Melon Fruit Quality Research Articles

INFLUENCES OF GRAFTING ON AROMATIC COMPOUNDS IN MUSKMELON BY SOLID PHASE MICROEXTRACTION WITH GC-MS

There has been an increase in popularity of grafting technique on muskmelon in agricultural production because grafting of melon increased its disease resistance to fusarium wilt, but melon's (Cucumis melo L.) quality has been more serious inferior than its own-rooted melon. The volatiles substance plays an important role in melon fruit quality. We have found very little reports in literature for melon grafting varieties and using solid-phase microextraction (SPME). The objective of this experiment was to identify volatile and semivolatile compounds in two melon cultivars 'Lu135' and 'Lu7475', using solid-phase microextraction (SPME) with gas chromatography-mass spectrometry (GC-MS). Fully ripe melon was squeezed through miracloth to produce rapid juice extracts for immediate headspace SPME GC-MS. One hundred forty two volatile compounds were separated in ripe muskmelon, they consisted of 56 esters, 27 alcohols, 3 aldehydes, 17 ketones, 21 alkenes and 18 other substances. Among these compounds, types of esters and alcohols were the important aroma components accounting for over 74.75-93.46% of total peak area. The most abundant compounds in two cultivars were acetic acid, phenylmethyl ester (21.65-36.43%), acetic acid, hexyl ester (6.05-12.95%), ethyl acetate (2.89-9.94%), 1-butanol, 2-methyl-, acetate (5.84-7.82%). The total aromatic compounds and characteristic aromatic esters contents decreased in grafted melons than the own-rooted melon. The delightful fruit aroma in grafting melon was lower and thinner in comparison to own-rooted. Meanwhile, the aroma components of melon were altered because of grafting in adopting of melon. However, the effect of grafting on aroma components was different between two varieties. The total esters content and category in 'Lu135' was obviously lower in grafting melons than own-rooted and it had little chance on 'Lu7475'.

The Effects of Nutrient Solution Management on the Mineral Contents, Growth and Fruit Quality of Melon in Different Hydroponic Systems

The Effects of Nutrient Solution Management on the Mineral Contents, Growth and Fruit Quality of Melon in Different Hydroponic Systems

The Influence of Rootstock Selection on Fruit Quality Attributes of Watermelon

Grafting watermelon (Citrullus lanatus) to control Fusarium wilt has been practiced in Europe, the Middle East, and the Far East for decades. Until recently, grafting watermelon has not been practiced in the United States due to labor costs and land availability. There is some disagreement in the literature as to the effects that grafting has on water- melon fruit quality. This study was designed to determine the effects of grafted watermelon on fruit firmness, lycopene content, and total soluble solids (TSS) using five different rootstocks. When using Cucurbita ficifolia or Cucurbita maxima x Cucurbita moschata hybrid as the rootstock, watermelon fruit consistently had higher fruit firmness values. Other C. maxima x C. moschata hybrids or Lagenaria siceraria rootstocks generally produced lower or more varied fruit firmness values. Grafting increased fruit firmness by as much as 25% in some cases, but field and year effects were ob- served. In addition, grafting had no effect on lycopene content or TSS. Furthermore, no off-flavors were detected in fruit from grafted plants, but there was a 5- to 7 day delay in fruit maturity compared to their non-grafted counterpart. Although environment can have a major influence on fruit quality attributes, rootstock selection may be equally important in achieving the desired outcome.

