Resistance mechanism of Leptochloa chinensis Nees to propanil

The resistance mechanism of Leptochloa chinensis Nees to propanil was investigated, based on propanil metabolism, aryl acylamidase activity, and chlorophyll fluorescence at the 8 week growth stage of L. chinensis. The concentration of propanil in the leaf and culm extracts of the resistant (R) and susceptible (S) biotypes, as measured by gas chromatography (GC), was found to increase after propanil treatment. The concentration of propanil in the leaf and culm extracts of the S biotype at 72 h was 1.55 and 0.49 µg mL^?1, respectively. However, a lower concentration of propanil was observed in the R biotype, as compared to that in the S biotype. The residue of 3,4‐dichloroaniline, as measured by GC, was detected only in the leaf extracts of the R biotype. In contrast, no residue of 3,4‐dichloroaniline was observed in the S biotype. The level of aryl acylamidase in the leaf tissue extracts of the R biotype was ～140% higher than that in the S biotype. The fluorescence studies showed that propanil inhibited the quantum efficiency of the photosystem II in both the R and S biotypes after 2 h of incubation time. However, when the leaf disks were transferred and incubated in deionized water for 48 h, the quantum efficiency increased in the R biotype but decreased in the S biotype. These results suggest that propanil metabolism, enhanced by aryl acylamidase activity, is the most likely factor contributing towards the mechanism of propanil resistance in L. chinensis plants at the 8 week growth stage.     

峨眉雪胆微丸对断奶仔猪生产性能及腹泻的影响

【目的】探究峨眉雪胆微丸对早期断奶仔猪生产性能及腹泻的影响。【方法】选用初始体重平均为7.86kg的杜×长×大三元杂交断奶仔猪96头,随机分为A、B、C、D组,每组3个重复,每个重复8头,分别在基础日粮中添加0.08%硫酸粘杆菌素、0.008%穿心莲提取物以及0.025%、0.05%比例添加峨眉雪胆微丸进行21d饲养试验,以采食量、日增重、腹泻率等为考察指标,研究添加峨眉雪胆微丸对断奶仔猪生产性能和腹泻的影响。【结果】结果表明,1与添加硫酸黏菌杆素对照组相比,0.025%添加组仔猪的末重、平均日增重变化不明显(P>0.05),料重比显著降低(P<0.05),0.05%添加组仔猪的末重有所提高,平均日增重有所调高,料重比有所提高但差异均不显著(P>0.05)。20.025%添加组仔猪的腹泻频率、腹泻指数与硫酸黏菌杆素组差异不显著(P>0.05)。【结论】饲粮中添加0.025%的峨眉雪胆微丸在改善断奶仔猪生产性能方面与穿心莲及硫酸黏菌杆素组相当,并具有抗腹泻效果。     

Germination and seedling emergence of glyphosate‐resistant and susceptible biotypes of goosegrass (Eleusine indica[L.] Gaertn.)

Effects of environmental factors on the germination and seedling emergence of glyphosate‐resistant (R) and ‐susceptible (S) biotypes of Eleusine indica (L.) Gaertn. were examined under laboratory and greenhouse conditions. The R biotype exhibited a higher germination percentage compared with the S biotype at constant temperatures of 20 and 35°C under dark conditions, and alternating temperatures of 30/25°C, and 35/25°C during a 12 h photo period. For both biotypes, germination was optimal at alternating temperatures of 30/20°C and 35/20°C. However, there was no significant difference (P > 0.05) in the germination between the R and S biotypes at these temperature regimes. The germination of both biotypes was inhibited by osmotic stress imposed by a water potential of ?0.80 MPa. When the moisture stress was released and the seeds were subsequently transferred to distilled water, the germination was enhanced to approximately 90% and 16% for the R and S biotype seeds, respectively. Higher emergence rates were obtained in shallow seed depths (0 or 2 cm) compared to deep depths. Emergence percentage of the R biotype was higher than that of the S biotype at 0 cm and 2 cm depths. The maximum emergence percentage of the R biotype was higher than that of S biotype when seeds were sown on the surface of either loamy or clay loam soil taken from three different sites.     

角果毛茛中矿质营养元素含量及季节动态

2011年4－6月,对四爪陆龟（Testudo horsfieldi）保护区内不同生育期角果毛茛(Ceratocephalus testiculatus)不同器官中的7种矿质元素含量进行测定,综合分析了各矿质元素在植物体内不同器官的分布与动态变化趋势。结果表明,不同生育期角果毛茛中矿质元素在营养器官根、叶中呈现5种变化趋势;繁殖器官花、果实在开花期和结实期内含量变化较明显;不同生育期角果毛茛中矿质元素在各器官中的相对变异量因其是否能参与循环而呈现不同情况;不同生育期角果毛茛各器官中钙磷比超过2∶1的是营养期和结实期的根。     

Reduced rates of tank mixtures for red sprangletop (Leptochloa chinensis [L.] Nees) and greater club-rush (Scirpus grossus [L.] f.) control in rice

A study on the efficacy of tank-mix combinations on the growth of Leptochloa chinensis (L.) Nees and Scirpus grossus (L.) f. at the 3–4-leaf stage was conducted under glasshouse conditions. Sethoxydim plus cyhalofop-butyl at 8 + 25, 16 + 25, 32 + 25, 32 + 12.5, and 32 + 6.25 g ai ha⁻¹ provided good control of L. chinensis , ranging from 89–95%. However, a comparison of the costs of herbicide mixtures revealed that sethoxydim at 32 g ai ha⁻¹ plus cyhalofop-butyl at 6.25 g ai ha⁻¹ were the most cost-effective among the combinations. For Scirpus grossus , bensulfuron plus 2,4-D dimethylamine at 2.5 + 18, 5.0 + 18, 1.25 + 36, 2.5 + 36, and 5.0 + 36 g ai ha⁻¹ gave good control that ranged from 88–93%. Tank-mixing bensulfuron with 2,4-D at 1.25 + 36 g ai ha⁻¹ was, however, the most cost-effective mixture compared to the other mixtures. None of the tank mixtures tested in this study caused injury to the rice seedlings. However, further field studies need to be undertaken to verify these findings.     

