Murcian Institute of Agriculture and Food Research and Development IMIDA

Murcia, Spain

Murcian Institute of Agriculture and Food Research and Development IMIDA

Murcia, Spain
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Conesa A.,University Miguel Hernández | Manera J.,University Miguel Hernández | Brotons J.M.,University Miguel Hernández | Porras I.,Murcian Institute of Agriculture and Food Research and Development IMIDA
Acta Horticulturae | Year: 2015

This study analyze the influence of temperature on the evolution of the colour coordinate 'a' in the peel of the lemon cultivars 'Eureka Frost', 'Lisbon Frost' and the clone 'Fino 49', all on Citrus macrophylla rootstock. The study covered six seasons (2003/04 and 2005/06 to 2009/10) with measurements made every week or fortnight. The results point to greater correlation between the colour coordinate 'a' in peel and low temperatures than medium temperatures. The correlation between the colour coordinate and low temperatures is the greatest for the mean value recorded during the previous 21 days. The correlation for the loss of greenness in lemon peel increases when the average of the minimum temperatures, rather than the average of the means, is considered. The negative values of the colour coordinate 'a' decrease below 15-17° C, increasing as the minimum temperatures fall until they reach zero. The colour coordinate 'a' and the average minimum temperature for the 21 days preceding the measurement provide excellent adjustments. The good values of R2 for the cultivars 'Eureka', 'Fino' and 'Lisbon' show that the synthesis of the many carotenoids in the peel varies as a function of temperature. The model presents a higher correlation considering the variable 'a' for a period and for the previous observation. For this purpose we use a fixed type model.


Conesa A.,University Miguel Hernández | Nicolas J.M.,Murcian Institute of Agriculture and Food Research and Development IMIDA | Javier F.,University Miguel Hernández | Porras M.I.,Murcian Institute of Agriculture and Food Research and Development IMIDA
Acta Horticulturae | Year: 2015

Every few years frosts affect the cultivation area surrounding Murcia (Spain). The most important frosts in recent years occurred during the winter of 1994-95 and the latest ones in 2004-05, 2010-11 and 2011-2012. In this work we describe and compare the effects of the last two frost periods on fruit and vegetative damage in lemon trees cultivars (Citrus limon Burm. f.) and grapefruit (Citrus paradise Macf.) in the above mentioned area. During the season of 2010-2011, frost damage was more severe than in the current year 2011-2012. Temperatures in citrus fields reached -6.63° C with 10 hours of temperatures below 0° C. Frost-induced damage in fruits and vegetative tissue in orange and mandarin cultivars was scarce but more frequent in grapefruit and severe in lemon trees, two last cultivars grafted on Citrus macrophylla. Among lemon cultivars studied, the most sensitive to frost was Messina. The risk of frost in the citrus area of Murcia for a critical temperature of -3° C was also studied. The probability of frost damage is 2% on the coast and 60% in the inland valleys of Murcia.


Porras I.,Murcian Institute of Agriculture and Food Research and Development IMIDA | Perez-Perez J.G.,Murcian Institute of Agriculture and Food Research and Development IMIDA | Garcia-Lidon A.,Murcian Institute of Agriculture and Food Research and Development IMIDA | Sanchez-Banos M.,Murcian Institute of Agriculture and Food Research and Development IMIDA | And 2 more authors.
Acta Horticulturae | Year: 2015

South-east of Spain is the major exporter of lemon for the fresh market. 'Fino' is the main group of lemon varieties with more than 80% of the total production. To continue leading the international lemon market is necessary to incorporate new varieties which improve fruit quality and diversify supply. Three new selections of lemon have been evaluated in a citrus breeding program at IMIDA: 'Finolate', 'Fino Callosa', and 'Garpo', that were compared with 'Fino 49', the most widespread lemon variety in this region. These varieties were originated by spontaneous mutation. The agronomic evaluation indicated that 'Fino Callosa' entered into production earlier than 'Fino 49' and had the highest accumulated yield. In addition, all new lemon selections produced bigger and heavier fruits, allowing earlier harvest than 'Fino 49'. In addition, these new lemon cultivars had less juice content, but the quality of the juice was better than 'Fino 49'. 'Garpo' produced fruits more yellow than 'Fino 49'. Based on these preliminary results, 'Fino Callosa' was more productive and 'Garpo' had better rind color than 'Fino 49', and could be a possible alternative to 'Fino 49' cultivar.