Effects of different irrigation programs on the growth, yield, and fruit quality of drip-irrigated melon

A field study was conducted in Ankara, a semi-arid region of Central Anatolia, Turkey, on clay-loamy soils in the vegetation seasons of 2005 and 2006. Kırkağaç melon cultivar (Cucumis melo L. cv. Kırkağaç) was irrigated by the drip method from transplantation to the beginning of the flowering (IS_f), fruit setting (IS_{fs}), ripening (IS_r), and harvesting (IS_h) periods. Water amounting to 50% (P_{50}), 75% (P_{75}), and 100% (P_{100}) of full irrigation water were applied. Some analyses were carried out regarding the growth, yield, and fruit quality parameters in these irrigation programs. Moreover, the amount of water, the seasonal evapotranspiration, and the water use efficiency having been used were determined for each irrigation program. Carrying on the irrigation during the ripening period furthered shoot growth except P_{100} application, did not significantly affect fruit yield and the soluble solids content of the fruit flesh. Similar but relatively larger fruit size and heavier weight were found in the treatments of IS_r and IS_h. Fruit yields in the P_{75} and P_{100} applications were found similar, but they were found to be higher than the P_{50} application. The soluble solids contents and the ratings of sensory characteristics were higher in the P_{75} application. As a result of this study, with respect to the considerably high yield and fruit quality, it was suggested that irrigation be kept on going until the beginning of fruit setting, not during the ripening period, and the application of 75% of full irrigation water amount (IS_r P_{75}) is the most convenient irrigation program. In addition, irrigation water amounting to 319.6-331.1 mm was applied and 427.1-472.6 mm seasonal evapotranspiration and 8.9-9.2 kg m^{-3} water use efficiency was determined in the (IS_r P_{75}) irrigation program.

Relações entre cátions trocáveis do solo e suas correlações com a qualidade de frutos de melão

A qualidade dos frutos de melão pode ser prejudicada pelo excesso de nutrientes no solo e pelo desequilíbrio entre eles, causados por adubações excessivas e desuniformes. A amostragem em duas áreas de produção de melão foi realizada para identificar entre relações catiônicas do solo (K:(Ca+Mg), K:Ca, K:Mg, K:CTC, Ca:Mg, Ca:CTC, Mg:CTC, Na:Ca, Na:Mg e PST) aquelas melhor correlacionadas com características de qualidade (espessura de polpa, firmeza da polpa e teor de sólidos solúveis totais). Para tanto se utilizou a estatística descritiva, o coeficiente de correlação de Spearman e a regressão múltipla. As variáveis de qualidade de frutos de melão apresentaram poucas correlações com as relações catiônicas do solo. No Goldex, as melhores correlações foram de K:CTC com espessura de polpa; Ca:CTC e Mg:CTC com firmeza de polpa e K:CTC, K:Ca, K:(Ca+Mg), Na:Ca e Na:Mg com SST, todas positivas. No Orange Flesh, observaram-se correlações apenas de firmeza de polpa com Ca:CTC (positiva), K:Mg, K:Ca, K:(Ca+Mg) e Na:Ca (negativas). No Orange Flesh, através da contribuição para as regressões, identificou-se como mais importantes as relações catiônicas Ca:CTC para espessura (6,2%) e firmeza de polpa (10,9%), e Mg:CTC para o teor de sólidos solúveis totais (1,5%).

Genetic dissection of fruit quality components in melon (Cucumis melo L.) using a RIL population derived from exotic × elite US Western Shipping germplasm

