大兴安岭地区兴安落叶松种子园球果花蝇防治技术

利用综合防治方法对加格达奇兴安落叶松种子园落叶松球果花蝇进行防治,结果表明:防治效果达到90%时,种子园出种率提高了10%,大幅度减少良种种子损失,增加良种供给率。     

引种栽培西蒙得木的适应性研究Ⅰ——生物学习性观察及枯萎病研究

概述了西蒙得木的经济价值和国内外发展状况,根据在云南发展中出现连续枯萎死亡的现象,首先研究了生物学习性和生态适应性,分离接种了来自病健根的菌类,得到的4种镰刀菌都要在根系衰弱时才能侵染根系,引起根系衰弱的原因需要进一步研究。     

Selection for partial resistance to downy mildew in peas by means of greenhouse tests

Summary A partially downy mildew resistant pea line was back-crossed to a susceptible cultivar with more pods per node and lower seed weight. Breeding lines with different degrees of infection in a greenhouse test were selected. These lines and the two parental lines were investigated in field trials and tested in the greenhouse for four generations. Significant genetic variation among lines was found for infection of seedlings in greenhouse tests, and infection of pods, pod set and seed weight in field-trials. Infection of seedlings in the greenhouse was correlated with infection of pods in the field. In greenhouse tests, the non-genetic variance component was large in comparison with the genetic component and a significant genotype trial interaction was found. Significant repeatability was obtained for downy mildew on seedlings and pods, number of pods per node and seed weight. An unfavourable correlation between susceptibility to downy mildew and number of pods per node was found. No single breeding line showed the ideal combination of good resistance, high number of pods per node and small seeds. However, one line showing better resistance than the susceptible parent, with smaller seeds and more pods per node than the resistant parent was found. The susceptible parent also carries some resistance factor that is not present in the resistant parent.     

The response to saprol (systemic fungicide) in lettuce species and cultivars and its inheritance

Summary The response of Lactuca sativa, L. serriola and L. saligna to saprol was studied. Spraying the whole plant or part of a leaf caused wilting of susceptible plants. A similar effect was observed when leaves were soaked in a solution containing saprol.Inheritance studies with L. sativa and L. serriola showed that resistance to the wilting reaction caused by saprol is controlled by a single recessive gene.Contribution no. 198-E, 1978 series.     

Field assessment of partial resistance to powdery mildew in spring barley

Summary Partial resistance to powdery mildew in spring barley was evaluated in three plot types: large isolation plots, in 1.4 m² plots in chessboard design with guard plots of spring wheat and in single rows. Percentage leaf area covered by powdery mildew was scored four to six times during the season and partial resistance was characterized by the area under the disease progress curve. Varietal differences were revealed in al three plot designs, differences between the most resistant and susceptible genotypes being of a factor five. Differences between varieties decreased with decreasing plot size. The relationship between single scores of amount of powdery mildew on the upper four leaves and the area under the disease progress curve was high in all plot designs during the first two to three weeks after heading, allowing selection for the trait by one or two scorings. Differential ranking of varieties between different plot designs was observed, and is assumed to be due to increasing plot interference with reduced plot size and reduced distance between plots. A reliable selection for partial resistance could be made in large isolation plots and in 1.4 m² plots, but hardly in single rows.     

蒿属植物提取物对棉花枯萎病菌和红腐病菌的抑制活性研究

在实验条件下,采用菌丝生长速率测定法,以棉花枯萎病菌、棉红腐病菌为供试菌,对茵陈、黄蒿、艾蒿等3种蒿属植物提取物的抗菌活性进行了研究。结果表明,供试3种蒿属植物提取物对棉花枯萎病菌和棉花红腐病菌均具有较好的抗菌活性,其中尤以艾蒿提取物的抗菌活性强而稳定,48~96h对上述两病菌的菌丝抑制率均达80%以上;丙酮提取物的抗菌活性强于乙醇提取物,前者的EC50为1.4785 mg/L ,后者的为3.2090 mg/L。间歇振荡法、超声波法、冷浸法提取物对供试菌的72h菌丝抑制率分别为84.34% 、84.56%、88.7% ,可见同种溶剂不同提取方法所得提取物抗菌活性基本一致。     

