地膜覆盖技术在杂交玉米制种上的应用

杂交玉米制种成败的关键是父母本花期能否相遇。确保花期相遇良好的基础是掌握好父母本的播期以及捉全苗 ,促齐苗。经过多年的工作实践 ,笔者认为 ,采用地膜覆盖是解决杂交玉米制种捉全苗、调花期、保产量、上质量最有效的方法。1　杂交玉米制种中存在的一些问题在杂交玉米制种中 ,父母本播期有三种不同的状况 :一是同期播种 ,二是先播母本后播父本 ,三是先播父本后播母本。不同于大田生产的是 ,父母本花期相遇状况、父本花粉量的多少决定母本的结实率 ,母本的成熟度决定种子的发芽率。山西十年九春旱 ,多数地区无灌溉条件。杂交玉米制种区…     

杂交稻制种人工辅助授粉工具选择与应用研究

杂交水稻制种人工辅助授粉，采用双型授粉竿定期定位定操作进行授粉，母本穗层的花粉分布密度较为均匀，提高了及时花粉与非及时花粉的有效利用率，异交结实率比现有人工辅助授粉有明显提高。     

提高油葵制种田母本结实率的措施

在杂交油葵制种过程中,因气候、父母本播期、父母本行比、栽培管理等因素的影响,使制种田母本授粉不良,结实率低,制种产量与质量难以提高。因此,在对亲本适应性、生育期等特征特性详细观察的基础上,针对油葵制种田不利于母本授粉的具体情况,采取相应的措施,协调好父母本花期,保证父母本花期正常相遇,使母本充分接受父本的花粉,利于提高母本的结实率,进而提高制种产量和质量。1花期调控1.1错期播种大多数油葵杂交种的双亲生育期不一致,尤其在晚播的情况下,常采用错期播种调控技术,确保父、母本花期相遇,有效解决花粉量不足的问题。     

提高杂交水稻制种结实率的途径和措施

提高杂交水稻制种结实率的途径和措施江苏省响水县种子公司周钧在中高产制种实践中，母本的异交结实率是左右产量的关键。影响异交结实率的因素归纳起来有：（１）抽穗扬花期间的气候环境；（２）父母本的花期和花时相遇水平；（３）母本受粉状态；（４）父本花粉的利用率...     

转基因油菜雄性不育系15A结实性的研究

本研究以转基因油茱雄性不育系15A为材料，采用自交，异交。天然异交研究了3种不同授粉方式的结实性表现，采用隔离制种方式研究了不同行比制种对结实性的影响，采用不同辅助授粉方式研究了辅助授粉对结实性的影响。结果表明：15A自史结实为0。不育性彻底。异交和天然异交结实好，有利于杂交制种。隔离制种父母本1：5行比的情况下，母本的结实正常，单株产量高。3种人工辅助方式对15A的结实性没有明显的影响。     

八两优96父母本倒播差高产制种技术

经过连续4年的父、母本生物学特性观察和制种生产，针对八两优96制种父母本倒播差，总结出相应的高产制种技术：合理安排母本育性安全期、最佳抽穗扬花期和父、母本播差期，创建强父稳母的高产群体结构，科学使用“920”改良亲本异交态势、人工辅助授粉提高异交结实率、严格除杂保纯和加强防治病虫害等。     

提高杂交水稻不育系异交结实率的综合措施

提高不育系异交结实率是杂交水稻制种高产的关键。根据高产典型分析,制种亩产150～200公斤,异交结实率要达40％～50％。因此,要提高制种产量,必须从提高不育系异交结实率入手。由于母本结实率高低受到花期花时是否相遇、种性包颈程度、柱头外露率、父本花粉量、花粉柱头生活力、开花授粉时的气候条件和生态环境等因素的影响,要提高不     

