大连气候变暖及其对农业的影响

选取大连地区7个观测站1961—2007年历年月平均气温、最高气温、最低气温、≥0 ℃积温、≥10 ℃积温、<0 ℃负积温和无霜冻等指标,统计分析了近47年其变化特征,研究了大连地区热量资源对气候变暖的响应及其对农业生产的影响。结果表明: 月平均气温、最高气温、最低气温、≥0 ℃积温、≥10 ℃积温1988—2007年比1961—1987年的平均值明显增高(多),尤以最低气温增幅最大,冬季升温幅度大于夏季,大连地区气候变暖主要来自最低气温升高的贡献;<0 ℃负积温绝对值明显减少;初霜推后,终霜提前,无霜期日数增多;20世纪80年代后期大连气候明显变暖,尤其是21世纪初异常偏暖事件频发,热量资源增加,对冬季大棚蔬菜等设施农业的生产有利,病虫等越冬存活率上升,农业投入增加,气候变暖对大连地区农业影响是利弊并存。     

甘肃陇东黄土高原冬小麦对气候变暖的响应

使用地面试验田平行观测资料,就甘肃陇东黄土高原冬小麦对气候变暖的响应进行了比较分析。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的缩短,返青期与收获期提前,而越冬前和返青后的生长期总日数并无明显变化;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至起身至拔节和生殖生长阶段的开花及成熟日期提前,乳熟日期和开花至成熟期间的总日数无明显变化,但增温使生殖生长阶段的开花至乳熟有延长趋势,而乳熟至成熟期有缩短趋势。籽粒重随≥10℃积温的增加而增加,随3月至收获期最高气温的升高而减少;产量随平均最低气温的升高和≥0℃、≥5℃、≥10℃和≥15℃积温的增加而增加,随≥20℃积温的增加而减少,表明高温天气增加对冬小麦产量有一定程度的逼熟减产负作用产生。     

温度对玉米生长和产量的影响

为了明确气温变化对玉米生长发育和产量的影响,建立玉米低温冷害监测和气象评估模式,在东北地区中部的榆树市进行了玉米分期播种试验。试验采用3个品种,设置早、中、晚3个播种期,进行玉米生长发育进程、叶面积指数、生物量、产量和温度等观测。结果表明：玉米的生长速率与温度密切相关,平均气温每升高1 ℃,出苗速率提升17%,营养生长速率提升5%;积温每增加100 ℃·d,玉米最大叶面积指数增加10%,最大生物量和产量增加8%;玉米生长发育期(日平均气温稳定>10 ℃期间)间平均气温降低0.7 ℃,或活动积温减少100 ℃·d,玉米成熟期将延迟7 d,发生一般低温冷害,玉米单产减少8%;气温下降1 ℃,或积温减少140 ℃·d,生育期延迟10 d,发生严重低温冷害,减产10%以上;在水分条件比较适宜的前提条件下,气候变暖对东北地区玉米单产提高是有利的。     

气候变暖对河西走廊绿洲灌区玉米产量影响及对策研究

利用河西走廊绿洲灌区西(酒泉)、中(张掖)、东部(武威)代表站25年的气温和玉米产量资料,计算出各区域玉米生育期内≥0℃、5℃、10℃、15℃、20℃活动积温,用正交多项式拟合分离出玉米气候产量。采用多项式法、线性倾向、累积距平等统计学方法分析积温和玉米气候产量的变化特征,以及气候变暖对玉米产量的影响。结果表明:随着全球气候变暖,河西走廊灌区不同区域积温变化均呈明显上升趋势;玉米生育期内≥10℃的活动积温与产量关系最为密切,是影响当地玉米产量的关键气象因子,玉米产量随≥10℃积温的增加而提高;灌区气候变暖后玉米气候产量比变暖前明显增加,自西向东分别增加124%、186%和301%。气候变暖、热量资源增加有利于提高喜温作物玉米产量,表明河西走廊绿洲灌区可以进一步扩大玉米种植面积,建立玉米种植基地。     

气候变暖对中国西北地区农作物种植的影响

采用对农作物生长有指标意义的≥10℃积温和<0℃负积温与农作物适宜种植面积、生长发育速度及产量进行对比统计分析研究,指出气候变暖对中国西北地区农作物种植结构发生了较大改变,冬小麦种植区西伸北扩,棉花面积迅速扩大,多熟制向北和高海拔地区推移.农作物生长发育速度发生了明显变化,春播作物提早播种,喜温作物生育期延长,越冬作物推迟播种,生育期缩短.棉花气候产量明显增加.     

