基于MOD13Q1的辽宁省主要农作物时空分布研究

获取农作物种植结构,对农作物生长状况监测、农作物灾情监测及产量估算等具有重要的意义。利用MODIS NDVI产品数据,构建辽宁省主要农作物(玉米、大豆和水稻)的时间序列物候特征曲线,通过分层分类方法,提取辽宁省农作物种植结构信息,研究表明,支持向量机分类方法分类效果更好,分类精度可达96%以上。将农作物提取模型推广应用于2003年、2007年、2011年、2015年和2019年的MODIS数据,探讨近17年来辽宁省农作物种植结构时空格局现状与变化,为快速、大范围、高精度提取农作物种植面积提供有效方法,同时为相关政策提供科学依据。     

基于Landsat 8影像提取豫中地区冬小麦和夏玉米分布信息的最佳时相选择

遥感技术对大尺度农业实时监测提供了一个理想的手段,遥感影像植被分类的最佳时相对作物种植面积遥感监测非常重要。本文选取2020年至2021年的6景Landsat 8影像,覆盖了夏玉米从乳熟到收获、冬小麦从越冬到成熟的生育期,以此分析不同时相的冬小麦-夏玉米与其他地类在光谱特征和NDVI上的差异,通过决策树的方法提取豫中地区冬小麦-夏玉米的空间分布情况。结果表明,冬小麦-夏玉米在不同生长发育时期,提取到的面积比有所不同,对于夏玉米而言,乳熟时期的提取效果要优于之后的时期,其在2020年8月26日的总体精度最高,为83.60%,Kappa系数为0.72,分类质量很好;对于冬小麦而言,最佳识别时期则处于冬小麦的越冬期,其在2021年1月1日的总体精度最高,为92.36%,Kappa系数为0.81,信息提取效果很好。除了作物自身生长过程的覆盖度变化,分类精度随成像时间而改变。多时相信息提取也发现,受到天气等环境条件限制,夏玉米和冬小麦的种植区域不完全重叠,山区冬季不适合冬小麦种植从而没有与夏玉米出现重叠分布。本研究有助于我们从宏观上对作物分布及生长状况作出及时有效的判断,对农业监测,特别是对轮作...     

基于HJ-1数据的冬小麦种植面积、长势与收割进度遥感监测

及时、准确地获取冬小麦种植面积、长势、收割进度等信息对冬小麦产量预报和农田精细管理具有重要意义。本研究采用HJ-1A/B CCD1/CCD2影像,结合S-G滤波算法、波段最大化的光谱角目标探测器、阈值分割等方法进行新乡市冬小麦种植面积、小麦长势和收割进度等遥感监测。结果表明：（1）利用HJ卫星NDVI时间序列数据结合波段最大化的光谱角度目标探测器方法,可以进行冬小麦种植面积提取,各县市冬小麦种植面积提取相对误差在10%以内;（2）单景影像NDVI值阈值分割可以反映冬小麦长势在时空差异;（3）冬小麦达到抽穗期的时间不一致,NDVI值在4月15日和21日附近达到最大值;（4）利用成熟期和收割期不同时间的NDVI影像,可监测各县市冬小麦收割进度的时空差异。各县市冬小麦在6月4日前开始收割与6月15日左右完成收割工作。HJ卫星时间序列遥感数据可以进行冬小麦种植面积、长势、收割进度等遥感监测。     

基于植被指数的夏玉米不同生育期叶绿素含量遥感估算

叶绿素含量是间接判断玉米营养状况的重要农学参数,估算叶绿素含量对农作物长势监测有重要意义。笔者利用ASD便携式地物光谱仪和SPAD-502叶绿素仪实测了夏玉米关键生育期冠层光谱反射率及叶片叶绿素相对含量,对3种植被指数与叶绿素相对含量进行了相关性分析,建立了基于归一化植被指数(NDVI)、比值植被指数(RVI)和差值植被指数(DVI)的叶绿素估算模型,并进行精度检验,从中选出最佳拟合模型。研究结果表明：拔节期RVI、抽穗期和灌浆期NDVI以及蜡熟期DVI的均方根差(RMSE)和相对误差(RE)均最低,RMSE分别为5.688、5.323、2.751、4.111,RE分别为9.84%、8.56%、3.75%、7.15%,故为各个时期的最佳模型。因此得到了NDVI、RVI和DVI3种植被指数在不同生育期的最佳模型,对指导夏玉米种植与田间管理具有重要的指导意义。     

