不同肥力下玉米杂交种及其亲本雄穗性状与产量关系研究

对沈单7号、沈单10、沈玉21等10个玉米杂交种及其亲本自交系的雄穗分枝数、雄穗长度和重量等性状进行研究。方差分析和相关分析表明,杂交种及其亲本自交系雄穗分枝数和雄穗长度对肥力的反应差异不显著,雄穗重量对肥力的反应极显著,肥力与亲本自交系间雄穗重量的交互作用差异显著。在不追施氮肥的条件下,雄穗分枝数和雄穗重量与子粒产量间呈显著负相关,雄穗重量与雄穗分枝数间呈极显著正相关;在追施氮肥的条件下,雄穗分枝数与产量间呈显著负相关,雄穗重量与雄穗分枝数间呈极显著正相关。     

普×爆F3家系的膨爆特性及其与穗粒性状的相关分析

在春播和夏播两种环境条件下，对普通玉米自交系与爆裂玉米自交系杂交组配的259个F₃家系的膨爆特性及其与穗粒性状的相关分析结果表明：F₃家系膨爆特性较差，采用常规系谱法从中选育出优良爆裂玉米自交系的几率较小；膨爆特性都是由多基因控制的数量性状；膨爆特性间呈极显著正相关，膨爆特性与穗粒性状间多呈显著或极显著负相关；膨化体积对膨化倍数的直接正向作用最大，百粒重的直接负向作用最大，爆花率通过膨化体积对膨化倍数的间接作用为最大正效应，穗粒重通过百粒重对膨化倍数的间接作用为最大负效应。     

吉林省黑土区玉米子粒营养元素的品质效应研究

利用吉林省黑土区62个玉米样点数据,通过相关分析、通径分析、决策分析相结合的方法探讨玉米子粒中10种营养元素与其品质的关系。相关分析表明,P、Mg和Mn与粗蛋白呈极显著正相关,与粗脂肪呈显著负相关;Fe与粗蛋白和粗淀粉呈显著正相关;K与粗淀粉呈极显著负相关;另外,粗蛋白和粗脂肪呈极显著负相关。通径分析和决策分析表明,Mn、P、Mg和Fe对粗蛋白有较大的正向影响作用;P和Mg对粗脂肪有较大的正向影响作用;Mn对粗脂肪起限制作用;K对粗淀粉有较大的正向影响作用,Fe次之。 B、Ca、Mo、Se和Zn这5种元素对玉米粗蛋白、粗脂肪以及粗淀粉含量的影响均不明显。     

夏玉米叶片生理特性与生态因子间关系的研究

通过对防雨棚下测坑中种植的夏玉米设置不同的土壤水分控制下限,研究了不同的土壤水分状况及气象因子对夏玉米叶片生理特性的影响。结果表明,各生理指标受生态因子的影响有着明显的日变化特征,不同处理气孔导度(Gs)峰值出现的时间早于光合速率(Pn)和蒸腾速率(Tr),高水分下Tr峰值出现的时间滞后于Pn,随着土壤水分胁迫程度的增加,Gs、Tr、Pn的峰值有提前出现的趋势;不同土壤水分条件下细胞液浓度(CSC)的峰值及叶水势(LWP)的低谷均在14:00左右出现。土壤水分与Tr、Pn、Gs、LWP呈极显著正相关,而与CSC呈极显著负相关。此外,气象因素对夏玉米生理指标的影响程度会随着土壤水分状况而发生变化,生理指标与生态因子的逐步回归结果表明,土壤水分和光合有效辐射是影响夏玉米生理指标最主要的生态因子。     

吉林省气候变化对玉米气象产量的影响

利用吉林省梨树县1986～2008年的气象资料和玉米产量资料,在确定梨树县玉米的气象产量与积温、降雨以及日照时数之间关系的基础上,分析吉林省气候变化规律及其对玉米产量的影响。结果表明：玉米的气象产量(Y_w)与降雨量(x₁)呈显著正相关,与生育期内的积温(x₂)呈显著负相关,与日照时数无显著相关关系,与生育期内的降雨量和积温存在显著的二元线性关系：Y_w=15768.77+2.87x₁-5.42x₂,(r=0.63)。吉林省整个生育期内的平均气温、积温分别以每年0.05℃和10℃左右增加,降雨量以每年5mm左右减少,日照时数没有明显变化。随着吉林省气候变暖和降雨减少现象的加剧,对吉林省的旱情和玉米产量的影响越来越重。     

