不同温度下外施6-BA和ABA对棉花(Gossypium hirsutum L.)产量和纤维品质的影响

以棉纤维比强度高的科棉1号、比强度中等的美棉33B 2个品种为材料,于2006-2007年在江苏南京设置大田分期播种试验,使棉铃发育处于不同温度条件,于棉株7～9果枝第1、2果节棉铃开花时喷施6-苄基腺嘌呤(6BA)和脱落酸(ABA),研究不同的铃期日均最低气温条件下6-BA和ABA对棉花产量和纤维品质的影响。结果表明:由晚播造成的低温降低了棉花产量及纤维品质。外施6-BA、ABA对棉株中部果枝铃铃重和纤维品质影响最大。正常播期下,外施6-BA可增加中部果枝棉铃铃重,外施ABA降低铃重,但二者对其纤维品质影响较小;迟播时,外施6-BA可提高中部果枝棉铃铃重,ABA处理的作用则相反,二者均可提高纤维长度和比强度、优化麦克隆值。不同的温度条件下,外施6-BA均提高了单株铃数、单株平均铃重和皮棉产量,外施ABA则降低了棉花单株铃数和产量。外施6-BA和ABA对高强纤维品种产量和纤维品质的影响较中强纤维品种更为明显。低温下,在棉铃发育初期喷施6-BA对改善棉纤维品质的效果最好。     

棉铃对位叶生理特性的基因型差异及其与铃重形成的关系

在大田栽培条件下,研究了4个基因型棉铃对位叶花后碳氮比,可溶性蛋白含量及内源保护酶活性动态变化的基因型差异及其与铃重形成的关系.试验结果表明,棉铃对位叶花后N代谢活跃,内源保护酶活性高,叶片生理活性较强的基因型(如苏棉15和科棉1号),其铃重的快速增长期长,单铃棉纤维干重高,最终铃重较高;反之,棉铃对位叶生理活性弱、功能期短的基因型(如德夏棉1号),棉铃对位叶中C/N高,内源保护酶活性低或下降过快,造成铃重快速增长期缩短,单铃纤维干重降低,最终铃重较低;美棉33B棉铃对位叶中C/N和内源保护酶活性变化特征介于上述两种类型之间.由以上结果可以得出,在本试验条件下,棉铃对位叶生理特性的基因型差异是导致不同铃重形成的重要生理原因之一.     

品种和整枝方式对棉花产量及品质构成因素的影响

为了探究简化栽培措施对不同类型棉花品种产量和纤维品质性状的影响程度,以3种类型棉花品种为试验材料,在中等密度（5.2万株/hm²）条件下研究常规整枝和不整枝2种栽培方式对棉花产量及纤维品质性状的影响。结果表明整枝措施对不同类型棉花品种的铃重、籽指、衣分、纤维长度、马克隆值、整齐度指数、伸长率均没有显著影响,对纤维比强度影响显著(F=7.27);整枝和品种类型对棉花产量构成因素（铃重、籽指、衣分）和纤维品质性状均没有互作效应。在种植密度5.2万株/hm²时,整枝措施能提高棉花品种的纤维比强度,对棉花产量构成因素（铃重、籽指、衣分）无显著影响。     

棉铃对位叶C/N的变化及其与棉铃干物质积累和分配的关系

以产量差异显著的14个棉花品种为材料, 研究棉铃对位叶C/N的变化特征及其与棉铃干物质积累与分配的关系。结果表明, 棉铃对位叶C/N随铃龄的变化可用y=at²+bt+c拟合[ y为C/N, t为铃龄(d), a、b、c为常数], 其主要特征值(a、b、c和C/N最大值)与单铃干物重(即单个棉铃的铃壳、棉籽和纤维3部分干重之和)和铃重(即棉籽和纤维两部分干重之和)存在极显著相关关系, 而与衣分和铃壳率无显著相关关系。以a、b、c和C/N最大值为变量可将14个棉花品种聚类为Ⅰ(美棉33B等6个品种)、Ⅱ(科棉1号等6个品种)和Ⅲ(中棉所35和中棉所38) 3个类群, 三者棉铃对位叶C/N及单铃干物重的变化特征差异显著, 其中类群Ⅲ铃龄10~17 d期间的棉铃对位叶C/N显著高于类群Ⅰ和类群Ⅱ, 铃龄24 d之后仍保持在2.5左右, 整个铃期内变幅最大, 平均值最高, 其单铃干物重快速增长期最长, 平均增长速率最小, 最终单铃干物重和铃重均最大, 但3个类群棉花棉铃干物质在棉铃各部分分配率的动态变化无明显差异, 最终衣分和皮棉产量与棉铃对位叶C/N变化特性无明显相关性。棉铃对位叶C/N变化的基因型差异显著, 棉铃对位叶C/N在铃龄10~17 d期间高、铃龄24 d之后仍维持在相对较高的水平, 有利于棉铃干物质的积累。     

棉铃发育不同时期的质量变化研究

为探索棉铃发育过程中重量及品质的变化情况,通过挂牌选取不同时期棉铃进行测定分析。结果发现：在常规种植方式下,棉花上部（7台以上）、中部（4~6台）和下部（1~3台）果枝铃重有所差异,中部铃重最高,下部次之,上部最低,最大差值可达1.6 g;棉铃发育上,花后40~50天籽棉、铃壳、皮棉重量增加最快,且均在花后70天最重,而衣分则在花后55天最高;纤维品质指标中除了短纤维率呈不断下降趋势,花后45~55天下降最大,其余指标整体呈随生育进程增加而增加趋势,但长度、整齐度、断裂伸长率分别在花后65、70、60天出现最高值并有下降趋势。综上所述,棉铃发育并不是越长越好,花后超过70天,棉花重量、衣分、长度、强度、整齐度等多项指标都会降低,不利于棉花质量提升。     