安徽省冬小麦长势遥感监测与评估方法研究

沿淮淮北是安徽省主要的冬小麦种植区,为了对该区域冬小麦长势进行实时、动态地监测,通过采用变化向量分析方法,利用2005-2010年EOS/MODIS数据,在HANTS算法重构无云NDVI时间序列图像以及安徽省冬小麦种植区提取等数据处理基础上,研究基于NDVI变化向量、曲边梯形面积的长势综合监测模型,对研究区的年际与年内长势变化进行时间和空间上的定量分析。结果表明：HANTS处理平滑后的MODIS的10天合成植被指数的年时序曲线有效消除了云和数据缺失的影响,重构后的生长曲线可以更清楚地反应作物生长变化趋势和规律,有利于监测模型的建立;冬小麦种植区提取,大大提高了卫星监测精度,构建的综合监测模型适合单一生长季苗情长势遥感监测,该模型在2011年冬小麦长势评估中取得了良好的监测效果。     

近10年浙江植被物候的遥感监测及时空动态

为了全面认识浙江植被物候变化规律,进一步完善区域气候变化的植被响应机制,基于改进的Savitzky-Golay滤波算法重构了2001-2010年MODIS NDVI时间序列数据,利用分段多项式拟合和动态阈值法提取了浙江省近10年的植被重要物候期（生长季开始时间、结束时间和生长季长度）,分析植被物候期的年际变化趋势和空间分异特征。结果表明：（1）浙江省植被生长季为3月下旬-11月中旬,平均生长季长度为222天。近10年的生长季开始时间有提前趋势,但提前不显著,结束时间显著推迟,生长季有所延长,每10年延长约7天。（2）浙江植被的生长季开始时间从北往南逐渐推迟,生长季结束时间相对集中。浙江植被生长季延长的区域面积和生长季缩短的区域面积相当。（3）不同植被类型物候特征差异较大,分析针叶林和灌丛草地2类典型样区植被的物候变化发现,灌丛草地NDVI的年内和年际变幅均较针叶林的大,且针叶林的平均生长季长度比灌丛草地短约35天,针叶林生长季有延长的趋势,而灌丛草地生长季变化不明显。     

气候变化对青岛主要作物生育期的影响

为了研究气候变化对青岛主要作物生长发育的影响,利用青岛市胶州农业气象观测站1982—2014年冬小麦、1986—2014年夏玉米的生育期观测资料和同期的气象资料,分析了这2种作物生育期的变化趋势及对气候变化的响应。结果表明:青岛市冬小麦从播种到返青各生育期均延迟,其中以分蘖期延迟最明显;起身至孕穗各生育期提前;生育期内平均气温的上升是导致冬小麦全生育期缩短的主要原因。夏玉米播种到七叶各生育期均提前,拔节到成熟各生育期均延迟,成熟期延迟的程度最大;6月降水减少是导致夏玉米成熟期延迟、全生育期延长的主要原因。未来10年,气候变化会导致冬小麦成熟期提前,全生育期缩短;夏玉米成熟期推迟,全生育期延长。     

中国东部南北样带植被绿度期变化与降水关系研究

为了探索陆地生态系统如何响应全球气候变化,基于植物物候遥感监测的原理和特点,笔者应用野外物候观测数据和植物物候遥感监测相结合的方法,采用中国国家气象局355个站点1951-2004年观测的相关资料,以及美国地球资源观测系统数据中心的探路者数据集中的NOAA/AVHRR NDVI数据,构建Logistic模型。将其应用于中国东部南北样带上以物候为指示的植被格局动态与气候变化研究之中,分析1982-2003年样带植被绿度期参量与降水相关关系。在全球气候变暖的情况下,植被绿度初期提前趋势明显,特别是在20世纪90年代中后期,平均绿度初期提前8天左右;样带北部温度升高、降水减少,特别是春季降水减少,会使温带荒漠地区荒漠化趋势加重。     

华北平原冬小麦-夏玉米种植体系周年水分高效利用研究进展

在保证周年较高产量的同时,进一步提高水分利用效率是促进华北平原冬小麦-夏玉米一年两熟种植体系可持续发展的关键。从20世纪中晚期开始国内学者便从节水灌溉技术创新、灌溉制度优化、替代节水种植制度构建和节水抗旱新品种选育等方面开展了以冬小麦-夏玉米两熟种植体系为核心的周年水分高效利用途径的探索,取得了重要进展,显著提高了作物水分利用效率(WUE)。本文综述了华北平原冬小麦-夏玉米种植体系水分高效利用的研究进展,并提出了通过耕作或播/收期调控冬小麦-夏玉米周年降水与地下水平衡利用,促进周年水分(灌溉水和降水)高效利用的技术途径,以充分挖掘华北平原水分生产潜力,为该区冬小麦-夏玉米种植体系节水高产栽培及节水种植制度建立提供思路和依据。     

