山地不同树龄枣园土壤水分状况研究

为研究黄土高原梨枣林地土壤水分状况,利用TRIME管和洛阳铲对灌溉及雨养两种条件下不同种植年限(1 a、4 a、9 a、12 a)的梨枣林0~160 cm、0~700 cm范围深度内土壤水分状况进行监测研究。研究结果显示:随着树龄增长梨枣林地土壤水分储量下降;灌溉梨枣林与雨养梨枣林相比,其主根系层0~160 cm土壤水分储量较高;现有灌溉定额条件下,灌溉梨枣林地根区平均土壤水分满足度仍然相对较低;旱作梨枣林随树龄增大,土壤干层的分布深度和土壤干燥化强度趋于增加。     

干旱胁迫下梨枣抗旱性研究

为探索陕北黄土丘陵区梨枣的抗旱性与耐旱能力,以大规格盆栽梨枣（Ziziphus jujuba Mill.cv.Lizao）2年生苗木为试验材料,在连续不供水情况下研究了梨枣的萎蔫到致死过程。依据干旱缺水后枣树生长衰退过程中的特征将枣树萎蔫致死分为：暂时萎蔫、初始萎蔫、表征永久萎蔫及耐旱致死四个阶段。结果表明：梨枣的初始萎蔫系数在2.017%～3.054%之间,平均为2.494%;表征永久萎蔫系数在1.199%～1.998%之间,平均为1.489%,永久萎蔫系数在1.250%～1.489%之间;耐旱致死点为1.250%,致死时间为135±11 d。试验结果证明枣树是一种十分抗旱的树种,在半干旱黄土丘陵区枣树不会出现干旱致死。     

Effects of air temperature,relative humidity and canopy wetness on gray mold of cucumbers in unheated greenhouses

Microclimatic variables were monitored in cucumber crops grown in polyethylene-covered, unheated greenhouses in Israel during the winter of 1987/88. The winter was characterized by a relatively large number of rainy days. The relative humidity (RH) in the greenhouses was high (>97%) during most of the day, resulting in long periods of dew persistence. Dew point temperature and duration of dew deposition were calculated for the plant canopy. Disease incidence was monitored in 2-m-high plants, both on senescing female flowers (‘fruits’) and on stems. Multiple linear correlations were calculated for gray mold incidence and duration of air temperature and RH at specific ranges, and of leaf wetness (LW). Disease was characterized by two stages, according to the rate of its development and the microclimatic conditions influencing it. In the first phase of the epidemic a high correlation was found between infected fruits and air temperature in the range of 11–25°C, and RH in the range of 97–100% or LW. In the second phase, disease incidence was better correlated with air temperature in the range of 11–16°C and RH above 85% (R² = 0.681); there was no correlation between disease and LW at this stage. Development of stem infections was correlated with air temperature in the range of 11–16°C during the first phase of the epidemic. By contrast, the second phase was characterized by a close correlation between stem infections and RH in the range of 80–100% but also with air temperature in the range of 11–16°C, or with air temperature in the range of 11–25°C and RH 80–100%, and LW.     

两种新的旱作管理技术对山地梨枣树生长及结果的影响

以9 a生梨枣树(Ziziphus jujubaMill.)为试材,在无灌溉条件下,研究节水型修剪技术和竹节式聚水沟技术及常规矮化修剪技术(CK)对梨枣营养生长及生殖生长的影响。结果表明:节水型修剪与竹节式聚水沟技术的单独及联合应用,能有效提高叶面积增长量、梨枣单叶面积和叶绿素含量,有效提高枣吊个数和着花数量;与对照相比,节水型修剪技术可提高产量83.1%,竹节式聚水沟技术可提高产量38.4%,节水型修剪技术+竹节式聚水沟技术效果更好,产量可提高155%。综合分析认为在旱地无灌溉条件下的陕北黄土丘陵区,以节水型修剪树体管理为主,在林下采用聚水沟措施结合,能显著提高梨枣的结果性能和产量。     