气候变暖对内蒙古地区小白杨物候的影响

基于1982—2006年内蒙古地区17个小白杨物候观测站的气温以及小白杨春季和秋季物候资料,对该区小白杨春季和秋季物候的变化趋势进行了研究,分析了物候期变化与气候变暖的关系,并利用逐步回归方法建立了小白杨始花期和落叶期变化的预估模型.结果表明：1982—2006年间,研究区气温呈增加趋势,该区小白杨春季物候呈提前趋势,秋季物候呈延后趋势;小白杨始花期与冬、春季气温呈负相关,主要影响因子为3—4月的平均气温;落叶期与秋季气温呈正相关,主要影响因子为8—10月的平均气温;根据气候变化国家评估报告,未来内蒙古地区春、秋季平均气温分别升高1.5 ℃～5.4 ℃和1.2 ℃～4.4 ℃,小白杨始花期将提前3.9～17.8 d,落叶期将延后3.0～12.4 d.     

气候变化背景下中国农业气候资源变化Ⅴ.宁夏农业气候资源变化特征

基于1961—2009年宁夏21个气象站点的气象资料,分析了宁夏各区农业气候资源的时空变化趋势.结果表明：研究期间,宁夏各地气温逐渐升高,呈北高南低的空间分布特征,年均气温的气候倾向率为0.4 ℃·(10 a)^-1;大部分地区年降水量呈逐渐减少趋势,年降水量的气候倾向率为4.26 mm·(10 a)^-1;无霜期和作物生长季天数随着气候变暖逐渐延长;≥10 ℃积温在3200 ℃·d以上的区域向南扩展,宁夏适宜种植中晚熟水稻的区域有所扩大;2001—2009年,宁夏大部分地区适宜种植冬小麦,全区各地几乎都适宜种植春小麦;宁夏南部山区各地7月平均气温≤20 ℃的区域面积逐渐缩小,适宜种植马铃薯的地域也随之缩小.     

气候变暖对贺兰山东麓酿酒葡萄热量资源及冷冻害的影响

利用宁夏贺兰山东麓各地1981年以来气象资料,分析了气候变暖对酿酒葡萄生育关键期主要热量资源和冷冻害的影响。结果表明:1981年以来,随着气候变暖,贺兰山东麓酿酒葡萄发育期4—9月各地各月平均气温显著上升,1997年前后发生突变,突变后部分年份较常年同期偏高1℃以上,其中放条萌芽期4月平均气温上升显著,但月内波动幅度增大,酿酒葡萄遭受霜冻或强降温危害的风险增加;7—8月浆果生长和成熟期低温事件发生的可能性仍然较大;气候变暖使活动积温显著增加,中晚熟品种积温保证率达100%,4—9月3300℃(成熟度高,葡萄酒质量好的临界积温)的积温保证率明显提高;无霜期延长,晚熟品种的保证率提高,部分年份活动积温和无霜期满足极晚熟品需求;大部分地区冬季低温冻害相关要素变化趋势都不显著,其中出现持续低于-17℃(冬季受冻临界气温)日数减少,极端最低气温升高,但仍然低于-17℃,惠农、贺兰、平罗、银川20 cm深度-4℃以下日数减少;春季适宜放条期后出现霜冻的年份和日数增多,霜冻过程的最低气温明显降低,出现伴随霜冻的中等及以上强度冷空气频率和次数增加,强度增强。气候变暖对宁夏贺兰山东麓酿酒葡萄生产有利有弊,不同品种酿酒葡萄对气候的适用性不同,因此在酿酒葡萄生育各关键期,仍需加强极端天气气候事件和气象灾害的监测和防范工作,减轻或避免气候条件变化对酿酒葡萄产业发展的不利影响。     

气候变化背景下中国农业气候资源变化V.宁夏农业气候资源变化特征

基于1961-2009年宁夏21个气象站点的气象资料,分析了宁夏各区农业气候资源的时空变化趋势.结果表明:研究期间,宁夏各地气温逐渐升高,呈北高南低的空间分布特征,年均气温的气候倾向率为0.4℃·(10 a)-1;大部分地区年降水量呈逐渐减少趋势,年降水量的气候倾向率为4.26 mm·(10 a)-1;无霜期和作物生长季天数随着气候变暖逐渐延长;≥10℃积温在3200℃·d以上的区域向南扩展,宁夏适宜种植中晚熟水稻的区域有所扩大;2001-2009年,宁夏大部分地区适宜种植冬小麦,全区各地几乎都适宜种植春小麦;宁夏南部山区各地7月平均气温≤20℃的区域面积逐渐缩小,适宜种植马铃薯的地域也随之缩小.     

春玉米最大叶面积指数的确定方法及其应用

玉米叶面积指数达到最大时光合产物基本停止向营养器官分配,是玉米进入生殖生长阶段的标志.对锦州农田生态系统野外观测站2005-2011年多品种的春玉米大田试验资料分析发现春玉米最大叶面积指数出现于吐丝后2周左右,提出了春玉米叶面积指数达到最大时的积温指标,即播种至叶面积指数最大时的≥10℃有效积温为1085.3℃·d和(或)出苗至叶面积指数最大时的≥10℃有效积温为1010.4℃·d.在此基础上,采用修正的Logistic方程构建了春玉米相对叶面积指数动态普适模型.研究结果为准确模拟春玉米叶片生长及光合产物分配提供了依据.     

