Chen Ya-jun

Effects of Nitrogen Supply on Water Stress and Recovery Mechanisms in Kentucky Bluegrass Plants

Non-irrigated crops in temperate and irrigated crops in arid regions are exposed to an incessant series of drought stress and re-watering. Hence, quick and efficient recuperation from drought stress may be amongst the key determinants of plant drought adjustment. Efficient nitrogen (N) nutrition has the capability to assuage water stress in crops by sustaining metabolic activities even at reduced tissue water potential. This study was designed to understand the potential of proper nutrition management by studying the morphological and physiological attributes, and assimilation of nitrogen in Kentucky bluegrass under drought stress. In present study, one heterogeneous habitat and four treatments homogenous habitats each with four replications were examined during field trial. Drought stress resulted in a significant reduction in the nitrogen content of both mother and first ramets, maximum radius, above and below ground mass, number of ramets per plot, leaf water contents and water potential and increased the carbon content and the C:N ratio in both homogenous and heterogeneous plots compared to well-watered and nutritional conditions. Observation using electron microscopy showed that drought stress shrunk the vessel diameter, circumference and xylem area, but increased the sieve diameter, and phloem area in the leaf crosscutting structure of Kentucky bluegrass, first, second, and third ramet leaf. Thus, it can be concluded that water stress markedly reduced all the important traits of Kentucky bluegrass, however, proper nutritional management treatment resulted in the best compensatory performance under drought assuaging its adversity up to some extent and may be considered in formulating good feasible and cost-effective practices for the environmental circumstances related to those of this study.

Research progress on water use efficiency and drought resistance of turfgrass

Improving turfgrass drought resistance and save-water features are very important to solve water deficiency in turfgrass production and management. This research did some surveys of systematic literature review about turfgrass drought tolerance morphological characteristics, physiological characteristics and water use efficiency, and provided the detailed information for enhancing turfgrass drought resistant and water use efficiency in the future.

Study on Classification and Genetic Diversity of Kentucky Bluegrasses by Using RAPD Markers

Abstract A total of 69 random primers were screened by using random amplified polymorphic DNA (RAPD) markers to analyze the genetic bands of 32 Kentucky bluegrass cultivars. A total of 197 bands were amplified from 46 primers, among which 195 bands were polymorphic. Each primer could amplify one to nine polymorphic bands with an average of 4.3 per primer. Based on similarity coefficient analysis of RAPD results and by using NTSYS software to cluster analyze with the average UPGMA method, the result showed that 18 cultivars of the 32 were in group 1, three cultivars were in group 2, two cultivars were in group 3, eight cultivars were in group 4, and only one cultivar in group 5.

Landscape Transformation in Mining Wastelands

Abstract Mining provides a wealth of mineral raw materials to human beings, while also causes serious damage to environment and ecology. For decades, landscape renovation in mining wastelands has become a multi-disciplinary research focus. However, compared with the developed countries, China has disadvantages of the relevant theoretical researches developing slowly with lacking supporting technology. According to the design principle of “reservation and utilization”, we reviewed and summarized the methods of landscape transformation in mining wastelands, furthermore, using the way of researching successful cases at home and abroad. In lined with the specific circumstances in China, the target of landscape transformation and basic theories as methods of strategy was developed. Finally, the overall thinking and suggestions were put forward for the development of landscape transformation in mining wastelands.

Research Progress on Nitrogen Use and Plant Growth

The application of nitrogen (N) fertilizers in agriculture has been increasing dramatically since 1970s. However, the over-fertilization causes could cause environmental problems, as well as low N use efficiency (NUE). Promoting NUE in plants and minimizing the environmental impacts of N fertilizers had been the focus of the current research. We reviewed the importance of N, N metabolism and plant growth, plant N physiology and the molecular aspect of N metabolism in this paper. The future development of N use and NUE of plants was also discussed.

Nutrient Status and Dynamics of Trifolium spp. at Different Growing Stages

Abstract The nutrient status and dynamics of three clover ( Trifolium spp.) varieties at different growth stages were investigated with the crude protein content as an indicator of nutrient equilibrium. The crude protein, neutral detergent fiber (NDF), phosphorus (P), and calcium (Ca) content followed a decreasing trend at the initial growing stage and increased later. NDF and Ca content peaked in May, while crude protein and P content reached the highest in May and the lowest in July. The crude ash content followed an uncertain pattern as plants growing. The ash content of both wild-type red clover ( T. pratensis L.) and ‘Sativum’ decreased at the beginning and then increased. However, the ash content of ‘Revendel’ white clover ( T. repens L.) decreased all through the experimental period. The general trend was observed for all three clover varieties as the ash content was the highest at vegetative growing stage (May), and the acidic detergent fiber (ADF) content increased with time. The nutrient equilibrium value was ranked as ‘ Revendel ‘>wild-type red clover>‘ Sativum ‘.

Effects of Drought Stress on Photosynthetic Characteristics of Kentucky Bluegrass

Abstract Drought stress is one of the major constraints on turf growth and performance in northern China. Based on previous assessments of drought tolerance levels, four varieties of Kentucky bluegrass ( Poa pratensis L.) representing different types (‘Baron’, BVMG type; ‘Blackstone’, Cheri type; ‘Kenblue’, Midwest type; and ‘Bluemoon’, Midnight type) were chosen for this study. Grass materials were established in a glasshouse, and the changes in their photosynthetic and metabolic characteristics were analyzed during a period of imposed drought stress. Drought stress led to decrease in chlorophyll content, photosynthetic rate, stomatal conductance and transpiration rate in all four cultivars, but the relative changes in each characteristic varied among varieties. The results also showed that changes in the photosynthetic and metabolic characteristics of different varieties under drought stress were related to the morphological characteristics of the plants. Varieties with longer narrow leaves, longer roots, higher root-to-shoot ratios, and higher chlorophyll contents showed greater rates of photosynthesis and stomatal conductance, and lower transpiration rates.