气候变化对甘肃胡麻生产的影响

利用1981—2000年甘肃全省71站点胡麻产量和生长期(4～10月)气象资料,用EOF、小波分析和积分 回归等统计分析方法分析胡麻产量的时空特征,以及不同气象因子对胡麻产量的影响。结果表明,胡麻产量分布 由北向南依次递减;在降水量变化一定的条件下,胡麻产量随温度的升高而降低;在温度变化一定的条件下,胡麻 产量随降水的增加而增加,适时早播可避免胡麻籽粒期高温对产量的影响。为适应气候变化,应积极试验扩大复 种面积,提高商品量。     

Methodologies for simulating impacts of climate change on crop production

Ecophysiological models are widely used to forecast potential impacts of climate change on future agricultural productivity and to examine options for adaptation by local stakeholders and policy makers. However, protocols followed in such assessments vary to such an extent that they constrain cross-study syntheses and increase the potential for bias in projected impacts. We reviewed 221 peer-reviewed papers that used crop simulation models to examine diverse aspects of how climate change might affect agricultural systems. Six subject areas were examined: target crops and regions; the crop model(s) used and their characteristics; sources and application of data on [CO₂] and climate; impact parameters evaluated; assessment of variability or risk; and adaptation strategies. Wheat, maize, soybean and rice were considered in approximately 170 papers. The USA (55 papers) and Europe (64 papers) were the dominant regions studied. The most frequent approach used to simulate response to CO₂ involved adjusting daily radiation use efficiency (RUE) and transpiration, precluding consideration of the interacting effects of CO₂, stomatal conductance and canopy temperature, which are expected to exacerbate effects of global warming. The assumed baseline [CO₂] typically corresponded to conditions 10-30 years earlier than the date the paper was accepted, exaggerating the relative impacts of increased [CO₂]. Due in part to the diverse scenarios for increases in greenhouse gas emissions, assumed future [CO₂] also varied greatly, further complicating comparisons among studies. Papers considering adaptation predominantly examined changes in planting dates and cultivars; only 20 papers tested different tillage practices or crop rotations. Risk was quantified in over half the papers, mainly in relation to variability in yield or effects of water deficits, but the limited consideration of other factors affecting risk beside climate change per se suggests that impacts of climate change were overestimated relative to background variability. A coordinated crop, climate and soil data resource would allow researchers to focus on underlying science. More extensive model intercomparison, facilitated by modular software, should strengthen the biological realism of predictions and clarify the limits of our ability to forecast agricultural impacts of climate change on crop production and associated food security as well as to evaluate potential for adaptation.     

Yield benefits of triticale traits for wheat under current and future climates

Triticale often out-yields wheat in both favourable and unfavourable growing conditions. Observed traits suggested for the higher yields in triticale include greater early vigour, a longer spike formation phase with same duration to flowering, reduced tillering, increased remobilization of carbohydrates to the grain, early vigorous root growth and higher transpiration use efficiency. To quantify the impact of these traits systematically across seasons and contrasting rainfall regions and soil types, these triticale traits were introduced into a wheat model (APSIM-Nwheat). The impact of each individual trait and their full combination was analysed in a simulation experiment for three Mediterranean growing environments, two contrasting soil types and long-term historical weather data. The simulated impact of these traits was compared with measured impacts from a range of field experiments across several environments. Simulated responses of various crop characteristics including yield, were in general similar to responses observed in wheat-triticale comparison field experiments across a large range of growing conditions. The simulation analysis indicated that the yield response to the incorporation of the triticale traits into wheat was positive, in both low and high yielding growing conditions, similar to measured differences, but the simulated benefit was on average lower than the range observed in data of triticale and wheat. This suggests that other traits might also be involved in higher-yielding triticale, or the magnitude of some of the traits may be underestimated in field experiments due to ‘trait by environment’ interactions. The simulation results suggest the highest yield benefit can be achieved from increasing transpiration use efficiency in wheat, but early vigour, remobilization of stem carbohydrates and early root growth also contribute positively to a yield increase in the different growing environments. The yield benefits from the triticale traits increased in the future climate change scenario in particular on soils with high water-holding capacity from contributions of increased early vigour, remobilization of stem carbohydrates and transpiration use efficiency, and remained stable on the lighter soils.     