Dew amount and its long-term variation in the Kunes River Valley,Northwest China

Dew is an essential water resource for the survival and reproduction of organisms in arid and semi-arid regions. Yet estimating the dew amount and quantifying its long-term variation are challenging. In this study, we elucidate the dew amount and its long-term variation in the Kunes River Valley, Northwest China, based on the measured daily dew amount and reconstructed values (using meteorological data from 1980 to 2021), respectively. Four key results were found: (1) the daily mean dew amount was 0.05 mm during the observation period (4 July-12 August and 13 September-7 October of 2021). In 35 d of the observation period (i.e., 73% of the observation period), the daily dew amount exceeded the threshold (>0.03 mm/d) for microorganisms; (2) air temperature, relative humidity, and wind speed had significant impacts on the daily dew amount based on the relationships between the measured dew amount and meteorological variables; (3) for estimating the daily dew amount, random forest (RF) model outperformed multiple linear regression (MLR) model given its larger R² and lower MAE and RMSE; and (4) the dew amount during June-October and in each month did not vary significantly from 1980 to the beginning of the 21^st century. It then significantly decreased for about a decade, after it increased slightly from 2013 to 2021. For the whole meteorological period of 1980-2021, the dew amount decreased significantly during June-October and in July and September, and there was no significant variation in June, August, and October. Variation in the dew amount in the Kunes River Valley was mainly driven by relative humidity. This study illustrates that RF model can be used to reconstruct long-term variation in the dew amount, which provides valuable information for us to better understand the dew amount and its relationship with climate change.     

Spatial-temporal characteristics and influencing factors of relative humidity in arid region of Northwest China during 1966–2017

Playing an important role in global warming and plant growth, relative humidity(RH) has profound impacts on production and living, and can be used as an integrated indicator for evaluating the wet-dry conditions in the arid and semi-arid area. However, information on the spatial-temporal variation and the influencing factors of RH in these regions is still limited. This study attempted to use daily meteorological data during 1966–2017 to reveal the spatial-temporal characteristics of RH in the arid region of Northwest China through rotated empirical orthogonal function and statistical analysis method, and the path analysis was used to clarify the impact of temperature(T), precipitation(P), actual evapotranspiration(ETa), wind speed(W) and sunshine duration(S) on RH. The results demonstrated that climatic conditions in North Xinjiang(NXJ) was more humid than those in Hexi Corridor(HXC) and South Xinjiang(SXJ). RH had a less significant downtrend in NXJ than that in HXC, but an increasingly rising trend was observed in SXJ during the last five decades, implying that HXC and NXJ were under the process of droughts, while SXJ was getting wetter. There was a turning point for the trend of RH in Xinjiang, which occurred in 2000. Path analysis indicated that RH was negatively correlated to T, ETa, W and S, but it increased with increase of P. S, T and W had the greatest direct effects on RH in HXC, NXJ and SXJ, respectively. ETa was the factor which had the greatest indirect effect on RH in HXC and NXJ, while T was the dominant factor in SXJ.     

Effect of pruning intensity on soil moisture and water use efficiency in jujube(Ziziphus jujube Mill.) plantations in the hilly Loess Plateau Region,China

Jujube(Ziziphus jujube Mill.) is a traditional economic forest crop and is widely cultivated in hilly areas of the Loess Plateau, China. However, soil desiccation was discovered in jujube plantations. Pruning is recognized as a water-saving method that can reduces soil water consumption. In this study, we monitored the jujube plots with control(CK), light(C_1), medium(C_2) and high(C_3) pruning intensities during the jujube growing period of 2012–2015 to explore the effect of pruning intensity on soil moisture and water use efficiency(WUE) of jujube plantations in the hilly Loess Plateau Region. The results showed that pruning is an effective method for soil water conservation in jujube plantations. Soil moisture increased with increasing pruning intensity during the jujube growing period of 2012–2015. C_1, C_2 and C_3 pruning intensities increased soil water storage by 6.1–18.3, 14.4–40.0 and 24.3–63.3 mm, respectively, compared to CK pruning intensity. Pruning promoted soil moisture infiltration to deeper soil layer. Soil moisture infiltrated to soil depths of 240, 280 and >300 cm under C_3 pruning intensity, 220, 260 and 260 cm under C_2 pruning intensity, 200, 240 and 220 cm under C_1 pruning intensity, and 180, 200 and 160 cm under CK pruning intensity in 2013, 2014 and 2015, respectively. Soil water deficit was alleviated by higher pruning intensity. In 2013–2015, soil water change was positive under C_2(6.4 mm) and C_3(26.8 mm) pruning intensities but negative under C_1(–20.5 mm) and CK(–40.6 mm) pruning intensities. Moreover, pruning significantly improved fresh fruit yield and WUE of jujube plants. Fresh fruit yields were highest under C_1 pruning intensity with the values of 6897.1–13,059.3 kg/hm2, which were 2758.4–4712.8, 385.7–1432.1 and 802.8–2331.5 kg/hm~2 higher than those under CK, C_2, and C_3 pruning intensities during the jujube growing period of 2012–2015, respectively. However, C_3 pruning intensity had the highest WUE values of 2.92–3.13 kg/m~3, which were 1.6–2.0, 1.1–1.2 and 1.0–1.1 times greater than those under CK, C_1 and C_2 pruning intensities, respectively. Therefore, C_3 pruning intensity is recommended to jujube plantations for its economic and ecological benefits. These results provide an alternative strategy to mitigate soil desiccation in jujube plantations in the hilly Loess Plateau Region, which is critical for sustainable cultivation of economic forest trees in this region.     

