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1.
Phenological development of spring cereals was investigated using observations from several sites in Finland during the period 1970–1990. Different mathematical models which relate temperature to development rate were examined to predict the duration of phenological phases. A photoperiodic response of plant development before heading was also tested. For all phases the relationship between temperature and development was approximately linear. There was no significant response of plant development to photoperiod. This was explained by consistently long photoperiods in the observational material. Parameters for a linear model were derived from a regression analysis of mean development rate of each phase against mean temperature. However, a different response may occur under higher or lower temperatures or under shorter photoperiods than those experienced here.  相似文献   

2.
基于BP神经网络的冬季日光温室小气候模拟   总被引：6，自引：3，他引：3  
为了系统分析日光温室内外气候特征的关系,向日光温室作物环境调控及小气候预报提供支持,根据冬季日光温室内小气候观测试验资料和附近气象站观测资料,利用BP神经网络方法建立3个模型,分别对3种不同天气状况下石家庄地区日光温室冬季小气候特征进行模拟。结果表明,3个模型气温训练值与实测值的均方根误差(RMSE)都在2℃以内,决定系数都在0.95以上;相对湿度训练值的RMSE都在2个百分点以内,决定系数均高于0.95;接受到的太阳辐射的训练值与实测值的RMSE都在16 W/m2以内,决定系数也均超过0.95。利用此模型得到的气温预测值与实测值的RMSE都在2℃以内,决定系数都在0.9以上;相对湿度预测值与实测值的RMSE都在4个百分点以内,晴天和少云-多云状况下决定系数均高于0.9,寡照状况下的决定系数略低,约为0.8;接受到的太阳辐射的预测值与实测值的RMSE都在26 W/m2以内,决定系数均超过0.95。说明所建BP神经网络模型对于不同天气状况下石家庄地区日光温室冬季小气候特征模拟都有较高的精度,可以用于预测。  相似文献   

3.
We start by outlining the general effects of climatic variability and temperature extremes on wheat yields in the context of extreme event effects on crop processes for climatic impacts studies. We then review literature describing the responses of wheat plants to extreme temperatures. Cardinal temperature thresholds for different phenological processes in wheat are identified and we outline the effects of temperature on rates of growth and development. Finally, we assess the implications of the above for future climatic impact studies.Our summary shows how relatively small and consistent are the standard errors of the cardinal mean temperatures for many of the processes examined. Cardinal temperatures are conservative between studies and are seemingly well-defined in wheat. Into this category we put the lethal limits for wheat, the sterility response at anthesis, the cardinal temperatures for vernalization and some of the base and optimal temperatures. Important questions for the future involve the effects of combinations of extreme events and the modelling of specific effects such as the influence of high temperatures on grain set.  相似文献   

4.
基于生理发育时间的水稻发育期预测方法   总被引：1，自引：0，他引：1  
水稻发育期模型研究是开展现代农业气象服务工作的基础。基于作物生理发育时间守恒原理,综合考虑温度和日长因子对水稻发育期的影响,利用云南省12个农气观测站2011—2014年水稻发育期观测和地面气象观测资料,分别构建并验证了适用于籼稻种植区和粳稻种植区的发育期预报模型。结果表明,2套模型在全发育期和各发育阶段的预报值与观测值模拟效果总体较好,平均全发育期RMSE值为7.47,RE值为7.99%,粳稻模型和籼稻模型的RE值分别为6.49%和9.5%,粳稻区模拟效果优于籼稻区。模型生物学意义明确、参数通用性强,适用于农业气象业务服务中水稻发育期预测,具有推广应用价值。  相似文献   

5.
Arguably the most important adaptive criterion in annual crops is appropriate phenology that minimizes exposure to climatic stresses and maximizes productivity in target environments. To date this has been achieved empirically by selecting among diverse genotypes in target locations. This approach is likely to become inadequate with pending climate change because selection is imposed on the outcome (flowering time) rather than the underlying mechanism (i.e. responses to daylength, ambient or vernalizing temperatures). In contrast to the cereals, in legumes the interaction between phenological mechanisms and environmental selection pressure is largely unknown. This paper addresses this shortcoming through photothermal modelling of chickpea germplasm from the world’s key production areas using a meta-analysis of multi-environment trials located from 49° N to 35° S. Germplasm origin had significant effects on temperature and daylength responsiveness, the former strongly correlated to vegetative phase temperatures at the collection or development site (r = 0.8). Accordingly, temperature responses increase from winter- to spring-sown Mediterranean and Australian material, and then to north, central & southern India. Germplasm origin also affects the relationship between photoperiod and temperature response. In Eastern Mediterranean material a strong negative relationship (r = −0.77) enables temperature insensitive genotypes to compensate through a strong photoperiod response. Clearly, chickpea evolution has selected for different phenological mechanisms across the habitat range. Given that under the anticipated global warming temperature sensitive cultivars will flower relatively earlier than those responding largely to photoperiod, it is important to exploit this diversity in developing better-adapted genotypes for future cropping environments.  相似文献   