Effect of climate change on Spodoptera litura Fab. on peanut: A life table approach

Investigations were conducted to understand the direct effects of rising temperature and the host-mediated effects of elevated CO₂ (eCO₂) on Spodoptera litura (Fabricius) (Noctuidae: Lepidoptera). This study involved i. the construction of life tables of S. litura at six constant temperatures viz., 20, 25, 27, 30, 33 and 35°C ± 0.5 °C reared on peanut (Arachis hypogaea L.) grown under eCO₂ (550 ppm) concentration in open top chambers ii. Estimation of threshold temperatures and thermal constants and iii. Prediction of the pest scenarios during near and distant future climate change periods. Significantly lower leaf nitrogen, higher carbon and a higher relative proportion of carbon to nitrogen (C:N) were observed in peanut foliage grown under eCO₂ over ambient CO₂ (aCO₂). The mean development time (days) of each stage, egg, larva, pupa, pre-oviposition and total life span decreased from 20 to 35 °C temperature on eCO₂ foliage. The thermal requirement of S. litura from egg to egg (within the range of 20 °C–35 °C) was 538.5 DD on eCO₂ as against 494.5 DD on aCO₂ foliage. Finite (λ) and intrinsic rates of increase (r_m), net reproductive rate (R_o), mean generation time (T) and doubling time (DT) of S. litura varied significantly with temperature and CO₂ and were found to have quadratic relationships with temperature. The present results on life table parameters estimated by the bootstrap technique showed that the ‘r_m’ values of S. litura on eCO₂ foliage were higher than those in the literature indicating a significant influence of eCO₂. The reduction of ‘T’ was noticed from a maximum of 50 days at 20 °C to minimum of 22 days at 35 °C and ‘λ’ which is the indicator of reproductive value of new eggs was highest at 35 °C and showed a negative relationship with temperature. The data on these life table parameters were plotted against temperature and two non-linear models developed for both CO₂ conditions and used for predicting the pest scenarios. Prediction of pest scenarios based on PRECIS A1B emission scenario data at eleven peanut growing locations of the country during near future (NF) and distant future (DF) climate change periods showed an increase of ‘r_m’ and ‘λ’ with varied ‘R_o’ and reduced ‘T’. The present results indicate that temperature and CO₂ are vital in influencing the growth and life table parameters of S. litura and that pest incidence is likely to be higher in the future.     

麦蚜及植物病毒胁迫下小麦体内保护酶和解毒酶活性的变化

为探究蚜虫及植物病毒胁迫下小麦体内酶活性的变化规律,以麦二叉蚜Schizaphis graminum、禾谷缢管蚜Rhopalosiphum padi和麦长管蚜Sitobion avenae为试虫,以大麦黄矮病毒(BYDV)的GAV株系为测试病毒,研究蚜虫、植物病毒及两者共同胁迫下小麦体内超氧化物歧化酶(SOD)、过氧化氢酶(CAT)和过氧化物酶(POD)等保护酶及酸性磷酸酶(ACP)和碱性磷酸酶(AKP)等解毒酶的活性变化。结果表明,与健康小麦相比,麦二叉蚜胁迫下小麦体内的ACP活性提高100.46%,禾谷缢管蚜胁迫下小麦体内的POD活性降低34.59%,麦长管蚜胁迫下小麦体内的POD、CAT、SOD、ACP和AKP活性分别提高83.88%、126.45%、91.21%、197.26%和468.82%,差异均显著(P0.05);BYDV-GAV胁迫下小麦体内的SOD活性提高37.41%;与感染植物病毒但未受蚜虫胁迫的小麦相比,麦二叉蚜胁迫下小麦体内的POD、CAT和ACP活性分别提高73.66%、110.72%和50.49%,禾谷缢管蚜胁迫下小麦体内的CAT和ACP活性分别上升115.13%和37.00%,麦长管蚜胁迫下小麦体内的POD、CAT和AKP活性分别提高97.58%、70.19%和3 665.03%,差异均显著(P0.05)。这些结果说明,麦蚜和植物病毒均能改变小麦体内的生理生化进程,但效应有差异。     

