.

THE EFFECT OF DIFFERENT MOLECULAR WEIGHTS OF CHITOSAN ON THE YIELD, QUALITY, AND HEALTH-PROMOTING PROPERTIES OF STRAWBERRIES

Chitosan could be an alternative to synthetic plant protection chemicals commonly used in strawberry cultivation. The aim of this study was to determine the effect of chitosan with different molecular weights on the yield, health, and quality of Korona cultivar strawberries. The largest number of strawberries was harvested from plants sprayed with chitosan with a molecular weight of 50k kDa (611 g/plant). On the other hand, the largest (1017 g/100 fruit) and the firmest (225 G mm) strawberries were harvested from plants sprayed with chitosan125k kDa. Compared with the control, chitosan with a molecular weight >50 kDa also increased the contents of l-ascorbic acid and polyphenols and the antioxidant activity and improved fruit colour compared with the control. The plants were also more resistant to grey mould infestation. The experiment has shown that how chitosan interacts with fruit depends on its molecular weight, and chitosan with a higher molecular weight has a better effect on most traits determining fruit quality.

When Plant Breeding Meets Population Genomics

Production of cherries with large fruit size, rich color and high firmness is extremely critical in today’s competitive market. The influence of Foliar TRIGGRR® (TRIGGRR®), a cytokinin-containing compound, on fruit quality attributes of ‘Bing’, ‘Chelan’, and ‘Lapin’ were studied under climate conditions of Intermountain West region in Southwest Idaho, USA. TRIGGRR® reduced fruit-stem removal force, fruit firmness, and soluble solids in ‘Bing’ cherry. However, application of TRIGGRR® significantly improved fruit color but did not have any effect on fruit weight, firmness, or soluble solids concentration in ‘Chelan’ cultivar. TRIGGRR® significantly improved fruit quality of ‘Lapin’ cherry by enhancing fruit size, fruit-stem removal force, and firmness. Thus, the application of this compound on ‘Chelan’ and ‘Lapin’ cultivars is recommended, as fruit from this region is mostly exported to far destinations, and fruit with higher rigidity and firmness can withstand damages and bruising during the transportation. Studying potential synergism or antagonism effect of TRIGGRR® with other growth regulators in cherries is strongly recommended.

The Influence of a Cytokinin-Containing Bio-Stimulant on Fruit-Stem Removal Force and Quality Attributes in Cherries

Production of cherries with large fruit size, rich color and high firmness is extremely critical in today’s competitive market. The influence of Foliar TRIGGRR® (TRIGGRR®), a cytokinin-containing compound, on fruit quality attributes of ‘Bing’, ‘Chelan’, and ‘Lapin’ were studied under climate conditions of Intermountain West region in Southwest Idaho, USA. TRIGGRR® reduced fruit-stem removal force, fruit firmness, and soluble solids in ‘Bing’ cherry. However, application of TRIGGRR® significantly improved fruit color but did not have any effect on fruit weight, firmness, or soluble solids concentration in ‘Chelan’ cultivar. TRIGGRR® significantly improved fruit quality of ‘Lapin’ cherry by enhancing fruit size, fruit-stem removal force, and firmness. Thus, the application of this compound on ‘Chelan’ and ‘Lapin’ cultivars is recommended, as fruit from this region is mostly exported to far destinations, and fruit with higher rigidity and firmness can withstand damages and bruising during the transportation. Studying potential synergism or antagonism effect of TRIGGRR® with other growth regulators in cherries is strongly recommended.

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.

Harpin Protein Influence on Fruit Quality Attributes, Ethylene, Respiration, and Minerals in Apples

The competitive global fruit market mandates production of apples with high quality attributes, particularly fruit color. Harpin Protein (Messenger®) is shown to trigger resistance to blue mold in apples, but limited information can be found on the effect of this compound on fruit quality. In this study, the impact of Harpin protein on quality attributes of four apple cultivars was studied. “Red Spur Delicious” apple fruit from trees receiving Harpin protein had significantly (about 23%) better color, earlier ethylene evolution, and higher respiration than those from untreated control trees, while their firmness was not adversely affected. Application of Harpin protein on “Red Chief Delicious” apple improved fruit color and increased fruit size in two locations, and advanced starch degradation pattern in one orchard but reduced fruit firmness in one location. Harpin protein tended (but not significantly) to improve fruit color in “Jonathan” and “Early Spur Rome” but reduced fruit size in “Jonathan” apples. Messenger® increased fruit percentage dry weight and Fe but decreased fruit Ca, Mg, K, and Zn. Improving apple fruit color by Harpin protein could have major impacts on apple industry and warrants further study.