Growing environment dramatically influences melon (Cucumis melo L.; 2n = 2x = 24) fruit development and quality. Consequently, the characterization of quantitative trait loci (QTL) controlling melon fruit quality for application in marker-assisted selection (MAS) requires an assessment of genotype by environmental interactions, trait correlations, and QTL efficacy. Therefore, fruit quality traits [soluble solids content (SSC), mesocarp pressure (MP), fruit diameter (mesocarp + exocarp; FD), seed cavity diameter (endocarp; SCD), seed cavity to FD ratio (C:D), fruit shape (FS), and percentage of exocarp netting (PN) at time of harvest] were examined in 81 recombinant inbred lines (RIL) at two growing locations (California. and Wisconsin, USA) to identify the map position and consistency of QTL for MAS in a Group Cantalupensis U.S. Western Shipping market type background. RIL developed from a cross between U.S. Department of Agriculture line USDA-846-1 and ‘Top Mark’ were used to identify 57 QTL in both location tested (SSC = 10, MP = 8, FD = 6, SCD = 9, C:D = 8, PN = 6, and FS = 10). The QTL were distributed across 12 linkage groups and explained a significant portion of the associated phenotypic variation (R 2 = 4–29%). Twelve of such QTL were consistently identified in the two locations tested [SSC (ssc7.4 and ssc10.8), MP (mp7.2, mp10.3, and mplg7.5), SCD (scd1.1, scd5.4, and scd8.5), C:D (cd2.1), and PN (pn2.1), FS (fs1.1 and fs2.3)]. The map positions of 18 QTL (FS = 7, SSC = 6, C:D = 3, SCD = 1, and PN = 1) were in equivalent (i.e., collinear) genomic regions with previous studies in Group Inodorus-based maps. Six of the collinear QTL were detected in both locations in our study (ssc7.4, ssc10.8, fs1.1, fs2.3, pn2.1, and scd5.4). The collinearity of these QTL with those identified in other maps, and their consistency across diverse growing environments portends their broad applicability in melon MAS.

Reuse of inland low-salinity shrimp farm effluent for melon irrigation

Environmental impacts associated with inland shrimp farming may be attenuated by using its effluent for crop irrigation. The objective of this study was to evaluate melon (Cucumis melo L.) yield and changes in soil chemical characteristics, in response to irrigation with low-salinity shrimp farm effluent, and to compare the results with freshwater irrigation. The following treatments were applied: two sources of water for melon drip irrigation (shrimp effluent and river water) as main factors and two nitrogen doses applied through fertigation (120 and 90kgNha−1) as sub-factors. There were no significant differences among treatments regarding melon yield and fruit quality. Compared to river water, effluent irrigation decreased pH, calcium, and magnesium levels in the soil, increasing the exchangeable sodium ratio (ESR).

Effect of nitrogen fertilisation levels on melon fruit quality at the harvest time and during storage

AbstractBACKGROUND: The quality of melon fruit depends upon many factors that can be affected by growing conditions and post‐harvest management. The aim of this work was to investigate the effect of nitrogen fertilisation levels on the fruit quality at harvest time and during storage. Experiments were performed in an open field using melon plants (Cucumis melo L. Var. Reticulatus cv. Prodigio). The nitrogen (N) was applied through fertigation using four fertilisation levels: 0, 55, 110 and 165 kg ha−1. After harvest the fruits were stored at 10 °C for 8 days. At harvest time the yield, flesh firmness, skin and pulp colours, content of carotenoids, total phenols, ascorbic acid (AsA) and ethylene production were measured on fruits differently fertilised.RESULTS: The total marketable fruit yield and fruit nitrogen content linearly increased with N levels. Antioxidant compounds decreased after storage but were not affected by N fertilisation levels. However, total carotenoids, total phenols, and AsA declined during storage.CONCLUSION: All the quality parameters did not appear to be affected by N level at either harvest time or after storage. Therefore it is advisable to reduce nitrogen input for cultivation without compromising quality and yields. Copyright © 2007 Society of Chemical Industry