6.
油菜生育期动态模拟模型的构建   总被引：1，自引：0，他引：1  
在13个不同熟期甘蓝型油菜品种的2年大田试验中,调查不同播期条件下各品种的生育进程及发育状态。依据油菜生理发育时间恒定原理、生理生态理论及各生育阶段与温度、光周期等外部环境关系,采用Logistic曲线描述油菜光周期效应,谐波分析法分析气温昼夜变化,分段正弦指数函数分析热效应和低温春化效应,结合上述因素构建油菜生育期动态模拟模型;确定模型光周期敏感因子、温度敏感性、生理春化时间和角果期因子4个遗传参数;模型的检验分析表明,对不同播期模拟值与观测值的根均方差平均值为2.67 d,对不同品种模拟值与观测值的根均方差平均值为3.74 d;4个遗传参数值对13个油菜品种聚类分析的结果符合品种特性。因此,该模型在一定范围内可准确揭示油菜对温、光的反应规律,具有较强的可靠性和预测性。  相似文献   

7.
An experiment to determine the effect of temperature and photoperiod on Lupinus albus under controlled environmental conditions was carried out, using the three Lupinus albus genotypes 'Tifwhite', 'Esta' and 'Kiev', and three temperature (10/20, 18/28 and 20 °C continuously) and two photoperiod (8 and 16 h daylength) regimes, in all combinations. Half of the seeds were vernalized for 21 days at 4 °C to alleviate the obligate vernalization requirement of Tifwhite. Although Esta and Kiev do not have obligate vernalization requirements, they were influenced by this vernalization period. Observations included the duration of the period from planting to seedling emergence, the duration of the period from planting to the beginning of flowering and the duration of flowering. The vernalization treatment accelerated plant development in all genotypes. The period from planting to emergence was shorter under the higher temperature regime. For all genotypes, the period from planting to flowering was shorter under the longer photoperiod, the same trend as would be expected for long-day plants. Duration of flowering periods were, in contrast to pre-flowering periods, shorter for all genotypes at cooler temperatures. The results of this study confirm that photoperiod does contribute to the growth period from planting to flowering in L. albus and that this species does behave as a long-day plant.  相似文献   

8.
Crop models have been widely used in simulating and predicting changes in rice phenology in the major rice production regions of China, however the uncertainties in simulating crop phenology at a large scale and from different models were rarely investigated. In the present study, five rice phenological models/modules (i.e., CERES-Rice, ORYZA2000, RCM, Beta Model, SIMRIW) were firstly calibrated and validated based on a large number of rice phenological observations across China during 1981–2009. The inner workings of the models, as well as the simulated phenological response to climate change/variability, were compared to determine if the models adequately handled climatic changes and climatic variability. Results showed these models simulated rice phenological development over a large area fairly well after calibration, although the relative performance of the models varied in different regions. The simulated changes in rice phenology were generally consistent when temperatures were below the optimum; however varied largely when temperatures were above the optimum. The simulated rice growing season under future climate scenarios was shortened by about 0.45–5.78 days; but in northeastern China, increased temperature variability may prolong the growing season of rice. We concluded more modeling and experimental studies should be conducted to accelerate understanding of rice phenology development under extreme temperatures.  相似文献   

9.
Predicting and understanding the progress towards flowering in faba bean are important to achieve the adaptation and high productivity of the crop under varying environmental conditions. Traditional controlled‐environment experiments showed that the rate of progress towards flowering was dependent mainly on photoperiod and temperature. Here, we highlight the need to include measures of solar radiation and water deficit in order to achieve an adequate model for field conditions. The improved model was assessed in two steps: first with a “basic” model across all 20 cultivars and then with an “extended” model that included terms to fit exceptional cultivars. The two new parameters were necessary to achieve an acceptable fit of progress towards flowering and clearly separated two cultivars, “Kontu” and “Witkiem Manita,” that were significantly quicker to flower than the other 18, which fit a single line. As the regression coefficients of the two exceptional cultivars differed only in intercept, not slope, we conclude that flowering responses to day length, temperature, solar radiation and drought stresses were consistent in this set of germplasm and that the two cultivars differed in earliness “per se.” Growth‐chamber experiments added information about differing ceiling temperatures for progress to flowering in four cultivars and different sensitivities to supraoptimal temperatures.  相似文献   