基于分布式水文模型的小麦渍害对气候变化响应研究

为探讨长江中下游地区小麦渍害对气候变化的反应,以湖北省监利县为研究对象,收集1970-2018年监利气象观测数据和CMIP5（coupled model intercomparison project phase 5）四种情景［RCP(representative concentration pathway)2.6、RCP4.5、RCP6.0和RCP8.5］2020-2069年全球气候模式模拟气象结果数据,通过分布式水文模型（DHSVM模型：distributed hydrology soil vegetation model）模拟了近100年四种情景监利农田土壤表层（0~30 cm）土壤体积含水量,并以此来计算小麦受渍指数［sub-surface waterlogging index(SSWI),每年3-4月（小麦拔节至灌浆期）受渍天数比率］。结果表明,监利小麦受渍指数有逐年递减的趋势,但受渍时间的年际间差异会越来越大,四种情景也呈现出相同的变化规律,其中RCP4.5情景规律最明显,其主要原因是全球CO₂排放增加。降雨量增加可能会加大渍害的危害程度,但同期辐射量和气温升高会导致农田蒸散和空气中水汽含量提高,降低农田土壤含水量,有利于渍害的危害程度降低。由于农田水平衡建立在高降水、高蒸散的基础上,因此出现极端天气的可能性增加。     

稻茬小麦不同栽培模式产量差异形成的群体结构分析

为探究江苏稻茬小麦不同栽培模式下产量差异形成的原因,明确提高产量的调控途径,以小麦品种扬麦25为材料,分别在江苏省扬州市和兴化市两地种植,设置高密无氮(Y0,基本苗300×104株·hm-2,不施氮)、高密高氮(Y1,300×104株·hm-2,施氮300 kg·hm-2)、低密中高氮(Y2,150×104株·hm-2...     

Impact of UV-B radiation on aspects of germination and epidemiological components of three major physiological races of Puccinia striiformis f. sp. tritici

Global climate change is increasingly being recognized as an uncertainty of plant diseases. In particular, the increased solar UV-B (280–315 nm) radiation reaching the earth's surface has stimulated considerable studies on plant diseases in recent decades. The effects of UV-B radiation on the urediospore germination of three physiological races of Puccinia striiformis f. sp. tritici (Pst), namely, CYR31, CYR32 and CYR33, and on epidemiological components of wheat stripe rust caused by Pst were investigated in this study. In the germination experiments, seven UV-B intensity treatments including 0 (control), 50, 100, 150, 200, 250 and 300 μw/cm², were set. Under each UV-B intensity, Pst urediospores were irradiated for 15, 30, 45 and 60 min. The results showed that the germinability of Pst urediospores was reduced with an enhancement of the radiation intensity and an increase in the radiation time and that CYR31 was more sensitive to UV-B radiation than CYR32 and CYR33. To investigate the effects of UV-B on the epidemiological components of wheat stripe rust, three treatments with different UV-B radiation doses were set. The results indicated that an enhancement in UV-B radiation could reduce the infection efficiency, lesion expansion rate, sporulation quantity and AUDPC and could prolong the incubation period. The results demonstrated that CYR33 was the most stable and exhibited the strongest tolerance and that CYR31 was the most vulnerable under different UV-B radiation levels. This finding indicated that CYR33 may have more advantages to survive under enhanced UV-B radiation.     

