控制高粱分蘖与主茎株高一致性的基因定位

用分蘖与主茎株高一致的高粱品系K35-Y5与分蘖明显高于主茎的高粱恢复系1383杂交, F1自交获得F2分离群体,构建两混池,采用BSA (bulked segregation analysis)和SLAF (specific length amplified fragment sequencing)技术将高粱分蘖与主茎株高一致基因定位。遗传分析表明,分蘖与主茎株高一致性状由1对隐性核基因控制。参考已公布高粱基因组设计酶切方案,构建SLAF文库并测序。对高粱参考基因组序列进行电子酶切预测,确定限制性内切酶为Rsa I+Hae III,酶切片段长度为364～414 bp;测序Q30为91.70%, GC含量为45.79%,达到测序要求;与水稻的测序数据相比,高粱的双端比对效率为93.35%,酶切效率为90.60%, SLAF建库正常。共获得30.80 M reads,开发出133,246个SLAF标签,再通过分析SLAF标签的多态性,检测到319,428个SNP位点。利用SNP-index法和Euclideandistance法及取两者交集进行关联分析,最后得到一个关联区域,位于第9染色体上的54,788,026～56,740,873区间内,关联区域长度1.95 Mb。分析关联区域内的基因在2个亲本之间SNP,对这些SNP进行变异的注释,发现4个非同义突变的SNP。经验证,这4个SNP位点和分蘖与主茎株高一致性状相关。对应到Sobic.009G197901.1、Sobic.009G213300.1和Sobic.009G221200.1三个基因上,这些基因可能是与性状直接相关的功能基因。     

62份从美国引进高粱不育系种质能源相关产量和品质性状评价

为提高能源高粱品种改良效率,以62份美国高粱不育系为试验材料,采用完全随机区组设计,在半干旱(山西省介休市)和半湿润(河北省涿州市)气候条件下种植,测定其产量和品质等10个能源利用相关性状。结果表明:62份不育系生物产量和可溶性糖含量的遗传变异较大,介休市和涿州市试点生物产量的变异系数分别为34.4%和38.1%,可溶性糖含量的变异系数分别为21.8%和36.7%。而纤维素、半纤维素和木质素以及灰分的含量变异幅度较小,在介休市和涿州市试点分别为5.5%～9.1%和5.9%～8.9%。环境对不育系生育期、茎粗、生物产量、可溶性糖、纤维素、半纤维素、木质素和灰分的影响起主导作用。对介休市试点材料主成分分析将产量及品质相关性状聚合为株高因子、碳水化合物因子和生育期因子等3个主成分,而对涿州市试点材料聚为株高因子和碳水化合物因子2个主成分。可将山西省介休市和河北省涿州市不育系种质均聚为3大类群。高粱植株高大和碳水化合物含量高意味着更适合用作生产能源的原料,是能源高粱育种时应重点关注的性状。不育系‘AMP428’和‘AMP469’在2个试点均表现出较高的能源潜力为适应性广的优良高产亲本;介休市和涿州市试点能源潜力较高的亲本分别为‘AMP443’、‘AMP468’、‘AMP480’、‘AM 488’和‘AMP438’、‘AMP459’、‘AMP466’、‘AMP470’和‘AMP 472’。     

温度与NaCl处理对甜高粱种子萌发及幼苗抗氧化酶活性的影响

为探讨温度与盐胁迫及其交互作用对甜高粱种子萌发及幼苗生长的影响，以‘辽甜1号’甜高粱种子为试验材料，设置15/5、20/10、25/15、30/20和35/25 ℃共5个变温处理及0、50、100、200、300 mmol·L-1 5个NaCl浓度处理，研究不同处理的甜高粱种子萌发、早期幼苗生长及幼苗抗氧化酶活性的差异及规律。结果表明，相同温度条件下，高浓度NaCl处理显著抑制甜高粱的种子萌发，其种子残留干重随着NaCl浓度的增加呈升高趋势，其余萌发指标和种苗转化指标则随着NaCl浓度的增加呈降低趋势。相同浓度NaCl处理下，温度对甜高粱种子萌发和幼苗生长影响显著，其种子萌发指标、种苗转化指标（除种子残留干重）随着温度的上升均呈先升高后下降的趋势；低温（≤20/10 ℃）条件下，抗氧化酶活性均随着NaCl浓度的升高呈降低趋势，而高温（>25/15 ℃）条件下，随着NaCl浓度的升高，酶活性均呈先升高后下降的趋势。双因素方差分析显示，盐分、温度及二者互作均显著影响甜高粱种子的萌发和早期幼苗的抗氧化物酶活性，其中，盐分对种子发芽率、活力指数、种苗转化指标（除种子残留干重）、超氧化物歧化酶、过氧化物酶、过氧化氢酶活性的影响更大，而温度对发芽势、发芽指数、种子残留干重、抗坏血酸过氧化物酶活性的影响较大。在NaCl胁迫下，甜高粱种子萌发最适温度为30/20 ℃。     