基于MERSI数据的处理及旬植被指数生成方法

为了实现自动批量处理国产FY-3A/B MERSI光学影像数据,提取全国范围植被指数特征,为今后全国植被类型制图方法研究做准备,对MERSI数据经过物理量计算、几何校正、拼接、掩膜等处理、提取植被指数特征和水云标识数据、按旬生成最大植被指数时间序列影像和合成旬水云标识影像等方法进行了研究;利用IDL 7.1编程语言实现了自动批量处理全国范围MERSI数据,按旬生成时间序列250 m空间分辨率的植被指数数据的算法程序;并对基于以上方法生成的归一化植被指数(NDVI)和增强性植被指数(EVI)结果进行比较分析。结果表明：NDVI的旬影像比EVI旬影像植被指数值分布更均匀,能够更好地反映全国植被分布与物候变化特点。该研究采用程序算法实现对FY-3A MERSI光学影像数据的处理,操作简单易行,节省了大量人力和时间;且生成的结果可为今后按MERSI NDVI时间序列影像进行全国植被类型分布研究、监测植被长势、开展国产数据在林业中的应用等后续工作做准备。     

A note on the origin of Kalanchoë x vadensis Boom & Zeilinga (Crassulaceae)

Summary K x vadensis is a hybrid of K. blossfeldiana and K. marmorata obtained after doubling the number of chromosomes.     

Avoidance of leaf rust fungi in wild relatives of cultivated cereals

Summary Avoidance of rust fungi that was based on poor appressorium induction was previously found in Hordeum chilense. In the present study 95 accessions of Triticeae were screened for avoidance of Puccinia hordei. The percentage of appressorium formation per germinated spore ranged from 6 to 90%. On none of the 41 accessions of Aegilops, Agropyron, Elymus, Secale, Thinopyrum or Triticum studied was the rate of appressorium formation lower than 25%. Lower rates of appressorium formation were, however, found on accessions of wild barley species Hordeum brachyantherum, H. marinum, H. parodii and H. secalinum. Its implications in cereal breeding are discussed.     

Relation between wheat-rye crossability and seed set of common wheat after pollination with other species in the Hordeae

Summary Cultivars of common wheat (Triticum aestivum L. em. Thell.) of high wheat-rye (Secale cereale L.) crossability set more seed with pollen of other related species than did wheats of low wheat-rye crossability. This was found to be true for pollen parents from the genera Triticum, Aegilops, Secale, Agropyron and Elymus.     

Mechanisms and diversity of resistance to sorghum shoot fly,Atherigona soccata

Sorghum shoot fly, Atherigona soccata, is one of the important pests of postrainy season sorghums. Of the 90 sorghum genotypes evaluated for resistance to this pest, RHRB 12, ICSV 713, 25026, 93046 and 25027, IS 33844‐5, Giddi Maldandi and RVRT 3 exhibited resistance in postrainy season, while ICSB 463, Phule Anuradha, RHRB 19, Parbhani Moti, ICSV 705, PS 35805, IS 5480, 5622, 17726, 18368 and 34722, RVRT 1, ICSR 93031 and Dagidi Solapur showed resistance in rainy season, suggesting season‐specific expression of resistance to A. soccata. ICSB 461, ICSB 463, Phule Yasodha, M 35‐1, ICSV 700, 711, 25010, 25019 and 93089, IS 18662, Phule Vasudha, IS 18551 and 33844‐5 and Barsizoot had fewer deadhearts than plants with eggs across seasons, suggesting antibiosis as one of the resistance mechanism. Five genotypes exhibited resistance with high grain yield across seasons. Correlation, path and stepwise regression analyses indicated that leaf glossiness, seedling vigour, trichome density, oviposition and leaf sheath pigmentation were associated with the expression of resistance/susceptibility to shoot fly, and these can be used as marker traits to select and develop shoot fly‐resistant sorghums.     

Reaction of tritordeum to Fusarium culmorum and Septoria nodorum

Summary Hordeum chilense is a wild barley extensively used in wide crosses in the Triticeae. It could be a valuable source of resistance to Fusarium culmorum and Septoria nodorum. Some H. chilense x Triticum spp. amphiploids, named tritordeums, were more resistant than the parental wheat line to these diseases, others were not. Average contents of ergosterol and deoxynivalenol (DON) suggested that resistance to colonization by Fusarium was the highest for Hordeum chilense, followed by tritordeum and wheat in decreasing order. In particular, the H. chilense genotypes H7 and H17 enhanced the wheat resistance to F. culmorum in its tritordeum offsprings. Resistance to S. nodorum in tritordeum was not associated with tall plant height. There is sufficient genetic variation for resistance to F. culmorum and S. nodorum among tritordeum to allow the breeding of lines combining short straw and resistance to both diseases.     

