Influence of mycorrhizal fungi on growth,chlorophyll content,and potassium and magnesium uptake in maize

Mycorrhizal fungi affect growth and nutrition of host plants positively. In this research, influence of vesicular-arbuscular mycorrhiza (VAM) ongrowth, chlorophyll content, and potassium (K) and magnesium (Mg) uptake in maize seedlings in pot culture was studied. This experiment was performed using natural soil containing a mixture of spores of Glomus spp. Mycorrhizal spores were exposed to four concentrations of K solution, i.e. 0.61 (soil K content), 0.92, and 1.23 meq/L and three concentrations of Mg, i.e. 4.8 (soil Mg content), 7.2, and 9.6 meq/L concurrently. Plants were watered every 4 days for 16 days with 50 mL distilled water. A pot with sterilized soil was used as negative control. For study of mycorrhizal colonization, very thin manually prepared longitudinal sections of plant roots (>1 mm in diameter) were stained with lactophenol-cottonblue and examined microscopically. Percentage of mycorrhizal colonization was determined using the grid-line intersect method. Samples from root and shoot of maize were collected for further analysis. Results showed mycorrhizal plants had significantly higher dry and fresh weight and chlorophyll content than plants grown in sterilized soil (p ≤ 0.05). Treatments with concentrations of 7.2 meq/L of magnesium alone and in combination with 0.92 meq/L of potassium with7.2 meq/L of Mg had better effect on morphological characters (dry and fresh weight of root and shoot). Mycorrhizal colonization increased Mg uptake but decreased K uptake.     

Root water uptake of pepper plants (Capsicum annuum L.) under deficit irrigation system

Root water uptake is a component of water balance that has not been clearly understood. This study was carried out in a completely randomized design with three replications under the greenhouse condition at Shahrekord University, Shahrekord, Iran. In this study, the root water uptake (RWU) by pepper plant under various irrigation water levels was investigated. Irrigation treatments included control (full irrigation level, FI) and three deficit irrigation levels, 80%, 60% and 40% of the plant's water requirement called DI₈₀, DI₆₀ and DI₄₀, respectively. A no-plant cover treatment with three replications was also used to measure evaporation from the soil surface. Daily measurements of volumetric soil moisture (VSM) were made at 10 cm intervals of the soil column. The differences between the measured VSM and the VSM in the next day, and evaporation rate at the soil surface at the same layer of the no-plant cover treatment were calculated and, eventually, the RWU in each layer per day was estimated. The results showed that the maximum and minimum RWUs were found in the FI and DI₄₀ treatments, respectively. The averages of root water uptakes in the DI₈₀, DI₆₀, and DI₄₀ treatments were reduced by 17.08%, 48.72% and 68.25%, respectively. Furthermore, in the DI₈₀ treatment, the reduced rate of water uptake was less than the reduced rate of water applied to the plants.     

鸡Apo VLDLⅡ基因内含子Ⅰ的多态性研究

本研究根据鸡Apo VLDL-Ⅱ基因内含子Ⅰ的基因序列设计3对引物,分别采用PCR-RFLP、PCR-SSCP技术对文昌鸡、如皋黄鸡、丝羽乌骨鸡、安卡肉鸡及红色原鸡5个鸡种进行多态性研究。结果表明,鸡Apo VLDL-Ⅱ基因内含子Ⅰ存在4处突变,分别为:1950处G/A、2522处A/C、2705处A/C及2793处C/T。统计结果显示:安卡肉鸡基因型频率的分布与如皋黄鸡、红色原鸡存在显著差异,文昌鸡基因型频率的分布与乌骨鸡差异不显著,除安卡肉鸡外所有鸡种均处于Hardy-Weinberg平衡状态。