Genetic variation, heritability and progeny testing in meadow bromegrass

Meadow bromegrass is a recently introduced pasture grass in western Canada. Its leafy production and rapid regrowth have made it a major grass species for pasturing beef animals in this region. Because relatively little breeding work has been done on this species, there is little information on its breeding behaviour. The main objective of this study was to estimate genetic parameters and assess breeding methodologies for meadow bromegrass. Forty half‐sib (polycross and open‐pollinated) and full‐sib (selfed) progenies were evaluated for dry matter and seed yield, fertility index, harvest index, plant height, plant spread, crude protein, neutral detergent fibre and acid detergent fibre. Genetic variation for seed yield, harvest index, and plant height was significant in the open‐pollinated and selfed tests. Genetic variation estimates for dry matter yield were negative (polycross), not significant (open‐pollinated), or significant (selfed). Estimates of genetic variation for quality traits were not significant, except for acid detergent fibre (selfed). Correlations among characters indicated that it is possible to simultaneously improve seed and forage yield. Rankings of progenies by the half‐sib tests for forage and seed yield were not altered by the use of the synthetic parental value (SV_i), which includes information from selfed progeny. The polycross progeny test did not discriminate parents as well as the open‐pollinated and selfed tests; this may have been a result of non‐random pollination in the polycross. Correlation among the progeny tests, showed that open‐pollinated and selfed progeny tests agreed for all characters, except for harvest index, while correlation between polycross and selfed tests were significant for six characters but not dry matter yield, and acid and neutral detergent fibres. The most dissimilar tests were polycross and open‐pollinated, with significant correlations found only for fertility index, height, spread and neutral detergent fibre. It was concluded that there was significant variation and moderate heritability for most traits in the meadow bromegrass populations evaluated, and that the open‐pollinated progeny test is the method of choice for selecting parents for synthetics of this species.     

Trueness-To-Type and Yield Components of the Banana Hybrid Cultivar FHIA-18 Plants Regenerated Via Somatic Embryogenesis in a Bioreactor

Summary A population of 1,500 plants of the banana hybrid ‘FHIA-18’ (AAAB), regenerated from somatic embryos, which were multiplied in bioreactors, showed similar characteristics to plants propagated from shoot tip cultures both in the acclimatization stage and in field experiments carried out in Cuba. The plants originating from somatic embryos were similar to the plants obtained from shoot tips with respect to plant height, diameter of the pseudostem and number of suckers. Both groups of plants obtained from in vitro cultures were significantly different to the plants obtained from suckers during the flowering period of the mother plants, which was shortened by two months. The greater plant height and diameter of the pseudostem in the plants coming from somatic embryos and shoot tip is due to the effect of in vitro culture, and this was observed in different banana and plantain cultivars. During the second cycle of evaluation, the plants coming from the three propagation methods studied in this work had similar growth habits without significant differences in the majority of the morphological parameters evaluated. These results confirm that the difference obtained during the first cycle between the distinct populations is attributed to temporary changes. The original characteristics of the cultivar were evident from the second cycle of culture. Only 0.13% somaclonal variant was observed in the plants coming from somatic embryogenesis. These percentages are low taking into consideration that other propagated methods accept up to 5% variants in field conditions.     

Breeding widely adapted, popular maize hybrids

Summary World trend is to more maize hectarage grown to fewer, more widely-adapted hbrids. My purpose is to document research events leading to the most popular corn hybrids, Pioneer Brand 3780 and 3732. I provide background on maize adaptedness, on the seed maize business, on commercial maize hybrid development process, and on cultural practice change. I provide historical information on the cultivars: Leaming corn, Reid Yellow Dent, and Minn. 13 were widely-adapted open-pollinated varieties. Shift from open-pollinated to hybrid maize caused a shift in emphasis from local to wider adaptation. The first widely-adapted hybrids were Iowa 939 and U.S. 13. DEKALB 404A was the first popular and most popular double-cross hybrid. Pioneer 349 was the second-most popular double-cross hybrid. The first popular single cross hybrids were DEKALB 805 in medium and DEKALB XL45 in early U.S. Corn Belt in the early-1960's. Cultural practices (higher planting density, narrower rows, more nitrogen, better pesticides, and larger equipment allowing more timely operations) changed greatly in the 1960's and 1970's; allowing fewer, more widely-adapted genotypes to prevail. First hybrid 3780, then 3732 became the most popular hybrid; each exceeded one billion (1 × 10⁹) dollars sales. They were the result of wide-area testing, of utilizing higher plant density stress for selecting inbred lines and for screening hybrids, and of modern information management.     

