旱作覆膜玉米生长和水分利用对气候变化的响应

基于3 a连续冬小麦-夏玉米覆膜轮作试验校准和验证AquaCrop模型的适用性,模拟研究了气候变化对夏玉米生长、产量和水分利用的影响,分析了覆膜措施对气候变化的应对效果。结果表明:关中地区(以武功、宝鸡和西安地区为例)年平均温度呈逐年递增趋势,温度增加幅度由高到低依次为宝鸡、西安和武功,增温速率分别为0.20、0.12℃·10a~(-1)和0.09℃·10a~(-1);降雨量呈逐年递减趋势,减少幅度大小依次为西安、宝鸡和武功,减小量分别为3.59、3.23 mm·10a~(-1)和2.64 mm·10a~(-1)。AquaCrop模型在关中地区表现出了良好的适用性,可以较好地模拟连续覆膜条件下作物的产量指标、水分利用和生长的动态变化,冠层覆盖度模拟值和实测值之间的均方根误差(RMSE)介于1.1%～15.3%,生物量模拟值和实测值之间的RMSE介于0.626～2.540 t·hm~(-2),土壤贮水量模拟值和实测值之间的RMSE介于12.6～47.4 mm。模拟研究表明,上世纪60年代以来,随着气温不断升高,武功、宝鸡和西安地区的夏玉米生育期均呈逐年缩短趋势,特别是1980s以来,减少幅度达2.76、4.82 d·10a~(-1)和5.94 d·10a~(-1);在不同的降水年型下,覆膜处理产量均高于裸地处理,且其变异系数较小;在干旱气候条件下,覆膜处理依然可以获得一定的籽粒产量,与裸地处理相比,覆膜处理表现出了较好的稳产效应。同时,覆膜处理有效减少了玉米苗期土壤表层蒸发(平均减少7.6 mm),从而在土壤中保蓄更多的降雨;覆膜处理虽然增加了土壤耗水量,但其通过保蓄土壤水分,稳定作物产量,有效提高了玉米的水分利用效率。因此,关中地区旱作覆膜可以有效适应当地气候变化,在一定程度上应对干旱气候,具有较好的增产稳产效应。     

近52年来北疆≥10℃初日时空变化特征及其对春玉米播期的影响

利用1961—2012年北疆48个气象台站的气象资料,采用气候倾向率、t-检验、一元线性回归、IDW插值等方法分析了北疆以及各地州近52年≥10℃初日的变化及其对春玉米播期的影响。结果表明:(1)1961—2012年北疆平均≥10℃初日整体以-0.9 d·10a-1的倾向率呈提前趋势,20世纪80年代之前,以平均4.8 d·10a-1的倾向率呈推迟趋势,之后至今呈持续提前趋势,20世纪90年代提前趋势最为明显,倾向率达-13.5 d·10a-1。(2)北疆春玉米平均播期的提前受气候变暖显著影响,21世纪初北疆春玉米平均播期在3月26日—5月5日,且较20世纪60年代,平均播期最多提前达10~21 d,大部分县市提前1~9 d。随着气候持续变暖,北疆地区春玉米平均播期将进一步提前。     

榆林地区近43a玉米气候资源变化特征分析

基于榆林地区8个气象站1970—2012年日平均气温、≥10℃初日和≥14℃终日气象资料,计算80%保证率下≥10℃初日、≥14℃终日、全生育天数及≥10℃积温,采用线性趋势分析、累积距平、t检验和基于Surfer的空间插值等方法对榆林地区近43 a春玉米气候资源时空变化特征进行分析。结果表明:近43 a榆林≥10℃初日以~(-1).9 d·10a~(-1)倾向率呈显著提前趋势,1992年发生突变性提前,≥14℃终日有推后趋势,1981年发生突变性推迟。春玉米生育期天数和≥10℃积温分别以2.1 d·10a~(-1)和83.12℃·10a~(-1)的倾向率呈显著增加趋势,分别于1986年和1995年发生突变性增加。突变前后各要素变化量区域差异明显,≥10℃初日提前幅度和≥14℃终日推后幅度均呈由西北向东南递减分布特征;生育期天数及≥10℃积温增幅呈现西多东少的特点。80%保证率下≥10℃初日呈逐渐提前的年代际变化特征,2001—2012年80%保证率下≥10℃初日较20世纪70年代提前3~9 d,玉米适宜播种期为4月23日至26日。80%保证率下的≥14℃终日20世纪80年代出现最晚,较其它年代推后3~14 d。近43a间80%保证率下春玉米全生育期天数榆林西北部增加6~16 d,东南部增加3~4 d。近12 a来80%保证率下春玉米生育期≥10℃积温较70年代普遍增加200℃~483℃,使玉米熟制和布局发生变化,种植界限西移,范围扩大。     