气象因子对大豆主要贮藏蛋白组分及亚基含量的影响

以20个大豆品种为材料，同年同地点分六个播期种植，考察了整个生长期以及营养生长和生殖生长两个时期的气象因子(总积温、总日照时数、总降水量、日均温差和日均相对湿度)，对春大豆和夏大豆籽粒总蛋白以及主要贮藏蛋白组分、亚基相对百分含量的影响。结果表明：(1) 大豆籽粒总蛋白含量以及组分、亚基相对百分含量会随播期的改变而变化。(2)整个生育期间，5个气象因子极显著影响20份大豆总蛋白含量，对春大豆总蛋白含量的影响也达极显著水平，仅总积温、总日照时数和总降水量对夏大豆总蛋白含量影响达显著水平。(3)整个生育期的总积温和总日照时数与20份大豆蛋白11S相对百分含量和11S/7S比值显著负相关，总积温与20份大豆蛋白7S含量显著正相关；但气象因子对春、夏大豆的7S、11S相对百分含量和11S/7S比值的影响不显著。(4)整个生育期间气象因子对各组分亚基的影响程度存在差异；夏大豆各蛋白组分亚基的相对百分含量受两个生育时期的气象因子的影响皆不显著，而春大豆许多蛋白亚基相对百分含量受两个生育时期的气象因子的影响达到显著或极显著水平。     

麦田降雨产流时间计算模型研究

为探讨多种因素对麦田降雨产流时间的影响及其相应的定量关系,通过模拟降雨试验,研究了麦田降雨强度、冠层覆盖及初始土壤剖面含水量对降雨产流时间的影响。结果表明,在相同初始土壤剖面含水状态条件下,降雨强度与产流时间呈显著幂函数关系(P<0.01);产流时间与叶面积指数呈极显著线性正相关(P<0.01),与株高相关性较差;0～20、0～40cm土层初始土壤剖面含水量与产流时间具有较明显的线性正相关关系(P<0.01),40cm以下土层土壤含水量对产流时间影响相对较小。通过多元回归分析建立的产流时间幂函数计算模型具有较好的模拟效果。     

Determinants of groundnut rosette virus disease occurrence in Uganda

Groundnut rosette virus disease (GRVD) is the major constraint to groundnut (Arachis hypogaea) production in Uganda. It is principally transmitted by the groundnut aphid (Aphis craccivora Koch). The disease is known to cause total crop failure in cases where susceptible varieties are used. During any particular season, GRVD displays variations in incidence and severity in different agro-ecologies within the country, but the reasons for the varying disease patterns remain unclear. This study was aimed at establishing the factors influencing the occurrence of GRVD in Uganda. Trials were established for three seasons in four groundnut growing locations situated in different agro-ecologies in Uganda. Four groundnut genotypes were used as treatments in a randomized complete block design with four replications. Disease progress and aphid populations were assessed at 4, 8 and 12 weeks after planting. Data on environmental factors; particularly rainfall, temperature and wind speed were obtained from standard meteorological stations located at/near the study sites. Soil samples and yield data were also obtained in each season. The study revealed that disease incidence; severity and groundnut yields were significantly affected by season, location and genotype. The same applied to their three way interactions. Levels of disease infection were found to be majorly influenced by rainfall and wind speed. Disease incidence and severity were generally higher in conditions with less rainfall and low wind speeds. The Pearson's two tailed correlation between total rainfall and disease incidence for all trial sites was negative and highly significant (r = −0.280, P ≤ 0.01). The same was true for wind speed and disease incidence (r = −0.476, P ≤ 0.01). However, there was no conclusive trend between temperature and disease incidence with the Pearson's two tailed correlation showing significantly positive and negative trends depending on location.     

优质小麦重要性状的相关分析

利用7个优质小麦品种（品系），分析了优质小麦籽粒产量与品质性状的关系，以及品质性状之间的关系。结果表明，籽粒产量与蛋白质含量、湿面筋含量和干面筋含量等营养品质性状呈极显著或显著负相关，与Zeleny沉淀值、面团形成时间和稳定时间等加工品质性状相关不显著。蛋白质含量与湿面筋含量和干面筋含量逗号地极显著正相关，湿面筋含量与干面筋含量呈极显著正相关。Zeleny沉淀值与面团形成时间和稳定时间呈显著或极显著正相关，面团形成时间与稳定时间呈极显著正相关。据此提出优质高产结合改良的重点是协调好粒产量与加工质量，充分利用蛋白质优质基组合。     

