The storage temperature is one of the most important factors affecting on the fruit peels composition and quality after harvesting. The pink grapefruit (Citrus paradise L.) peels was subjected in current study to examine the effect of different storage conditions on phytochemical constituents, the antioxidant activity and constants of peels oil. The phytochemical constituents of the pink grapefruit peels such as lycopene, phenolics, flavonoids and vitamin C were assessed the level of their concentrations for examine their antioxidant activities and the effect of storage on those components. The antioxidant effects was determined from the changes in acid value, peroxide number, conjugated diene and triene contents and the delay of rancidity of pink grapefruit peels oil during storage conditions for 60 days in refrigerator temperature at 8 ±1°C and for 40 days in room temperature at 16± 4°C. Results of a proximate composition of pink grapefruit peels during storage conditions showed that significantly decreased (P ≤ 0.05) in moisture, carbohydrate and energy values at most storage periods. On the other side, Protein, fat, fiber and ash contents were significantly increased (P ≤ 0.05) in most different storage periods. The Antioxidants components such as:  Lycopene, total phenolics, and total flavonoids content; as well as, antioxidant activity of pink grapefruit peels were significantly increased (P ≤ 0.05) during storage conditions, while, ascorbic acid levels were significantly (P ≤ 0.05) decreased during storage periods at different storage conditions. The rates of increase in antioxidant activity of samples stored at room temperature were higher than in the refrigerator. The contents of peroxide number, conjugated diene and triene was significantly (p ≤ 0.05) increased for most storage periods at room temperature (16± 4°C), while, non-significant differences (p ≤ 0.05) were found during storage periods at refrigerator temperature (8 ±1°C). On the other hand, acid value was significantly decreased (p ≤ 0.05) after 20 days of storage at room temperature, while, non-significant differences (p ≤ 0.05) were found during storage periods at refrigerator temperature. The storage at refrigerator temperature (8 ±1°C) improved the shelf-life of pink grapefruit peels and to maintain health promoting compounds.

Key words: Grapefruit peels, Bioactive compounds, Antioxidant activity, Storage conditions, Peels oil properties.

Abstract

Experiment was carried out throughout two successive seasons of 2016 and 2017 on Flame Seedless, Ruby Seedless and Thompson Seedless grapevines grown at the Experimental Orchard of Assiut University, Faculty of Agriculture. The aim of this study was to assess the impacts of abscisic acid (ABA), cluster thinning and their combinations with GA3 on yield weight of three important grape cultivars grown under hot region. Data revealed that, the application of abscisic acid (ABA) increased yield weight (kg/vine), while cluster thinning decreased it. During the 1st season of study (2016), all individual ABA treatments and ABA at 400 ppm combined with GA3 at 10 ppm significantly increased yield weight (kg/vine) comparing with the control treatment. As a result of ABA treatments at 200, 400 and 600 ppm and ABA at 400 ppm plus GA3 at 10 ppm, the yield was increased by 15.5%, 10.5%, 9.8% and 9.2%, respectively. During the 2nd season of study (2017), only ABA at 600 ppm treatment significantly surpassed the control treatment with an increment percentage of 20.5%.  The rest of treatments either had no effect or reduced the yield weight comparing with the control. On the other side, cluster thinning by removing 30% of the total clusters that the vine bearing significantly reduced the yield weight (kg/vine) during the two studied seasons. As a result of such treatment, the yield was reduced by 37.2% and 39.2% in 2016 and 2017 seasons, respectively.

Keywords

grape; Vitis vinifera; ABA; Cluster thinning; yield

The predatory mites, Neoseiulus longispinosus (Evans) and N. womersleyi (Schicha) (Phytoseiidae) are two morphologically close species. Although they can be mainly separated by the length of the dorsal seta S5, misidentifications may occur. The present study investigated various strains of the two closely related species collected from Japan, Taiwan and/or Thailand using a combination of morphological and molecular data. We described and illustrated the adults and immature stages. We also sequenced the 28S region of nuclear ribosomal DNA to determine whether these strains represent different species. The two species could be clearly separated based on the length of seta S5 and the ratio of setae Z5/S5. In a 28S tree, the examined strains also formed separate clades with 100% bootstrap values. We conclude that a combination of different methods is often necessary to precisely distinguish these closely related taxa.

The objective of  this study was to determine the plant density  that result in the best marketable yields and gross crop value per fedan of onion Giza 6 cv. that grown   by sets .Sets were grown at the Experimental Farm of the Faculty of Agriculture, Assuit University, Assuit on September 13 and 15 in 2007/2008 and 2008/2009 seasons, respectively. Sets were grown on rows of 3.5 m long and 50 cm wide. Three rows were included each plot. Sets were grown at 4, 6 and 8 cm between plants (175,116 and 87 plants when sets grown on two sides of row and  262,175and131 plants when sets grown on three sides of row). Results showed  that  , plants gave the smallest bulb diameter when sets were grown at 4 cm space(high density) .The largest space between plants (low density) ,the highest value for both percentage of bolters and doubles were. The highest value of marketable yield was obtained when sets grown at 4 and 6 cm (262 and 175 plants/ row) and on 3 sides per row .Maximum economic returns occurred at higher plant populations.  High incidence of double onions was closely related to low onion plant population. Doubles clearly decreased with increased plant density. Wide plant spacing reduced onion bulb yield, but it significantly increased individual bulb weight and bulb diameter.

Field experiment were carried out on the clay soil of the Experimental Farm, Faculty of Agriculture, Assiut University,Assiut in two consecutive  winter seasons 2007-2008 and 2008 -2009.The aim of this investigation was to study the effects of three planting dates and three seeding rates in cv. Giza 6 on yield and quality of onion sets un- der Assiut conditions. The obtained results indicated that the onion plants. Average bulb diameter increased significantly with earlier planting compared with later planting. Lower seeding rate gave significantly the biggest average bulb diameter. The authenticity bulb was obtained from planting on December 1st in the second sampling date (105 days).However, no true bulb was obtained from any planting date in the first sampling date (75 days)in both seasons. Lower seed rate (30 kg/feddan) significantly gave the truth bulb in both seasons.