The Improvement of Productive Performances of Clementine Trees (Citrus Clementina Hort. Ex Tan.) Sprayed with Reflective Material

ABSTRACT Decrease in photosynthesis results from high leaf temperature, photosynthetic photon flux density, and UV-B. Here, we investigated whether a reflective material (kaolin) could improve photosynthetic performance and yield of clementine (Citrus clementina Hort. ex Tan., “Comune” cultivar) in southern Italy. Kaolin was sprayed on tree canopies every month during two summers; gas exchange, fluorimetry, and qualitative and productive parameters were measured. Kaolin increased the total average yield per tree and improved fruit color. PCA indicated that the best performances were obtained with kaolin in the last harvest. Kaolin affected the final fruit price by 3%, justifying its use.

Tomato Fruit Yield, Quality, and Nutrient Status in Response to Potassium: Calcium Balance and Electrical Conductivity in the Nutrient Solution

Tomato fruits of high quality and yield are of interest to greenhouse growers. As potassium (K) and calcium (Ca) have been associated with fruit quality, we studied the effect of the balance between such cations and the electrical conductivity (EC) on fruit yield and quality. Plants were fertigated with K (Kext) and Ca (Caext) balances in the nutrient solution varying from 0.54–1.22 and 0.69–1.44 at ECs of 2.3 ± 0.1 dS m−1 and 2.7 ± 0.1 dS m−1, respectively. Optimum balance for fruit yield was 0.82–0.85, and it was associated with high fruit K internal (Kint) concentration (~ 200 mmol kg−1). Higher EC increased firmness when the balance was ≤ 1.00, with the optimum at 0.85; firmness was correlated with Caint when EC was 2.3 dS m−1; however, at 2.7 dS m−1, increasing Kext increased firmness and intensified the effect of Caext. Increasing a* values were associated with high lycopene and uniform maturation when that balance was 0.82 and 1.00 at low and high EC, respectively. Highest a* values were observed when Kint in the fruit was ~ 200 mmol kg−1, while 91 to 130 mmol kg−1 were associated with lower a* values. Fruits contained higher starch (+ 20%), total (+ 12%), and reducing sugars (+ 29%) at high EC. The optimum K and Ca balance, 0.82–0.85, is independent of their concentration and was associated with high yield and firmness, improved fruit color, and increased lycopene and sugar concentrations.

Pre-harvest spray application of prohexadione-calcium and paclobutrazol improves rind colour and regulates fruit quality in M7 Navel oranges

Abstract Sweet orange (Citrus sinensis L. Osbeck) cv. ‘M7’ Navel exhibits poor flavedo colour at harvest in Western Australia. Gibberellins are known to retard fruit colour development in citrus fruit, therefore the efficacy of different concentrations and timings of spray applications of two inhibitors of gibberellin biosynthesis such as prohexadione calcium (Pro-Ca) and paclobutrazol (PBZ) on flavedo colour development and fruit quality was investigated. The effects of an aqueous solution containing different concentration of Pro-Ca (200, 400, 600, 800, 1200, 1600 or 2000 mg L−1), and PBZ (100, 250, 500, 1000, 1500 and 2000 mg L−1) sprayed at 6 or 3 weeks before anticipated harvest (WBAH) on flavedo colour development particularly from yellow to deep orange and on the fruit quality were investigated during 2015 and 2016. Unsprayed trees were kept as control. The spray application of Pro-Ca (800 mg L−1) resulted in decreased hue angle (h°) (57.5), and increased citrus colour index (CCI) (10.2) and, total carotenoid levels (38.3 mg kg−1) in the flavedo during 2015. Furthermore, Pro-Ca (600 or 800 mg L−1) showed enhanced levels of total carotenoids (39.2 and 38.3 mg kg−1) respectively, during 2015. In 2016, a single spray application Pro-Ca (1200 mg L−1) at 3 WBAH exhibited reduced h° (56.6) and increased CCI (10.7), and levels of total carotenoids (36.8 mg kg−1) as compared to the control. Additionally, a single spray application of Pro-Ca (800, 1200 or 1600 mg L−1) was able to increase total carotenoids in the flavedo (32.7, 36.8 or 33.1 mg kg−1) respectively. In 2016, Pro-Ca (800 mg L−1) exhibited increased SSC (13.0%) and reduced TA (1.08%) in the fruit juice. A single spray application of PBZ (1000 mg L−1) at 6 WBAH significantly reduced h° (56.7) and increased CCI (10.6) and levels of total carotenoids in the flavedo (42.6 mg kg−1). However, a single spray application of PBZ (1500 mg L−1) at 3 WBAH showed lower h° (55.4) and enhanced CCI (11.2) and level of total carotenoids (47.1 mg kg−1) in the flavedo during 2016. In conclusion, pre-harvest spray application of Pro-Ca (800 and 1200 mg L−1) applied at 6 and 3 WBAH respectively enhanced fruit colour. A single pre-harvest spray application of PBZ (1000 and 1500 mg L−1) applied at 6 and 3 WBAH respectively improved fruit colour in early maturing ‘M7’ Navel.