Conesa A.,University Miguel Hernández | Brotons J.M.,University Miguel Hernández | Manera F.J.,University Miguel Hernández | Porras I.,Murcian Institute of Agriculture and Food Research and Development IMIDA
Scientia Horticulturae | Year: 2014

Lemons and grapefruit are harvested commercially before the fruit have reached their characteristic colour and are submitted to a process of degreening in special chambers before entering the retail chain. The aim of this work is to make a cost analysis of this process for different times of harvest. The period analysed ran from October to December in 2012 and 2013. Fruit were harvested on six occasions in each year (T1-T6) and the fruit classified into seven lots each time (three for lemon and four for the grapefruit cultivars studied). The lemon cultivars studied were 'Eureka', 'Fino 49' and 'Lisbon' on Citrus macrophylla and the grapefruit cultivars were 'Marsh', 'Red Blush', 'Río Red' and 'Star Ruby' on the mandarin Cleopatra. Each lot remained in the ethylene chamber for 7 days, and the colour coordinates were measured every 2 days to obtain the Colour Index (CI*) of the fruit for each harvesting date. The data showed that the greener the fruit when they entered the ethylene chamber, the greater the degreening rate. The different costs of degreening were estimated for each harvesting date and cultivar. The findings showed that the costs involved in degreening the grapefruit cultivars 'Red Blush' and 'Rio Red' were three times greater than the costs associated with 'Marsh' and 'Star Ruby'. The costs of degreening lemon did not differ during the first half of the harvesting period and fell gradually during the second half. The findings provide a useful tool for calculating the cost of degreening as a function of harvesting date for each cultivar. © 2014 Elsevier B.V.


Porras I.,Murcian Institute of Agriculture and Food Research and Development IMIDA | Brotons J.M.,University Miguel Hernández | Conesa A.,University Miguel Hernández | Manera F.J.,University Miguel Hernández
Scientia Horticulturae | Year: 2014

This contribution analyses the influence of net radiation and temperature on the colour changes that take place in the peel of two cultivars of grapefruit (Citrus paradisi Macf.), Rio Red and Star Ruby. The study, which covered four growing seasons (2005/6, 2006/7, 2010/11 and 2011/12) shows that, while net radiation influenced the colour change in both varieties, it was not sufficient in itself to explain when the degreening starts. This process only started when the mean of the minimum daily temperatures for the 14 days preceding the measurement was 13-14. °C or when the daily minimum temperature was below 12.5. °C on two (not necessarily consecutive) days. This information shows that, for new plantations of these two grapefruit cultivars to be successful, not only must the thermal integral be high, but that temperatures must fall below 13 or 14. °C for degreening to begin during ripening. If these conditions are not met, grapefruit intended for commercial distribution will have to be subjected to artificial degreening in an ethylene chamber, thus increasing production costs. © 2014 Elsevier B.V.


Manera J.,University Miguel Hernández | Brotons J.M.,University Miguel Hernández | Conesa A.,University Miguel Hernández | Porras I.,Murcian Institute of Agriculture and Food Research and Development IMIDA
Australian Journal of Crop Science | Year: 2012

This study describes the relationship between air temperature and the loss of greenness in lemon peel and the appearance of the typical yellow color in the lemon varieties Eureka Frost, Lisbon Frost and the Fino 49, all on Citrus macrophylla rootstock. The change in the colorimetric coordinate a was studied, and the hue angle and chroma were calculated to ascertain the influence of temperature on these parameters. The study covered six campaigns (2003-2009), with measurements being made every week or fortnight in 10 fruit per tree and 4 trees per variety. The results show that the values of the colorimetric coordinate a (of the HunterLab) was most closely correlated with the mean of the minimum daily temperature of the 21 days prior to the measurement (adjusted R2 >0.93). Identical results were obtained for Chroma and hue angle. It was determined that the color of the peel begins to change from green to yellow when the minimum temperature falls below 15 °C, reaching full " lemon yellow" below 6 °C. This means that in areas where the mean of the minimum temperatures of the 21 days prior to the measurement do not reach 15 °C, natural degreening will not occurr. As a consequence, artificial degreening, with the increased expense that this entails for the crop, will be necessary. The knowledge gained with this study will be of interest for determining the suitability of areas of the world where lemon tree plantations are being considered, so that prospective growers will not have to resort to artificial degreening.


Manera F.J.,University Miguel Hernández | Brotons J.M.,University Miguel Hernández | Conesa A.,University Miguel Hernández | Porras I.,Murcian Institute of Agriculture and Food Research and Development IMIDA
Scientia Horticulturae | Year: 2012

The loss of greenness (degreening) in citrus fruit during ripening is associated with autumnal falls in temperature, and there is a close correlation between the color of the fruit measured in the HunterLab space (colorimetric coordinate a) and the mean daily minimum temperatures recorded for the 7 and 21 days prior to the measurement being made. The term colorimetric coordinate a expresses the variation from green to yellow during lemon fruit ripening.In this work we attempt to determine the temperature below which degreening begins in three varieties of lemon fruit on the tree: Eureka, Lisbon and Fino. Only the results for Eureka are described since all three varieties showed the same behavior. The colorimetric coordinate a was measured weekly in the peel of previously marked and identified lemon fruit over a period of 7 years, and the temperature was recorded in a weather station situated on the same farm.The results show that degreening begins when the minimum temperatures fall below 10.5. °C for 2 days (not necessarily consecutive). In our experiment the mean daily minimum temperature recorded for the previous 7 and 21 days were 12.14. °C and 13.64. °C, respectively.This implies that a knowledge of autumn temperatures should enable growers to know when it is best to harvest the fruit - when degreening has just begun (with a shortened artificial degreening period) or when more time has elapsed, although this may mean that the commercial opportunity associated with early fruit may be lost. © 2012 Elsevier B.V.