早稻空秕率与抽穗开花期气象条件分析

为探讨早稻抽穗开花期气象因子对空秕率的影响,趋利避害,确保高产稳产,利用娄底农业气象观测站1981～2010年的早稻空秕率、发育期资料,以及娄底国家地面气象站的气象要素,分析早稻抽穗开花期光、温、水等气象条件与空壳率、秕粒率、空壳率＋秕粒率的相关性,选取相关性好的气象因子,阐述气象条件对空秕率的影响。结果表明：降水量、降水日数、日平均相对湿度、日最高气温是引起空秕率变化的主要气象因子。降水量、降水日数、日平均相对湿度与空秕率成正相关,日最高气温与空秕率成负相关。     

8个茶树品种的黑茶适制性研究

品种是决定茶叶品质的基础,目前黑茶缺乏专用品种.本研究对尖波黄13号等8个湖南主栽茶树品种进行了黑茶适制性研究.感官审评结果表明:在5%显著性水平下,桃源大叶和槠叶齐感官审评结果显著优于其它6个茶树品种.不同品种不同季节鲜叶水浸出物、儿茶素、茶氨酸、氨基酸总量、咖啡碱、粗纤维、还原性糖7个指标与相应黑茶感官审评结果相关性分析表明:春季氨基酸总量和粗纤维分别与感官审评呈显著正相关和显著负相关;夏、秋季咖啡碱、水浸出物、还原性糖、粗纤维与感官审评结果的相关性基本一致,都达到了显著相关(粗纤维为显著负相关,其余为显著正相关),儿茶素在夏季表现为显著负相关,其余各指标与感官审评结果相关性较低.考虑到氟对黑茶质量安全的重要性,本研究还对8个品种一芽五叶氟含量进行了测定,结果表明:8个参试品种氟含量都小于300 mg·kg-1.     

Total phenolics,flavonoids, antioxidant capacity in rice grain and their relations to grain color,size and weight

Total phenolics, flavonoid contents and antioxidant capacity from a wide collection of rice germplasm were measured, and their relations to grain color, grain size and 100-grain weight were investigated. Highly significant genotypic differences were observed in total phenolics, flavonoid contents and 2,2-azino-bis-(3-ehylbenzothiazoline-6-sulphonic acid) diammonium salt (ABTS) radical cation antioxidant capacity. They displayed an increasing order in the white rice, red rice and black rice, yet several white rice had higher phenolics and flavonoids contents than the red rice. Significant positive pair-wise correlations were found among the phenolics, flavonoid contents and antioxidant capacity, and the coefficient between the phenolic contents and antioxidant capacity was extremely high (r = 0.96). Among all rice accessions, the grain color parameters had negative correlations with the phenolics, flavonoid contents and antioxidant capacity (p < 0.001). The negative correlation between a* and antioxidant capacity, and the positive correlation between H° and antioxidant capacity were consistent within the respective white rice and red rice groups. Flavonoid contents had positive correlation with grain length and length to width ratio, and had negative correlation with the 100-grain weight among all rice accessions. It was also found that 100-grain weight still had negative correlations with phenolics, flavonoid contents and antioxidant capacity within the white rice genotypes. These relationships may serve as indexes to indirectly select breeding lines high in the phenolics, flavonoids and antioxidant capacity. Principal component analysis including the information for phenolics, flavonoids, antioxidant capacity, grain color parameters, grain size and 100-grain weight extracted five principal components that explained 83.7% of the total variances. The results of this study may provide new opportunities for rice breeders and eventually commercial rice growers to promote the production of rice with enhanced nutritional quality.     

晚粳稻籽粒中砷、镉、铬、镍、铅等重金属含量的品种和粒位效应

 选用籽粒着粒密度差异较大的密穗型品种秀水63和散穗型品种秀水11，种植于受重金属轻度污染的土壤，研究了晚粳稻籽粒中有毒重金属As、Cd、Cr、Ni、Pb含量的品种与粒位效应。结果表明，重金属含量的粒位间差异秀水63明显大于秀水11，As、Cd、Cr、Pb含量粒位间差异显著， Ni含量差异较小。穗上部籽粒As、Cd、Ni含量高于中部籽粒，穗下部籽粒最低，而Cr、Pb则正好相反。稻米中几种重金属含量与粒重的关系因重金属种类不同存在着差异，籽粒As、Cd、Ni含量与粒重呈正相关，而Cr和Pb含量与粒重呈负相关。秀水63和秀水11不同粒位的籽粒灌浆模式存在差异，下位粒灌浆速率较低，使粒重较上、中位粒低，导致粒重有较大的粒位差异，而这种差异也与穗部着粒密度有关，秀水63明显大于秀水11。籽粒As、Cd、Ni含量与最大灌浆速率（GRm）呈正相关，与到达最大灌浆速率时间（Tpoi）呈负相关，而Cr和Pb含量与以上两个籽粒灌浆特性参数分别呈负相关和正相关，说明籽粒As、Cd、Ni的积累与碳水化合物的积累具有相同或相近的模式，而Cr和Pb表现为不同的积累模式。     

