严格意义的无霜期统计方法探讨

根据霜冻和无霜期对农作物生长的影响及农业气候区划的指导意义,比较无霜期与严格意义上的“无冻期”的关系和区别,分析霜冻出现的初、终日与霜、结冰现象及气温、地面温度、草面温度≤0℃出现的初日、终日之间的关系,探讨“无霜冻期”的合理统计方法,并通过对鄂东地区的麻城、浠水、黄石三地的无霜期和“无冻期”的统计,总结两者的差异和特征,从而为正确理解和统计无霜冻期,提出一套新的观点和方法,为指导农业生产和农业气候区划提供依据。     

玉林市2017年低温霜冻对马铃薯生产的影响分析

根据玉林市发展马铃薯的自然资源条件,分析2017年冬种马铃薯生长期玉林市温度、降水、日照时数及地面温度等气候要素变化,探讨该时期低温霜冻天气及对马铃薯的影响,提出发展冬种马铃薯防御霜冻危害的对策建议。     

寿光1961—2015年初、终霜日、无霜期变化特征 及对农业的影响

笔者利用寿光市1961—2015年的气候资料，通过对初、终霜日期、无霜期观测资料，利用现代气候诊断分析方法，分析寿光市初、终霜日期、无霜期变化特征，科学评估初、终霜日变化对冬小麦和棉花产量的影响，为寿光农业生产防灾减灾提供参考依据。结果表明，（1）初霜日总体呈推迟趋势,终霜日呈提早趋势,无霜期延长。（2）初霜日呈推迟趋势，气候倾向率为2.23 d/10 a，1991年初霜日发生突变；（3）终霜日呈提前趋势，气候倾向率为-1.35 d/10 a。（4）无霜期日数呈增多趋势，气候倾向率为3.58 d/10 a，1994年无霜期日数发生突变。（5）初霜日和无霜期与小麦和棉花产量呈正相关，终霜日与小麦和棉花产量呈负相关，初霜日推迟比终霜日提前对小麦和棉花的产量贡献大。     

Estimation of Crown Temperature of Winter Wheat and the Effect on Simulation of Frost Tolerance

Accurate estimation of winter wheat frost kill in cold‐temperate agricultural regions is limited by lack of data on soil temperature at wheat crown depth, which determines winter survival. We compared the ability of four models of differing complexity to predict observed soil temperature at 2 cm depth during two winter seasons (2013‐14 and 2014‐15) at Ultuna, Sweden, and at 1 cm depth at Ilseng and Ås, Norway. Predicted and observed soil temperature at 2 cm depth was then used in FROSTOL model simulations of the frost tolerance of winter wheat at Ultuna. Compared with the observed soil temperature at 2 cm depth, soil temperature was better predicted by detailed models than simpler models for both seasons at Ultuna. The LT50 (temperature at which 50 % of plants die) predictions from FROSTOL model simulations using input from the most detailed soil temperature model agreed better with LT50 FROSTOL outputs from observed soil temperature than what LT50 FROSTOL predictions using temperature from simpler models did. These results highlight the need for simpler temperature prediction tools to be further improved when used to evaluate winter wheat frost kill.     

草面温度在霜预报中的应用

为了避免农作物遇霜后遭受冻害,本研究采用草面温度对霜进行预测。利用连云港气象观测站2014—2016年逐时气象要素,包括气温、0 cm地温、露点温度、水汽压、气压以及2 min平均风速等气象要素作为影响连云港地区草面温度的关键因子,并以这6个要素作为属性特征,以草温作为标志量构建训练样本集,结合KNN数据挖掘算法构建草温预测模型,并根据草温判别是否有霜出现。结果表明：基于该算法构建的草温预测模型效果较好,预报平均误差1.2℃;根据草温预测霜的准确率高达90.2%,尤其对初终霜的预报具有很好的指示意义。因此,引入草温作为霜的预报指标,对于避免农作物遭受霜害具有十分重要的意义。     