Melon Fruits: Genetic Diversity, Physiology, and Biotechnology Features

Among Cucurbitaceae, Cucumis melo is one of the most important cultivated cucurbits. They are grown primarily for their fruit, which generally have a sweet aromatic flavor, with great diversity and size (50 g to 15 kg), flesh color (orange, green, white, and pink), rind color (green, yellow, white, orange, red, and gray), form (round, flat, and elongated), and dimension (4 to 200 cm). C. melo can be broken down into seven distinct types based on the previously discussed variations in the species. The melon fruits can be either climacteric or nonclimacteric, and as such, fruit can adhere to the stem or have an abscission layer where they will fall from the plant naturally at maturity. Traditional plant breeding of melons has been done for 100 years wherein plants were primarily developed as open-pollinated cultivars. More recently, in the past 30 years, melon improvement has been done by more traditional hybridization techniques. An improvement in germplasm is relatively slow and is limited by a restricted gene pool. Strong sexual incompatibility at the interspecific and intergeneric levels has restricted rapid development of new cultivars with high levels of disease resistance, insect resistance, flavor, and sweetness. In order to increase the rate and diversity of new traits in melon it would be advantageous to introduce new genes needed to enhance both melon productivity and melon fruit quality. This requires plant tissue and plant transformation techniques to introduce new or foreign genes into C. melo germplasm. In order to achieve a successful commercial application from biotechnology, a competent plant regeneration system of in vitro cultures for melon is required. More than 40 in vitro melon regeneration programs have been reported; however, regeneration of the various melon types has been highly variable and in some cases impossible. The reasons for this are still unknown, but this plays a heavy negative role on trying to use plant transformation technology to improve melon germplasm. In vitro manipulation of melon is difficult; genotypic responses to the culture method (i.e., organogenesis, somatic embryogenesis, etc.) as well as conditions for environmental and hormonal requirements for plant growth and regeneration continue to be poorly understood for developing simple in vitro procedures to culture and transform all C. melo genotypes. In many cases, this has to be done on an individual line basis. The present paper describes the various research findings related to successful approaches to plant regeneration and transgenic transformation of C. melo. It also describes potential improvement of melon to improve fruit quality characteristics and postharvest handling. Despite more than 140 transgenic melon field trials in the United States in 1996, there are still no commercial transgenic melon cultivars on the market. This may be a combination of technical or performance factors, intellectual property rights concerns, and, most likely, a lack of public acceptance. Regardless, the future for improvement of melon germplasm is bright when considering the knowledge base for both techniques and gene pools potentially useable for melon improvement.

Identification of Melon Fruit Quality Quantitative Trait Loci Using Near-isogenic Lines

A collection of melon (Cucumis melo L.) near-isogenic lines (NILs) derived from the cross between the Spanish C. melo cultivar Piel de Sapo (PS) and the exotic Korean accession Shongwan Charmi [SC (PI161375)], was used to study the genetic control of a large number of melon fruit quality traits, including morphological, external appearance, texture, flavor, and the overall differences between NILs and PS that might be detected by consumers with a triangle test. Heritability was significant for all the traits, being >0.5 for the whole area of the longitudinal section of the fruit, flesh proportion, skin lightness color, hue angle coordinate of flesh color, and flesh-extractable juice. NILs were classified by principal-component analysis. The first principal component (22% of the variation) was affected mostly by morphological traits, the second component (10%) was influenced by internal and external morphology pattern and color, and the third component (9%) was controlled mainly by flavor traits. An average of 5.6 quantitative trait loci (QTL) per trait were identified (range, between 1 and 12 QTL; 134 QTL in total). In most cases, allele effects with opposite actions were detected. A substantial number of QTL may be good candidates to introduce new quality attributes in modern melon cultivars.

Candidate genes and QTLs for fruit ripening and softening in melon

Different factors affect the quality of melon fruit and among them long shelf life is critical from the consumer's point of view. In melon, cultivars showing both climacteric and non-climacteric ripening types are found. In this study we have investigated climacteric ripening and fruit softening using a collection of near-isogenic lines (NILs) derived from the non-climacteric melon parental lines PI 161375 (SC) and "Piel de Sapo" (PS). Surprisingly, we found that QTL eth3.5 in NIL SC3-5b induced a climacteric-ripening phenotype with increased respiration and ethylene levels. Data suggest that the non-climacteric phenotypes from PI 161375 and "Piel de Sapo" may be the result of mutations in different genes. Several QTLs for fruit flesh firmness were also detected. Candidate genes putatively involved in ethylene regulation, biosynthesis and perception and cell wall degradation were mapped and some colocations with QTLs were observed. These results may provide additional data towards understanding of non-climacteric ripening in melon.

