Sprouting tolerance and falling number in South African hybrid bread wheat cultivars and their parent lines

The aim of this study was to measure tolerance to sprouting in bread wheat hybrids and their parental lines over two consecutive seasons. Sprouting scores obtained from a rain simulator at physiological maturity and then at 7, 14 and 21 days after maturity as well as Hagberg Falling Number (HFN) were used as criteria. Sprouting score at 14 and 21 days after physiological maturity gave reliable and consistent data. Hybrids generally had much higher sprouting scores and lower HFN values than conventional cultivars. The male genepool, from which the hybrids were compiled, mainly contributed to the poor sprouting tolerance of the hybrids. Female lines had sprouting tolerance equal to that of conventional cultivars. HFN was strongly influenced by the season, and multi-year data should be used for effective selection. Grouping trends of genotypes for sprouting score and HFN were similar. Combining males and females with excellent sprouting tolerance should give highly tolerant hybrids.     

小麦抗穗发芽研究进展

穗发芽对小麦的生产、加工和消费等方面带来诸多不利影响。小麦穗发芽受自身与环境因素的影响,其中子粒本身的休眠特性和α-淀粉酶活性与穗发芽联系紧密。近年来,利用分子标记和比较基因组学等方法研究小麦穗发芽发展迅速,已鉴定出大量与穗发芽抗性相关的分子标记,并定位到不同的染色体上。本文从穗发芽的危害、抗性机制、抗性遗传等方面阐述了小麦抗穗发芽的研究进展,并对今后重点研究方向进行了展望,以期为小麦抗穗发芽育种提供理论参考。     

春秋两季马铃薯微型薯休眠期及发芽特性比较分析

本研究以Favorita和南中552两个早熟品种的微型薯为试验材料,对春秋两季生产的微型薯在4℃和20℃条件下贮藏的休眠期及其发芽动态进行了系统观察。结果表明,两个基因型在20℃和4℃下贮藏,春季微型薯休眠期比秋季分别短30d左右和60d左右,有光贮藏的微型薯打破休眠的时间比黑暗贮藏时分别延长一周和两周。块茎打破休眠后,发芽动态呈"S"曲线,但生产季节、贮藏温度间存在显著差异。春季微型薯发芽持续时间均长于秋季微型薯,低温贮藏使发芽持续时间更加延长。     

湖北省白皮小麦品种穗发芽抗性鉴定及改良

鉴定了湖北省本省育成和外引的12个白皮小麦(Triticum aestivum L.)品种的穗发芽抗性,比较了室内整穗发芽法和田间自然鉴定法的优劣,分析了系谱法经验选择的效果。结果表明,湖北省本省育成的白皮小麦品种具有一定的穗发芽耐性,而外引品种高感穗发芽;室内整穗发芽法和田间自然鉴定法均可提高穗发芽选择,以室内整穗发芽法效果较好,采用改良系谱法结合室内整穗发芽法鉴定是抗穗发芽育种的一种有效途径。     

大巴山粉葛组织培养技术

为了实现大巴山粉葛Pueraria lobata （wild） Ohwi Dabashan种苗的规模化快速繁殖,以大巴山粉葛茎段为外植体,研究了灭菌时间、MS培养基大量元素、植物生长调节剂对大巴山粉葛组织培养过程中消毒、初代培养、增殖培养及生根培养的影响。结果表明,（1）先用75%乙醇消毒20 s,再用0.1%氯化汞消毒10 min,成活率达67.56%。（2）初代培养基为1/2 MS+0.5 mg·L-1 6-BA+0.3 mg·L-1 IBA,腋芽萌发率可达92.2%;（3）增殖培养基为1/2 MS+1.0 mg·L-1 6-BA+0.05 mg·L-1 IBA,增殖系数约5.0;（4）生根培养基为1/2 MS+0.01 mg·L-1 NAA+0.1 mg·L-1 IBA,生根率达96.03%。     

截干高度对红锥的促萌效果研究

以20株7 a生红锥(Castanopsis hystrix)优良单株为材料,研究不同截干高度对红锥萌芽效果的影响.结果表明:120 cm截干处理下,促萌效果优于其他处理,初始萌芽期最早,萌枝数、萌枝丛数、萌枝平均距地高都最高;红锥截干后的萌枝情况对光照的响应不显著;红锥截干可刺激主干上的隐芽萌发.     