10.
In this study, phenological and meteorological data have been used to interpret variations in a time series of regional average yields and quality parameters of malting barley (Hordeum vulgare L). The analyses were focused mainly on the grain filling period. Duration and occurrence of this development stage showed remarkable differences from year to year, as heading varied over more than four weeks and yellow ripeness over two weeks in the investigation period from 1974 to 1996. Yields above average were achieved only in years when grain filling duration exceeded 42 d. Protein concentrations below 10.5 % and grading percentages over 90 % required at least 44 d of grain filling. Temperature had the strongest influence on the length of grain filling, even though the calculated Growing Degree Days (base temperature 3 °C) were not absolutely constant. Mean daily temperature and relative air humidity were the best estimators with respect to grain yield. An optimum temperature range was found between 14 and 18 °C. Assuming a linear relationship, yield reductions between 4.1 and 5.7 % have been calculated for every 1 °C increase of the mean daily temperature. Relative air humidity was the best single estimator for grain protein concentration. The results of this study suggest that relative humidity during grain filling can be a more suitable parameter to describe drought stress effects than precipitation amounts from heading to yellow ripeness or from January 1 to yellow ripeness.  相似文献   

11.
The use of Mucuna spp. in cover crop and green manure technologies is proving to be successful in the tropics and subtropics following intensive efforts in technology transfer to farmers by NGOs (Non-Governmental Organizations). This includes the transfer of seeds of Mucuna spp. for which the range of adaptation and the effect of environment on crop phenology are poorly understood. A selection of Mucuna spp. germplasm was evaluated over a range of contrasting photothermal conditions in controlled-environment glasshouses. Dates of emergence and first flowering were recorded. Where possible, triple-plane rate of development models were fitted to the first flowering data to quantify the relative sensitivity of each species to photoperiod and temperature. All accessions showed short-day responses but there were substantial differences in the sensitivity of rate of progress to first flowering to environment, particularly to photoperiod. This results in differences in maturity period between accessions which, with appropriate understanding, could be functionally exploited by NGOs and NARS. However, if ignored, it could result in the promotion and use of accessions ill adapted to the environment in which they are tested. In consequence there might be unnecessary resistance from farmers to the adoption of green manure and cover crops technologies which are vital to the design and maintenance of sustainable farming systems in low-income countries in the tropics.  相似文献   

12.
为克服避雨栽培局域潜在不利气象因子对梨生长发育的影响,采取定点观测记载的方法,分析梨周年避雨栽培主要物候期气象因子变化趋势。结果表明,与露地栽培相比,避雨栽培全年及梨树各主要物候期的日均温偏高、昼夜温差趋大;休眠期≤7.2℃时数累积减少5.57%,差异显著;开花期最低温、≥25℃高温时数提高0.5℃和17.72%,差异均极显著;果实发育中前期和中后期≥35℃超高温、夜间≥25℃时数分别增加25.76%、25.93%和38.73%、37.72%,差异均极显著。避雨栽培下空气湿度偏低且趋稳,开花期(<60%)、果实发育中前期和中后期(<50%)的较低相对湿度的累积时数分别减少3.36%、8.53%、10.56%,其中后2个时期的差异水平显著;而处于100%相对湿度时数分别减少42.78%、56.14%、77.11%,差异均极显著。避雨栽培光照弱化严重,果实发育期<2000 lx光补偿点光强时长增加8.64%,而≥2000 lx光补偿点光强时长减少3.61%。梨周年避雨栽培可改善花期授粉受精条件,创造不利病害发生的生态环境,但会提高梨树因休眠期需冷量不足而出现生长发育障碍的概率,加剧形成光照不足、高温和超高温等不利果实发育的气候环境,应注重选择适宜梨品种,采取合理避雨栽培方式,选用透光率高覆盖材料与高光效整形修剪方法,以及应用地面铺设反光膜、棚内安装补光装置等措施加以克服。  相似文献   