Estimating the Genetic Architecture of Fruit Quality Traits in Melon Using a Genomic Library of Near Isogenic Lines

A melon (Cucumis melo L.) genomic library of near-isogenic lines derived from the cross between the Spanish cultivar Piel de Sapo and the exotic accession PI 161375 has been evaluated for fruit quality traits in four different locations. Traits evaluated were fruit weight, soluble solids content, maximum fruit diameter, fruit length, fruit shape index, ovary shape index, external color, and flesh color. Among these traits, soluble solids content showed the highest genotype × environment interaction, whereas genotype × environment interactions for fruit shape and fruit weight were low. Heritability was high for all traits except soluble solids content, with the highest value for fruit shape and ovary shape. Ten to 15 quantitative trait loci were detected for soluble solids content, fruit diameter, fruit length, and fruit shape; and four to five for ovary shape, external color, and flesh color. Depending on the trait, between 13% and 40% of the detected quantitative trait alleles from PI 161375 increased the trait, and between 60% and 87% of them decreased it, resulting in some PI 161375 alleles of interest for breeding. Most of the quantitative trait loci detected in previous experiments could be verified with the near-isogenic line population. Future studies with the melon near-isogenic line genomic library will provide a better understanding of the genetic control of melon fruit quality in a wider context related to agronomy, genetics, genomics and metabolomics studies.

Qualidade de melões (Cucumis melo L. var. cantalupensis Naud.), híbrido Torreon, produzidos em hidroponia e armazenados em embalagens de polietileno

Este experimento teve por objetivos avaliar a permeabilidade de filmes de polietileno de diferentes espessuras e densidades ao O2 e ao CO2, a composição gasosa (O2, CO2 e etileno) formada no interior das embalagens e a qualidade físico-química de melões (Cucumis melo L. var. cantalupensis Naud.), híbrido Torreon, produzidos no sistema hidropônico "Nutrient Film Technique" (NFT) e armazenados em embalagens de polietileno. Os tratamentos avaliados foram: (1) armazenamento refrigerado (sem uso de filme); (2) polietileno de baixa densidade (PEBD) de 40µm; (3) PEBD de 60µm; (4) PEBD de 90µm; (5) polietileno de média densidade (PEMD) de 40µm; (6) PEMD de 60µm. Os frutos permaneceram armazenados durante 25 dias a 3,8±0,2°C e por mais dois dias a 20°C. Os filmes de PEBD de 60 e 90µm e o PEMD de 60µm apresentaram menor permeabilidade ao CO2, mantendo as maiores concentrações de CO2 nas embalagens. O filme de PEBD de 90µm apresentou menor permeabilidade ao O2. A menor concentração de etileno foi obtida com o uso de PEBD de 40µm. O uso de filmes reduziu drasticamente a perda de massa dos frutos, quando comparados aos frutos não embalados. Os frutos acondicionados na embalagem de PEBD de 40µm mantiveram uma maior firmeza da polpa após o período de armazenamento, não diferindo estatisticamente dos frutos armazenados em PEMD de 40µm. Já a incidência de podridões foi significativamente menor nos frutos armazenados em PEMD de 60µm. De modo geral, os filmes avaliados mantêm semelhante a qualidade físico-química de melões híbrido Torreon produzidos hidroponicamente no sistema NFT.

Variabilidade espacial da fertirrigação em Latossolo Vermelho Amarelo cultivado com melão

Este trabalho, realizado em Mossoró, RN, investigou a variabilidade de parâmetros da fertirrigação por gotejamento, sua dependência espacial e correlação com a produtividade e qualidade de frutos de melão. Em uma malha de 20 por 20 m foram tomadas 75 amostras, para se determinar: produção de frutos tipo exportação (PEXP), mercado nacional (PNAC) e comerciável (PCOM), peso médio de frutos comerciáveis (PMCOM), teor de sólidos solúveis totais (SST), firmeza de polpa, espessura da polpa (ESPOLP), elevação, distância até a entrada de água, além da quantidade de adubo aplicada e vazão dos gotejadores com os respectivos coeficientes de uniformidade de emissão (CUE). A variabilidade foi determinada através da estatística descritiva e da geoestatística. A vazão e a quantidade de adubo aplicada no primeiro teste, foram menores que o esperado. O CUE foi bom e excelente para vazão, e regular e bom para a quantidade de adubo aplicada. A dependência espacial foi observada para vazão e quantidade de adubo aplicada, cujas isolinhas permitiram localizar-se áreas onde ocorreu déficit ou excesso. As correlações sugerem influência da vazão sobre PNAC, PCOM e PMCOM, e da quantidade de adubo sobre PEXP e ESPOLP.