Responses of time of anthesis and maturity to sowing dates and infrared warming in spring wheat

Reliable prediction of the potential impacts of global warming on agriculture requires accurate data on crop responses to elevated temperatures. Controlled environments can precisely regulate temperature but may impose unrealistic radiation, photoperiod and humidity regimes. Infrared warming with automatic control of temperature rise has shown potential for warming field plots above ambient temperatures, while avoiding such biases. In a field experiment conducted at Maricopa, AZ, we assessed the utility of a temperature free-air controlled enhancement (T-FACE) approach by comparing phenology of wheat from a series of six sowing date treatments using T-FACE and an additional nine sowing dates that exposed crops to an exceptionally wide range of air temperatures (<0 °C to >40 °C). The T-FACE treatments were intended to achieve a warming of +1.5 °C during the daytime and +3.0 °C at night; the achieved warming averaged +1.3 °C during daytime and +2.8 °C at night. T-FACE and sowing date treatments had large effects on phenology. A regression-based analysis of simulations with the CSM-CROPSIM-CERES model showed that effects of T-FACE on phenology were similar to what would be expected from equivalent changes in air temperature. However, systematic deviations from the expected 1-to-1 relation suggested that assumed cardinal temperatures for phenology should be revised. Based on the single cultivar and location, it appeared that the base temperature for emergence to anthesis should be reduced from 0 °C to −5 °C, whereas the base temperature for grain filling should be increased from 0 °C to 4 °C and the optimal temperature, from 30 °C to 34 °C. Both T-FACE and extreme sowing date treatments proved valuable for improving understanding of high temperature effects on plant processes, as required for accurate prediction of crop responses to elevated temperatures under climate change.     

The intrinsic plasticity of farm businesses and their resilience to change. An Australian example

This paper examines the idea that plasticity in farm management introduces resilience to change and allows farm businesses to perform when operating in highly variable environments. We also argue for the need to develop and apply more integrative assessments of farm performance that combine the use of modelling tools with deliberative processes involving farmers and researchers in a co-learning process, to more effectively identify and implement more productive and resilient farm businesses.In a plastic farming system, farm management is highly contingent on environmental conditions. In plastic farming systems farm managers constantly vary crops and inputs based on the availability of limited and variable resources (e.g. land, water, finances, labour, machinery, etc.), and signals from its operating environment (e.g. climate, markets), with the objective of maximising a number of, often competing, objectives (e.g. maximise profits, minimise risks, etc.). In contrast in more rigid farming systems farm management is more calendar driven and relatively fixed sequences of crops are regularly followed over time and across the farm. Here we describe the application of a whole farm simulation model to (i) compare, in silico, the sensitivity of two farming systems designs of contrasting levels of plasticity, operating in two contrasting environments, when exposed to a stressor in the form of climate change scenarios;(ii) investigate the presence of interactions and feedbacks at the field and farm levels capable of modifying the intensity and direction of the responses to climate signals; and (iii) discuss the need for the development and application of more integrative assessments in the analysis of impacts and adaptation options to climate change.In both environments, the more plastic farm management strategy had higher median profits and was less risky for the baseline and less intensive climate change scenarios (2030). However, for the more severe climate change scenarios (2070), the benefit of plastic strategies tended to disappear. These results suggest that, to a point, farming systems having higher levels of plasticity would enable farmers to more effectively respond to climate shifts, thus ensuring the economic viability of the farm business. Though, as the intensity of the stress increases (e.g. 2070 climate change scenario) more significant changes in the farming system might be required to adapt. We also found that in the case studies analysed here, most of the impacts from the climate change scenarios on farm profit and economic risk originated from important reductions in cropping intensity and changes in crop mix rather than from changes in the yields of individual crops. Changes in cropping intensity and crop mix were explained by the combination of reductions in the number of sowing opportunities around critical times in the cropping calendar, and to operational constraints at the whole farm level i.e. limited work capacity in an environment having fewer and more concentrated sowing opportunities. This indicates that indirect impacts from shifts in climate on farm operations can be more important than direct impacts from climate on the yield of individual crops. The results suggest that due to the complexity of farm businesses, impact assessments and opportunities for adaptation to climate change might also need to be pursued at higher integration levels than the crop or the field. We conclude that plasticity can be a desirable characteristic in farming systems operating in highly variable environments, and that integrated whole farm systems analyses of impacts and adaptation to climate change are required to identify important interactions between farm management decision rules, availability of resources, and farmer's preference.     