Sorghum silage quality as determined by chemical–nutritional factors

Sorghum [Sorghum bicolor (L.) Moench] is an ensilable tropical plant known as a good alternative to maize crops in regions with scarce rainfall. The objective of this trial was to obtain prediction models based on nutritional contents and end products of sorghum silage fermentation as related to the dry-matter composition of fresh plants before ensiling. Eleven different sorghum cultivars (including silage, graniferous and sweet types) were used. Twenty-five sorghum plots were harvested between 80 and 120 days of growth. Fifty plastic buckets were used as experimental microsilos and opened between 60 and 90 days of storage. Statistical modelling was used to create a prediction equation that could explain the impact of fresh sorghum composition on the chemical and nutritional composition of its silage. A complex model was detected by stepwise multiple regression to predict the difference of in vitro dry-matter digestibility (IVDMD) before and after ensiling, but a simpler model, which involved only the sum of water-soluble carbohydrate (fWSC) and hemicellulose (fHemi) concentrations in the dry matter of fresh forage, was considered to more usable. It had an acceptable coefficient of determination (0.51). The higher amount of WSC and Hemi in fresh sorghum linearly decreased the difference between IVDMD before and after the ensiling process. A WSC concentration of 125.4 g/kg DM in fresh sorghum is recommended for an ideal silage fermentation when considering pH and lactic acid levels, although ethanol levels continued to increase.     

Crop residue retention suppresses seedling emergence and biomass of winter and summer Australian weed species

Crop residue retention could affect the emergence and biomass of weeds in different ways. A summer and winter pot study was conducted to evaluate the effect of different amounts of sorghum and wheat residue on the emergence and biomass of 12 summer and winter Australian weeds. The equivalent amount of sorghum residue to 0, 1, 2, 4 and 6 t/ha was used in the summer study and winter weed seeds were covered with wheat residue equivalent to the amount of 0, 1, 2, 4 and 8 t/ha in the winter study. The emergence and biomass of Amaranthus retroflexus and Echinochloa colona was not affected by sorghum residue treatment. For other summer weeds, the use of the 6 t/ha sorghum residue treatment resulted in 59–94% reductions in biomass compared to no‐sorghum residue retention. Similarly, the application of 8 t/ha wheat residue in the winter study resulted in a reduced biomass of 15–100% compared to no‐crop residue treatment. The results demonstrated the high potential of using crop residues in eco‐friendly weed management strategies, such as harvest weed seed control tactics.     

热带糯质高粱种质选育及改良利用

旨在分析热带糯质资源在高粱育种中的利用价值及对杂种优势的影响,以商丘市农林科学院自有种质作为研究对象,导入热带糯质资源,选育出稳定的不育系,并对所配组合的农艺性状进行方差及相关性分析。结果表明：‘M17A’所配组合的产量、穗粒重、单穗重等性状与其他组合比较均达到极显著水平,组合8的小区产量最高,为15.17 kg;穗部各性状与产量间的相关系数依次为穗粒重>单穗重>穗长>千粒重>轴长>着壳率>角质率,穗粒重与产量的相关系数为0.957,呈极显著正相关,说明在高粱高产育种中,应重点选择穗大、结实率高的种质;‘M17A’所配组合的淀粉含量与其他组合比较均达极显著水平,说明高粱淀粉含量受遗传基因控制。对于热带种质的利用应选择大穗型,角质率低的材料。     

Forage quality of species-rich mountain grasslands subjected to zero,PK and NPK mineral fertilization for decades

To maintain species-rich swards from which forage of a high nutritional quality can be produced, it is essential to adapt grassland fertilization strategies. In this study, we investigated how different long-term mineral fertilization treatments affect dry-matter (DM) yield, plant species composition, and nutrient and mineral concentrations of forage from mountain grasslands. During 2 years, forage was sampled from three different long-term fertilization experiments located at 930 (L), 1,190 (M) and 1,340 (H) m a.s.l. at different sites in Switzerland. At each site, three mineral fertilization treatments (0, PK and NPK) had been maintained for three to six decades, with two (L and M) or three harvests (H) per year. Yield, the botanical composition and concentrations of net energy, utilizable crude protein and different phenolic fractions were determined. Nutrient and mineral concentrations were also determined. For all three sites (L, M and H), unfertilized swards had lower annual DM yields (3.39, 5.17 and 2.73 t/ha) compared to PK (6.33, 7.17 and 4.44 t/ha) and NPK fertilized swards (7.69, 7.22 and 7.44 t/ha), respectively. Long-term fertilization had little effect on the gross nutrient and phenolic composition, but forage P and K concentration increased. The decades-long fertilization of either PK or NPK of up to 85 kg N, 80 kg P₂O₅ and 240 kg K₂O/ha reduced plant species richness only at site H. Fertilization of PK may allow to simultaneously increase forage productivity and maintain forage quality in mountain grasslands.     

Farmers' perceptions of sorghum stem-borer and farm management practices in eastern Ethiopia

A survey of 90 farmers, randomly selected over six sorghum-growing districts in eastern Ethiopia was carried out during July to August, 2001 in the long rainy season. The study investigated farmers' perceptions of the importance of stem-borer and farm practices influencing the pest. Sorghum farming was characterized by smallholdings with an average land size of 4.3 ha, an average family size of 6 and an average yield of 878?kg ha^???1. Farmers cited pests, drought, and shortage of seed, land and labour as the main constraints upon sorghum production. Stem-borers were perceived to be the major pests requiring control. The majority of the farmers never applied chemical insecticides against stem-borers due to lack of capital and unavailability of insecticides. Because of restricted access to improved varieties, farmers largely used local cultivars of sorghum selected for yield potential but with little emphasis on insect resistance. Very few farmers destroyed sorghum residues after harvest. The majority of farmers grew sorghum under intercropping mainly due to the high yield expected. Crop rotation in sorghum fields was not widely practised due to land shortage.