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  • Author or Editor: Xu Wang x
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Expressed sequence tags (ESTs) constitute a rapid and informative strategy for studying gene-expression profiles of specific stages of annual and perennial plant species. Compared with annual plants, the NCBI database has very little sequence information from perennial plant species. To date, only ∼145 ESTs of Vitis pseudoreticulata W.T. Wang have been deposited in databases. This is insufficient to understand the biology and development of this species. In this report, a cDNA library constructed from young leaf inoculated with powdery mildew pathogen [Uncinula necator (Schw.) Burr.] of Chinese wild Vitis pseudoreticulata. Leaf was harvested at various times after inoculation for total RNA extraction, which was used to generate ESTs. In our study, 107 cDNA clones were sequenced either from 5' or 3' end of the cDNAs. Among them, 60 unigenes (56%) were functionally characterized by the BLASTX matches to known function proteins, and 20 unigenes (18.6 %) matched significantly with those having unknown function in the public databases. The remaining 27 unigenes (25.2%) failed to show significant homology to any proteins in the public databases, suggesting that they represent novel sequences. Some functional genes identified from the cDNA library to be potentially associated with plant defence-related responses are discussed.

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The rate of fertilizer-N utilization by ginger was quite different in different applying stages. The results indicated that the rate of fertilizer-N utilization increased with the delay of application. The highest utilization rate was the fertilizer dressed at middle period of vigorous growth, which was 45.24%; while the basal manure utilization rate was only 27.67%. It was also shown that the nitrogen uptake from basal manure was distributed in highest level in main shoots and leaves, the nitrogen derived from fertilizer dressed at middle period of vigorous growth was mostly distributed into rhizomes, and nitrogen absorbed from fertilizer dressed at early period of vigorous growth was distributed evenly into all organs. The reclamation rate from fertilizer dressed at middle period of growth was the highest and lowest reclamation rate was the basal manure. The content of fertilizer-N and soil-N in ginger plant was determined, it was shown 56.57% plant-N was derived from soil-N, the remaining 43.43% was from fertilizer-N. The nitrogen from soil played a very important role in ginger production, therefore the problem of how to maintain high soil fertilizer must be paid more attention.

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Mulching with straw increase soil water content, air relative humidity and air temperature, but decreased soil temperature. Though mulching with straw didn't change light intensity, ginger growth and yield were the same as shading. The growth and yield under shading and mulching with straw were both higher than that of naked soil.

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To explore the falling morphology of multiscale fresh tea leaves at different speeds, this study evaluated the multiscale fresh tea leaves (one bud with two leaves, one bud with one leaf, single leaf, and damaged leaf) at different heights (0.7 m, 0.5 m, 0.3 m, and 0.1 m from the ground) during the process of dropping on the conveyor belt at different speeds (0.6 m/s and 1.2 m/s). The motion morphology of fresh tea leaves on multiple scales was analyzed by discrete element simulation, the results showed that the movement patterns of multiscale fresh tea leaves at different positions from the ground were different when the conveyor was dropping at different speeds, and that the multiscale fresh tea leaves all rotated around the long axis, short axis, and root of the fresh tea leaves. When the conveying speed of the conveyor belt was 0.6 m/s, the movement patterns of one bud with two leaves and of one bud with one leaf of fresh tea were near the ground, and the movement patterns of the fresh tea leaves were mostly oriented toward the ground. The leaf tips of the fresh tea leaves were mostly on the side near the ground, the damaged leaves were near the ground, and the movement patterns of the fresh tea leaves were mostly parallel to the ground. When the conveyor belt throwing speed was 1.2 m/s, the roots of one bud with two leaves moved toward the ground when they were close to the ground. When one bud with one leaf was close to the ground, the leaf tip moved toward the ground, and the single leaf and damaged leaf rotated around the root because of the inertia of the conveyor belt throwing.

