[Effects of salt and drought stresses on rhizosphere soil bacterial community structure and peanut yield]. / å¹²æ—±ä¸Žç›èƒè¿«å¯¹èŠ±ç”Ÿæ ¹é™ åœŸå£¤ç»†èŒç¾¤è½ç»“æž„å’ŒèŠ±ç”Ÿäº§é‡çš„å½±å“.

A pot experiment with Huayu 25 as experimental material was conducted, with treatments of drought and salt stresses. The effects of drought and salt stresses at the flowering stage on the plant morphology, pod yield, and soil bacterial community structure in the rhizosphere were examined. The results showed that Proteobacteria, Actinobacteria, Saccharibacteria, Chloroflexi, Cyanobacteria, and Acidobacteria were the dominant phyla in the rhizosphere soil of peanut. Compared with that under normal conditions, the relative abundance of Proteobacteria and Actinobacteria dramatically decreased, while that of Cyanobacteria evidently increased in drought-treated and salt-treated soil. Moreover, the variation of Cyanobacteria abundance caused by combined drought and salt stresses was stronger than that caused by single drought or salt stress. Functional meta-genomic profiling indicated that a series of sequences related to signaling transduction, defense mechanism and post-translational modification, protein turnover, chaperones were enriched in rhizosphere soil under stressed conditions, which might have implications for plant survival and stress tolerance. Drought and salt stress affectedpeanut growth and reduced pod yield. Results from this study would present reference on the future improvement of stress tolerance of peanuts via modifying soil microbial community.

Effects of calcium fertilizer application on absorption and distribution of nutrients in peanut under salt stress.

In order to solve the problems of nutrient absorption and accumulation and provide theoretical basis for rational amount of calcium fertilization of peanut in saline land, the effects of calcium fertilizer application on absorption and accumulation of nutrients including nitrogen, phosphorus, potassium, calcium and magnesium in peanut under salt stress were examined. Using 'Huayu 25' as experimental material, four Ca levels [T1 (0), T2 (75), T3 (150) and T4 (225) kg·hm-2 CaO] were set under 0.3% salt stress in a pot experiment. The results showed that nutrient contents in peanut followed the order of nitrogen > potassium > calcium > phosphorus > magnesium. At the seedling stage, leaves were the absorption center of nitrogen and calcium, while stems were the center of phosphorus, potassium and magnesium, with nearly half of nutrient accumulation being distributed in the corresponding growth center. At mature stage, the absorption centers of nitrogen, phosphorus and potassium were transferred to pod. The accumulation of nitrogen and phosphorus in seed kernel reached to 72.3%-78.9%. The absorption centers of calcium and magnesium was still in the leaves and stems, with a distribution ratio of 49.8% and 32.6%, respectively. Salt stress significantly inhibited nutrient absorption and distribution in peanut, especially decreased the nitrogen accumulation in leaves and seed kernels. However, salt stress increased the magnesium accumulation in pod. Exogenous calcium application had significant positive effect on absorption and accumulation of nitrogen, phosphorus, calcium and magnesium in different organs of peanut under salt stress. It had significant adjustment on phosphorus accumulation in seed kernel, which was increased by more than 50%. Appropriate calcium content could significantly promote the peanut nutrient absorption and accumulation under salt stress and improve the distribution ratio of nitrogen, phosphorus, potassium in mature pods of peanut. According to the responses of nutrient absorption and distribution, the optimized application amount for calcium fertilizer under 0.3% salt stress was 150 kg·hm-2 CaO.