Phenological development in spring cereals: response to temperature and photoperiod under northern conditions

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.     

冬小麦对不同土壤水分的生理和形态响应

采用深桶栽培结合测坑法，从冬小麦反青至蜡熟期保持不同的土壤水分，分生育期对小麦的形态、生理和根系进行了测定。结果表明：调控土壤水分可明显改变冬小麦根、冠生长量比率。适宜的土壤水分胁迫（田持的５０％－６０％）可促进冬小麦根系发育，高土壤水分更有利于地上部生长。土壤水分长期低于田间持水量的６０％时，较显著地叶片的增大，从而减小截获光能的总叶面积，最终降低生物学产量和经济产量。土壤水分由“田持”的４６％升高到５５％，光合速率增幅不大，由５５％提高到６４％，光合速率出现跃迁式增高，土壤水分超过６４％后，光合速率几乎为等值。说明光合作用对土壤水分存在一个“阈值”反应，此值为土壤田间持水量的６５％左右。冬小麦的蒸腾速率随土壤水分递增而一直递增；综合考虑蒸腾速率与光合速率及水分利用效率之间关系，可以得出高土壤水分条件下冬小麦存在奢侈蒸腾耗水现象。     

菜蛾的发育起点温度和有效积温研究

采用18、21、24、27、30℃5个温度对菜蛾(Plutella xylostellaL)各虫态(龄)发育起点温度和有效积温进行了测定。结果表明,卵、幼虫、蛹在18~30℃范围内均能正常生长发育,尤以24~27℃条件下最适宜于菜蛾的生长发育,发育速率与温度呈直线关系。卵、一龄幼虫、二龄幼虫、三龄幼虫、四龄幼虫和蛹的发育起点温度分别为11.07、9.49、9.96、10.20、9.96、8.96℃,有效积温分别为47.10、36.90、34.03、33.62、34.03、72.83日.度。在宁夏菜蛾一年可发生6~7代,在沙芥生长期发生3~4代。     

玉米对持续干旱的反应及红壤干旱阈值

 【目的】研究玉米对红壤干旱的反应以及红壤干旱程度定量表达和干旱阈值。【方法】在田间小区遮雨条件下种植夏玉米，设置连续干旱12～36 d等6个处理，用FDR水分仪每日测量0～60 cm不同土层含水量，定期观测玉米植株生长状况和气孔导度，收割后考种。【结果】玉米的株高、茎粗、气孔导度、根系数量等测量值在不同干旱天数之后显著降低，在不同土壤干旱程度下出现阈值反应，连续干旱25 d之后，玉米籽粒产量显著降低5%。干旱过程中，土层贮水量和累积相对失水量之间的关系可以用对数线性方程表示，将方程的斜率转换为取值在［0，1］区间的指数D，可以定量表达土壤干旱程度。【结论】D值既可以表示土壤干旱状况又可以表示作物受旱程度，玉米拔节－抽穗期红壤干旱程度D达到0.55则产量显著降低。     

亚洲玉米螟化性类型的初步研究

本文对自然发生的亚洲玉米螟的一代越冬型和二代越冬型的滞育后发育历期和临界光周期等进行了初步研究。结果表明，在26℃、16小时光照条件下，一代越冬幼虫的滞育后发育历期是：雌虫54.88±1.14天，雄虫53.59±1.42天．二代越冬幼虫的滞育后发育历期是：雌虫28.14±0.99天，雄虫28.47±1.24天。一代越冬型的冬蛹重为0.0757±0.0036克，二代越冬型的冬蛹重为0.0593±0.0021克。在26℃条件下，一代越冬型的临界光周期为14小时30分钟．二代越冬型的临界光周期为13小时40分钟。在26℃、15.50小时光照条件下，一代越冬型的发育历期是：幼虫17.7284±0.2664天，蛹8.3276±0.9930天，二代越冬型的发育历期是：幼虫15.9500±0.2235天，蛹重7.7129±0.1102天．经分析认为，公主岭地区自然发生的亚洲玉米螟存在一化性类型和二化性类型，这两种化性类型具有明显的差异，可以区分开．对此项内容的深入研究有助于解决亚洲玉米螟大发生预测预报和综合防治的疑难问题。     

An improved algorithm for mapping burnt areas in the Mediterranean forest landscape of Morocco