Relationship among color development, anthocyanin and pigment-related gene expression in ‘Crimson Seedless’ grapes treated with abscisic acid and sucrose

‘Crimson Seedless’ is one of the most important table grape varieties in Chile, but under certain environmental conditions, the fruit exhibits inadequate red color development, causing economic losses due to lower product quality. The use of plant growth regulators, such as abscisic acid (ABA) and ethylene, during development increases the anthocyanin content of the skin, improving the color of the berry. Recently, sucrose has been identified as a signaling molecule capable of regulating the expression of genes of the anthocyanin biosynthesis pathway. The aim of this study was to analyze the effect of application of ABA and/or sucrose on color development and their relationship with anthocyanin metabolism. Applications of ABA (400 ppm or 200 ppm) and/or sucrose (90 mM) were performed close to the véraison stage. During development and at harvest, quality attributes such as berry firmness, total soluble solids and titratable acidity were not affected by these treatments. Increased red color development was observed in fruits treated with ABA and/or sucrose, due to accumulation of anthocyanins. Fruits subjected to sucrose treatment showed higher levels of anthocyanins than untreated fruits but lower levels than fruits treated with ABA. Increased expression of genes involved in anthocyanin biosynthesis was observed in ABA- and sucrose-treated fruits compared to untreated fruits. Based on these findings, we demonstrated that sucrose improved fruit color development by increasing synthesis and accumulation of anthocyanins, thus allowing earlier harvests and improving table grape quality.

Studies on Macronutrient Fertilization in Pomegranate under Sub-Tropical Plains

An investigation was carried out to study the influence of different levels of NPK fertilizers on plant growth, fruit yield and quality, and leaf NPK content in pomegranate cv. Kandhari under sub-tropical conditions. Graded doses of nitrogen (0-300g/plant), phosphorus (0-150g/plant) and potassium (0-300g/plant) fertilizers were applied through soil, in addition to a basal dose of FYM. Control plants were fed FYM only. Maximum increase in plant growth and fruit yield was recorded in plants receiving NPK @ 300:50:100g/plant, while Control plants registered least growth and yield. Potassium levels improved fruit weight over the Control. Higher dose of potassium also improved fruit colour and enhanced peel thickness and grain weight. Maximum TSS:acid ratio was seen with NPK @ 200:50:100g/plant. Reducing sugars were not affected by any treatment. Leaf N, P and K content increased with application of the respective nutrient.

Isolation and Expression Analysis of Anthocyanin Biosynthesis Genes from the Red Chinese Sand Pear, Pyrus pyrifolia Nakai cv. Mantianhong, in Response to Methyl Jasmonate Treatment and UV-B/VIS Conditions

The effects of UV-B/VIS on the expression of genes involved in anthocyanin biosynthesis in the red Chinese sand pear cultivar ‘Mantianhong’, and the role played by the plant hormone methyl jasmonate (MJ) in this effect, were investigated. Four full-length cDNAs and three partial cDNA fragments of genes involved in anthocyanin biosynthesis were isolated from the cultivar. PpPAL2 and PpCHS2 showed considerable sequence identity to the reported PpPAL1 and PpCHS1 sequences. Other genes showed low pronounced sequence identity to other reported members of the same gene family. Bagged mature pear fruits were harvested and then used for postharvest treatment. Fruits were immersed in distilled water, then irradiated with UV-B/VIS light; or treated with MJ first, and then irradiated with UV-B/VIS light. Fruits immersed in distilled water and kept in darkness were used as controls. During UV-B/VIS irradiation, most anthocyanin biosynthesis genes were upregulated in pears in quantities commensurate with the accumulation of anthocyanin, but PpDFR1, PpDFR2, PpbHLH, and PpWD40 were not. MJ treatment had two effects on the expression of genes related to anthocyanin biosynthesis. It advanced the peak time and increased mRNA levels. Each family member of genes involved in anthocyanin biosynthesis showed a differential expression profile. The expression patterns of two genes regulating MJ-mediated plant responses, PpJAZ1 and PpCOI1, were also analyzed. More obvious downregulation and upregulation of PpJAZ1 and PpCOI1, respectively, were detected at 2 days of irradiation (DI) in fruits that were subjected to MJ treatment, as the expressions of most genes related to anthocyanin biosynthesis peaked at this time. We also showed that the regulation of MJ and UV-B/VIS occurred at the transcriptional level. These findings should improve our understanding of the molecular mechanism(s) underlying anthocyanin biosynthesis, which may in turn facilitate the development of new methods to improve fruit color.

