[Leaf spreading duration and its influencing factors for two Pottiaceae species in hilly Loess Plateau, Northwest China]. / é»„åœŸä¸˜é™µåŒºä¸¤ç§ä¸›è—“ç§‘æ¤ç‰©å±•å¶æ—¶é•¿åŠå ³é”®å½±å“å› å­.

Mosses are poikilohydric plants. The duration of leaf spreading time is a key factor affecting their growth and development in the field. The dynamics of field growth and development and influencing factors of mosses in arid and semi-arid areas are largely unknown. In the study, we examined leaf spreading situation under natural conditions from September 5th to November 25th for Didymodon vinealis and Barbula unguiculata, two common species in hilly Loess Plateau. The results showed that the leaves of both species showed a regular diurnal dynamic change of 'spreading-closing-spreading' from September to October, and that the average leaf closing time of D. vinealis in the morning was 0.68 hours earlier than that of B. unguiculata, while leaf spreading time was delayed by 1.79 hours in the afternoon. Both species spread their leaves for longer time in the rainy season. The average leaf spreading duration of D. vinealis was 251 min, which was 30.4% lower than B. unguiculata of 361 min. The relative humidity near the surface was the key factor affecting leaf spreading duration. The morphological structure of moss species would affect leaf spreading duration. Compared with D. vinealis, B. unguiculata was relatively short, with a large proportion of costa in leaves, and the mosaic structure of stem cortex cells was more prominent. The humidity threshold during leaf spreading of B. unguiculata (54.3%) was lower than that of D. vinealis (60.1%). The leaf spreading duration was mainly affected by humidity. B. unguiculata was more adaptable to the environment than D. vinealis.

[Effects of foliar selenium fertilizer on fruit yield, quality and selenium content of three varieties of Vitis vinifera]. / 叶面喷施硒肥对3个葡萄品种果实产量、品质和硒含量的影响.

With three grape varieties, Red Barbara, Summer Black and Hutai No. 8 as test mate-rials, we investigated the effects of foliar spraying of organic selenium fertilizer on greenhouse grape quality and selenium content. The results showed that spraying 12 mg·L-1 amino acid chelated selenium-enriched foliar fertilizer on grape leaves significantly increased selenium content and the quantity and quality of grape yield, including the contents of soluble sugar, organic acid, soluble protein, soluble solids, vitamin C and proanthocyanidins. However, there was no increase in resveratrol. Among the three varieties, selenium content of Summer Black in 2017 and 2018 was increased by 36.7% and 37.1%, respectively, being higher than that of Red Barbara and Hutai No. 8. Red Barbara sprayed with selenium fertilizer had better quality due to high sugar and low acid contents, as well as high health-care components. Moreover, the selenium content of Hutai No. 8 in 2018 was 53.26 µg·kg-1, higher than the others, indicating a stronger ability of selenium enrichment. We concluded that the increase range of Se content was larger in Summer Black, Red Barbara showed the better nutrition value and quality, and Hutai No. 8 was a suitable variety for selenium-rich grape production.

[Effects of soil moisture content and light intensity on the plant growth and leaf physiological characteristics of squash].

A pot experiment with artificial shading was conducted to study the effects of soil moisture content and light intensity on the plant growth and leaf physiological characteristics of squash variety "Jingyingyihao". Under all test soil moisture conditions, 30% shading promoted the growth of "Jingyingyihao", with the highest yield at 70% - 80% soil relative moisture contents. 70% shading inhibited plant growth severely, only flowering and not bearing fruits, no economic yield produced. In all treatments, there was a similar water consumption trend, i. e., both the daily and the total water consumption decreased with increasing shading and decreasing soil moisture content. Among all treatments, 30% shading and 70% - 80% soil relative moisture contents had the highest water use efficiency (2.36 kg mm(-1) hm(-2)) and water output rate (1.57 kg mm(-1) hm(-2)). The net photosynthetic rate, transpiration rate, stomatal conductance, and chlorophyll content of squash leaves decreased with increasing shading, whereas the intercellular CO2 concentration was in adverse. The leaf protective enzyme activity and proline content decreased with increasing shading, and the leaf MAD content decreased in the order of 70% shading, natural radiation, and 30% shading. Under the three light intensities, the change characteristics of squash leaf photosynthesis, protective enzyme activity, and proline and MAD contents differed with the increase of soil relative moisture content.

[Soil respiration variations in winter wheat field in different previous crops and its influencing factors].