Transgenic approach to improve quality traits of melon fruit

Melon is one of the economically important and widely cultivated vegetable crops in the world. There is a wide genetic diversity in the cultivated and wild species of melon. Melon as one of the most consumed fruits, the development and ripening of fruit is known to be a complex developmental process that involves many biochemical and physiological changes including the breakdown of chlorophyll, degradation of the cell wall, increase in sugars content, alteration in pigment biosynthesis, and the accumulation of flavour and aromatic compounds. However, the information on genetic engineering and molecular biology of melon is very limited. With the development of genetics and molecular biology, a large number of quality/ripening-regulated genes involved in pigmentation, vitamin, soluble carbohydrate metabolism, cell wall metabolism and ethylene biosynthesis have been identified in melons. Some genetic manipulations of melons have been proved to be useful technology to improve quality, sensory attributes, shelf life and other agronomic traits of melon fruit. This paper reviewed some progresses in the trangenic approach to improve quality traits of melon fruit.

POTENTIAL OF A CORN STARCH-BASED BIODEGRADABLE PLASTIC FILM FOR SOIL SOLARIZATION

In temperate regions soil solarization with plastic films represents a valuable alternative to the use of methyl bromide for the control of soil borne diseases. However, large quantities of wastes are derived by plastic materials used for solar heating, whose inappropriate management could affect negatively the whole agro-ecosystem. Use of biodegradable films, which spontaneously start up a degradation process after their soil application, could represent a potential solution to these disposal problems. Greenhouse and open field experiments were undertaken in 2002 and 2003 in Southern Italy with the aim to assess the effect of soil solarization with a corn starch-based biodegradable plastic film on soil temperature, root-knot nematode (Melodogyne spp.) and weed control and crop yield, in comparison with EVA and LDPE plastic films. Mechanical and spectroradiometrical properties of the films were also studied. Use of biodegradable films resulted effective, particularly in greenhouse, for the control of nematodes and weeds improving yield and quality of melon fruits. INTRODUCTION Soil solarization is widely applied as an effective alternative to the use of chemicals for the control of soil phytoparasitic nematodes and weeds (Katan, 1981). However, the disposal of the large amounts of wastes deriving by the massive application of plastic materials in agriculture is more and more a serious environmental problem to solve. A possible solution could be represented by the use of innovative materials, such as biodegradable films, that spontaneously start up a degradation process after their application (Castronuovo, 2003). Nevertheless, technical performances of these films should be verified, more specifically if their mechanical and spectroradiometrical properties are comparable to those of traditional materials. Therefore, greenhouse and open field experiments were undertaken in southern Italy in 2002 and 2003 in order to verify the effectiveness of a corn starch based biodegradable film for solarization against phytoparasitic nematodes and weeds, in relation to its mechanical and spectroradiometrical properties. MATERIALS AND METHODS Three solarizing films, a corn starch-based biodegradable milky coloured film (40 μm thick) and two traditional transparent films (LDPE 50 μm; EVA 35 μm) were examined. Mechanical and spectroradiometrical characteristics of the films were determined at 15 days intervals during solarization using a computerized press (Galdabini PMA 10) and two spectrophotometer, working in UV-VIS-NIR (Jasco V-570) and IR (Jasco FT/IR-430), respectively. Mechanical measurements were determined by tensile (UNI 8422) and tearing (UNI 9563) strength tests, in order to obtain values of ultimate tensile strength, percentage stretch at break and tearing strength resistance (Manera et al., 2003). Proc. VI IS on Chemical and Non-Chemical Soil and Substrate Disinfestation Ed. A. Vanachter Acta Hort. 698, ISHS 2005 202 After laboratory tests the plastic films were used in two solarization trials in 2002 and 2003, either in metal and plastic tunnel greenhouse (LDPE 200 μm) and in open field in the Experimental Farm Pantanello at Metaponto (40°20’N; 16°48’E; 10 m a.s.l.). In both years, solarization treatment was applied from July 13 to September 13 on 30 m plots, after rotavation and irrigation of the soil. Plots were arranged according to a randomized block design with three replications for each treatment. During solarization soil temperatures were monitored at 10 and 30 cm depth every 30 min by precision probes (PT 100) and a CR10x data logger. Moreover, for each film the number of hours above 40°C, assumed as the minimum effective temperature on soil pathogens, was also calculated. Melon (Cucumis melo L. var. reticulatus Naud. cv. ‘Drake F1’) was cultivated in experimental plots in spring (March – July) 2003, either in greenhouse and in open field, with the aim to verify the yield response of a vegetable crop to the solarization treatment. In each plot, number and weight of marketable fruit were recorded on a 16 m area (eight plants) and soluble solids (°Brix) and pulp dry matter content were determined on ten fruits. Moreover, root-knot nematode M. javanica gall index was determined on eight plants of each plot, according to a 0-5 scale (Di Vito et al., 1979) and weeds from a 2 m sample area were counted and weighed. Data were subjected to analysis of variance and means separated by Duncan’s Multiple Range Test.

