Growth,yield and fruit quality of ‘Marisol’ clementine grown on four rootstocks in Egypt

To evaluate the most appropriate rootstocks for mandarin production in Egypt, vegetative growth, yield and fruit quality of ‘Marisol’ clementine (as newly introduced cultivar in Egypt) grafted on Sour orange (the common rootstock), Cleopatra mandarin, Carrizo citrange and ‘Swingle’ citrumelo were evaluated under the Egyptian conditions during 2004/2005 and 2005/2006 seasons. Trees were grown in a private farm at ‘Wady El-Mullak’ region, Ismailia Governorate (Latitude, 30°36′ N; longitude, 32°14′ E; Altitude, 10 m above sea level).     

Effect of a cytochrome P450 inhibitor on abscisic acid biosynthesis and stomatal regulation in citrus trees in water-stressed conditions

The effect of diniconazole, an inhibitor of cytochrome P450, on drought tolerance was examined in ‘Shiranui’ [(Citrus unshiu Marc. × Citrus unshiu Osbeck) × Citrus reticulate Blanco] trees. Diniconazole treatment increased abscisic acid (ABA) concentration in leaves compared with untreated controls in water-stressed conditions after 20 days of water-stress treatment. Diniconazole significantly decreased the stomatal aperture at 9 h after application compared with untreated controls in water-stressed conditions. The photosynthetic rate decreased in water-stressed conditions; however, regardless of the earlier stomatal closure induced by diniconazole application, the decrease of photosynthetic rate was delayed by the application.     

Effect of maturity and storage temperature on the development of peteca in lemons (Citrus limon (L.) Burm. F.) cv. Eureka

To evaluate the effect of maturity and storage temperature on the development of the physiological disorder peteca, lemons cv. Eureka were harvested from a grove with northern exposure located in Mallarauco (33°45′ Latitude South) Metropolitan Region of Chile, at 2 levels of maturity (silver or yellow). After storage for 60 d at 3 or 7 °C, under 90% R.H., fruits were evaluated visually for incidence of epidermal and subepidermal peteca. At that time, the concentration of galacturonic acid and degree of methylation were measured in the albedo, and calcium, hydrogen peroxides and total oxalate concentrations, peroxidase and polyphenoloxidase (PPO) activities were determined in the juice and albedo. Yellow lemons at 3 °C developed more epidermal peteca than fruit stored at 7 °C, and that silver fruit stored at 3 and 7 °C, with these last lemons presenting a higher pectin quality than fruit stored at 3 °C. Maturity and temperature interacted significantly on the concentrations of peroxide and calcium in the albedo, which in average were much higher than in the juice, while for PPO and peroxidases, this interaction was highly significant both in juice and albedo, with higher activity in the albedo. These biochemical evaluations suggest that peteca is a result of some kind of stress on the fruit. It is concluded that yellow lemons are more prone to develop peteca than silver fruit. They will develop greater incidence of the disorder when stored at temperatures as low as 3 °C for 60 d, and that this condition affects the degree of methylation in the albedo, which would end up altering the quality of pectins.     

Identification of QTLs related to sugar and organic acid composition in melon using near-isogenic lines

The soluble sugar and organic acid composition of melon (Cucumis melo L.) fruit flesh has become a major focus of plant breeding worldwide in an attempt to improve taste. Thus, sugar and organic acid profiles were characterized using near-isogenic lines (NILs) derived from the Spanish cultivar Piel de Sapo (PS) and the exotic Korean accession Shongwan Charmi (PI 161375). Fruits were cultivated in only one environment. These data were used to map 60 quantitative trait loci (QTLs): 18 for individual sugars, eight for sucrose equivalents, five for the glucose-to-fructose ratio, seven for the total sugar content and 21 for organic acids. Within the QTLs that were associated with the sugar profile, 27 defined the sugar content: eight for fructose, six for glucose, four for sucrose, and nine for sucrose equivalents. Although increased sweetness of selected NILs compared with the parental PS was achieved by an increased glucose or fructose content, only glucose heritability was above 0.5. A total of 21 QTLs (two with positive effects and nineteen with detrimental effects compared with the PS levels) controlled the organic acid profile: l-glutamic, ascorbic and succinic acids (the principal ones) and fumaric, citric, oxalacetic, and isocitric acids. The levels of sugars imparted by the PI 161375 introgression frequently decreased the score grades given to NILs by consumers. Within the 32 QTLs mapped for sensory traits, 27 were associated with lower scores in taste (nine QTLs), sweetness (eight QTLs) or global quality appreciation (nine QTLs); two with increased fruit sourness or sweetness and three with increased fruit bitterness. The QTLs defined herein may assist breeders to understand the overall organoleptic balance (sweetness, sourness, and umami taste) in melon fruit, particularly those located within linkage groups III, V, VI, and VIII to XI.     