陆地棉染色体片段代换系及F1皮棉产量与产量构成因素的相关和通径分析

探讨棉花染色体片段代换系皮棉产量与产量构成因素之间的相关关系,明确其产量育种的主攻方向,以1套陆地棉染色体片段代换系及F1为材料,采用相关与通径分析的方法,对5种环境条件下代换系亲本及F1的皮棉产量与产量构成因素进行分析。结果表明,产量构成因素的变异系数以铃数最大,铃重次之,衣分最小,且F1产量构成因素的变异系数在所有环境下均比代换系亲本要小。铃数、衣分及铃重与皮棉产量均呈正相关,除个别环境外均达到显著性水平,其与皮棉产量的相关和偏相关系数在代换系亲本中以铃数最大,而F1中则以衣分最大。衣分,铃数与皮棉产量的相关程度受环境影响小,而铃重受环境影响较大。除1种环境外,代换系亲本的直接通径系数以铃数最大,衣分次之,铃重最小,而F1中则以衣分最大,铃数次之,铃重最小;代换系亲本中各因素的间接通径系数均为正值,而F1中铃数与铃重相互之间的间接通径系数均为负值。材料类型和环境条件不同,其产量构成因素与皮棉产量的相关程度及贡献大小也存在较大差异。代换系亲本产量育种的主攻目标前期应该重在衣分,后期重在铃数,而F1则始终以提高衣分为主。     

温度对棉纤维强度及超分子结构的影响

利用短季棉中棉所16号品种, 研究了温度对棉纤维断裂比强度与超分子结构的影响, 结果 表明： 纤维断裂比强度随铃龄增大而升高; 相同铃龄随温度下降断裂比强度降低。 较高 温度条件下α角随铃龄增大不断宽化(变大), 对纤维强度提高不利; 较低温度条件下α角 随纤维发育不断变小(优化), 某种程度上有利于纤维强度提高;     

调亏灌溉对海岛棉产量及品质的影响研究

为了探明不同调亏程度对海岛棉产量及品质的影响,通过田间小区试验,以正常灌水量为对照,设置轻度调亏（正常灌水量的75%）、中度调亏（正常灌水量的50%）和重度调亏（正常灌水量的25%）,研究调亏灌溉对海岛棉不同部位优质成铃特性的调节效应。结果表明：轻度调亏对棉花产量品质无显著影响,而中度和重度调亏使皮棉产量分别下降了10.8%和25.4%,主要是单株铃数和单铃重显著下降。轻度和中度调亏对衣分影响较小,但重度调亏使衣分显著下降。轻度和重度调亏使纤维长度略有下降,中度调亏则纤维长度增加。纤维比强度和马克隆值随调亏程度增加呈增大趋势,但差异不显著。从不同结铃部位分析,轻度调亏使棉花中部铃重、纤维长度、比强度增大,上部铃重、纤维长度显著降低。而中度和重度调亏均使中部铃重、衣分显著下降,中度调亏使中部棉铃纤维比强度增加,而重度调亏可显著提高下部棉铃纤维比强度。轻度调亏使中部、中度调亏使下部、重度调亏使上部棉铃纤维马克隆值显著增大。     

转Bt基因棉中棉所3O不同开花期棉铃发育及产量构成因素的研究

转Bt基因棉中棉所30第Ⅰ期(1998年7月25～26日开花)棉铃花后10d的体积和单铃重分别较轮回亲本中棉所16增加8．57％和11．88％,表明其库强度较高;而第Ⅱ期(8月3～5日开花)和第Ⅲ期(8月12～14日开花)棉铃的早期(铃龄10d前)及各期棉铃的中后期(铃龄10d后)体积和单铃重均低于中棉所16,并且其瘪子数随开花期推延快速增加,反映了该品种源器官供应能力的不足。中棉所30棉铃纤维对同化产物的竞争力较强,每饱子纤维数、每饱子皮棉重、每铃皮棉重和衣分基本上极显著或显著高于中棉所16,而铃壳和种子的物质积累减少,铃壳比例、饱子数、饱子重和子指降低,瘪子数上升。     

多环境下陆地棉染色体片段代换系及F_1皮棉产量与纤维品质的表型分析

以1套陆地棉染色体片段代换系为亲本材料,采用株系间随机成对杂交组配F1,在5个环境下鉴定片段代换系亲本及F1的皮棉产量与纤维品质性状表现。结果表明,与轮回亲本(中棉所36)相比,F1在铃重与皮棉产量性状上具有一定的对照优势,亲本与F1的纤维长度与比强度均表现出明显的对照优势,且环境间表现一致。F1铃重、衣分与皮棉产量在各个环境下的中亲优势均值全部为正,且相对较大。除个别环境外,纤维长度、马克隆值与比强度的中亲优势均值也全部为正,但数值相对较小。片段代换系及F1的遗传变异丰富,部分亲本与F1在多个环境下的综合表现优异,其皮棉产量与纤维品质得到同步提高,群体材料的遗传改良与杂种优势利用具有广阔前景。     

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.