湖北双季稻区免耕直播油菜生长及产量形成

长江流域双季稻区因茬口紧、土壤黏重,晚稻收获后大都未种植下茬作物而形成冬闲田。本研究以华双5号油菜品种为材料,在湖北双季稻区三试验点进行裂区试验,测定油菜各生育期在不同氮素及密度水平下的个体及群体指标,成熟期考察经济性状及产量构成,为双季稻区免耕直播油菜示范及管理提供依据。结果表明：(1)双季稻区免耕直播油菜全生育期尤其是苗期显著缩短,苗期生长量严重不足,蕾薹期至开花期油菜生长快,春发特性明显;(2)氮肥及种植密度水平对双季稻区免耕直播油菜生长及产量有着显著影响,增施氮肥可改善个体素质、增加产量,提高密度可提高群体素质、增加产量;(3)湖北各试点每公顷纯氮用量270 kg、种植密度为45万株及60万株处理的产量均接近或达到2 250 kg hm^–2,超湖北平均单产,说明油菜免耕直播栽培模式可在湖北双季稻区试验示范;(4)生产实践中,应重视氮肥与密度的双重调节,以肥促长、以密补迟,相互配合。     

多效唑处理对直播油菜机械收获相关性状及产量的影响

以阳光2009与沣油520为材料,于封行期及蕾薹初期喷施不同浓度多效唑,测定倒伏、角果抗裂性及产量相关指标,研究多效唑对油菜产量和机械收获相关性状的影响,为高产及机械收获条件下油菜的多效唑调控提供技术支撑及理论依据。结果表明,不同时期多效唑处理均显著提高2个油菜品种的抗倒性、抗裂角性及产量,蕾薹初期喷施300 mg L–1多效唑后油菜抗倒与抗裂角指数增量大,封行期喷施150 mg L–1多效唑则后产量的增量大。多效唑处理降低每角果粒数,但增加油菜品种的单株角果数及千粒重,故而增加产量;且可通过增加油菜根颈粗、鲜重根冠比及抗折力降低株高和倒伏指数,提高油菜抗根倒与抗茎倒能力;通过增加角果含水量、延缓角果成熟度、增加角果皮干重提高油菜角果抗裂性。本研究认为封行期喷施150 mg L–1的多效唑是最佳喷施时期与喷施浓度,既可显著增强易倒伏而减产油菜田块的抗倒与抗裂角能力,最大幅度地提高产量,又可满足油菜机械化生产模式所需的高产、抗倒及抗裂角要求。     

Prediction of heterosis using QTLs for yield traits in rapeseed (Brassica napus L.)

Three double low (erucic acid and glucosinolates) self-incompatible lines and 22 varieties from different origins were selected to produce 66 hybrids according to a NC II mating design. Field experiments for identification of hybrid performance and heterosis were conducted in two successive rapeseed growing seasons in Wuhan, China. After heterosis identifications, SI-1300 and Eagle were chosen to construct an F₂ segregating population. One hundred and eighty four F_2:3 lines were planted at Wuhan and Jingmen to test yield traits. F₂ plants and the 25 parents were analyzed using simultaneously AFLP (amplified fragment length polymorphism) and SSR (simple sequence repeat) markers. A total of 270 and 718 polymorphic loci were detected in the F₂ population and among the 25 parental lines, respectively. Of the 718 polymorphic loci, 178 were significantly correlated to yield traits. With the use of one-way ANOVA, 84 common QTLs were detected for 12 traits at two trial locations. Although the genetic distances based on general/specific heterozygosities and single-locus QTLs showed significant correlations with hybrid performance and heterosis for some yield traits, the determination coefficients were low. The results suggested that neither heterozygosities nor QTLs for yield traits were suitable to predict hybrid performance and heterosis in Brassica napus.     

土壤干旱胁迫对玉米叶片水分状况、膜透性及酶抗氧化系统的影响

A simulation experiment on the responses of maize （Zea mays L.） from the third leaf stage to maturity for different soil water levels （well-watered, moderately stressed, and severely stressed） was conducted by controlling irrigation and using a mobile rain shelter in a neutral loam, meadow soil to determine the effects on leaf water status, membrane permeability and enzymatic antioxidant system for different growth stages. The results indicated that drought stress relied on drought intensity and duration, with more severe drought stress creating more serious effects on maize. Compared with wellwatered conditions, during the silking and blister stages moderate stress did not significantly change the relative water content （RWC） and did change significantly the relative conductivity （RC） （P 〈 0.05） of the leaves; however, severe stress did significantly decrease （P 〈 0.01） the leaf RWC and increase （P 〈 0.01） membrane permeability （leaf relative conductivity）. Furthermore, under severe drought stress antioxidant enzyme activities declined significantly （P 〈 0.01） in later stages, namely for superoxide dismutase （SOD） the tasseling and blister stages, for peroxidase （POD） the milk stage, and for catalase （CAT） during the tasseling, blister, and milk stages. Meanwhile, membrane lipid peroxidation （measured as malondialdehyde content） significantly increased （P 〈 0.01） in all stages.     