Development of a genomic library of near isogenic lines (NILs) in melon (Cucumis melo L.) from the exotic accession PI161375

A doubled haploid line (DHL) population of melon derived from a cross between the Korean cultivar "Songwhan Charmi" accession PI161375 (SC), included in the horticultural group conomon, and the Spanish cultivar "Piel de Sapo" (PS), included in the horticultural group inodorus, was used to develop a collection of near isogenic lines (NILs). These parental lines represent very different melon cultivar groups, with important differences at fruit, plant, disease response and molecular level. This cross is one of the most polymorphic ones within melon germplasm. Selected DHLs were backcrossed to PS and further backcrossing and selfing was performed, monitoring introgressions from SC using molecular markers covering the melon genetic map. A final collection of 57 NILs was obtained, containing a unique independent introgression from SC in the PS genetic background. The introgressions within the collection cover at least 85% of the SC genome with an average introgression size of 41 cM, corresponding to 3.4% of the SC genome. The average resolution for mapping genes or quantitative trait loci is 18.90 cM. This set of NILs is a potentially powerful tool for the study of quantitative trait locus involved in melon fruit quality and other important complex traits, and the introduction of new genetic variability in modern cultivars from exotic sources. The NILs can also be used as pre-competitive breeding lines in melon breeding projects.

Aspectos quantitativos e qualitativos de melão cultivado sob doses de fertilizantes orgânicos