2006-2017年国家黄淮海夏大豆品种区域试验参试品种 （系）分析

为促进夏大豆育种,对2006-2017年国家黄淮海夏大豆品种区域试验参试品种（系）的产量、主要农艺性状、品质及抗性性状进行了综合分析。结果表明：参试品种（系）产量水平明显提高;株高、单株有效分枝数、单株有效荚数、单株粒数、单株粒重、百粒重整体呈上升趋势,主茎节数略有上升;生育日数整体呈下降趋势,底荚高度略有下降。粗蛋白含量整体略有上升,粗脂肪含量呈下降趋势;参试品种（系）中达到高蛋白和高脂肪标准的品种 （系）分别有20个、82个。参试品种（系）对大豆花叶病毒病的抗性水平不断提高,对大豆胞囊线虫病的抗性水平明显降低。相关性分析表明：各性状间存在复杂的相关性,产量与单株粒重、百粒重呈极显著正相关,与单株粒数呈显著正相关,与接种大豆花叶病毒SC7株系病情指数呈极显著负相关。多元回归、偏相关和通径分析结果表明：单 株粒重是产量的正向作用因子;主茎节数是产量的负向作用因子。以上结果综合表明：单株粒重是黄淮海地区大豆产量提高的关键因素。因此,夏大豆品种选育时,应注重主茎节数适中、单株粒重较高的亲本组配及后代单株的选择,同时还要重视品质,强调抗性,从而选育出适宜黄淮海地区的高产、优质、多抗、广适大豆新品种。     

冬小麦冠层降水截留性能研究

为定量分析冬小麦冠层降水截留量,采用"简易吸水法"分别研究了冬小麦单茎和群体的冠层截留性能,并对其影响因素进行了探讨。结果表明,在冬小麦抽穗前,叶数对单茎截留量影响显著(P<0.05),而对截留率影响不明显。在叶数相同条件下,单茎截留量在不同生育期间差异显著(P<0.01)。冬小麦单茎截留量随叶面积的增大而增大,而叶面积对截留率影响不显著。冬小麦单茎截留量与株高、鲜重呈线性正相关,相应截留率则与株高、鲜重呈线性负相关;群体截留量与叶面积指数(LAI)、地上部生物量呈线性正相关,相应截留率则与LAI、地上部生物量呈线性负相关。从拔节至成熟,冬小麦冠层截留量先增加后减少,最大冠层截留量出现在抽穗期(1.28mm),且不同生育期截留量差异极显著(P<0.01);相应截留率在不同生育期的变化无规律,各生育期间差异不显著。     

Climate Change and Potato Production in Contrasting South African Agro-ecosystems 1. Effects on Land and Water Use Efficiencies

Explorations of the impact of climate change on potential potato yields were obtained by downscaling the projections of six different coupled climate models to high spatial resolution over southern Africa. The simulations of daily maximum and minimum temperatures, precipitation, wind speed, and solar radiation were used as input to run the crop growth model LINTUL-Potato. Pixels representative for potato growing areas were selected for four globally occurring agro-ecosystems: rainy and dry winter and summer crops. The simulated inter-annual variability is much greater for rainfall than for temperature. Reference evapotranspiration and radiation are projected to hardly decline over the 90-year period, whilst temperatures are projected to rise significantly by about 1.9 °C. From literature, it was found that radiation use efficiency of potato increased with elevated CO₂ concentrations by almost 0.002 g?MJ^?1?ppm^?1. This ratio was used to calculate the CO₂ effect on yields between 1960 and 2050, when CO₂ concentration increases from 315 to 550 ppm. Within this range, evapotranspiration by the potato crop was reduced by about 13% according to literature. Simulated yield increase was strongest in the Mediterranean-type winter crop (+37%) and least under Mediterranean summer (+12%) and relatively warm winter conditions (+14%) closer to the equator. Water use efficiency also increased most in the cool rainy Mediterranean winter (+45%) and least so in the winter crop closer to the equator (+14%). It is concluded from the simulations that for all four agro-ecosystems possible negative effects of rising temperatures and reduced availability of water for potato are more than compensated for by the positive effect of increased CO₂ levels on water use efficiency and crop productivity.     