Thirteen‐year variation in biomass allocation under climate change in an alpine Kobresia meadow,northern Qinghai–Tibetan Plateau

Alpine grassland ecosystems are thought to be the most sensitive ecosystems to climate change, yet the responses of their belowground biomass and potential climatic controls are poorly understood. Thirteen‐year (2004 ‐ 2016) time‐series of observational belowground biomass data and environmental factors were analysed in a humid alpine Kobresia meadow on the Northern Qinghai–Tibetan Plateau. Results showed that the mean air temperature increased by 0.44°C from 2004 to 2016, while annual precipitation remained relatively stable. The belowground biomass across all soil depths (0–10 cm, 10–20 cm, 20–40 cm) increased significantly, while aboveground biomass showed little change. The proportion of 0–10 cm belowground biomass decreased, whereas the other proportions both increased, which could be mostly attributed to variations in maximum air temperature. There was no significant relationship between aboveground biomass of plant functional groups and belowground biomass across all depths, indicating that the impact of maximum air temperature on belowground biomass should not be limited by aboveground biomass. The asymmetrical response of aboveground and belowground biomass under current climate fluctuations could provide new insights for the appropriate management of the alpine ecosystem.     

Intercropping potatoes in early spring in a temperate climate. 3. The influence of planting date, row width and temperature change on the potential for intercropping

Summary The effects of planting date and row width on canopy development, intercepted radiation and yield were studied in two experiments, with the variety Wilja in 1988 and Cara in 1989. Planting dates were between mid March and early May and were combined with row widths of 0.75 and 1.25 m. Increasing the row width decreased intercepted radiation and yields in both years. Delayed planting reduced the yield of Cara, but not of Wilja. Early planting increased radiation use efficiency of Cara. It is argued that intercropping in spring without potentially reducing tuber yield might be favoured by delaying the planting of a determinate variety such as Wilja but by increasing the row width for an indeterminate variety such as Cara. Trends in mean monthly and soil 10 cm temperatures however suggest that opportunities for intercropping potatoes in the spring in a temperate climate may become more restricted.     

Progress and challenge towards reducing wheat spot blotch threat in the Eastern Gangetic Plains of South Asia: Is climate change already taking its toll?

Spot blotch, caused by Cochliobolus sativus, is a serious constraint to wheat production (Triticum aestivum L.) in the warmer plains of South Asia. Fourteen genotypes were tested in Bangladesh, India and Nepal during 6 years (2000–2005) to determine disease severity and resistance stability over these years. We analyzed the area under the disease progress curve per day (AUDPC/day) to assess spot blotch severity, and examined grain yield, 1000-kernel weight (TKW), days to heading, and plant height. Disease severity differed in the 6 years and several genotypes showed low disease severity in all years. A few genotypes had high grain yield and low disease severity in all years. Genotype Altar-84/Ae. Sq. (224)//Yaco, with the lowest disease severity and highest 1000-kernel weight (TKW) and grain yield was also the most stable for spot blotch resistance, TKW and grain yield. Results demonstrated that wheat genotypes with improved spot blotch resistance, high grain yield, acceptable TKW, and plant height are available as a result of the regional and international collaboration in South Asia. Despite this progress, the challenge lies ahead because of an apparent tendency of increasing spot blotch overall severity in the region and decreasing TKW over 6 years (2000–2005). Higher, average night time temperature during the month of March is an indicator showing that wheat crop performance is challenged in two ways—increasing spot blotch severity and decreasing TKW causing lower yield. The results underline the possible effect of changing climatic factors on disease pressure and the continuous need to identify new resistance sources to develop more spot blotch resistant wheat for the warmer Eastern Gangetic Plains of South Asia.