A produtividade e qualidade do melão cultivado sob doses de fertilizantes orgânicos foram avaliados em experimento realizado de agosto a novembro de 2002 em campos de produção comercial no estado do Ceará. O híbrido de melão AF 646 (sementes Sakata) foi semeado diretamente com espaçamento de dois metros entre linhas e meio metro entre plantas. O delineamento experimental foi em blocos ao acaso com quatro repetições. Os tratamentos avaliados foram: 1) 100 g de Ribumin® por metro linear; 2) 150 g de Ribumin® por metro linear 3) 200 g de Ribumin® por metro linear; 4) 1400 g de composto Pole® por metro linear; 5) 700 g de composto Pole® + 100 g Ribumin® por metro linear, respectivamente e 6) testemunha sem adição de composto. Todos os tratamentos foram aplicados um dia antes da semeadura. Após a colheita os frutos foram contados e uma amostra aleatória de quatro frutos por parcela foi retirada para análise no laboratório. As variáveis analisadas foram peso dos frutos (PF), peso estimado da produtividade (PE) diâmetros longitudinal (DL) e transversal dos frutos (DT), espessura de polpa (EP), teor de sólidos solúveis totais (SST) e firmeza de polpa (FP). A produtividade foi calculada com os dados de número de frutos (NF) por parcela e peso médio de frutos. Avaliou-se também o custo de produção. A análise de variância revelou significância para as variáveis PF, PE, DL, EP e SST. As médias do DL e da EP e SST apresentaram diferença significativa entre a testemunha e os demais tratamentos que não diferiram entre si. Apesar de não ter sido constatada diferença estatística significativa entre as médias de produtividade, para os tratamentos onde se adicionou fertilizante orgânico, observou-se que os tratamentos nos quais foram utilizados o fertilizante Ribumin® apresentaram os menores custos de produção.

Effect of Potassium on Yield, Fruit Quality, and Chemical Composition of Greenhouse-Grown Galia Melon

ABSTRACT The effect of different potassium (K) rates on yield, fruit quality, and chemical composition of greenhouse-grown melon (Cucumis melo L., cv. Galia) was investigated. The experiment was carried out in a greenhouse similar to that used by farmers in the coastal Mediterranean region of Turkey. Control and three rates of potassium (0, 200, 400, 600 mg L−1) were applied to cv. Galia in a randomized complete block design with 3 replications. Leaf and fruit quality analyses were carried out and yield was determined. Different rates of potassium had no effect on yield. However, fruit number and fruit firmness were higher than the control at the 400 and 600 mg L−1 rates. Total soluble solids were higher than the control at the 600 mg L−1 rate. Average fruit weight was lower than the control at the 600 mg L−1 rate. Treatments did not affect nitrogen (N), phosphorus (P), calcium (Ca), magnesium (Mg), and zinc (Zn) contents of leaves, but leaf K content was higher than the control at all three rates. Iron (Fe) content was lower than the control at the 600 mg L−1 rate and manganese (Mn) content was lower at the 400 and 600 mg L−1rates. The data from our study indicate that 300 mg L−1 K in the root zone was sufficient for optimum yield of greenhouse-grown Galia melons. In terms of total yield, it is not necessary to apply higher rates of K. However, results show that it is possible to improve fruit quality by applying as much as 600 mg L−1 additional K to the plants without a reduction in yield.

Concentração de potássio na solução nutritiva e a qualidade e número de frutos de melão por planta em hidroponia

O experimento foi conduzido em hidroponia (NFT) no período de junho a novembro de 2001, na FCAV-UNESP em Jaboticabal-SP, situada a 21º15’ 22" Sul, 48º18’58" Oeste, e altitude de 575 metros. O híbrido Bônus n0 2 foi cultivado em blocos casualizados, em esquema de parcelas subdivididas, com seis repetições. Os elementos avaliados foram número de frutos por planta (2, 3, 4 e fixação livre) e concentração de potássio na solução nutritiva (66; 115,5; 165 e 247,5mg L-1). O experimento teve como objetivo avaliar a concentração de potássio na solução nutritiva e número de frutos por planta sobre a qualidade dos frutos do meloeiro. Concentrações maiores do que 66mg L-1 de potássio na solução nutritiva não promoveram incrementos nas características de qualidade dos frutos do meloeiro como: teor de sólidos solúveis médio de todos os frutos da planta, do segundo fruto, da acidez total titulável média de todos os frutos da planta, do primeiro fruto, do segundo fruto, do índice de maturação, da espessura da polpa e do índice de formato dos frutos. Frutos oriundos de plantas de melão com dois frutos apresentaram maior teor de sólidos solúveis e acidez total titulável, independente da concentração de potássio na solução nutritiva. O maior número de frutos por planta reduziu a espessura do mesocarpo dos frutos.