13.
基于2011—2018年油菜开花日挂牌标记试验,考种不同开花时段油菜结荚率、单荚子粒数,分析不同时期低温对油菜结实的影响,建立气象因子与油菜子粒损失率的影响定量关系。结果表明,2月25日前的低温对油菜结实的影响以中度和重度为主,3月中下旬的低温对油菜结实的影响以轻度为主,2月26日—3月10日的低温对油菜结实的影响以轻度和中度为主。油菜子粒损失率与开花时日最低气温平均值、日平均降雨量相关不显著,与开花时平均气温、日最高气温平均值、日照时数平均值、日平均相对湿度相关显著。随开花平均气温下降,日最高气温平均值下降,空气相对湿度升高。开花时空气相对湿度为70%,且日平均气温≤6.9℃,或空气相对湿度为80%,日平均气温≤8.0℃,油菜中度受害;开花时空气相对湿度为80%,且日平均气温≤4.3℃,或空气相对湿度为85%,日平均气温≤4.8℃,油菜重度受害。其次分析确定了不同天气类型下油菜开花结实的冷积温指标,当日照低温天气的冷积温指标为≥16.5℃,或无日照低温阴雨天气的冷积温指标为≥5.0℃,为中度受害。当日照低温天气的冷积温指标为≥37.5℃,或无日照低温阴雨天气的冷积温指标为≥26.0℃,为重度受害。试验结果可为油菜灾害预警评估和减灾防灾农业气象服务提供技术支撑。  相似文献   

14.
Summary Forty strains of mungbeans, including all of the entries in the 1st and 2nd International Mungbean Nurseries (IMN), were grown in plant growth chambers in photoperiods of 12, 13, 14, 15, and 16 hours and mean temperatures of 18, 23, and 28°C. Results show that (1) mungbean strains differ in their flowering response to photoperiod and to mean temperature; (2) increasing the photoperiod of reducing the mean temperature delayed flowering, the amount of delay varied with the strain: (3) variations in mean temperature may alter the effect of the photoperiod on flowering in particular strains. Twenty-five strains which flowered in all photoperiod-temperature treatments could be divided into four groups, each group being successively later in flowering. The remaining 15 strains could be divided into four groups, according to their failure to flower within 105 days in specific photoperiod-temperature treatments. Flowering response in the growth chamber is useful in explaining flowering response in the 2nd IMN at three locations varying from 14°N to 49°N latitude.Contribution No 7516 from the Missouri Agricultural Experiment Station.  相似文献   

15.
A Simplified Method to Calculate the Wet Bulb Globe Temperature   总被引：1，自引：0，他引：1  
The wet bulb globe temperature (WBGT) is difficult to measure and calculate in field observation and numerical simulation. To solve this problem, the air dry bulb temperature, wet bulb temperature, globe temperature, relative humidity, mean air velocity, solar radiation and wet bulb globe temperature in Guangzhou, P. R. China, first were collected during the summer (July). Next, correlation and regression analyses were used to derive a simplified model for calculating WBGT. The results show that dry bulb temperature, relative humidity, solar radiation, mean air velocity and WBGT were interrelated to some extent. These four parameters with high linear correlation can be used to predict WBGT in a simplified model with high precision. The simplified WBGT model can be used in field observation and simulation research regarding urban thermal environments.  相似文献   

16.
Summary Photoperiod response of flowering in common bean (Phaseolus vulgaris L.) is thought to be controlled by the genes Ppd and Hr. However, cultivars also vary in the degree that cooler temperatures reduces their sensitivity to photoperiod. To examine the inheritance of this temperature sensitivity, crosses of cvs. Gordo x de Celaya and Flor de Mayo × Rojo 70 were evaluated at two sites differing in mean temperature and using 12.5-h natural photoperiod or 18-h artificially extended photoperiod. Under 18-h photoperiod at the warmer site, Palmira, no plants of the parents or of the F2 populations flowered, confirming that the parents were sensitive to photoperiod. Under 12.5-h photoperiod at the cooler site, Popayan, the parents for each cross flowered at similar dates and no segregation for days to flower was observed. However, under 18-h photoperiod, de Celaya and Rojo 70 and the F1 populations did not flower within 100 days after planting, while the F2 and F3 populations showed segregation that was consistent with single gene inheritance, late flowering being dominant. Late flowering at Popayan under 18-h photoperiod indicates a lack of temperature sensitivity, so temperature insensitivity of the photoperiod response was dominant to sensitivity. The name Tip, for temperature insensitivity of photoperiod response, is proposed for this gene, with the recessive form of this gene conditioning earlier flowering at cooler temperatures with long daylengths. It is recognized that the observed segregation patterns could represent the effect of multiple alleles at the Ppd or Hr loci, and studies are proposed to test this possibility with molecular markers and recombinant inbred lines.  相似文献   