NEW MANGO HYBRIDS FROM AUSTRALIA

The Australian National Mango Breeding Program has been breeding mangoes since 1994. In recent years, evaluation of the elite selection have identified three high performing hybrids, NMBP1243, NMBP1201 and NMBP4069, which are in the process of commercial release. These hybrids all have 'Kensington Pride' as their paternal parent and are characterised by improved fruit colour and tree productivity over 'Kensington Pride'. NMBP1243 is noted for its early season production, and NMBP1201 and NMBP4046 for their firm fruit. The hybrids were produced using hand pollination breeding and selection techniques. The breeding program is ongoing with the current hybridisation program being supported by a multidiscipline approach, that includes marker assisted screening, disease screening, postharvest evaluation and a genomics gene discovery program.

Delayed harvest and cold storage period influence ethylene production, fruit firmness and quality of ‘Cripps Pink’ apple

The effects of harvest date and cold storage period on ethylene production, fruit firmness and quality of ‘Cripps Pink’ apple were investigated. Fruit were harvested from Perth Hills and Donnybrook (Western Australia) at commercial maturity (CM), 2, 4 and 6 weeks after CM prior to 0, 45, 90 and 135 days cold storage in 2003 and 2004. Delayed harvest significantly increased ethylene production, CIE values a* and C* at both locations in 2 years. Delayed harvest and extended cold storage period increased the internal ethylene production and reduced fruit firmness, soluble solids concentration: titratable acidity (SSC:TA) ratio and reduced CIE values L*, b*, h° during both years and locations. Fruit harvested 2 weeks after CM can be cold-stored for 90 days with acceptable fruit quality. If the fruit is intended to be sold fresh immediately in local markets, the harvest can be delayed up to 6 weeks after CM to harness substantially improved fruit colour with acceptable fruit quality.

‘Mountain Majesty’: A Tomato Spotted Wilt Virus-resistant Fresh-market Hybrid Tomato and Its Parents NC 714 and NC 1CS

‘Mountain Majesty’, the F1 hybrid of NC 714·NC 1CS (Fig. 1), resulted from a tomato breeding effort to develop a superior largefruited hybrid tomato with improved fruit color based on the crimson (og) gene combined with fusarium wilt, verticillium wilt, and TSWV resistances adapted to vine-ripe production in North Carolina (NC). NC 714 resulted from selfing NC 03113, the F1 hybrid of Fla 8044 · NC 00318–15(x)-1 (Fig. 1). Fla 8044 is a large-fruited, hightemperature fruit set line with desirable horticultural traits and multiple disease resistance genes obtained from the University of Florida tomato breeding program. NC 00318–15(x)-1 is an F2 selection obtained by crossing a male sterile version of NC 84173 with an F3 generation line derived from selfing the North Carolina State University (NCSU)-released hybrid ‘Mountain Crest’ (NC 84173 · NC 1 rinEC) (Gardner, 2006). The crimson gene in NC 714 was derived from the NC 1rinEC parent of ‘Mountain Crest’ and Fla 8044. The objective of breeding NC 714 was to incorporate desirable fruit characteristics and superior combining ability from NC 84173 (Gardner, 1992) together with the crimson gene for increased red fruit color and lycopene content. Single plant selections were made for large fruit size, high yield, and other desirable horticultural traits in the F2 through F5 generations derived from selfing NC 03113. NC 1 CS resulted from selfing NC 056, the F1 hybrid of NC 123S ·NC 0255(x)-1 (Fig. 1). NC 123S, which combines single dominant gene resistances to TSWV, fusarium wilt race 3, and nematodes (Sw-5, I-3, Mi genes) and was released from the NC breeding program. ‘Amelia’ F1 hybrid, from which NC 123S was developed, is a codeveloped hybrid using NC 111F-2(98) as a source of the I-3 gene for fusarium wilt race 3 resistance crossed with a Clause Seed Company proprietary line having the Sw-5 and Mi genes. NC 0255(x)-1 is an outstanding large-fruited selection with the crimson gene that traces its pedigree back to breeding lines and cultivars developed in the NC tomato breeding program over a 25year period (Fig. 1). The source of the crimson gene in NC 0255(x)-1 is ‘Suncoast’, an inbred cultivar released from the University of Florida breeding program.