Effects of humidity, leaf wetness, temperature and light on conidial production by Phaeoisariopsis personata on groundnut

Controlled-environment studies of conidial production by Phaeoisariopsis personata on groundnut are described. With constant relative humidity (RH), conidia were only produced above a threshold (94·5% RH) and there was a linear increase between 94·5% RH and 100% RH. Conidial production was less with continuous leaf wetness (resembling heavy dew) than with continuous 98–99% RH, but it was similar with intermittent leaf wetness and intermittent 98–99% RH (8 h at 70% RH each day). With alternate high (≥97% RH) and low humidity, daily conidial production depended both on the duration of high RH and on the low RH value. With 99% RH at night (12 h), night-time conidial production decreased with the previous daytime RH. After conidial production had started, small numbers of conidia were produced even when the RH was well below the threshold (94·5%). Conidia were produced in continuous light when the photon flux density was 2 μmol/m²/s, but production was completely inhibited with 60 μmol/m²/s. With constant RH, more conidia were produced with a 12 h photoperiod than in continuous darkness. However, more than 75% of the conidia were produced in the dark. With continuous darkness, more conidia were produced during the night (18.00–06.00 h) than during the day, but this biological rhythm was overcome with a (light-night)/(dark-day) regime. With constant 98–99% RH there was a linear increase in conidial production with temperature between 10 and 28°C, and virtually no conidia were produced at 33°C. The daily production of conidia increased with time for 2 to 6 days, depending on the treatment.     

环境因子对草茎点霉SYAU-06菌株侵染鸭跖草的影响

以病叶率、病情指数和鲜重抑制率为评价指标,研究了环境条件包括温度、相对湿度、露水期和光照对草茎点霉SYAU-06菌株侵染鸭跖草的影响。结果表明,SYAU-06菌株侵染鸭跖草达到理想的除草效果,要求最适的温度范围是28～32℃,环境相对湿度保持在80%以上,接种后露水持续时间至少需要48h。保湿期的光照时间与病害发生程度成反比,光照时间越短,病害发生越严重。     

Can climate change influence agricultural GTFP in arid and semi-arid regions of Northwest China?

