Ethylene-inhibiting compound 1-MCP delays leaf senescence in cotton plants under abiotic stress conditions

Cotton （Gossypium hirsutum L.） plants produce more ethylene when subjected to abiotic stresses, such as high temperatures and drought, which result in premature leaf senescence, reduced photosynthetic efficiency, and thus decreased yield. This study was conducted to test the hypothesis that the ethylene-inhibiting compound 1-methylcyclopropene （I-MCP） treatment of cotton plants can delay leaf senescence under high temperature, drought, and the aging process in controlled environ- mental conditions. Potted cotton plants were exposed to 1-MCP treatment at the early square stage of development. The protective effect of 1-MCP against membrane damage was found on older compared to younger leaves, indicating 1-MCP could lower the stress level caused by aging. Application of 1-MCP resulted in reduction of lipid peroxidation, membrane leakage, soluble sugar content, and increased chlorophyll content, in contrast to the untreated plants under heat stress, suggesting that 1-MCP treatment of cotton plants may also have the potential to reduce the effect of heat stress in terms of delayed senescence. Application of 1-MCP caused reductions of lipid peroxidation, membrane leakage, and soluble sugar content, together with increases in water use efficiency （WUE）, water potential, chlorophyll content, and fluorescence quantum efficiency, compared to the untreated plants under drought, suggesting that 1-MCP treatment of cotton plants may also have the ability to reduce the level of stress under drought conditions. In conclusion, 1-MCP treatment of cotton should have the potential to delay senescence under heat and drought stress, and the aging process. Additionally, 1-MCP is more effective under stress than under non-stress conditions.

Changes in Nutritive Materials in Off-season Mango in Flower Bud Differentiation Stage

Under off-season production mode, change laws of nutritive materials in leaves of fruiting mother branches of mango in flowering process induced by dif- ferent agents were investigated. The results showed that the flowering time of manga trees in the potassium nitrate treatment was earlier than the ethephon treatment by 7 d, and changes trends of materials in leaves of the potassium nitrate and ethephon treatments were substantially the same. The nutritive materials in leaves showed trends of increasing at first and decreasing then. In early flower bud differentiation stage, soluble sugar and starch in leaves increased rapidly, and content of soluble protein also increased rapidly and showed its their peak values, thereby providing energy substances and structural substances demanded by flower bud formation. With flower bud differentiation going on, soluble sugar, starch and soluble protein decreased gradually. It was indicated that the accumulation of soluble sugar, starch and soluble protein is beneficial to flower bud differentiation.

Quality of Melon 'UFERSA-05 var.ACIDULUS and Pele de Sapo“Mabel”Minimally Processed,Kept in Different Packages

This study aimed at evaluating the quality of melon Pele de Sapo “Mabel” and Yellow melon “UFERSA-05” minimally processed preserved in different packages. The fruits were harvested at Mossoró-RN and transported to Serra Talhada-PE. In the first study, melon fruit Piel de Sapo “Mabel” was selected, washed, weighed, cooled, peeled, cut into cube shape, sanitized in chlorine solution, drained, packaged in rigid polypropylene tray, sealed with polypropylene film or polypropylene rigid cap and kept for 8 days at 8℃. In the second study, fruits of yellow melon “UFERSA-05” and Pele de Sapo “Mabel” were minimally processed and kept in rigid polypropylene tray, sealed with polypropylene film and stored for 8 days at 8℃. There was no significant interaction between packaging (sealed with film and polypropylene cover) and period of conservation, for pH, total titratable acidity (TTA), total soluble solids (TSS) and Loss of fresh mass (LFM) for Melon “Mabel”. While there was significant interaction between types of melon (“UFERSA-05” and “Mabel”) and storage period (0, 2, 4, 6, and 8 days) for pH, TTA and TSS. In sensory evaluation were noticeable changes in appearance, flavor, aroma and flesh firmness, characterized by translucency, alcoholic aroma and softening in “Mabel” melon kept in tray with lid. Melon “UFERSA-05” showed lower pH, total soluble solids, total soluble sugars, PME activity, lack of translucency high flesh firmness compared to “Mabel” melon during storage. The high levels of sugars in melon “Mabel” may be related to the incidence of translucency, which was not observed in “UFERSA-05” melon, with a strong potential to minimal processing.

Physiological Responses of Zea mays Seedlings to Interactions Between Cadmium and Salinity

The effects of 0, 2.5, 5.0, and 10.0 pmol/L Cd^2＋（Cd（NO3）2.4H2O） and 0, 10, 25, 50, and 100 mmol/L NaCl on growth, photosynthesis and the content of some ions in maize （Zea mays L.） were investigated in the present study. With Increasing concentrations of Cd^2＋ or NaCI alone in Hoagland nutrient solution, the chlorophylls and starch content decreased. Combination treatment with salinity and cadmium increased the negative effects observed following the two stresses alone. Plants exhibiting growth retardation in response to one mild stress factor （25-50 mmol/L NaCl） became more tolerant to the other stress factor （Cd）. The exposure of plants to cadmium caused a partial reversal of the effects of salinity. Root and shoot growth, ion accumulation and levels of photosynthetic pigments were improved at moderate concentrations of the two stress factors Imposed jointly.