HIGH TEMPERATURE EFFECTS ON CITRUS ORANGE LEAF GAS EXCHANGE, FLOWERING, FRUIT QUALITY AND YIELD

High midday temperatures in subtropical citrus growing regions can lead to excessively high leaf temperature (Tlf) and large leaf-to-air vapor pressure difference (D) in sun exposed leaves. This heat stress reduced net CO2 assimilation (AC), growth, fruit yield and quality. 50% shading reduced average mid-day Tlf and increased AC, stomatal conductance (gs) and leaf water use efficiency, but decreased the internal concentration of CO2 (Ci) in the mesophyll compared with sun-exposed trees throughout the season. However, shade had little effect on leaf transpiration. Heat stress increased non-stomatal limitations to AC in the mesophyll of sunlit leaves that were greater than stomatal limitations. Shade treatment reduced leaf carbohydrates but did not affect tree canopy volume or fruit size. Shading in the late fall until harvest increased orange yield and juice content more than compensated for the lower total soluble sugars (TSS) and resulted in net increases in TSS per tree. Shaded ‘Navel’ orange fruit developed better external color but lower TSS than sun-exposed fruit. Shade did not affect orange fruit yields. In warm citrus producing regions, shading could improve photosynthesis and fruit quality especially in young trees where most of the leaves are exposed to direct sunlight. Improved fruit color, yield and/or TSS per hectare of high-value varieties could offset the costs of particle film sprays or shading in commercial orchards.

REFLECTIVE GROUND COVERS INCREASE YIELDS OF TARGET FRUIT OF APPLE AND PEAR

Reflective ground covers, such as Extenday ™ or Daybright ™ , increase the amount of light within the canopy available for photosynthesis, especially in the lower, shaded portions of tree canopies. These white woven polyethylene mulch cloths can be moved between crops in a single growing season and reused for up to ten years, thus reducing waste. Since 2005, the Washington Tree Fruit Research Commission (WTFRC), in collaboration with Extenday Ltd., has evaluated the horticultural effects of reflective ground covers in commercial Washington apple (Malus domestica) and pear (Pyrus communis) orchards. Extenday ™ and Daybright ™ have consistently improved fruit color and yields of desired fruit by increasing fruit set and/or harvest size; neither fruit set nor harvest size have ever been reduced relative to untreated controls. Fruit color development has frequently been advanced by these materials, enabling earlier harvests and in some cases, fewer picks. Yields have increased every year in Extenday ™ treated apple plots, suggesting a cumulative effect on increasing productivity. Aluminium-based ground covers such as Mylar ™ (1.75 m wide in the central alleyways) did not increase 'Gala' apple color as much as Extenday ™ , and had no effect on fruit size or yield. While initial capital costs for Extenday ™ products are relatively high, our results have shown consistent positive increases of production of target fruit suggesting a significant return on investment. These impacts are most clear in high density, well-managed systems.

ORGANIC MANGO PRODUCTION IN MEXICO: STATUS OF ORCHARD MANAGEMENT

Eight percent of total planted area in Mexico is in the process to change from conventional to organic system mainly in the Pacific Coast under tropical dry and wet conditions. Mango cultivars in organic systems are ‘Tommy Atkins’, ‘Kent’, ‘Ataulfo’ which are demanded by market and early or late season of harvest. Cultivars are grafted on local polyembrionic rootstock well adapted to different soil types, they remain vigorous but tolerance to soil diseases has not been proved yet. Information of better combinations of rootstocks and cultivars appropriated for organic production and adapted to variable soil conditions, is needed. Plant densities range 100 to 200 trees ha-1, but are rapidly changing to higher tree densities. Either, tillage practices or cover crops are used to avoid herbicides to control weeds in between tree rows. Pruning of trees is a very important activity applied by growers to control tree size, avoid pest and diseases and promote better light conditions in internal canopy to improve fruit color. Many diseases affect tree foliage, flowering and fruits and are properly controlled using permitted products listed by IFOAM. However organic and more efficient alternatives are needed in order to control the wide diversity of diseases in the field. In addition to field applications, anthracnose damage on fruits is controlled by means of postharvest hot water treatments. Fruit flies are important pests, but they are kept under control with integrated management program applied to different regions according to population levels. Several organic products are used to fertilize orchards, but beneficial impact on fruit production and quality remain to be thoroughly clarified.