沙漠豆繁殖及育种的研究进展

对近年来国内外有关沙漠豆繁殖及育种研究的进展和成果进行了归纳总结。针对沙漠豆的繁殖及育种存在的问题提出了见解并展望了未来的发展趋势,旨在推动我国引种沙漠豆,并进行繁殖及育种的研究进程。     

沙芦草+胡枝子混播草地的生物量及土壤速效养分

采用田间调查取样和室内分析相结合的方法,在宁夏盐池县四墩子试验基地以单播沙芦草(Agropyron mongolicum)、单播达乌里胡枝子(Lespedeza davurica)、同行混播和灌木地同行混播栽培草地为研究对象,研究了不同播种方式对草地生物量和土壤速效养分分布的影响,结果表明,地上生物量表现为同行混播草地单播沙芦草草地灌木地同行混播草地单播达乌里胡枝子草地;随着土层深度的增加,地下生物量和土壤速效养分含量均呈降低的趋势,0-40cm各土层单播达乌里胡枝子草地地下生物量最小;土壤速效氮和速效钾含量均以同行混播草地最低,土壤速效磷含量以灌木地同行混播草地最低,说明混播不利于土壤速效养分的积累。     

二种化合物对二色胡枝子形态分化的影响

试验以组织培养为试验手段,以二色胡枝子播种得到的无菌苗作为试验材料,以头孢霉素、氯化钠2种化合物为添加剂,设置不同的浓度梯度,分别添加于二色胡枝子子叶节分化、茎段增殖、茎段生根培养基。结果表明:子叶节分化能力大于茎段,较低浓度的化合物对子叶节分化的影响不大,子叶节分化能力随化合物浓度增大而减弱。2种化合物对茎段增殖抑制作用明显,但随浓度变化不明显。2种化合物对茎段生根的抑制作用较子叶节分化、茎段增殖强。     

白羊草与达乌里胡枝子混播草地不同降雨年份土壤水分利用状况

为合理利用黄土丘陵区优良乡土草种,探索人工草地建设中乡土草种的最佳混播比例,选取白羊草(Bothriochloa ischaemum)和达乌里胡枝子(Lespedeza davurica)为研究材料,采用生态替代法,按照白羊草与达乌里胡枝子行比设置了7种组合比例(即0∶10,2∶8,4∶6,5∶5,6∶4,8∶2和10∶0),比较研究了丰水年(2011年,降雨量663.4mm)与偏旱年(2012年,降雨量458.2mm)混播草地土壤水分季节变化特征、年度生物量和水分利用效率。结果表明,白羊草与达乌里胡枝子混播草地土壤水分消耗和补充与混播比例密切相关,但主要受年度降雨量及其季节分配的影响。在2011年,充沛的降雨可补充20—260cm土层土壤水分,并弱化了不同混播比例和土层间土壤水分的时空差异。不同降雨量年份里,白羊草和达乌里胡枝子在6∶4与8∶2两混播比例下的地上生物量和水分利用效率均显著较高。     

4种化合物对离体培养二色胡枝子组织分化的影响

以BADH基因为选择标记基因进行遗传转化最适宜的选择剂、抑菌剂种类和浓度,通过不同浓度NaCl、甜菜碱醛、PEG及甜菜碱醛和NaCl的不同组合等进行胡枝子子叶节分化,茎段增殖以及生根培养,发现NaCl和甜菜碱醛都能抑制二色胡枝子的子叶节分化、茎段增殖和生根,可作为遗传转化中的选择剂。培养基中添加0.8g/L NaCl就能完全抑制二色胡枝子子叶节和茎段增殖,可作为遗传转化过程中子叶节和茎段增殖阶段的选择剂浓度。培养基中添加0.5g/L NaCl能抑制生根,适合作为离体培养生根阶段的选择剂浓度。随着培养基中甜菜碱醛浓度的增加,子叶节分化能力下降,当甜菜碱醛达到1.5g/L时子叶节不再分化,这可作为以甜菜碱醛为选择剂时子叶节分化阶段的最佳筛选。培养基中同时添加NaCl和甜菜碱醛时,NaCl 0.7g/L+甜菜碱醛0.3g/L就抑制了离体培养过程中茎段增殖和生根,比较适合二色胡枝子离体培养时茎段增殖和生根的筛选浓度。对头孢霉素的研究发现:培养基中添加200~300mg/L头孢霉素对离体培养的二色胡枝子子叶节分化影响不大,培养基中添加100mg/L的头孢霉素对离体培养的二色胡枝子茎段增殖和生根无显著影响。     

Response of Sericea Lespedeza Genotypes Low in Tannins to Different Environments

Transfer of the low-tannin trait to otherwise desirable sericea lespedeza high-tannin lines produced genotypes with considerably lowered forage yield. It is not known if low-tannin sericeas are proportionally less productive than high-tannin sericeas in high-yielding environments. If so, low-tannin sericeas would be less desirable to grow in more productive environments. Regression analysis was used to partition GE interactions between regressions and the residuals after regression, and to measure the response to changing environments, Shukla 's stability-variance parameters were used to measure genotype stability. Variance and coefficient of variation were calculated across environments for each genotype and rank correlated to the aforementioned parameters of stability to determine their usefulness in the early stages of cultivar testing. Stability analysis was carried out on the dry forage yield of 10 genotypes grown in 10 environments in Alabama. The only low-tannin genotype that consistently responded to environmental fluctuations like ‘Serala’ was 74-100-5. Low-tannin sericeas were found to be proportionally less productive than high-tannin sericeas in high-yielding environments. However, it is possible to select low-tannin lines with an environmental response similar to high-tannin sericeas. Rank correlations among stability parameters indicated that EV is a stability parameter which is easy to calculate and could be used in the early stages of cultivar testing.     