Comparison of three types of adhesives in attaching coral transplants to clam shell substrates

• 1. Nubbins from 12 coral species were transplanted onto dead giant clam shells at three sites in a lagoon near Bolinao, north‐western Philippines. Transplants were attached using three types of adhesives: cyanoacrylate glue (SG), epoxy putty (EP) and marine epoxy (ME) and were monitored over five months for detachment, in situ mortality and natural self‐attachment by tissue growth.
• 2. Corals attached with SG showed a significantly higher rate of detachment (logrank test) than those attached with either EP or ME (P<0.001 in each case). Also, those attached with EP showed a higher rate of detachment than corals attached with ME (logrank=6.46, P<0.05).
• 3. ANOVA (P>0.05) and survival analysis (logrank=2.85, P>0.05) showed no among‐adhesives differences in in situ mortality. Among the species used, Porites cylindrica, Pavona frondifera, Heliopora coerulea and Porites rus had the highest survivorship with 82%, 80%, 76% and 73%, respectively, of nubbins alive at the end of the experiment and also displayed the highest cumulative rates of self‐attachment. Species with the lowest survival rates included Acropora muricata and four pocilloporids.
• 4. Although there was no significant difference in the number of self‐attaching transplants among the adhesives, corals transplanted using ME and EP self‐attached earlier than those transplanted using SG (logrank=11.19, P<0.01).
• 5. Results from this study highlight the importance of selecting the appropriate means of attaching corals to substrates and carefully considering species‐specific traits of candidate corals for transplantation.

Copyright © 2008 John Wiley & Sons, Ltd.     

The role of geomorphology in substratum patch selection by freshwater mussels in the Hawkesbury–Nepean River (New South Wales) Australia

• 1. Microhabitat preferences of freshwater mussels and associated substrate characteristics were investigated across a range of geomorphic reaches in the Hawkesbury–Nepean River, Australia.
• 2. The structure of substratum patches available was strongly influenced by geomorphic reach type. In each reach type, mussel distribution was most frequently correlated with coarse sand and a roughness element characteristic for that reach. Roughness elements such as boulders and cobbles create a flow refuge and were linked with mussel size.
• 3. Small mussels tended to be associated with boulder‐stabilized habitats and medium sized mussels with cobble habitats. Large mussels rarely co‐occurred with any particular roughness element. Individual species were strongly linked to geomorphic reach type. This association may be due to species' differences in ability to colonize available microhabitat types.
• 4. The highly tolerant Velesunio ambiguus dominated shale reaches, characterized by fine sediments and human impacts. In contrast, Hyridella depressa dominated in gorges, utilizing small flow refuges among boulders, while H. australis were present in low densities across a range of substrate conditions.
• 5. The persistence of multispecies assemblages in mussel beds throughout the Hawkesbury–Nepean River implies similar niche utilization among species. Partitioning of habitats across species on the basis of size suggests some degree of habitat selection, or differential survival. At the local scale, microhabitat characteristics influenced the size distribution and densities of mussel assemblages. Continuing declines in mussel densities are likely to result from ongoing channel modification and increased siltation resulting from changes to riparian vegetation.

Copyright © 2008 John Wiley & Sons, Ltd.     

Apparent digestibility coefficient of protein and amino acids of acid, biological and enzymatic silage for Nile tilapia (Oreochromis niloticus)

Using the fish silage to partially replace proteic feedstuff in aquafeeds is an alternative to mitigate sanitary and environmental problems caused by the lack of adequate destination for fisheries residues. It would also lower feed costs, consequently improving fish culture profitability. However, using fish silages in aquafeeds depends on determination of its apparent digestibility coefficients (ADC). This work aimed to determining the ADC of crude protein and amino acids of acid silage (AS), biological silage (BS) and enzymatic silage (ES) for juvenile Nile tilapia (94.5 ± 12.7 g). The ADC_CP was: 92.0%, 89.1% and 93.7% for AS, BS and SE respectively. The average ADC of amino acids was: 91.8%, 90.8% and 94.6% for AS, BS and ES respectively. Results encourage the use of AS, BS and ES to partially replace protein sources in balanced diets for neotropical fish.     