There are eight provinces and autonomous regions (Gansu Province, Ningxia Hui Autonomous Region, Xinjiang Uygur Autonomous Region, Inner Mongolia Autonomous Region, Tibet Autonomous Region, Qinghai Province, Shanxi Province, and Shaanxi Province) in Northwest China, most areas of which are located in arid and semi-arid regions (northwest of the 400 mm precipitation line), accounting for 58.74% of the country's land area and sustaining approximately 7.84×10⁶ people. Because of drought conditions and fragile ecology, these regions cannot develop agriculture at the expense of the environment. Given the challenges of global warming, the green total factor productivity (GTFP), taking CO₂ emissions as an undesirable output, is an effective index for measuring the sustainability of agricultural development. Agricultural GTFP can be influenced by both internal production factors (labor force, machinery, land, agricultural plastic film, diesel, pesticide, and fertilizer) and external climate factors (temperature, precipitation, and sunshine duration). In this study, we used the Super-slacks-based measure (Super-SBM) model to measure agricultural GTFP during the period 2000-2016 at the regional level. Our results show that the average agricultural GTFP of most provinces and autonomous regions in arid and semi-arid regions underwent a fluctuating increase during the study period (2000-2016), and the fluctuation was caused by the production factors (input and output factors). To improve agricultural GTFP, Shaanxi, Shanxi, and Gansu should reduce agricultural labor force input; Shaanxi, Inner Mongolia, Gansu, and Shanxi should decrease machinery input; Shaanxi, Inner Mongolia, Xinjiang, and Shanxi should reduce fertilizer input; Shaanxi, Xinjiang, Gansu, and Ningxia should reduce diesel input; Xinjiang and Gansu should decrease plastic film input; and Gansu, Shanxi, and Inner Mongolia should cut pesticide input. Desirable output agricultural earnings should be increased in Qinghai and Tibet, and undesirable output (CO₂ emissions) should be reduced in Inner Mongolia, Xinjiang, Gansu, and Shaanxi. Agricultural GTFP is influenced not only by internal production factors but also by external climate factors. To determine the influence of climate factors on GTFP in these provinces and autonomous regions, we used a Geographical Detector (Geodetector) model to analyze the influence of climate factors (temperature, precipitation, and sunshine duration) and identify the relationships between different climate factors and GTFP. We found that temperature played a significant role in the spatial heterogeneity of GTFP among provinces and autonomous regions in arid and semi-arid regions. For Xinjiang, Inner Mongolia, and Tibet, a suitable average annual temperature would be in the range of 7°C-9°C; for Gansu, Shanxi, and Ningxia, it would be 11°C-13°C; and for Shaanxi, it would be 15°C-17°C. Stable climatic conditions and more efficient production are prerequisites for the development of sustainable agriculture. Hence, in the agricultural production process, reducing the redundancy of input factors is the best way to reduce CO₂ emissions and to maintain temperatures, thereby improving the agricultural GTFP. The significance of this study is that it explores the impact of both internal production factors and external climatic factors on the development of sustainable agriculture in arid and semi-arid regions, identifying an effective way forward for the arid and semi-arid regions of Northwest China.     

毛乌素沙地凝结水动态变化及其影响因子的研究

基于2002年5~10月间运用直接称重法对毛乌素沙地臭柏(Sabina vulgaris Ant.)群落林间空地的0-1.5cm表层土壤凝结水连续观测资料,分析讨论了凝结水的日变化和季节变化特征以及影响凝结水形成的环境因子。结果表明:毛乌素沙地天然臭柏群落内各月均有凝结水发生,并且可从午后持续至翌日清晨,但各月间凝结水量和凝结持续时间有所不同。5月份凝结水持续时间最短,凝结水量也最少;而9月份凝结水持续时间最长,凝结水量也最多。影响毛乌素沙地凝结水形成的主要环境因子有风速、大气相对湿度、气-地温差及其相互作用。其中,风速与凝结量间存在较高相关性,而气温能否趋近或降至露点产生土壤凝结水是决定夜间水分凝结量的一个关键因素。     

陕北枣林病虫害生态调控复合模式的可行性分析

基于有害生物控制的原理,考虑陕北黄土高原环境特点和资源优势,结合国家退耕还林生态工程,提出乔木(枣树)—灌木—牧草(作物)—畜禽栽种养殖为一体作为陕北枣林病虫害生态调控的复合模式,并就其机制和可行性进行了较为深入的分析,对陕北红枣产业具有一定的实践指导意义。     

Effects of temperature, relative humidity and duration of wetness period on germination and infection by conidia of the pear scab pathogen (Venturia nashicola)

Experiments were conducted to determine the effects of temperature, relative humidity (RH) and duration of wetness period on in vitro germination of conidia and infection of detached pear leaves by Venturia nashicola , the causal agent of pear scab. Conidia germinated only in near-saturation humidity (RH > 97%). The final percentage germination (24 h after inoculation) at 100% RH without free water was less than half that in free water. Conidia germinated over the range of temperatures tested (5–30°C); the optimum temperature for germination was ≈21°C. Changes in percentage germination of conidia over time were fitted by logistic models at each individual temperature. Polynomial models satisfactorily described the relationships between two (rate and time to 50% of maximum germination) of the three logistic model parameters and temperature. The minimum length of the wetness period for successful infection of detached pear leaves by conidia was observed at several temperatures. The shortest length of wetness period required for infection was 7 h at 22°C. Two polynomial models fitted well the relationship between the minimum wetness duration required for infection, and temperature.     