The identification of burnt forests and their monitoring provide essential information for the suitable management and conservation of these ecosystems. This research focuses on the use of remote sensing with MODIS sensor data in a Mediterranean environment, precisely in the Rif region known for its high occurrence of forest fires and the largest burnt areas in Morocco. It mapped the burnt areas during the summer of 2016 using spectral indices from MODIS images, namely the Normalized Burn Ratio (NBR) and the Burnt Area Index for MODIS (BAIM). Two field surveys were used to calibrate spectral indices and validate the maps. First, a monotemporal analysis using a single pre-fire image determined the appropriate threshold of the spectral indices (BAIM and NBR) for burn detecting. Secondly, a multitemporal method was applied based on dBAIM and dNBR images which represented pre-fire and postfire differences of the BAIM and NBR images, respectively. The results show that separate use of monotemporal postfire and multitemporal methods produced an overestimation of the burnt areas. Finally, we propose a new algorithm combining both methods for burnt area mapping that we name Burnt Area Algorithm. MCD45A1 and MCD64A1 MODIS burnt area products were compared to the proposed algorithm. Validation of the estimated burnt areas using reference data of the Moroccan High Commission for Water, Forests and Fight against Desertification showed satisfactory results using the proposed algorithm, with a determination coefficient of 0.68 and a root mean square error of 44.0 ha.     

基于界限温度的贵德木本花卉观赏期确定

近年来,贵德县以生态为本、旅游为基,大力发展观光农业,为了做好观光农业的气象服务,选取贵德三河地区观光农业中主要种植的月季和牡丹两种木本花卉,应用贵德1961~2016年国家基本站观测资料,通过文献查证花卉的开始生长至开花期的气象指标,分析贵德地区月季和牡丹开始生长至开花期相关的界限温度,确定出贵德地区月季和牡丹萌芽期,利用积温法确定出开花期的积温指标,确定出最佳赏花期,以便提高各特色观光园中花卉的种植,来延长园中花卉观赏期,游客选择各花卉的最佳观赏期,提高观赏效果。     

Genetic parameters for maternal behaviour traits in sows

Data from 32 nucleus and multiplier herds in Germany was used to estimate variance components and breeding values for five maternal behaviour traits in sows. The estimation was performed univariately using an animal threshold model. About 31,000 farrowings recorded from December 2003 until July 2005 were included. The heritability coefficients were 0.07 (0.06) for group behaviour, 0.06 (0.03) for attitude to people, 0.05 (0.01) for maternal ability, 0.03 (0.01) for crushing of piglets and 0.02 (0.02) for savaging of piglets. Additionally, genetic correlations between the behaviour traits and between the behaviour traits and litter size, respectively, were estimated multivariately by REML with a linear model. Low heritability and weak genetic correlation to litter size at birth indicate that it may be difficult to genetically improve the maternal behaviour, and that selection for better mothering ability is not necessarily accompanied by reduced litter size at birth.     

合理施肥中投资风险预测研究

在合理施肥确定边际利润率值〔１〕的基础上,应用数学方法给出一种确定投资风险预测阈值Ｋ的方法。根据阈值Ｋ可预测施肥投资风险的大小。肥粮价格比例失调是造成投资风险过大的主要原因,本文通过计算机模拟可以计算出适宜的肥粮价格,为市场宏观调控提供可行性建议。     

Relationships between rainfall characteristics and ephemeral gully erosion in a cultivated catchment in Sicily (Italy)

Recent research has shown a lack of long-term monitoring for detailed analysis of gully erosion response to climate characteristics. Measures carried out from 1995 to 2007 in a wheat-cultivated area in Raddusa (Sicily, Italy), represent one of the longest series of field data on ephemeral gully, EG, erosion. The data set collected in a surface area of almost 80 ha, permits analysis of the influence of rainfall on EG formation and development. Ephemeral gullies formed in the study area were measured on a yearly scale with a Post-Processing Differential GPS for length and with a steel tape for the width and depth of transversal sections. Ephemeral gully formation was observed for 8 years out of 12, which corresponds to a return period of 1.5 years. The measurements show strong temporal variability in EG erosion, in agreement with the rainfall characteristics. The total eroded volumes ranged between 0 and ca. 800 m³ year⁻¹, with a mean of ca. 420 m³ year⁻¹, corresponding to ca. 0.6 kg m⁻² year⁻¹. Ephemeral gully erosion in the study area is directly and mainly controlled by rainfall events. An antecedent rainfall index, the maximum value of 3-days rainfall (H_max3_d), is the rain parameter which best accounts for EG erosion. This index is used here as a simple surrogate for soil water content. An H_max3_d threshold of 51 mm was observed for EG formation. The return period of the H_max3_d threshold is almost the same as the return period for EG formation. Although a mean of seven erosive rain events were recorded in a year, EG formation and development generally occur during a single erosive event, similarly to other semiarid environments. The most critical period is that comprised between October and January, when the soil is wetter and the vegetation cover is scarce. Empirical models for EG eroded volume estimation were obtained using the data set collected at this site. A simple power-type equation is proposed to estimate the eroded volumes using H_max3_d as an independent variable. This equation shows an R² equal to 0.67 and a standard error of estimation of 0.79.