不同播期夏大豆的产量、光合特性和气象因子效应研究

为探讨播期对黄淮海地区夏大豆产量的影响,以大豆品种齐黄34为材料,设置7个播期,比较了不同播期大豆产量性状的差异,并分析了降水和温度与夏大豆生育进程、光合性能指标、产量及产量构成因素的关系。结果表明：在黄淮海地区,夏大豆花后阶段降水和温度是决定产量高低的重要因子。适期早播可延长夏大豆的生育天数,增加花后积温,提高花后累积日温差,花后阶段获得充足降水,可使夏大豆后期衰老速度减慢,提高光合势, 增加干物质量,提高收获指数。降水和温度主要通过影响单株荚数、单株粒重、单株粒数和百粒重来影响产量,产量表现出随着播期推迟先增加后逐渐降低的趋势,适期早播有利于大豆增产。该研究可为黄淮海地区大豆播期的科学设置以及高产栽培提供依据。     

Spatio-temporal variability of drought characteristics across Pakistan

Climate change in Pakistan has a great impact on the spatial and temporal variation of precipitation and ultimately alters the frequency and duration of droughts. In this study, spatial and temporal trend analyses of precipitation and droughts were observed at 58 meteorological stations across Pakistan from 1981 to 2018. The existing trend analysis methods were evaluated to address the issue of serial correlation in the climatic data. Results of precipitation analysis showed significant decreasing trends in winter (November, December) and significant increasing trends were observed in summer (June and September) at a confidence level of 95 percent. The magnitude of the precipitation trends showed the highest variation during summer season and the least variation in winter season. Rotated Principal Component (RPC) analysis showed the severe droughts (high positive loading) in southeastern side (Sindh province) of Pakistan due to lack of summer rains. Furthermore, variance correction approaches are identified as the most suitable in coping with the effect of serial correlation. The highest drought frequencies were observed in the southern areas of Pakistan and the drought events are expected to occur more frequently in the late winter, early spring, and early autumn, while droughts were expected to occur least frequently in summer.

     

Extreme nighttime air temperatures in 2010 impact rice chalkiness and milling quality

Research shows that elevated nighttime air temperatures (NTATs) contribute to increased chalk formation and reduced milling quality in rice. Arkansas rice-growing regions experienced exceptionally warm weather conditions during the summer of 2010, providing an opportunity to test this hypothesis under extreme conditions. Data from a previous study, conducted in years 2007-2009 (Ambardekar et al., 2011), was extended to include 2010 data, and analyzed to evaluate the correlations of 95th percentiles of NTAT frequencies (NT₉₅) occurring during reproductive (R) stages of six rice cultivars with chalk and peak head rice yields (pHRYs). Long-grain cultivars produced chalk values that were positively correlated to NT₉₅, and pHRYs that were inversely correlated, during the R5 through R8 stages. Medium-grain cultivars, Bengal and Jupiter, which in the original study showed little or no response to elevated NTATs during all R-stages, showed significant positive correlations between chalk, and negative correlations between pHRY, and NT₉₅, during the R7 and R8 stages. The 2007-2009 analyses indicated quadratic relationships of chalk with NT₉₅ and linear relationships of pHRY with NT₉₅. However, addition of the 2010 data indicated that both of these relationships were quadratic in nature. The extreme temperatures observed in 2010 also verified that while cultivars vary in their level of resistance to NTAT effects, all of the rice cultivars analyzed throughout the four-year study exhibited some degree of susceptibility to extreme NTAT temperatures occurring during critical grain-filling stages.     

玉米品种穗轴重和出籽率等性状的相关及遗传关系研究

以先玉335的亲本及2个美系材料和自选系为试验材料,组配16个杂交组合,在保苗61 530株/hm2的条件下进行产量比较,同时分析子粒水分、穗轴重、出籽率等相关数据,进行简单相关和遗传分析。结果表明,杂交种穗轴重与出籽率呈极显著负相关;出籽率与双亲平均穗轴重、父本穗轴重呈极显著负相关,与双亲平均出籽率、父本出籽率呈极显著正相关;百粒重与产量呈显著正相关,与子粒水分呈显著负相关,与父本百粒重呈显著正相关;产量与父本百粒重呈极显著正相关,与双亲平均百粒重呈显著正相关。穗轴重、百粒重遗传累加效应极显著,超高亲效应明显;出籽率以遗传累加效应为主,存在超亲效应。组配新组合途径可以直接利用PH6WC及Reid系统的美系材料与自选系组配,从而获得高出籽率的品种。