Influence of relative humidity on development and egg-laying in Panonychus citri under controlled conditions

The influence of relative humidity on several aspects of the biology of citrus red mite, Panonychus citri , has been analysed. Five constant RH values (45, 55, 65, 75, 85%), with a fixed constant temperature of 25±2°C, have been studied. An RH of 65% was optimal for mite development and egg-laying potential, providing a maximum r_m value of 0.145.     

Effect of temperature, wetness duration, and planting density on olive anthracnose caused by Colletotrichum spp

The influence of temperature, wetness duration, and planting density on infection of olive fruit by Colletotrichum acutatum and C. simmondsii was examined in laboratory and field experiments. Detached olive fruit of 'Arbequina', 'Hojiblanca', and 'Picual' were inoculated with conidia of several isolates of the pathogen and kept at constant temperatures of 5 to 35°C in humid chambers. Similarly, potted plants and stem cuttings with fruit were inoculated and subjected to wetness periods of 0 to 48 h. Infection occurred at 10 to 25°C, and disease severity was greater and the mean latent period was shorter at 17 to 20°C. Overall, C. acutatum was more virulent than C. simmondsii at temperatures <25°C. When temperature was not a limiting factor, disease severity increased with the wetness period from 0 to 48 h. Disease severity was modeled as a function of temperature and wetness duration; two critical fruit incidence thresholds were defined as 5 and 20%, with wetness durations of 1.0 and 12.2 h at the optimum temperature. In the field, anthracnose epidemics progressed faster in a super-high-density planting (1,904 olive trees/ha) than in the high-density plantings (204 to 816 olive trees/ha) and caused severe epidemics in the super-high-density planting even with the moderately resistant Arbequina. Data in this study will be useful for the development of a forecasting system for olive anthracnose epidemics.     

Effects of shrub species and microhabitats on dew formation in a revegetation-stabilized desert ecosystem in Shapotou,northern China

Dew is an important supplement water source in arid and semi-arid areas. In order to determine the dew formation on different kinds of soils associated with various shrub species and microhabitats, we performed measurement of accumulated dew formation amount and duration in October 2009 in a revegetation-stabilized arid desert ecosystem in Shapotou area, northern China. The results indicated that the accumulated dew formation amount was four times larger at open spaces as compared to under the canopy, and it was nearly twice as much under living Artemisia ordosica plants（L.A.） as compared to under living Caragana korshinskii plants（L.C.）. The opposite characteristics were found for dew duration between different microhabitats. Dew amounts at different vertical heights around the shrub stands were in the order of 50 cm above the canopy〉the canopy edge〉under the canopy. Dew amount continued to increase after dawn, and the proportion of average accumulated dew amount after dawn accounting for the average maximum amount increased from above the canopy to under the canopy. Dew formation duration after sunrise accounted for more than 50% of the total formation duration during the day time. Contrary to the distribution characteristics of dew amount, dew duration after dawn and total dew formation duration during the day time were both highest under the canopy, followed by at the canopy edge and then at 50 cm above the canopy. The portion of dew duration after dawn accounting for the total dew duration during the day time increased from above the canopy to under the canopy. From these results, we may conclude that dew availability as a supplemental water resource for improving the microhabitats in water-limited arid ecosystems is position dependent especially for the plant microhabitats at different stands layers.     

Variations in acaricidal effect of wettable sulfur on Tetranychus urticae (Acari:Tetranychidae): effect of temperature,humidity and life stage

Under laboratory conditions, the acaricidal effect of wettable sulfur is influenced by climatic conditions and the stage of development of Tetranychus urticae. Its ovicidal effect results from the combined action of temperature and relative humidity (RH). Wettable sulfur becomes effective at 27.5 degrees C and 75% RH. Beyond this threshold, the acaricidal effect increases with rising temperature or humidity, to become complete at a temperature of 35 degrees C and 90% RH. Within the range of temperatures and humidities 20 degrees C/30% RH and 35 degrees C/90% RH the mortality of immatures (from protonymphs to teleiochrysalis) was total. Under similar experimental conditions, females usually died before the end of the experiment. Temperature and relative humidity increased the adulticidal potential of wettable sulfur. The fecundity of the sulfur-treated females and the viability of their progeny was found to depend on temperature and RH. According to the same climatic conditions, eggs were less susceptible than females, which were in turn less susceptible than juvenile stages.     