黄淮海地区夏玉米对干旱和涝渍的生理生态反应

利用黄淮海地区多站点的夏玉米水分控制试验,探讨旱涝对夏玉米发育进程、光合能力、干物质分配、叶面积扩展、产量结构及最终产量的影响,进而分析旱涝对夏玉米生长过程的影响机制。结果表明:干旱减缓了夏玉米营养生长阶段的发育速率,但加快了生殖生长阶段的发育进程,而涝渍对夏玉米发育进程的影响较小;夏玉米全生育期土壤湿度距适宜湿度减小1%,其叶片最大光合速率将下降0.3 mol·m~(-2)·s~(-1),比叶面积上升8×10-6hm~2·kg~(-1);夏玉米全生育期土壤相对湿度下降1%,其地上总干重和穗干重均下降0.55%,而产量将减少155kg·hm~(-2);干旱不仅使玉米灌浆时间变短,而且使叶片光合能力下降;营养生长阶段干旱使干物质更多地分配向茎秆,导致叶面积扩展乏力,生殖生长阶段干旱减少干物质向贮存器官的分配而影响产量构成;尽管干旱使叶片变薄而促进其扩展,但仍不足以减缓干旱的整体负面影响,最终导致玉米减产;而涝渍主要使玉米叶片光合能力下降,并导致干物质向穗的分配减少而减产。     

基于水分亏缺指数的北疆春小麦不同生育阶段干旱时空特征

基于水分亏缺指数模型，结合新疆历史干旱资料记载，对比分析典型年份干旱指数，确定北疆春小麦干旱等级指标，利用ArcGIS探究1986—2016年北疆春小麦各生育阶段干旱强度、干旱站次比的年际变化规律以及干旱频率的时空分布特征。结果表明：除春小麦营养生长和生殖生长并进阶段干旱站次比呈微弱增大趋势（0.355%·10a^-1），其余生长阶段干旱强度和干旱站次比均呈下降趋势；重旱和特旱在春小麦营养生长和生殖生长并进阶段发生频率最高（主要集中在50.00%~68.00%，0~3.87%），轻旱和中旱在春小麦生殖生长阶段发生频率最高（主要集中在12.00%~25.00%，12.91%~61.27%）；春小麦营养生长阶段，北疆北部地区重旱发生频率较其他地区高（主要集中在39.36%~54.19%），春小麦营养生长和生殖生长并进阶段，北疆东北部地区重旱和特旱发生频率更高（主要集中在67.72%~83.84%，7.74%~9.67%），春小麦生殖生长阶段，北疆西南部地区重旱发生频率较其他地区重旱频率更高（主要集中在46.44%~61.92%）；北疆地区在春小麦生长的3个生育阶段，生殖生长阶段中旱发生频率最高（主要集中在41.93%~51.6%），其余两个时期重旱发生频率均高于其他等级干旱发生频率（主要集中在39.36%~54.19%，51.61%~67.72%），而特旱发生频率均最低（主要集中在0~3%）。     