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Turf quality of creeping bentgrass (Agrotis palustris L.) often declines during summer months. Reducing soil temperature alleviates bentgrass quality decline at supraoptimal air temperatures. The objective of this study was to investigate whether reducing soil temperature during the night is more effective than during the day in improving shoot and root growth when air temperature was supraoptimal for creeping bentgrass. The experiment was conducted in growth chambers using water baths to manipulate soil temperatures. Plants were exposed to the following temperature treatments: 1) optimal air and soil temperature during the day and night (20/20 °C, day/night, control); 2) high air and soil temperature during the day and night (35/35 °C, day/night); 3) lower soil temperatures during the day (20/35, 25/35, and 30/35 °C, day/night); and 4) lower soil temperature during the night (35/20, 35/25, and 35/30 °C) while air temperature was maintained at 35 °C during the day and night. Turf quality (on 1-9 scale) increased to the level of 6.5, 3.0, and 2.5 by reducing day soil temperature to 20, 25, or 30 °C, respectively, at 28 days of treatment, compared to the quality of 2.0 at 35/35 °C. Turf quality increased from 2.0 at 35/35 °C to 7.0, 6.0, and 4.5, respectively, by 28 days of exposure to night temperatures of 20, 25, and 30 °C. Chlorophyll content, root number, and root weight also were increased by reducing day or night soil temperature, and the increases were more pronounced for reduced night temperatures than day temperatures. These results demonstrated that reduced night soil temperature was more effective than reduced day soil temperature in improving shoot and root growth in creeping bentgrass under high air temperature conditions.

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Heat injury in creeping bentgrass (Agrostis stolonifera var. palustris Huds) has been associated with decreases in carbohydrate availability. Extending light duration may increase carbohydrate availability and thus improve growth of creeping bentgrass under heat stress. The objective of this study was to investigate whether turf performance and carbohydrate status could be improved by extending daily light duration for creeping bentgrass exposed to supraoptimal temperature conditions. `Penncross' plants were initially grown in growth chambers set at a day/night temperature of 20/15 °C and 14-hour photoperiod and then exposed to a day/night temperature of 33/28 °C (heat stress) and three different light durations: 14 (control), 18, and 22 hours (extended light duration) for 30 days. Turf quality and tiller density decreased with the duration of heat stress, as compared to the initial level at 20 °C, regardless of the light duration. However, both parameters increased with extended light duration from 14 to 18 or 22 hours. Extended light duration, particularly to 22 hours, also improved canopy net photosynthetic rate from -1.26 to 0.39 μmol·m-2·s-1 and daily total amount of carbon assimilation from -6.4 to 31.0 mmol·m-2·d-1, but reduced daily total amount of carbon loss or consumption to 50% through dark respiration compared to 14 hours treatment by the end of experiment. In addition, extending light duration from 14 to 22 hours increased water-soluble carbohydrate content in leaves both at the end of light duration and the dark period. These results demonstrated that extending light duration improved turf performance of creeping bentgrass under heat stress, as manifested by the increased tiller density and turf quality. This could be related to the increased carbohydrate production and accumulation. Supplemental lighting could be used to improve performance if creeping bentgrass is suffering from heat stress.

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High air and soil temperatures are major factors limiting growth of cool-season grasses. A previous study by the authors reported that a soil temperature reduction of only 3 °C when air temperature was maintained at 35 °C significantly improved shoot and root growth of creeping bentgrass [Agrostis stolonifera L. var. palustris (Huds.) Farw. (syn. A. palustris Huds.)]. This study was designed to investigate the responses of photosynthetic activities of creeping bentgrass to lowered root-zone temperatures from the supraoptimal level when shoots were exposed to high air temperature. Two cultivars of creeping bentgrass, `L-93' and `Penncross', were exposed to the following air/root-zone temperature regimes in growth chambers and water baths: 1) optimal air and soil temperatures (20/20 °C, control); 2) lowering soil temperature by 3, 6, and 11 °C from 35 °C at high air temperatures (35/32, 35/29, and 35/24 °C); and 3) high air and soil temperatures (35/35 °C). Soil temperature was reduced from 35 °C by circulating cool water (18 °C) in water baths at variable flow rates. Both cultivars had similar responses to high or low root-zone temperatures with high air temperature. High air and root-zone temperatures caused significant reductions in canopy photosynthetic rate (Pcanopy), single-leaf photosynthetic rate (Pleaf), leaf chlorophyll content, photochemical efficiency (Fv/Fm), and ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) activity, beginning on day 1 of high air and soil temperature stress for Pcanopy and Pleaf, and day 7 for chlorophyll content, Fv/Fm, and Rubisco activity. The 3 °C reduction in root-zone temperature at high air temperature had no effect on those photosynthetic parameters, except chlorophyll content. Reducing root-zone temperature by 6 °C or 11 °C while maintaining air temperature at 35 °C significantly improved Pcanopy, Poleaf, leaf chlorophyll content, Fv/Fm, and Rubisco activity. Single leaf photosynthetic rate at 35/24 °C was not different from the control level, but Pcanopy at 35/24 °C was lower than the control level. A reduction in root-zone temperature enhanced canopy and single-leaf photosynthetic capacity even though shoots were exposed to supraoptimal air temperature, which could contribute to improved turfgrass growth.

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