Influence of incubation-period humidity on the development of brown rot blossom blight of sour cherry

ABSTRACT When detached sour cherry (Prunus cerasus) blossoms were inoculated with conidia of Monilinia fructicola and subjected to a standard 8-h wetting treatment at 20 degrees C, blossom blight incidence was proportional to relative humidity (RH) when RH was held constant during the subsequent 6-day incubation period (frequency = 1.0 at the maximum RH of 92%; frequency = 0.38 at the minimum RH of 57%). Similarly, when a primary incubation period at 87% RH was followed by a secondary incubation period at 54% RH, blossom blight incidence was proportional to the number of hours at the higher level (frequencies of 0.94, 0.80, and 0.38 with primary incubation periods of 6 days, 36 h, and 12 h, respectively). When intact blossoms on potted trees were exposed to common inoculation and wetting treatments, disease incidence was consistently high on trees that subsequently were incubated in a controlled environment chamber (20 degrees C, 90 to 95% RH) but was extremely variable when trees were incubated under variable ambient conditions. Ambient incubation temperature had little effect on disease incidence 9 days after inoculation, whereas ambient RH had a pronounced effect: the frequency of blighted blossoms was 0.53 to 0.61 when the number of hours at RH >90% was approximately two to six times that at RH <60%, whereas this frequency was only 0.02 to 0.07 when the number of hours at RH >90% was approximately one-third the number at RH <60%. After 48 h at a constant RH of 89 or 57%, the water potential of excised uninoculated blossoms was -1.15 and -1.93 MPa, respectively; however, growth of M. fructicola on osmotically adjusted potato dextrose agar was unaffected by changes in water potential within this range. Thus, although RH during incubation has an important influence on blossom blight development, the causal mechanism remains uncertain.     

Laboratory studies on the effect of temperature and humidity on the life table of the whitefly,Aleurotuberculatus takahashi David & Subramaniam (Hom., Aleyrodidae) from southeastern China

The present paper deals with developmental duration, emergence, longevity and fecundity ofAleurotuberculatus takabashi David & Subramaniam at different temperatures and humidity levels. The developmental time from egg to adult was 81.8, 56.9, 39.6, 29.9, 20.6 days at 15±1, 20±1, 25±1, 30±1, 35±1°C under constant relative humidity (RH) of 70±5%, respectively. At 25±1°C, the total developmental time was slightly affected by humidity, ranging from 46.4 days at 40±5% RH to 39.2 days at 90±5% RH. The developmental threshold and the thermal constant for the stage from egg to adult were 10.1°C and 542.8 day-degrees. It was estimated that the whitefly has about 10 generations a year in Fuzhou region in southeastern China. Lowest mortality rates of 12.4% for the egg, 6.8% for the nymph and 3.1% for the puparium were obtained at 15±1°C, while they were highest with 92.1% for the egg, 48.2% for the nymph and 36.3% for the puparium at 35±1°C. The mortality rates were slightly affected by humidity, ranging from 17.6% at 40±5% RH to 27.9% at 90±5% RH for the egg, 11.2% at 40±5% RH to 19.6% at 90±5% RH for the nymph, and 6.4% at 40±5% RH to 11.6% at 90±5% RH for the puparium. The emergence rate of adults decreased as temperature increased, ranging from 89.1% at 15±1°C to 21.5% at 35±1°C, so did the longevity of adults, ranging from 9.6 days at 15±1°C to 2.9 days at 35±1°C. The number of eggs per female was significantly affected by temperature (P.01), valuing 29.4 eggs per female at 15±1°C, 36.7 at 20±1°C, 52.4 at 25±1°C, 42.9 at 30±1°C, and 6.1 at 35±1°C. The optimal temperature for reproduction was about 25°C.