This study was to define the Variations of soil respiration, the response of influence factors to soil respiration and carbon sink in the total growing season, in winter wheat field of different previous crops. The results showed that: (1) as soil depth increases, the response of temperature to soil respiration rate also increased with a lag; (2) the soil respiration rate was quadric to soil moisture, phosphorus, potassium, soil urease activity, soil temperature, soil moisture as the main factors had an effect on soil respiration rate; soil temperature had the stronger effect on soil respiration rate when potassium had the weaker effect on soil respiration rate; (3) the average carbon emission rate in wheat filed of different previous crops showed as follow: Pepper of previous crops > celery of previous crops > corn of previous crops > eggplant of previous crops. The intensity of carbon "sink" displayed as follow: eggplant of previous crops > celery of previous crops > corn of previous crops > pepper of previous crops. As for the trials of this study, although the soil respiration rate is highest in the winter wheat filed of previous pepper, the amount of carbon fixed is the most. Its ratio of net primary productivity (NPP) and soil carbon release quantity was highest, so carbon sink was the strongest. If rotation planting was arranged according to the purpose of increasing carbon sink and reducing carbon emissions, pepper was relatively appropriate stubbles crop, followed by corn crop, celery and eggplant.

[Effects of different water and fertilizer supply on cucumber soil nutrient content, enzyme activity, and microbial diversity].

With cucumber (Cucumis sativus L.) variety Jinyou 1 as test material, a greenhouse experiment was conducted to study the effects of different water and fertilizer supply on the cucumber soil nutrient content, enzyme activity, and microbial diversity. Three water regimes (50%-60%, 70%-80%, and 90%-100% soil relative moisture content) and two fertilization practices (600 kg N x hm(-2) + 420 kg P2O5 x hm(-2) and 420 kg N x hm(-2) + 294 kg P2O5 x hm(-2)) were designed. The increase of water and fertilizer supply benefited the increase of soil available P content and sucrase activity. Increasing fertilization rate increased soil NH(4+)-N content but decreased soil protease activity, and increasing soil relative moisture content decreased the soil NH(4+)-N content and urease activity. Soil microbial diversity had no significant correlations with soil nutrient contents, but significantly positively correlated with soil urease activity and negatively correlated with soil sucrase activity. Among the treatments, the treatment 70%-80% soil relative moisture content + 600 kg N x hm(-2) and 420 kg P2O5 x hm(-2) had the highest soil nutrient contents, soil urease, sucrase, and phosphatase activities, and soil microbial diversity and evenness, being the best in soil potential productivity.

[Effects of soil covering on solar greenhouse pepper water use efficiency and soil nitrate N and available phosphorus contents].

A greenhouse study on the effects of soil covering on pepper (Capsicum anmuum L.) water use efficiency and soil nitrate and available phosphorus contents showed that straw mulch + plastic film mulch could get the highest pepper yield water use efficiency (33.04 kg . m(-3)) and economic water use efficiency (50.22 yuan . m(-3)), followed by plastic film mulch, with the two parameters being 18.81 kg . m(-3) and 28.57 yuan . m(-3), respectively. Significant differences of nitrate N content in 0-20 cm soil layer were observed among different treatments. The control had the highest nitrate N content (50.33 mg . kg(-1)), followed by straw mulch (31.98 mg . kg(-1)) and straw + plastic film mulch (31.96 mg . kg(-1)), and plastic film mulch and applying water preserving agent. Compared with the control, soil covering could increase the nitrate N use efficiency of pepper, and decrease the accumulation of nitrate N in plough layer. In 0-20 cm soil layer, treatment plastic film mulch had the lowest available phosphorus content (0.72 mg . kg(-3)), and the second (0. 92 mg . kg(-1)) was the treatment straw + plastic film mulch. Treatments straw + plastic film mulch and plastic film mulch could increase pepper fruit yield and fertilizer use efficiency, and decrease fertilizer loss.

[Effects of root exudates of squash grafted with cucumber shoot on seed germination].

Cucumber (Cucumis statirus L.) is commonly cultivated by grafting on squash (Cucurbita moschata) in commercial production. The effects of root exudates of squash grafted with cucumber on seed germination rate of cucumber and squash were tested. In this study, the exudates of cucumber-grafted squash roots were continuously collected with XAD-4 resin, and were further diluted with distilled water to make 5%, 10%, 20% and 40% concentrations. Cucumber and squash seeds were used for bioassay. The seeds were germinated in glass petri dishes with 2 filter papers at bottoms and containing 5 mL the diluted root exudates. The results showed that the exudates of cucumber-grafted squash roots significantly inhibit germination rate, radicel and hypocotyl elongation in cucumber and squash, and the inhibitory rate positively correlate with the concentration of the grafted cucumber root exudates. So grafted cucumber still have allelopathy. The exudates of cucumber-grafted squash roots significantly stimulated IAA oxidase activity in cucumber and squash. As a result, they decrease IAA level in cucumber and squash, and restrained their growth. The exudates of cucumber-grafted squash roots also decrease significantly the activities of amylase and alpha-amylase in cucumber and squash, and this decrease effects were strengthening with the increasing of the concentration of the grafted cucumber root exudates. So the exudates of cucumber-grafted squash roots can inhibit the hydrolysis and utilization of starch in cucumber and squash, and thereby suppress germination and seedling growth.