1.
Improving crop nutrient efficiency through root architecture modifications.
Li, X, Zeng, R, Liao, H
Journal of integrative plant biology. 2016;(3):193-202
Abstract
Improving crop nutrient efficiency becomes an essential consideration for environmentally friendly and sustainable agriculture. Plant growth and development is dependent on 17 essential nutrient elements, among them, nitrogen (N) and phosphorus (P) are the two most important mineral nutrients. Hence it is not surprising that low N and/or low P availability in soils severely constrains crop growth and productivity, and thereby have become high priority targets for improving nutrient efficiency in crops. Root exploration largely determines the ability of plants to acquire mineral nutrients from soils. Therefore, root architecture, the 3-dimensional configuration of the plant's root system in the soil, is of great importance for improving crop nutrient efficiency. Furthermore, the symbiotic associations between host plants and arbuscular mycorrhiza fungi/rhizobial bacteria, are additional important strategies to enhance nutrient acquisition. In this review, we summarize the recent advances in the current understanding of crop species control of root architecture alterations in response to nutrient availability and root/microbe symbioses, through gene or QTL regulation, which results in enhanced nutrient acquisition.
2.
Effects of carriers on nutrient removal and membrane fouling in combined process of inclined-plates hydrolytic tank and membrane bioreactor.
Li, X, Liu, Y, Chu, M, Liu, A
Water science and technology : a journal of the International Association on Water Pollution Research. 2016;(10):2364-2369
Abstract
A novel process, inclined-plates hydrolytic tank (IHT) and membrane bioreactor (MBR), was used to treat domestic sewage continuously. In this study, the effects of carriers' addition on operational performances of IHT-MBR were studied at the hydraulic retention time of 5.4 h and the recycling rate of 200%. Experimental results indicated the removal efficiencies of chemical oxygen demand, total nitrogen and total phosphorus reached 86.8%, 82.9% and 89.6%, respectively, corresponding trans-membrane pressure decreased to 1.50 kPa/d at a packing ratio of 20%. Simultaneously, the scanning electron microscope and soluble microbial products analysis demonstrated that high nutrient removal and low membrane fouling were attributed to the attached growth of microorganisms on carriers. The bioattachment and adsorption of carriers not only decreased the soluble proteins and polysaccharide in MBR, but also provided good living environments for denitrifying bacteria and phosphorus-accumulating bacteria.