不同氮肥和密度对油菜机械收获损失率的影响

以华油杂62为材料,采用机械直播的方式,设置不同氮肥和密度处理,在油菜籽粒含水量10.86%~13.17%时研究油菜机械收获各部分损失率及损失组成的差异。结果表明,机械收获总损失率在不同处理间存在差异,变幅在6.13%~7.82%之间。不同部分的损失占总损失比例差异较大,其中,自然脱落损失比例最小,各处理占总损失的比例在2.41%~3.90%之间;其次是割台损失,各处理占总损失的比例为17.99%~21.99%;清选和脱粒损失比例最大,占总损失的74.15%~79.52%,其中主要是夹带损失,占总损失的65.51%~69.05%,而未脱粒角果比例损失较小,占8.64%~10.47%。随着氮肥用量和密度的增加,产量增加;总损失率与产量、氮肥用量及密度的相关系数分别为0.970^**、0.918^**和0.358。本研究表明,在油菜机械化生产过程中首先要确定适宜的施氮量和种植密度以获得高产,在高产的基础上再降低收获损失率。     

甘蓝型油菜显性细胞核雄性不育基因的AFLP标记

用甘蓝型油菜双基因显性细胞核雄性不育系Rs1046A和欧洲油菜品种Samourai构建了一个回交分离群体。在群分法（BSA）构建的不育池和可育池中共筛选了256对AFLP引物组合,找到了与不育基因紧密连锁的两个AFLP标记(EA03MC1599和EA07MC01235), 它们与不育基因的遗传图距分别是3.5 cM和5.5 cM,而且位于不育基因的同一侧,标记间相     

甘蓝型油菜Pol CMS育性恢复基因的RAPD标记

采用恢、 保回交群体和集团分离分析(BSA), 筛选了860个10 mer随机引物, 找到了与甘蓝型油菜波里马细胞质雄性不育系(Pol cms)育性恢复基因(Rf)连锁的两个RAPD标记AH19690和AI16830。 它们位于Rf的一侧,与该基因的遗传图距分别为5.9 cM和13.6 cM,两标记间的遗传图距为7.8 cM。这两个RAPD标记的发掘,为进一步利用分子标记     

油菜感抗品种混播对根肿病防控效果的影响

近年来,油菜根肿病危害在我国呈蔓延趋势,主要原因是化学防治成本高且效果差。实际生产中,种植抗性品种是最经济、最有效的措施。不同抗感品种混播,在保证产量稳定的前提下可减轻对病原菌小种的选择压,从而稳定病原菌种群结构,延长抗性品种使用寿命。本试验在安徽绩溪、云南临翔2个油菜根肿病严重发生区域,选择2组互为近等基因系的感病、抗病的油菜品种,按不同比例混播(感病、抗病比例分别为10:0、1:9、2:8、3:7和0:10),在根肿病明显发生后调查发病率等指标。结果表明:不同比例感病、抗病油菜品种混播均降低了根肿病发病率和病情指数,并稳定油菜产量和品质;且油菜发病株率随抗病品种的比例下降而升高,但均低于理论发病率;不同抗性组合间混播的相对防效(REM)均低于1,且随着作物生育期的推迟呈现下降趋势。以上结果表明,油菜感抗品种混播对根肿病有较好的防控效果。本研究主要在大田条件下明确了2组不同抗感近等基因组合混播对油菜根肿病的防治效果,可为油菜根肿病防治提供思路和对策。     

苏云金素对智利小植绥螨及其猎物二斑叶螨的毒力测定

苏云金素处理后第3天智利小植绥螨和二斑叶螨幼螨的LC_(50)分别为211.33μg/ml和114.58μg/ml。两种雌成螨的产卵量第2天即明显减少,高剂量处理后3～4天,导致产卵停止。处理后第5天,智利小植绥螨和二斑叶螨成螨的LC_(50)分别为843.19μg/ml和279.88μg/ml。试验结果表明,苏云金素对两种幼螨是一种高效、无选择性的杀螨剂,对智利小植绥螨的卵和成螨毒性相对较低,但能抑制其雌成螨的产卵量,降低种群趋势指数,在释放智利小植绥螨期间应尽量避免用药。     

土壤有机碳和活性碳的梯度分布及其对环境变化的反应

Based on data from a field survey in 2001 along the Northeast China transect （NECT）, a precipitation gradient, and a short-term simulation experiment under ambient CO2 of 350μmol mol^-1 and doubled CO2 of 700μmol mol^-1 with different soil moisture contents of 30%-45%, 45%-60%, and 60%-80% soil water holding capacity, the distribution of soil organic carbon and labile carbon along the NECT, their relationships with precipitation and their responses to CO2 enrichment and soil moisture changes were analyzed. The results indicated that the soil labile carbon along the gradient was significantly related to soil organic carbon （r = 0.993, P 〈 0.001）. The soil labile carbon decreased more rapidly with depth than organic carbon. The soil organic and labile carbon along the gradient decreased with decrease in longitude in both the topsoils and subsoils, and the coefficient of variation for the labile carbon was greater than that for the organic carbon. Both the soil organic carbon and labile carbon had significant linear relationships with precipitation, with the correlation coefficient of soil organic carbon being lower （0.677 at P 〈 0.001） than that of soil labile carbon （0.712 at P 〈 0.001）. In the simulation experiment with doubled and ambient CO2 and different moisture contents, the coefficient of variation for soil organic carbon was only 1.3%, while for soil labile carbon it was 29.7%. With doubled CO2 concentration （700μmol mol^-1）, soil labile carbon decreased significantly at 45% to 60% of soil moisture content. These indicated that soil labile carbon was relatively more sensitive to environmental changes than soil organic carbon.