峨眉雪胆微丸对断奶仔猪免疫功能的影响

【目的】研究峨眉雪胆微丸对断奶仔猪免疫功能的影响。【方法】将96头"杜×长×大"三元杂交断奶仔猪随机分为4组,每组24头,分别饲喂基础日粮、基础日粮+硫酸粘杆菌素80mg/kg、基础日粮+峨眉雪胆微丸250mg/kg、基础日粮+峨眉雪胆微丸500mg/kg的试验日粮,试验期为21d,分别于饲喂后的第7,14和21天采集血样和肠黏膜,测定断奶仔猪的免疫功能指标,研究峨眉雪胆微丸对断奶仔猪免疫功能的影响。【结果】日粮中添加250mg/kg峨眉雪胆微丸可促进血清免疫球蛋白IgG、IgM、IgA的生成,显著提高补体C3、C4及免疫因子IL-6的质量浓度(P0.05),并可在一定程度上降低炎性因子IL-1β的分泌,提高十二指肠、回肠、盲肠的免疫球蛋白A(SIgA)分泌,其中对十二指肠、盲肠SIgA的分泌有显著促进作用(P0.05)。【结论】日粮中添加250mg/kg峨眉雪胆微丸可增强断奶仔猪的免疫功能。     

西藏主要河谷农区套复种多熟种植研究初探

根据西藏主要河谷农区夏闲地及其资源现状,利用多年旬积温和旬降水量,从热量和水分两方面评价夏闲地开发利用的可能性,以拉萨和山南地区为代表区域。结果表明:在冬麦区多熟作物组合86种,其积温参数变幅为2 000~4 750℃,平均为3 475.1℃,需水参数变幅为456~744 mm,平均值为636 mm;冬春麦兼种区,多熟作物组合有23种,其积温参数变幅为2 050~3 850℃,平均为2 778.7℃,需水参数的变幅为446~580 mm,平均值为528 mm。拉萨冬小麦/箭舌豌豆种植比例试验表明,66%∶33%种植比例产量和水分利用率表现最优;拉萨和山南乃东县春青稞间、套作箭舌豌豆、马铃薯、玉米试验中,粮食产量套作方式比单作、间作方式表现好,以春青稞/马铃薯和春青稞/玉米为优,饲草饲料产量单作方式优于间、套作方式。     

Changes in seed bank size and dormancy characteristics of the glyphosate-resistant biotype of goosegrass (Eleusine indica[L.] Gaertn.)

A study on changes in the seed bank size of a glyphosate ( N -(phosphonomethyl)glycine)-resistant (R) Eleusine indica biotype was carried out on a naturally occurring infestation of a young oil palm plantation. The total number of shed seeds collected was 53% of the predicted potential total number of seeds produced by the plants. Ametryn ( N -ethyl- N' -(methylethyl)-6-(methylthio)-1,3,5-triazine-2, 4-diamine) was found to be able to control the R seed population in the soil. The periodicity of seedling emergence was influenced by rainfall subsequent to the 1 month period of seed shedding. Seed burial at 2, 10 and 20 cm depths showed that 39, 33 and 79%, respectively, of viable seed persisted in the soil after 2 years. Seeds in the state of enforced dormancy played an important role in maintaining the seed population throughout the 2 year period of burial in the soil.     

花期前后高温对不同基因型玉米光合特性 及产量和品质的影响

【目的】研究花期前后高温胁迫对不同耐热性玉米光合特性及产量品质的影响。【方法】以耐热基因型浚单20和热敏感基因型驻玉309为材料,分别于花前（吐丝前0-8 d）和花后（吐丝后0-8 d）进行高温处理,测定叶片的叶绿素相对含量（SPAD）、光合及叶绿素荧光参数、磷酸烯醇式丙酮酸羧化酶（PEPCase）和核酮糖二磷酸羧化酶（RuBPCase）活性及籽粒的产量和品质。【结果】花期前后高温胁迫导致2个基因型玉米产量显著下降,浚单20产量下降幅度小于驻玉309,且花后高温处理影响大于花前处理;高温处理降低了穗位叶净光合速率（Pn）、气孔导度（Gs）、最大光化学效率（Fv/Fm）、光量子产量（ΦPSII）、光化学猝灭系数（qP）、磷酸烯醇式丙酮酸羧化酶（PEPCase）和核酮糖二磷酸羧化酶（RuBPCase）活性,提高了细胞间隙CO2浓度（Ci）和非光化学猝灭系数（qN）。【结论】花期前后高温胁迫对玉米的光合有显著影响,导致玉米产量显著降低,品质受到显著影响。高温胁迫下耐热玉米基因型比热敏感玉米基因型具有较高的叶绿素含量和光合能力,产量和品质受高温影响较小。