关中近40a冬小麦生育期热量资源变化及影响分析

利用关中10个代表站点1971-2010年气象资料和1986-2010年冬小麦生育期观测资料,采用数理统计方法分析冬小麦生育期热量资源变化及其影响。结果表明:近40a关中热量资源总体呈增加趋势,但年际波动较大,90年代增温较为明显。≥0℃初日呈明显提前趋势,终日略有推后,冬小麦越冬期推后。80年代开始14℃终日推后,18℃终日提前,冬小麦适宜播种期延长。≥0℃积温及日数呈明显增加趋势,越冬期负积温及日数均呈减少趋势。1986-2010年小麦生育期≥0℃积温平均增加180(℃·d)·10a-1,生育期天数减少6d·10a-1。冬前积温≥500℃·d且≤700℃·d保证率达80%的适宜播期为9月28日~10月11日。随着热量资源的增加,冬小麦适宜播期应比传统播期延迟3~5d,利于防止小麦旺长受冻。但实际播期受多种因素影响,应依据实际气候特点播种,提高热量资源利用率。     

两种轮作模式下垄沟覆膜夏玉米适播密度的研究

为确定基于垄沟集雨覆膜栽培的冬油菜-夏玉米和冬小麦-夏玉米2种轮作模式下夏玉米的最适播种密度,于2019年设置5月28日(B1,冬油菜-夏玉米轮作模式下夏玉米播期)和6月15日(B2,冬小麦-夏玉米轮作模式下夏玉米播期)2个播期,每个播期均设置平作不覆盖5万株·hm~(-2)(CK)、垄沟覆膜5万株·hm~(-2)(M1)、垄沟覆膜7.5万株·hm~(-2)(M2)和垄沟覆膜10万株·hm~(-2)(M_3)4个处理,分析比较了种植方式和密度对2种轮作模式下夏玉米田间土壤储水量、土壤温度、灌浆期根系及地上部生长特征、产量及水分利用效率等的影响。结果表明:垄沟覆膜可显著提高夏玉米全生育期内0～100 cm土层土壤储水量和0～200 cm土层水分利用效率50.2%～82.0%,提高生育前期0～25 cm土层土壤温度1.6～3.6℃,但对生育中后期(拔节后)的土壤温度影响不显著。同时,覆膜夏玉米具有更大的地上部干质量和更加发达的根系。随着种植密度的提高,B1和B2夏玉米茎粗、单株叶面积下降,群体叶面积指数和干物质量上升,其中密度每增加2.5万株·hm~(-2),单株叶面积平均下降6.7%～14.3%,群体叶面积指数平均增加20.4%～33.7%。成熟期穗长、穗粗、行粒数和百粒重均随着种植密度的增加而下降,其中密度每增加2.5万株·hm~(-2),百粒重平均下降4.5%～19.6%。B1夏玉米生育期内有效积温比B2高153.2℃,生育期延长8 d;同一密度水平下,B1覆膜处理夏玉米根系及地上部生长状况优于B2,其中产量较B2平均提高3.7%～21.3%。B1和B2夏玉米分别在垄沟覆膜10万株·hm~(-2)和垄沟覆膜7.5万株·hm~(-2)时获得最高产量,分别为12 522.5 kg·hm~(-2)和11 492 kg·hm~(-2),表明冬油菜-夏玉米轮作模式下,覆膜夏玉米的生长状况和产量均优于冬小麦-夏玉米轮作,其适宜种植密度也相应提高。     

陇东黄土高原冬小麦生长对气候变暖的响应特征

使用地面平行观测资料,就甘肃陇东黄土高原作物冬小麦对气候变暖的响应进行初步比较分析.结果表明:1981年以来,冬小麦对气候变暖的响应主要表征为全生育期与越冬期缩短,返青期与成熟期提前;各发育阶段对增温的响应差异明显,增温使营养生长阶段的返青～起身～拔节和生殖生长阶段的开花及成熟日期提前,乳熟日期和开花～成熟期间的总日数无明显变化,但增温使开花～乳熟有延长趋势,使乳熟～成熟有缩短趋势.产量随平均最低气温的升高和≥0℃、≥5℃、≥10℃及≥15℃积温的增加而增加,随≥20℃积温的增加而减少,表明乳熟期的高温天气对冬小麦产量有逼熟减产的负作用.     