提高特优559纯度的栽培技术

特优 5 5 9组合的母本龙特甫 A育性不稳定 ,稻株部分颖花中含有可育花粉 ,在适宜的温光条件下母本的可育花粉可先于父本授粉 ,造成母本自交结实率提高 ,种子纯度下降。改善制种授粉环境条件 ,控制母本自花授粉是提高特优 5 5 9种子纯度的关键。现将通过栽培措施提高特优 5 5 9种子纯度技术介绍如下 :1　修改花期相遇标准 ,调整父本花粉分配时间和密度父母本花期相遇标准改过去的父母本同期抽穗或母本略早为父本早 1～ 2 d,适当增大父母本的播差。父本改三期为二期 ,父母本栽插比例改过去的 3∶ 6、4∶8为 3∶ 7、2∶ 8,确保父本花粉早、密…     

Ⅱ优231高产制种技术

经过多年的父、母本生物学特性观察和制种实践,针对Ⅱ优231父母本生长发育特性,总结出相应的高产制种技术:合理安排播差期,确保花期相遇;合理密植,创建高产群体结构;科学喷施"920",搞好人工辅助授粉,提高异交结实率;加强田间病虫害防治,严抓除杂保纯,确保种子质量等。     

杂交稻制种人工授粉结实性能与技术研究

研究分析了杂交水稻制种现行人工辅助授粉的结实效应及其花粉的时间分布、空间分布、垂直分布和水平分布的授粉性能特点，提出并试验了根据父母本开花习性进行人工辅助授粉及其明抖、竖抖、暗抖、斜抖的授粉田间操作方法，采取留剑叶，轻割倒２叶、倒３叶，减少母本行间花粉传播障碍等配套技术。结果表明，比现行人工授粉方法提高异交结实率１１．１～１６．１个百分点     

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.     

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.     

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.     

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.     

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.     

Flag Leaf Senescence, as Evaluated by Numerical Image Analysis, and its Relationship with Yield under Drought in Durum Wheat

Senescence was evaluated at different stages of the grain‐filling period in eight durum wheat varieties using numerical image analysis (NIA). The varieties were grown under early, severe drought conditions on the high plains of Sétif in Algeria. After flowering, three different irrigation treatments were applied. Treatment effect was small, while a genotypic effect was noted for most of the senescence parameters. Senescence correlated to biomass, while the maximal rate of senescence, V_smax, correlated to thousand‐kernel weight. The potential of the method of numerical image analysis for monitoring flag leaf senescence, detecting genotypic variability and selecting genotypes with delayed senescence is discussed.     

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.     

Cowpea (Vigna unguiculata): Genetics,genomics and breeding

Cowpea, Vigna unguiculata (L.), is an important grain legume grown in the tropics where it constitutes a valuable source of protein in the diets of millions of people. Some abiotic and biotic stresses adversely affect its productivity. A review of the genetics, genomics and breeding of cowpea is presented in this article. Cowpea breeding programmes have studied intensively qualitative and quantitative genetics of the crop to better enhance its improvement. A number of initiatives including Tropical Legumes projects have contributed to the development of cowpea genomic resources. Recent progress in the development of consensus genetic map containing 37,372 SNPs mapped to 3,280 bins will strengthen cowpea trait discovery pipeline. Several informative markers associated with quantitative trait loci (QTL) related to desirable attributes of cowpea were generated. Cowpea genetic improvement activities aim at the development of drought tolerant, phosphorus use efficient, bacterial blight and virus resistant lines through exploiting available genetic resources as well as deployment of modern breeding tools that will enhance genetic gain when grown by sub‐Saharan Africa farmers.     

Screening for resistance to take-all in wheat,triticale and wheat-triticale hybrid lines

Summary Fifteen triticale and wheat-triticale hybrid lines were evaluated for resistance to the take-all fungus Gaeumannomyces graminis var. tritici and compared with five wheat and two rye lines in inoculated field and pot trials. The triticale and wheat-triticale hybrid lines varied in rye chromosome number and degree of resistance expressed. One line, Venus with seven pairs of rye chromosomes consistently showed levels of resistance intermediate between wheat and rye. A trend was observed where increasing rye chromosome content led to greater resistance but exceptions showed that variation within triticales could not be ascribed to rye chromosome content alone.     

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.