Entity

Time filter

Source Type


Conesa A.,University Miguel Hernandez | Brotons J.M.,University Miguel Hernandez | Manera F.J.,University Miguel Hernandez | 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. Source


Porras I.,Murcian Institute of Agriculture and Food Research and Development IMIDA | Brotons J.M.,University Miguel Hernandez | Conesa A.,University Miguel Hernandez | Manera F.J.,University Miguel Hernandez
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. Source


Manera F.J.,University Miguel Hernandez | Brotons J.M.,University Miguel Hernandez | Conesa A.,University Miguel Hernandez | 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. Source


Manera J.,University Miguel Hernandez | Brotons J.M.,University Miguel Hernandez | Conesa A.,University Miguel Hernandez | 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. Source


Manera F.J.,University Miguel Hernandez | Brotons J.M.,University Miguel Hernandez | Conesa A.,University Miguel Hernandez | 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. Source

Discover hidden collaborations