陇东地区冬小麦水分亏缺特征研究

利用陇东地区15个县(区)气象资料,计算各县(区)1967～2008年冬小麦生长期间逐旬参考作物蒸散量( ET0)、需水量(ETc)和作物水分亏缺指数(CWDI),确定农业干旱等级,研究陇东地区冬小麦生育期间水分亏缺时空分布特征.结果表明,陇东冬小麦生长期间各类干旱尤其是重旱发生频繁.冬小麦营养生长阶段干旱频率低,生殖...     

半干旱地区春旱对春小麦生长发育的影响

春旱使春小麦营养生长滞后，提前进入生殖生长，抽穗率降低，退化小穗的比例增加，造成大幅度减产。从春小麦的水分生态位适宜度看，五月上、中旬为水分伤害的第一个阈值点，五月下旬至六月初为水分伤害的第二个阈值点。后者是常住的。     

Changes in agronomic practices and incidence and severity of diseases in winter wheat in England and Wales between 1999 and 2019

In continuation of the annual national surveys of winter wheat, which began in 1970, samples from between 250 and 350 randomly selected wheat crops in England and Wales between 1999 to 2019 were visually assessed for disease symptoms during the milky ripe development stages (GS 73–75). Septoria tritici blotch was the most prevalent and severe foliar disease each year, although annual levels fluctuated considerably and there was no overall significant change over the two decades. Incidence of brown rust, yellow rust, take-all, and barley yellow dwarf virus also showed no significant overall change during the survey period, whereas glume blotch, powdery mildew, eyespot, and sharp eyespot all showed significant decline. Fusarium ear blight has significantly increased in both incidence and severity, causing a serious epidemic in 2012, when 96% of crops were affected. Tan spot has been the third most prevalent foliar disease since 2009 although severity is still very low. Regional disease levels were consistent over the two decades, providing reliable baselines to measure changes in seasonal disease severity. There were significant changes in agronomic practice with a rise to predominance of minimum tillage over the use of ploughing, decreases in overall disease susceptibility of cultivars grown, a major increase in the use of oilseed rape in the rotation and a long-term trend towards earlier sowing. Fungicide use increased considerably, with over 98% crops sprayed and an average of 3.5 applications made per crop each year since 2014. Implications of changes over the last 21 years are discussed.     

吡虫啉和百菌清在设施内外葫芦和黄瓜中的残留特性比较

采用高效液相色谱和气相色谱法,分别研究了吡虫啉和百菌清在薄膜大棚设施内外葫芦叶和黄瓜中消解动态及其在葫芦和黄瓜中的残留量,并结合气象因子对产生残留差异的原因进行了分析。样品中的吡虫啉经乙腈和盐酸溶液提取,中性氧化铝和弗罗里硅土层析柱净化后,用高效液相色谱检测;百菌清经乙腈提取,中性氧化铝层析柱净化后,用气相色谱检测。结果表明:吡虫啉在设施内外葫芦叶和黄瓜中均消解迅速,施药7 d后,其在设施内外葫芦叶上的消解率分别为90.4%和98.7%,在黄瓜中的消解率分别为67.8%和85.9%;而百菌清在葫芦叶上的消解速率均比在黄瓜中的稍慢,施药7 d后其在设施内外葫芦叶上的消解率分别为15.4%和38.1%,在黄瓜中的消解率分别为87.8%和91.5%。表明2种农药在设施外2种蔬菜上的消解速率均快于设施内的。两种农药均是在设施外葫芦及黄瓜中的残留量低于设施内的,而降雨和光照强度可能是引起农药在设施内外蔬菜上残留差异的主要因子。     