优良牧草——科尔沁尖叶胡枝子

科尔沁尖叶胡枝子为豆科多年生草本状半灌木，适应于干旱、半干旱区，在内蒙古农牧交错带东段种子9月中旬成熟，产量约636．89kg／hm^2，生育期约115—120d。成熟株高80-90cm，生长2年和3年的鲜干草产量平均为15310．7和5838．5kg／hm^2。科尔沁尖叶胡枝子生育后期基部叶易脱落，收获牧草宜在7月中下旬刈割，留茬高度10cm左右，可调制干草，尤以青贮效果较好，牛羊喜食，羊最喜食。     

丽草蛉三龄幼虫对斜纹夜蛾卵及低龄幼虫的捕食作用

为探明丽草蛉对斜纹夜蛾的捕食作用,本研究在室内测定了丽草蛉3龄幼虫对斜纹夜蛾卵和低龄幼虫的捕食能力及其功能反应。结果表明,丽草蛉3龄幼虫对斜纹夜蛾的卵及1龄、2龄和3龄幼虫均表现出积极捕食行为和较强的捕食能力,其捕食功能反应符合Holling II型,模型可信度较高。猎物的龄期和密度能显著影响丽草蛉的捕食能力,随斜纹夜蛾龄期增大,丽草蛉3龄幼虫的日均最大捕食量、对猎物的攻击系数和控害效能均显著下降,但对猎物的处理时间明显延长;当斜纹夜蛾密度增加时,丽草蛉3龄幼虫的捕食效率逐渐下降。综合各项捕食作用参数,丽草蛉3龄幼虫对斜纹夜蛾卵的捕食能力最高,其理论日最大捕食量为313.7粒,控害效能为23.5;其次是对斜纹夜蛾1龄幼虫,其理论日最大捕食量为130.5头,控害效能为9.9。本研究结果证实了丽草蛉是斜纹夜蛾卵和低龄幼虫的重要天敌,且具较高的控害潜能,可用于斜纹夜蛾的生物防治。     

丽蚜小蜂和黄板诱杀防治温室白粉虱研究初报

温室白粉虱是温室内主要害虫之一。为了减少化学药剂的危害,提高产品安全性,通过丽蚜小蜂的天敌防治方法和黄板诱杀的物理防治方法对温室白粉虱的防治进行了初步研究。试验就丽蚜小蜂的最佳释放时机、释放密度、黄板悬挂高度、黄板防治效果等四方面进行了研究。研究结果表明:在每株番茄上有0.5头温室白粉虱时,连续两次以150000头/hm2的密度释放丽蚜小蜂进行生物天敌防治,即可有效防治温室白粉虱的发生,有效率可达95.6%。同时使用黄板诱杀这一物理防治方法,也可有效减少温室内白粉虱数量,并且确定了植物顶端上方5￣15cm处是白粉虱较活跃的区域,因此黄板应尽可能多的覆盖这一区域,以达到最好的防治效果。     

Aboveground biomass response to increasing nitrogen deposition on grassland on the northern Loess Plateau of China

Abstract

The fragile ecosystem of China's Loess Plateau is being exposed to increasing atmospheric nitrogen deposition but little information about the response of the region's natural vegetation is currently available. We studied the responses of aboveground biomass (AGB) to simulated nitrogen deposition in a field experiment conducted on natural grassland on sunny and shady slopes. Three levels of simulated nitrogen deposition were applied, and two treatments with phosphorus were included to test for secondary phosphorus limitation. For the same level of nitrogen deposition, grass generally grew better on the shady slope than on the sunny slope. Compared to a control treatment with no additional nitrogen, we found: (1) the 2.5 g N m^?2 yr^?1 treatment significantly increased biomass only on the sunny slope; (2) the total AGB increased significantly in the 5 g N m^?2 yr^?1 treatment on both the shady slope (by 31%) and the sunny slope (by 25%); and (3) for 10 g N m^?2 yr^?1, AGB was also significantly increased, however, phosphorus limitation became more apparent, and soil nitrate N levels increased significantly, suggesting nitrogen saturation and the potential for nitrate pollution. The AGB of Stipa bungeana (the dominant grass) was significantly increased by nitrogen, but not by phosphorus. The biomass of the second dominant species Lespedeza davurica Schindl., was not affected by increased nitrogen but addition of phosphorus had some positive impact. Therefore, nitrogen deposition was proven to have effects on plant growth in our study area on the Loess Plateau of China, but high level of nitrogen deposition would result in P limitation. Furthermore, increasing nitrogen deposition is likely to induce diversity change.