Mapping QTLs for pre-harvest sprouting traits in the spring wheat cross ‘RL4452/AC Domain’

Pre-harvest sprouting (PHS) in spring wheat (Triticum aestivum L.) is a major downgrading factors for grain producers and can significantly reduce end-use quality. PHS resistance is a complex trait influenced by genotype, environment and plant morphological factors. A population of 185 doubled haploid (DH) lines from the spring wheat cross ‘RL4452/AC Domain’ were used as the mapping population to detect quantitative trait loci (QTLs) associated with three PHS traits, germination index (GI), sprouting index (SI) and falling number (FN). Six major QTLs linked with PHS traits were mapped on bread wheat chromosomes 3A, 3D, 4A (2 loci), 4B and 7D. ‘AC Domain’ alleles contributed to PHS resistance on 3A, 4A (locus-2) and 4B, and ‘RL4452’ alleles contributed resistance on 3D, 4A (locus-1) and 7D. QTLs detected on chromosome 4B controlling FN (QFN.crc-4B), GI (QGI.crc-4B) and SI (QSI.crc-4B) were coincident, and explained the largest amount of phenotypic variation in FN (22%), GI (67%) and SI (26%), respectively.     

Developing a prescription for brush control in the Chaco region,effects of combined treatments on the canopy of three native shrub species

Shrub encroachment is frequent in grazing lands in the Chaco region, Argentina. Fire is used by cattlemen to reduce the dominance of the shrub stands, improve forage standing biomass and quality, and enhance grazing accessibility. In this research, we assessed the combined effect of roller chopping?+?fire on the plant canopy of three native shrub species, Acacia gilliessi, Celtis ehrenbergiana, and Schinus bumelioides. We used a randomized design, with three factors, year, burn dates, and fine fuel load. Before the burn, the area received a roller-chopping treatment. Canopy volume reduction was assessed using, DifV?=??1*(V_i???V_a) and DifS?=??1*(S_i???S_a), respectively, where V?=?plant volume and S?=?sprout number. Suffixes i and a represent measurements taken before the roller-chopping treatment and one growth season after the fire, respectively. Fire intensity, headfire residence time, woody residues, and initial plant volume were evaluated as covariates. Results indicate a negative fire effect on canopy volume and sprouting. A. gilliesi was more susceptible to fire than the other two species. High fine fuel load and high fire intensity generated a severe effect on sprout number. The same trend was observed for coarse fuels. The canopy volume reduction was greater in A. gilliesi than the other species, reaffirming its high susceptibility to fire. Head fires were faster in 2009 than in 2008 and in the late than in the early burn dates. These results suggest that mechanical?+?fire treatments can be useful management tools for controlling shrub encroachment in the western Chaco.     

Harvesting and extraction impacts on Eucalyptus grandis × E. urophylla coppicing potential and rotation-end volume in Zululand,South Africa

From the early 2000s there has been a general shift in South Africa in harvesting and extraction systems from the use of semi- to fully-mechanised systems. Any increase in mechanisation, as is occurring in Zululand, will need to take into consideration damage to stumps and the subsequent ability to regenerate by coppice. In 2002, four types of harvesting and extraction systems, arranged in a randomised complete block design, were used to clearfell a stand of E. grandis × E. urophylla. A motor-manual harvesting system was used to carry out the manual harvesting system (Man). The fully mechanised system (Mech) consisted of a single-grip harvesting head used with a tracked excavator to carry out all felling and processing operations. Two additional systems (Man_Mech_3W and Man_Mech_Flexi) had increased levels of mechanisation over that of the Man treatment. Both these harvesting systems made use of a Bell debarker, with loading carried out by a Bell three-wheeled loader in the Man_Mech_3W, and by a Flexiloader in the Man_Mech_Flexi treatments. Data collected from these four treatments were used to determine the effects of mechanised harvesting systems on type and severity of stump damage, coppicing potential and coppice growth over the rotation. Irrespective of harvesting system, more damage occurred to the top than bottom half of the stump, with a significant decrease in coppice regrowth with increasing stump damage. Most damage and least coppice regrowth occurred in the extraction rows where the damage recorded could be attributed to vehicle movement, tear-outs and/or log stripping. There was no significant difference between the harvesting systems in terms of stump mortality, final stem stocking and rotation-end volume. Thus, individual components within each harvesting system can have a larger impact than the overall harvesting system used. Future research should focus on these components, and where associated damage occurs for a specific component, this should be lessened through management intervention, training or technological improvements.