Porras I.,Murcian Institute of Agriculture and Food Research and Development IMIDA | Brotons J.M.,University Miguel Hernández | Conesa A.,University Miguel Hernández | Castaner R.,University Miguel Hernández | And 2 more authors.
Journal of Applied Botany and Food Quality | Year: 2015

While most lemon cultivars in the northern hemisphere are harvested in autumn-winter, Verna, an autochthonous Spanish cultivar, is harvested later (February to August), supplying the European market when lemons are in short supply, a market that is also served by imports from the southern hemisphere, mainly Argentina and South Africa. The aim of this study was to determine the temperature at which degreening begins naturally in Verna lemon, noting the evolution of colorimetric parameter a and comparing the same with the equivalent measurements made in Eureka lemon, the most widely cultivated lemon worldwide. The influence of solar radiation on the colorimetric parameters in Verna was studied, and the influence of the minimum temperatures on the change from green to yellow, using the data collected over five growing seasons, was assessed. The results confirmed the relation between net solar radiation and degreening, a process that begins when net solar radiation reaches a value of between 2 and 4 MJ/m2.day and when the mean temperature of the 14 days prior to sampling is 8.8 °C or when the daily mean temperature reaches 5.5 °C on two consecutive days. The information obtained will enable growers to predict the colour changes that will occur in the field and potential growers to ascertain whether a given geographical zone is suitable for the crop in question. © 2015 The Author(s).


Manera F.J.,University Miguel Hernández | Brotons J.M.,University Miguel Hernández | Conesa A.,University Miguel Hernández | Porras I.,Murcian Institute of Agriculture and Food Research and Development IMIDA
Scientia Horticulturae | Year: 2013

The grapefruit varieties Marsh (white-fleshed) and Redblush (pink-fleshed) are the most widely cultivated varieties in the world. In this work we attempt to determine the temperature below which degreening begins in these two varieties of grapefruit, first studying the influence of radiation on the colorimetric coordinates and then the influence of minimum temperatures on the change from green to yellow, based on the data gathered during the 2005/6, 2006/7, 2010/11 and 2011/12 growing seasons. The results show that net radiation alone does not explain when degreening begins, but that the process depends on the mean of the minimum temperatures for the 14 days preceding the sampling being below 14°C.Finally, we discuss the relationships between coordinate a, and each of the following variables: maturity index (MI), °Brix, and percentage of acidity, concluding that the indices show that grapefruit are mature at the beginning of autumn when the peel is still green. Therefore, these indices are not related with natural degreening, which occurs in autumn.This knowledge will help predict the color that fruit will reach according to the temperatures of a given geographical area and whether or not degreening chambers will have to be used, with the additional costs that this implies. © 2013 Elsevier B.V.


Rio J.A.D.,University of Murcia | Diaz L.,University of Murcia | Ortuno A.M.,University of Murcia | Garcia-Lidon A.,Murcian Institute of Agriculture and Food Research and Development IMIDA | Porras I.,Murcian Institute of Agriculture and Food Research and Development IMIDA
Acta Horticulturae | Year: 2015

Fungi of the genus Alternaria are responsible for substantial pre-harvest losses in Citrus, althoughsusceptibility to A. alternata depends on the Citrus species. In this work the metabolism of flavonoids and mycotoxins were analyzed in 'Fortune' fruits infected by A. alternata. HPLC-MS analysis revealed the presence of two A. alternata mycotoxins involved in the evolution of brown spot in fruits. These were identified as 3,7,9-trihydroxy-1-methyl-6H-dibenzo [b,d] pyran-6-one, known as alternariol (AOH), and 3,7-dihydroxy-9-methoxy-1-methyl-6H-dibenzo[b,d] pyran-6-one, known as alternariol monomethyl ether (AME). The flavanones hesperidin and isonaringin, and the polymethoxyflavone sinensetin increase the biosynthesis of these micotoxins. Inoculation of fruits with the above-mentioned toxins showed that both molecules caused necrosis in the inoculated citrus tissues, suggesting that the mycotoxins may be involved in the evolution of brown spot caused by A. alternata. The increased expression of the above mycotoxins was associated with: (i) the end of mycelial growth, high sporulation and an increase in hyphal melanisation; (ii) catabolism of the flavonoids present in these fruits.

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