中国的沙暴、尘暴及其防治

沙尘暴在进入 90年代以来有进一步加剧趋势 ,其原因在于此期我国西北地区气候干暖化态势明显 ,人类超负荷开发资源加剧 ,从而导致沙尘暴的频繁发生 ,但总体上仍属于正常的灾害现象。我国沙暴只能发生于干旱半干旱区 ,尘暴则可波及半湿润与湿润区 ,由此而论 ,北京的沙尘暴属于尘暴范畴 ,北京不会形成沙漠区。防治沙尘暴必须采取水、土、植被综合防治措施 ,基本对策是 :1 .搞好流域为单元的水土资源合理利用规划 ,进行水土保持综合防治 ;2 .增加地表植被复盖 ,搞好防护林体系建设 ;3 .减轻土地利用强度 ,恢复提高土地抗蚀能力 ;4.加强管理体系建设 ,依法建设生态环境。建议国家设立水土保持为主要职能的生态环境建设委员会 ,统一协调布署我国的生态环境建设工作。     

Trends and expectations for research and technology in weed science in Thailand

There are many possible ways to improve the economic crisis in Thailand, and it is agreed that development of agricultural production is ideal for improving the economic situation in an agricultural country such as Thailand. A strategic plan for agricultural and agro‐industry research is included in the national research agenda and can be classified into nine groups covering different research areas. Most research is based on the agricultural production of four main product groups: (i) crops; (ii) aquatic animals/plants and fisheries products; (iii) poultry, livestock and animal products; and (iv) forest resources. Trends in research and development in weed management for crop production will continue to support the food demands and the development of efficient production of quality products.     

北京地区明代、清代干旱灾害与气候事件研究

根据北京地区历史时期旱灾资料,利用数学统计方法中的参数区间估计研究了明清时期该地区旱灾的差异和气候的不同。结果表明：在北京地区明代（1368-1643年）276年内,共发生旱灾166次,平均1.66年发生1次;轻度旱灾47次,中度旱灾56次,大旱灾55次,特大旱灾8次。在清代（1644-1912年）的269年里,共发生...     

Variation in seed dormancy and light sensitivity in Alopecurus myosuroides and Apera spica-venti

Variation in seed dormancy and light sensitivity was studied in Alopecurus myosuroides and Apera spica-venti . Seeds were collected from different populations, at different dates and from plants emerging in autumn or spring, and used in four experiments. In the first experiment, initial dormancy was investigated in light and darkness. In Expt 2, buried seeds were exhumed on 16 occasions, from September 1997 to March 2000, and germinated in light, in darkness and after a 5-s light exposure. In Expt 3, emergence was recorded for seeds sown in pots outdoors. In Expt 4, stratified seeds of A. myosuroides only were exposed to photon irradiance ranging from 0.1 to 25 600 μmol m⁻². Variation was high among seed collections, but both species showed winter annual dormancy patterns. Apera spica-venti germinated to high percentages in autumn but negligibly in spring. Alopecurus myosuroides germinated less in spring when tested in darkness and after a short light exposure and emerged poorly in spring, which reflected photo-desensitisation during cold stratification. We conclude that the peak of emergence in A. myosuroides , and to some extent in A. spica-venti , is largely regulated by exposure to light interacting with low-level dormancy. This offers valuable information regarding optimal timing of weed control measures.     

西安夏、秋季降水与太阳黑子的关系

基于西安市1960-2007年的降水数据和太阳黑子相对数,采用一元线性回归、Mann Kendall检验等方法,对西安降雨量进行分析,然后采用小波分析方法研究了西安夏、秋两季降水量与太阳黑子之间的关系。结果表明：夏、秋两季降水量约占西安全年降水量的80%;西安夏季降水量呈上升趋势,秋季降水量则呈下降趋势;降水量的变化与太阳黑子数多少密切相关,在太阳黑子出现极值年及2 a左右,降水量也出现极值;西安夏季降水量有10 a左右的周期,秋季降水量有9 a左右周期;太阳黑子在9 a时间尺度上与降水量有很强的相关性,且夏季降水量与太阳黑子相差1～2 a的正相关,秋季降水量则与太阳黑子提前2 a左右的负相关关系。     

Relationship between azinphos-methyl usage and residues on grapes and in wine in Australia