Influence of suboptimal temperature on biomass production of potato populations of Andean and European origin

Summary Plants grown from seed derived by crossing conventional European S. tuberosum material were compared with plants grown from seed derived by crossing S. tuberosum with various, Andean frost resistant tuberbearing Solanum species. Biomass growth at optimal (20°/10°) and suboptimal (10°/4°) temperatures was studied.Differences in increase of fresh and dry matter were found between populations of Andean and European orgins at 10°/4°. At 20°/10° no such differences were found.At suboptimal temperature, Andean hybrids produced significantly more fresh and dry matter than European crosses in two harvests (64 and 178 days old plants). Statistically, Andean hybrids were found to produce the same amount of dry matter per day at both temperatures, over the complete growth period.Height increase and flower development were strongly depressed in European crosses under the suboptimal temperatures, but much less so in Andean crosses.The Andean material appears to be an under utilized resource in potato breeding for cool climates.     

Race-specific aspects of partial resistance in wheat to wheat leaf rust,Puccinia recondita f.sp. tritici

Summary Partial resistance (PR) in wheat to wheat leaf rust (Puccinia recondita f.sp. tritici) is characterized by a slow epidemic build-up despite a susceptible infection type. Two greenhouse tests and two field tests, in which 11 spring wheat cultivars were exposed to five wheat leaf rust races, revealed some indication for race-specificity of PR.In the greenhouse, the expression of PR was highly dependent on the environment. Significant cultivar-race interactions in the first experiment were lost in the second experiment probably due to cultivar-environment and cultivar-race-environment interactions.In the polycyclic field tests several factors played a role in explaining the inconsistency of the cultivar-race interactions, such as differences in initial inoculum, genotypic differences in earliness, interplot interference or environmental conditions.One cultivar-race combination showed a significant but small interaction towards susceptibility in both field experiments. The interaction was probably too small to detect in the monocyclic greenhouse tests. The results do not conflict with the idea that a gene-for-gene relationship could exist between PR-genes in the host and genes in the pathogen.Some problems with regard to the selection of PR in wheat to wheat leaf rust are discussed.     

Screening for resistance to Nectria galligena Bres. in cut shoots of apple

Summary To find a fast and reliable test to assess resistance to Nectria galligena in apple, different methods of inoculation were compared using macroconidia of N. galligena and one-year-old cut shoots from mature trees of Cox's Orange Pippin, IVT 69078-19, James Grieve and Jonathan.With the best inoculation method 11 genotypes were screened for resistance. Elstar, Golden Delicious, Jonathan and Lombart's Calville were highly resistant and the level of resistance of Ingrid marie, Gloster, Melrose, IVT 69078-19, Cox's Orange Pippin, James Grieve and Idared decreased in this order.The best inoculation method proved to be simple, giving results within four to nine weeks after inoculation.     

Race Specific Powdery Mildew Resistance in 31 Northwest European Wheat Cultivars

Race specific powdery mildew resistance in 23 winter wheat cultivars, eight spring wheat cultivars, and 14 lines/cultivars possessing known powdery mildew resistance genes, has been studied by analyzing host/pathogen interactions. The cultivars were tested as intact seedlings, and as detached primary leaf segments on water agar; both methods revealed reproducible and concordant results. The 45 cultivars/lines were divided into 24 resistance spectra according to the patterns of reaction to the powdery mildew isolates used. Of the 31 cultivars investigated, eight did not possess any of the resistance genes detected, and the remaining 23 were divided in 16 resistance spectra. The race specific resistance of nine cultivars was conferred by the single resistance genes Pm2, Pm4b, Pm5/Ml-i: or Pm6, while the race specific resistance of 14 cultivars was conferred by 2, 3, 4 or 5 genes in combination.