Scurvy in capybaras bred in captivity in Argentine

In order to determine if the absence of vitamin C in the diet of capybaras (Hydrochoerus hydrochaeris) causes scurvy, a group of seven young individuals were fed food pellets without ascorbic acid, while another group of eight individuals received the same food with 1 g of ascorbic acid per animal per day. Animals in the first group developed signs of scurvy-like gingivitis, breaking of the incisors and death of one animal. Clinical signs appeared between 25 and 104 days from the beginning of the trial in all individuals. Growth rates of individuals deprived of vitamin C was considerably less than those observed in the control group. Deficiency of ascorbic acid had a severe effect on reproduction of another population of captive capybaras. We found that the decrease in ascorbic acid content in the diet affected pregnancy, especially during the first stages. The results obtained suggest that it is necessary to supply a suitable quantity of vitamin C in the diet of this species in captivity.     

Changes in lactate dehydrogenase activity in chicken tissues in hyperthyreosis in ontogenesis

The lactate dehydrogenase activity in reactions of lactate oxidation and synthesis was studied in subfractions of the chicken brain, heart and liver at the embryonal, early postembryonal and adult stages of development after thyroxine administration. It has been shown that during embryogenesis thyroxine predominantly enhanced the rate of lactate oxidation in the mitochondrial tissues. A marked increase in the lactate synthesis was found in cytoplasm of the adult chicken tissues. Specificity of enzyme activity alterations was detected in the chicken brain during ontogenesis after thyroxine administration.     

Role for dopamine in malonate-induced damage in vivo in striatum and in vitro in mesencephalic cultures

Defects in mitochondrial energy metabolism have been implicated in the pathology of several neurodegenerative disorders. In addition, the reactive metabolites generated from the metabolism and oxidation of the neurotransmitter dopamine (DA) are thought to contribute to the damage to neurons of the basal ganglia. We have previously demonstrated that infusions of the metabolic inhibitor malonate into the striata of mice or rats produce degeneration of DA nerve terminals. In the present studies, we demonstrate that an intrastriatal infusion of malonate induces a substantial increase in DA efflux in awake, behaving mice as measured by in vivo microdialysis. Furthermore, pretreatment of mice with tetrabenazine (TBZ) or the TBZ analogue Ro 4-1284 (Ro-4), compounds that reversibly inhibit the vesicular storage of DA, attenuates the malonate-induced DA efflux as well as the damage to DA nerve terminals. Consistent with these findings, the damage to both DA and GABA neurons in mesencephalic cultures by malonate exposure was attenuated by pretreatment with TBZ or Ro-4. Treatment with these compounds did not affect the formation of free radicals or the inhibition of oxidative phosphorylation resulting from malonate exposure alone. Our data suggest that DA plays an important role in the neurotoxicity produced by malonate. These findings provide direct evidence that inhibition of succinate dehydrogenase causes an increase in extracellular DA levels and indicate that bioenergetic defects may contribute to the pathogenesis of chronic neurodegenerative diseases through a mechanism involving DA.     

SSTR5 ablation in islet results in alterations in glucose homeostasis in mice

Somatostatin (SST) peptide is a potent inhibitor of insulin secretion and its effect is mediated via somatostatin receptor 5 (SSTR5) in the endocrine pancreas. To investigate the consequences of gene ablation of SSTR5 in the mouse pancreas, we have generated a mouse model in which the SSTR5 gene was specifically knocked down in the pancreatic beta cells (betaSSTR5Kd) using the Cre-lox system. Immunohistochemistry analysis showed that SSTR5 gene expression was absent in beta cells at three months of age. At the time of gene ablation, betaSSTR5Kd mice demonstrated glucose intolerance with lack of insulin response and significantly reduced serum insulin levels. Insulin tolerance test demonstrated a significant increase of insulin clearance in vivo at the same age. In vitro studies demonstrated an absence of response to SST-28 stimulation in the betaSSTR5Kd mouse islet, which was associated with a significantly reduced SST expression level in betaSSTR5Kd mice pancreata. In addition, betaSSTR5Kd mice had significantly reduced serum glucose levels and increased serum insulin levels at 12 months of age. Glucose tolerance test at an older age also indicated a persistently higher insulin level in betaSSTR5Kd mice. Further studies of betaSSTR5Kd mice had revealed elevated serum C-peptide levels at both 3 and 12 months of age, suggesting that these mice are capable of producing and releasing insulin to the periphery. These results support the hypothesis that SSTR5 plays a pivotal role in the regulation of insulin secretion in the mouse pancreas.     

我国葫芦科植物离体培养研究进展

葫芦科植物包括多种瓜类蔬菜,对其进行离体培养研究具有重要的理论和实践意义。综述了国内在葫芦科植物器官培养、体细胞胚胎发生、花药培养、原生质体培养和体细胞杂交及离体遗传转化等方面取得的研究进展,并对葫芦科植物离体培养、遗传转化与育种的前景作了展望。