Breeding apomictic bahiagrass (Paspalum notatum Flügge) with improved turf traits

The development of a turf‐type bahiagrass could have a remarkable impact on the billion‐dollar turf industry in the south‐eastern United States. The goals of this study were to (i) select bahiagrass genotypes with improved turf attributes and (ii) determine the reproductive mode and seed fertility of selected genotypes. The population included mutants, wild types, hybrids and standard cultivars evaluated at two locations for two years. Morphological variation was observed and clonal repeatability (H²) ranged from 0.27 to 0.90. Flowering was extremely reduced in some mutants, which also exhibited dark green colour, finer texture and reduced canopy height. Cytoembryological observations revealed that diploids reproduced sexually and tetraploids by obligate or facultative apomixis. Genotypes with superior seed fertility were identified, while others were comparable to the standard cultivars. While mutant plants exhibited great morphological variation, the random mutations did not affect their reproductive mode, validating the use of mutagenesis in apomictic species. The high H² indicated that selection for improved turf attributes could be successfully performed with the advantage of clonal seed propagation.     

Disease resistance in protected crops and mushrooms

Summary Cultivars of tomatoes, cucumbers, lettuce and peppers have been bred for resistance to one or more pathogens. Some tomato and cucumber cultivars have resistance to a wide range of diseases. Resistance has been transient in many cases and a succession of cultivars with new genes or new combinations of resistance genes has been necessary to maintain control. There has been a number of notable exceptions and these have included durable resistance to such pathogens asFulvia fulva and tomato mosaic virus. With lettuce the resistance situation is complicated by the occurrence of fungicide resistant pathotypes. There are no strains ofAgaricus bisporus purposely bred for disease resistance.In protected flower crops only resistance to Fusarium wilt in carnations has been purposely bred but differences in disease resistance are apparent in cultivars of many ornamental crops. This is particularly so in chrysanthemums where there are cultivars with resistance to many of the major pathogens. Similar situations occur with other flower crops and pot plants. Cultivars of some species have not been systematically investigated for resistance.The need for genetic resistance will increase with the further reduction, in the limits on pesticide use and an increasing public awareness and importance of pesticide pollution.ADAS is an executive agency of the Ministry of Agiculture, Fisheries and Food and the Welsh Office.     

Genetic constitution and diversity in four narrow endemic redwoods from the family Cupressaceae

The genetic constitution and diversity of four relictual redwoods are discussed in this review. These include monotypic genera of the family Cupressaceae: coast redwood (Sequoia sempervirens), giant sequoia (Sequoiadendron giganteum), dawn redwood (Metasequoia glyptostroboides), and alerce (Fitzroya cupressoides). All four species are narrow endemics, share a number of common phenotypic traits, including red wood, and are threatened species. Fossil history suggests that the ancestors of redwoods probably originated during the Cretaceous and Tertiary periods and flourished thereafter for millions of years. Towards the end of the Tertiary period began their decline and struggle for existence that continued during the subsequent geologic upheavals and climate changes, until the survival of the present-day redwoods in the current restricted locations in the world (USA, China, and South America). Although two species, Sequoiadendron and Metasequoia, are diploids (2n = 22), and the other two are polyploids: Fitzroya a tetraploid (2n = 4x = 44), and Sequoia a hexaploid (2n = 6x = 66); they all share the same basic chromosome number x = 11. The genome size in the hexaploid Sequoia is one of the largest (31,500 MB) in the conifers, while the genome sizes of diploid Metasequoia and Sequoiadendron are about one-third (~10,000 MB) of Sequoia. Genetic diversity in the redwoods is lower than most other gymnosperms, except in Sequoia, which seems to rank near the upper quarter of the coniferous forest trees. Genomic research is sparse in the redwoods, and should be pursued for a better understanding of their genome structure, function, and adaptive genetic diversity.     

Inheritance of fruit colour in a wild Russian red raspberry seedling

Summary A new gene, i, from a self-incompatible wild Russian Rubus idaeus seedling is described. The gene i interacts with the fruit colour gene T, Tii plants having apricot instead of red fruits, and spines, leaves and stems pigmented to varying degrees. A deficit of apricot-fruited seedlings in progenies segregating for i could be explained by linkage between i and the self-incompatibility S locus with a crossover value of approximately 26.7%.Segregations for spine colour in crosses and backcrosses of the Russian seedling with two green-spined (ttII) raspberries selected for their yellow fruit colour, showed that both the latter carried the spine colour intensifier gene P. This suggests that earlier authors were incorrect in attributing the apricot fruit colour developed by some tt plants to a pleiotropic effect of P.     

The induction in vitro of adventitious shoots in Rosa

Summary Adventitious shoots were formed on excised leaves, roots and callus of Rosa persica x xanthina and on excised leaves of R. laevigata and R. wichuraiana on culture media that included BAP and NAA as growth regulators. Shoots formed freely on freshly cultured callus of R. persica x xanthina but their production declined in successive cultures and ceased after twelve weeks. Transplantation to soil was improved by rooting plantlets in cellulose plugs in vitro and transferring plantlets to soil while still in the plugs.