Azinphos-methyl was applied to Shiraz winegrapes by commercial high-volume and hand-held sprayers during seasons 1993/94 and 1994/95. Residue levels in grapes resulting from treatments applied by commercial sprayer were below the maximum residue level (MRL) of 2 mg kg^-1 for grapes in Australia, whereas residues resulting from treatments applied by hand-held sprayer still exceeded the MRL five weeks after final application. There was a strong correlation for most treatments between treatment concentration of azinphos-methyl and residue level in grapes, and in wine made from treated grapes. Applied at the recommended rate (1·2 g litre^-1 wettable powder (WP) and 2·4 ml litre^-1 suspension concentrate (SC)) by commercial high-volume sprayer, azinphos-methyl residue levels in wine were well below the MRL, and below the MRLs of most importing countries, except Denmark and Sweden. When applied by hand-held sprayer, residue levels in wine were 5·9–29·6 fold higher than those previously obtained by commercial application of insecticide. Since wines are often blends from different grape blocks and grape-growing districts, in practice, this is unlikely to be of concern. Wine made from grapes treated by commercial sprayer showed no detectable residues of azinphos-methyl after one year of storage. In both years, residue levels in grapes of both formulations of azinphos-methyl fluctuated during the five-week post-treatment period, although there was an overall downward trend. Previously unrecorded systemicity in azinphos-methyl was demonstrated in laboratory studies with barley seedlings, and this may explain these fluctuating data in grapes. The reduction of azinphos-methyl residues in grapes over time appears to be a complex phenomenon involving translocation of active ingredient combined with an increase in the size and weight of berries, producing fluctuating residue levels. © 1998 SCI     

Comparative ecophysiology of grain sorghum and Abutilon theophrasti in monoculture and in mixture

Selection of crop genotypes that are more competitive with weeds for light interception may improve crop yield stability in the presence of weeds. The effects of interference on ecophysiological characteristics of Abutilon theophrasti Medic. and three morphologically diverse grain sorghum hybrids was evaluated to determine the relative tolerance and suppressive ability of the three hybrids and specific traits that may contribute to those differences. A tall hybrid was more tolerant to A. theophrasti interference than two medium stature hybrids. Early leaf area growth of two medium-stature sorghum hybrids was reduced by A. theophrasti interference, whereas early growth of a tall hybrid was unaffected. The height of A. theophrasti was greater than two moderate-stature hybrids but lower than the tall hybrid. Greatest leaf area density (L_D) of the tall sorghum hybrid was above that of A. theophrasti , whereas greatest L_D of medium-stature hybrids was below that of the weed. In monoculture, the partitioning of new biomass to various plant organs was similar among sorghum hybrids, whereas the tall sorghum hybrid partitioned less biomass to leaves and more to stems than medium hybrids in mixture. The results indicate that the three hybrids differ in their susceptibility to A. theophrasti competition. Crop traits that may contribute to greater crop competitiveness include greater maximum height and its growth rate and greater height of maximum leaf area distribution.     

新疆湖泊沉积记录的气候水文变化及其环境效应

在综合分析湖泊沉积记录的西北干旱区全新世气候特征及演变规律基础上,对新疆不同时间尺度上湖泊的水文变化进行了研究.新疆不同地区全新世气候环境存在差异,北疆全新世主要经历了早期温干、中期暖湿以及后期温十的气候演化过程,但不同湖泊记录的气候转型时间有所差别.南疆全新世以来湖泊记录研究较少,对气候演变规律有不同的认识,但中全新世暖湿气候特征具有一致性.根据近千年来的湖泊沉积记录研究,近百年来新疆处于暖干化阶段.总体来看,全新世以来湖泊水位出现了明显的波动.并呈现总体下降的趋势.然而,近50年来,随着流域人口增加、社会经济发展等强烈的人类活动影响,造成流域水资源的匮乏,导致湖面的快速萎缩,引起严重的区域环境问题.地质历史时期的湖面升降,敏感地体现了气候的波动过程,由气候因子波动及人类活动趋势分析,新疆湖泊水面将继续萎缩.