17.
Although experiments have previously been carried out to determine the optimum sowing time of sesame, very few attempts have been made to determine the effects of macro and micro climatic variation on yield. Thus a field experiment was conducted at the University Research Farm, Bidhan Chandra Krishi Viswavidyalaya, Kalyani, India on an Entisol (alluvial, sandy loam) in the summer seasons of 1996 and 1997 to assess the effects of macro and micro climatic variations on yield of sesame for various dates of sowing. The number of seeds per capsule of sesame was highest in the crop sown on 19 February, although up to the 18 April sowing there was no significant variation. There was no appreciable variation in thousand-seed weight with date of sowing. Crops sown on 19 February and 1 March produced statistically similar yields. The average reduction in yield of sesame was 78.5 and 213 %, respectively, for crops sown on 10 February and 28 April, compared with the crop sown on 19 February. The cultivar Rama produced higher yields than B-67 and Kanke-1. Ambient temperature above 30 °C up to 100 % flowering had a direct positive effect on sesame yield. Crop exposure to 60–70, 70–80 and  80 % relative humidity up to 100 % flowering had a direct negative effect. Temperature profile at 50 days after emergence (DAE), relative humidity at 60 DAE, and photosynthetically active radiation (PAR) at 30 and 40 DAE within the crop canopy had direct positive effects on yield. Regression models suggested that temperature profile and PAR within the crop canopy produced 72 and 35 % variation in yield, respectively.  相似文献   

18.
民勤荒漠区36种植物物候期积温变化动因分析   总被引：1，自引：1，他引：0  
中国西北荒漠区植物物候随气温变暖表现为提前趋势。那么,在物候提前的过程中,是物候日数变化敏感呢,还是物候持续期积温变化敏感呢？变动的主要原因是什么？为了回答这个问题,本文以中国西北荒漠区36种植物34年的物候观测资料,利用一次趋势线方程、相关系数及其T检验等方法进行了分析。结果表明,随着气温升高,物候持续日数有不同程度的增长趋势,物候持续期的积温变化较物候持续日数变化敏感。积温的增减在很大程度上是由物候持续日数增加或减少引起的,其次才是由于气温增高引起的,这一点是其他相关研究文献未曾报道过的。年平均气温对物候持续日数的影响＞物候开始当月平均气温＞物候开始上月平均气温＞物候持续期间平均气温和以及物候结束月平均气温。  相似文献   

19.
The main objective of the CHIP project was to perform ‘standardised’ investigations of potato (Solanum tuberosum L. cv Bintje) responses to increased O3 and CO2 concentrations by means of open-top chambers (OTC) and free air carbon dioxide enrichment (FACE) systems. The experimental sites are located across Europe representing a broad range of different climatic conditions. In 1998 and 1999 a total number of 12 OTC experiments and four FACE experiments were conducted. According to the specific needs for subsequent modelling purposes, environmental data were collected during experiments, i.e. air temperature, global radiation, air humidity (vapour pressure deficit (VPD)), soil moisture and trace gas concentrations. In the present paper, the results of these measurements are summarised. It was shown that the experiments covered a considerable range of growing season mean air temperatures (13.8–19.9 °C) and global irradiances (12.0–21.3 MJ m−2 per day), the most important driving variables for crop growth simulation models. Analysis of the soils used during the experiments demonstrated that in most cases sufficient nutrient elements were available to guarantee an undisturbed growth. Mean concentrations of CO2 and O3 in ambient air and in different treatments illustrate the observed variability of trace gas exposures between different sites and experiments. However, the effects of these parameters on growth and yield are subject of separate papers. The general climatic conditions across Europe are also causing important growth and yield effects. Comparison of marketable tuber yields revealed an increase at higher latitudes. This result was associated with lower temperatures and VPD and longer day lengths at the higher latitudes, which in turn were associated with longer growing seasons.  相似文献   

20.
Summary The effect of gibberellic acid containing mixtures, silver thiosulphate and extended photoperiod on flowering induction in 16 non-flowering potato genotypes and on flowering enhancement in 14 normally potato flowering genotypes was studied in sub-tropical plains of India during short-day autumn crop season of 2000–2001 and 2001–2002. Extended photoperiod alone was not successful in induction of flowering. Silver thiosulphate in combination with extended photoperiod effectively induced flowering in 16 potato genotypes studied for flowering induction. Induced flowers of some genotypes were male fertile. Normal berry setting was observed on induced flowers and seeds obtained from such berries germinated normally. Gibberellic acid containing treatments were not very effective in flower induction as they induced some flowering only in few genotypes. In the normally flowering genotypes silver thiosulphate enhanced maximum flowering and duration of flowering to a great extent.  相似文献   

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