An integrated water trading-allocation model, applied to a water market in Australia

Temporary water trading is an established and growing phenomenon in the Australian irrigation sector. However, decision support and planning tools that incorporate economic and biophysical factors associated with temporary water trading are lacking. In this paper the integration of an economic trading model with a hydrologic water allocation model is discussed. The integrated model is used to estimate the impacts of temporary water trading and physical water transfers. The model can incorporate economic and biophysical drivers of water trading. The economic model incorporates the key trade drivers of commodity prices, seasonal water allocations and irrigation deliveries. The hydrologic model is based on the Resource Allocation Model (REALM) framework, which facilitates hydrologic network simulation modelling. It incorporates water delivery system properties and operating rules for the main irrigation and urban centres in a study area.The proposed integration method has been applied to a case study area in northern Victoria, Australia. Simulations were conducted for wet and dry spells, a range of commodity prices and different irrigation distribution system configurations. Some example analyses of scenarios incorporating water trading were undertaken. From these analyses potential bottlenecks to trade that constrain the economic benefits from temporary water trading were identified. Furthermore, it was found that in certain areas of the system, trading can make impacts of long drought spells worse for water users, e.g. irrigators. Thus, the integrated model can be used to quantify short-term and long-term third party impacts arising from temporary water trading. These findings also highlight the need to link “paper trades” (estimated by economic models) to physical water transfers (estimated by biophysical models).     

Irrigation management practices of cabbage farmers in Botswana using saline groundwater

All horticultural production in Botswana is irrigated, as average rainfall is less than average reference evapotranspiration in all parts of the country for all of the year, and most of the irrigation in the country is used for horticultural crops. In the main, the water used for irrigation comes from groundwater, and much of this can be classified as moderately saline. A survey was carried out of 60 cabbage farmers in five regions of the country to identify the level of salinity of irrigation water and the irrigation practices used. It was concluded that there was no relationship between the irrigation rate (average irrigation depth divided by average irrigation interval) and the salinity of the water used or the salinity of the soil, such that some farmers were over-irrigating and others under-irrigating. This means that water is being wasted and yields are likely to be reduced. In addition, there is a risk of long-term build-up of salinity and soil degradation.     

Mineral content of three olive cultivars irrigated with treated industrial wastewater

The reuse of saline treated industrial wastewater generated by textile firms mixed with municipal domestic effluent for irrigation was used to asses its effect on the mineral content of three olive (Olea europaea L.) cultivars under greenhouse and field conditions during two complete vegetative cycles. Chemical analysis of the treated wastewater indicated that the element concentrations fall within the permissible range of irrigation water used for plants. However, little impermissible accumulation of Na and Mg higher than the recommended maximum concentration was observed. Irrigation water with six electrical conductivities (EC = 0.78, 1.0, 2.0, 3.0, 4.0 and 5.0 dS m⁻¹ in treatments T₀, T₁, T₂, T₃, T₄, T₅, respectively) were compared in the greenhouse experiment. The olive trees in the field experiment were trickle irrigated with potable water and treated wastewater (average EC = 4.2 dS m⁻¹). The results of the greenhouse experiment showed that leaf N, Cu, Mn, Fe, Pb, and Na contents increased with increasing salinity of the treated wastewater. This increase was accompanied with a decrease in K and Mg contents. Leaf Ca and Cl concentrations were not considerably affected. Ion analysis in roots indicated that the contents of P, Na, Cl, Mn, and Pb increased while K decreased as treated wastewater salinity increased. Consequently, in most cases T₄ and T₅ gave a highly significant increase or decrease in accumulation of the previously mentioned minerals. A considerable variation in the studied cultivars was noticed. ‘Nabali’ was considered the most tolerant cultivar for the high salinity levels of the treated wastewater; its transporting selectivity of Na from root to leaf was higher and more Na was retained in the roots. Tissue analysis of leaves indicated that the element concentrations were within the adequate levels except those of Fe in ‘Nabali’ and ‘Manzanillo’, Na in ‘Improved Nabali’ and Cu in ‘Nabali’ and ‘Manzanillo’. In view of these findings, the negligible accumulation of minerals in leaves and roots indicated that this kind of textile effluent can be used as a valid alternative for irrigation of olive orchards with continuous monitoring of mineral levels.