JWSS - Journal of Water and Soil Science

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In this experiment the response of persimmon fruit, cv. Karaj, to astringency removal by ethanol and the effects of this treatment on some important fruit characteristics were investigated. Fruits were harvested at three different dates and at each date based on the previous results, and then modified treatments were applied. The best ethanol astringency removal treatment in this study was 10 ml of 38% ethanol per kg fruit for 48 hours. The period after ethanol treatments had no effect on the reduction of soluble tannin concentration, although it resulted in the reduction of flesh firmness and increased soluble pectin. Ethanol treatments and also temperature conditions reduced flesh firmness and increased ground color of fruits however, the effect of ethanol treatments was more than temperature conditions. Temperature conditions increased ethylene production, thus reducing the flesh firmness and increasing the ground color index of fruits. Ethanol treatments did not increase the ethylene production, and it seems that its effects on some characteristics are due to ethanol itself or factors other than ethylene.

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Various effects of methanolic extract of neem seed kernel on larvae of cotton boll worm, Helicoverpa armigera (Hubner) (Lepidoptera: Noctuidae) were studied and compared with those of Neem Azal T/S and Neem Plus, two commercial formulations. The pest was collected from Gorgan (Golestan Province, Iran) and reared on a bean based artificial diet. The neem seed was collected from Bandar-Abbas (Hormozgan Province) and extracted in laboratory. Growth inhibitory and antifeedant assays were carried out on larvae treated with seed kernel extracts in 3 concentrations,1, 2.5 and 5%, under choice and no-choice conditions. The neem extract had a significant antifeedancy effects on larvae. Neem Plus and 5% extract had the least and most antifeedancy effects, respectively. The most and least feeding rates belonged to Neem Plus and Neem Azal treatments, respectively, which differed significantly (P<0.05). Feeding deterrence index (FDI) was highest in 5% extract which also differed significantly from Neem Plus treatment. Larvae treated with extract led to malformation and prevented formation of pupa and ultimately caused death. The LT50 values with confidence limit (CL) of 95% were 3.84 and 4.13 d, for Neem Azal and 5% extract respectively. DC50 and EC50 of extract were 4.73% and 2.73% at similar CL, respectively.

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Soil water repellency can affect several soil properties such as aggregate stability. Soil texture and organic matter are two main internal factors responsible for the variability of soil water repellency. Major sources of organic matter in soil include plant residues, and exudates of plant roots and soil microorganisms. Tall fescue (Festuca arundinacea Schreb.) as an important cool-season perennial forage grass is usually infected by a fungal endophyte (Epichloë coenophiala) which often enhances resistance to biotic and abiotic stresses as well as altering the litter decomposition rate and soil properties. In this study, the effects of endophyte-infected (E+) and endophyte-free (E−) tall fescue residues (in three different levels of 0, 1 and 2%) on soil organic carbon, basal microbial respiration, water-dispersible clay and water repellency index (determined by intrinsic sorptivity method) were investigated in four texturally-different soils in the laboratory. E+ and E− tall fescue residues were completely mixed with moist soil samples and then were incubated at 25 °C. During two months of incubation period, the amended soil samples were subjected to 10 wetting and drying cycles and then, the above-mentioned soil properties were measured. The results indicated that soil organic carbon and water-dispersible clay were greater, while basal soil respiration and repellency index were lower in fine-textured soils. Water repellency index was increased by production of hydrophobic substances (for the rate of 1%) and was reduced by induced greater soil porosity (for the rate of 2%). Presence of endophyte in plant residues had no significant effect on water sorptivity, ethanol sorptivity and water repellency index; nevertheless, E+ residues increased soil organic carbon and decreased water-dispersible clay significantly. Overall, it is concluded that tall fescue residues, especially those with E+, can improve soil physical quality due to improving soil organic carbon storage and water repellency index and decreasing water-dispersible clay (as an index for aggregate instability). These E+ species and the residues have great potential to be used in sustainable soil conservational managements.
 

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