空气湿度对富士系苹果花过冷却点的影响

【目的】明确不同湿度条件下富士系苹果花过冷却点的分布频率,为苹果霜冻监测和预测提供参考。【方法】以中国种植最广泛的富士系苹果为研究对象,使用人工霜冻试验箱控制温湿度,模拟霜冻降温过程,设置高、中、低3个湿度范围,对富士系苹果花蕾和花朵子房过冷却点进行监测,研究环境相对湿度对富士系苹果花器官过冷却点的影响。【结果】富士系苹果花蕾和花朵子房过冷却点在-6.4^-1.9 ℃,50%的过冷却点集中在-4.4^-3.5 ℃,80%的过冷却点集中在-4.4^-2.5 ℃,平均过冷却点为-3.7 ℃。苹果花蕾和花朵子房的累积冻害率达到30%(轻度)的温度为-3.2 ℃,累积冻害率达到50%(中度)的温度为-3.6 ℃,累积冻害率达到80%(重度)的温度为-4.2 ℃。花蕾过冷却点的变异大于花朵子房过冷却点,不同湿度处理下花蕾和花朵子房过冷却点差异显著。中湿(相对湿度50%~70%)条件下,过冷却点最高,抗寒性最差,而低湿(相对湿度50%以下)和高湿(相对湿度大于70%)处理均可降低植株的过冷却点。【结论】-4.4^-2.5 ℃是富士系苹果花组织开始出现损伤的主要温度范围。干燥和高湿的环境均可降低富士系苹果花蕾和花朵的过冷却点,尤其是干燥的环境可降低苹果花蕾的过冷却点0.6 ℃,可降低苹果花朵子房的过冷却点0.4 ℃,提高苹果花蕾及花朵子房抗寒性。     

Frost response in wheat and early detection using proximal sensors

Frost can significantly reduce production of field crops grown in Mediterranean‐type environments, where significant economic losses for Australian wheat occur annually. If non‐destructive sensors could make rapid, spatial assessment of frost damage, this could limit economic losses through timely management decisions. This paper reports on a methodology for imposing frost treatments to wheat under field conditions and the utility of canopy reflectance data for detecting early crop damage. Purpose‐built chambers using stepped additions of dry ice allowed for a range of frost scenarios to be tested when applied at wheat heading and anthesis. For frost treatments applied at anthesis, grain number and yield were reduced by 8.8% and 7.2%, respectively, for every degree Celsius below zero (down to ?4°C). This effect was additive over two consecutive nights. For cold load equivalent, there was a 2.2% and 1.9% reduction in grain number and yield, respectively, per °C hr (below 0°C). For wheat, spectral indices PRI and NDVI (reflectance) and FRF_G and SFR_G (fluorescence) showed significant relationships, with cold load applied for heading treatments. Next steps include targeting frost intensities equivalent to cold loads between 20 and 80°C hr and testing the utility of these proposed indices in a commercial paddock setting.     

Relevance of Osmotic and Frost Protecting Compounds for the Winter Hardiness of Autumn Sown Sugar Beet

The cultivation of autumn sown sugar beet (winter beet) is supposed to result in a marked yield increase compared with spring sown sugar beet. Although the importance of the growth stage reached before winter for the survival of autumn sown sugar beet has already been shown, it is not clear to which extent osmotic and potentially frost protecting compounds may contribute to winter hardiness. The study thus aimed to analyse the acclimatization process of sugar beet to low temperatures and to identify compounds which are important for survival of frost. Field trials with autumn sown sugar beet were conducted at eleven environments in Germany from 2009/10 to 2012/13, which were accompanied by greenhouse experiments with controlled temperature regimes. In the field trials, the survival rates after winter varied from 0 % to 99 %, but only in four environments differences between the five genotypes occurred. During acclimatization, betaine, glutamine, proline and raffinose were markedly accumulated and osmolality was enhanced. In particular betaine, amino acids and osmolality showed a positive correlation to the survival rate and were thus identified as potentially frost protecting substances for sugar beet. In contrast, raffinose and proline seem to act rather as stress indicators as they were negatively related to survival. Possible frost protecting substances were identified which can be used in breeding to improve the winter hardiness of sugar beet.     

浙江乌牛早春茶始摘期及霜冻风险区划

为了解浙江省乌牛早春茶初始采摘期的时空分布特征和减少遭受春季霜冻的风险,应用1971—2014年浙江省71个常规站日资料和2005—2014年共2094个气象自动区域站小时观测资料,以乌牛早春茶发育热量为始摘期区划指标和乌牛早春茶各级冻害总灾损率为霜冻害区划指标,应用GIS技术,采用距离权重反比法(IDW,Inverse Distance Weighted),得到浙江省乌牛早春茶始摘期区划图和乌牛早春季霜冻风险区划分布图。结果表明:浙江全省乌牛早春茶始摘期在2月上旬—3月上旬,从南到北时间递增,温州沿海地区最早,29°N以南为2月中旬,30°N以北地区最晚。浙江沿海、盆地、低丘陵地区适宜种植乌牛早茶,海拔高的地区遭受春季霜冻风险大,不适宜种植乌牛早茶,区划结果将为茶叶主管部门和农技推广部门指导乌牛早种植的布局调整提供重要参考价值和科学依据。     

保温型刚性护面渠道设计

在刚性面层下设置一道性能良好的保温层来防止基土冻结,可以从根本上解决冻胀破坏的问题。这种带保温层的刚性护面渠道称为保温型刚性护面渠道,根据热工原理,提出了保温型刚性护面渠道横断面设计在构造方面的要求,进一步推导出计算保温层厚度的有关公式,并给出算例,还指出了需要进一步研究和探讨的问题。