Development of Static Characteristic Automatic Testing System About Brake Valves of Automobile

This paper describes a PC controlled brake valve automatic testing system which uses industrial control(computer) and Advantech powerful date acquition card PCI-1710L,and chooses Advantech PCI-1730 as the I/O card,(uses) FUJI servo systrm as the transmission mechanism.The system monitor the brake valve's quality based on analyseing the static characteristics of the brake valve.The authors also introduce the principle and structure of the system,hardware and software design process.The system works well in practice.     

High yield potential,shuttle breeding,genetic diversity,and a new international wheat improvement strategy

The main elements of the international wheat improvement program of the Centro Internacional de Mejoramiento de Maíz y Trigo (CIMMYT), also known as the International Maize and Wheat Improvement Center, have been shuttle breeding at two contrasting locations in Mexico, wide adaptation, durable rust and Septoria resistances, international multisite testing, and the appropriate use of genetic variation to enhance yield gains of subsequently produced lines. Such an approach yielded successes known collectively as the Green Revolution. However, at the beginning of the 21st century, this “cultivar assembly line” approach needs fine tuning to address crop needs under increasingly adopted resource conserving practices, as well as those related to nutritional requirements of the end-users. International wheat improvement will therefore focus on the targeting of traits in respective mega-environments, and the use of participatory methods, especially in marginal environments. The main features of this wheat improvement strategy include the introduction of new and novel sources of genetic variation through wild species, landraces, and, potentially, the use of transgenes for intractable traits. This variation will be combined using international shuttle breeding, and increased breeding efficiency will be achieved through marker-aided methods, more targeted use of crop physiology, plant genetics, biostatistics, and bioinformatics. Likewise, CIMMYT will increase its focus on the needs of end-users by emphasizing regional efforts in participatory research and client-oriented plant breeding.     

The effect of variation of genetic variance and correlation between mean and variance on efficiency of bulk yield testing

Summary Computer simulation techniques were used to examine the effect of variation of genetic variance and correlation between mean and genetic variance on the efficiency of bulk yield testing procedures. Assessment of the effect of variation in various parameters was made by comparing genetic gains with the maximum potential gain. The maximum potential gain was defined as that which would be achieved if the particular bulk which maximizes genetic advance were chosen for selection.Maximum potential gains increased with increasing mean genetic variance within bulks but showed only a slight response to increasing variation of the within bulk genetic variance. Negative correlations between bulk mean and genetic variance reduced maximum potential gains and positive correlations increased them but the effects were not large.A selection intensity of 5% among bulks seemed close to optimal for a wide range of parameters. Slightly more intense selection may be an advantage where the between bulk heritability is high, the within bulk variance is high, and the correlation between bulk mean and variance is high and positive.     

农用车制动称重复合检测试验台的研制

研究开发了一种用于农用车性能检测的新型制动称重复合检测试验台。该设备通过顺序动作完成轴荷称重和制动力的检测，由计算机对力传感器信号进行采集处理，能同时测量左右轮的轴荷和制动力。实际使用结果表明，能满足农用车的制动力台试检测的要求，并具有性能可靠、精度较高和易维护等优点。     

虚拟仪器技术在疲劳试验机功能改进中的应用研究

为了提高SVF-1E-01型电液伺服拉压疲劳试验机的测试精度、简化试验操作，应用虚拟仪器技术对其进行了改造。采用研祥工控集团的PCL-812pg多功能数据采集接口卡，在WIN98操作系统平台下，用面向对象的可视化编程环境Delphi5.0集成，设计了虚拟示波器及虚拟信号发生(合成)器。改进后的系统功能包括：模拟信号的采集与显示、单一及多路合成信号的产生及输出等。软件系统具有形象、直观、操作方便等特点。试验结果表明：控制信号精度较高，可以满足试验的要求。整个软、硬件系统接入拉压疲劳试验机中，完成该疲劳试验机     

我国农业中的测土配方施肥

根据笔者的实践,阐述了目前我国正在进行的测土配方施肥行动的意义、测土配方施肥的主要工作内容、目前需要解决的科学问题等。同时介绍了目前在我国测土配方施肥中土壤养分化验的新方法等。