基于离散元的柔性作物茎秆振动响应仿真

建立考虑柔性作物茎秆振动响应特性的动力学模型,对探索谷草分离机理、分析谷物分离过程和联合收获机参数优化具有重要意义。本文提出考虑柔性作物茎秆振动响应特性的动力学仿真模型,研究了作物茎秆的动力学响应特性。首先,给出了作物柔性茎秆的动力学模型和动力仿真方法;以成熟期小麦第3节间为例,测量了茎秆的内外径、单位质量密度和弹性模量等参数;对茎秆的横向弯曲振动和纵向拉伸振动进行仿真,研究茎秆的动力学响应特性,并与理论计算结果进行比较。通过仿真获得长度108mm、外径3.7mm、内径1.9mm、弹性模量5.27GPa的小麦茎秆的横向振动频率和纵向振动频率分别为164.28、7633.59Hz,与理论计算结果的相对误差分别为0.28%和0.12%。最后,通过谷草分离仿真实验,验证了柔性作物茎秆模型的实用性。     

新型腐植酸有机肥对马铃薯茎基腐病的防效

马铃薯茎基腐病是影响马铃薯生产的重要病害,目前尚未有效的综合防控措施.试验的目的是通过新型腐植酸肥料与同等养分配方化肥的田间比较试验,探讨新型腐植酸有机肥对马铃薯茎基腐病预防效果.结果表明,5～15 g壤动FT/100 kg种薯配合腐植酸肥料对马铃薯生长发育安全,在出苗率、苗高、单株根数、最大根长、芽长分别优于配方化肥...     

添加剂对番茄茎秆好氧堆肥发酵过程及氮素损失的影响

为研究减少在番茄茎秆好氧堆肥过程中氮素损失的途径,提高堆肥品质,以粉碎的番茄茎秆为原料,按物料干重分别加入5%的腐殖酸(T1)、氯化钙(T2)和过磷酸钙(T3),同时以不进行任何添加的堆体作为对照(CK),进行45 d的好氧堆肥试验。结果表明：3种添加剂均可降低堆肥过程中的氮素损失,同时减少了NH₃的挥发量;堆肥结束时,CK、T1、T2和T3处理的氮素损失率分别为18.04%、15.00%、12.65%和14.05%,累计NH₃挥发量为CK(1 648.11 mg/kg)>T1(1 330.35 mg/kg)>T3(995.35 mg/kg)>T2(528.11 mg/kg)。其中,添加氯化钙的处理保氮效果最好,与对照相比,氮素损失率低至12.65%,NH₃挥发量减少67.96%;各处理高温期均≥3 d,发芽指数≥80%,表明堆体已经腐熟,无植物毒性。综上,番茄茎秆好氧堆肥中添加氯化钙,对于减少堆肥过程中的氮素损失较为理想。本研究可为番茄茎秆好氧堆肥保氮工艺优化提供理论依据。     

7种生物药剂对百香果茎基腐病菌的抑菌效果试验

【目的】明确7种生物药剂对百香果茎基腐病的防治效果,筛选高效安全生物药剂用于指导百香果生产。【方法】采用菌丝生长速率法测定7种生物药剂对百香果茎基腐病菌的毒力效果,观察药剂对病原菌孢子生长及形态的影响,并用离体接种法测定药剂的防治效果。【结果】7种生物药剂处理对菌落生长均有抑制作用,但对孢子的生长和形态的效果不同。室内毒力测试结果显示植物源药剂中抑菌效果最佳为井冈霉素(EC₅₀为7.79 mg/L),其次为春雷霉素(EC₅₀为26.35 mg/L)、乙蒜素(EC₅₀为28.65 mg/L)、苦参碱(EC₅₀为339.13 mg/L)和多抗霉素(EC₅₀为1 150.29 mg/L)。微生物药剂以枯草芽孢杆菌效果较好,EC₅₀为3.2×10⁶ CFU/g。筛选毒力较强的4种生物药剂均可抑制百香果茎基腐病不同菌株生长。离体试验和田间防效试验表明井冈霉素和枯草芽孢杆菌生物药剂对百香果茎基腐病防治效果显著,两者的离体防效分别为58.8%和70...     

胚胎干细胞的研究进展及应用前景

干细胞(Stem Cell)是一类具有分化潜能和自我复制的早期未分化细胞。胚胎干细胞(Embryonic stem cells,ES细胞)是一种早期胚胎内细胞团(inner cell mass,ICM)或原始生殖细胞(primordial germ cell,PGC)经体外分化抑制培养,分离和克隆得到的具有发育全能性的高度未分化细胞。本文综述了胚胎干细胞的形态学、生长特性、免疫学鉴定方法,ES细胞抑制分化和诱导分化的机理以及饲养层、血清和细胞因子等影响胚胎干细胞分离克隆的因素,并进一步阐述了胚胎干细胞的应用前景以及存在的问题。     

Rapid seedlings regeneration from seeds and vegetative propagation with sucker and rhizome of Eremospatha macrocarpa (Mann & Wendl.) Wendl and Laccosperma secundiflorum (P. Beauv.) Kuntze

To develop efficient seedling production methods for Laccosperma secundiflorum and Eremospatha macrocarpa, a study was conducted to examine regeneration using offsets combined with several physical and chemical treatments of seeds. Offsets categorized into small, medium and large diameters, were planted in three conditions: shaded and open nursery, and greenhouse. We tested sucker from E. macrocarpa, and sucker and rhizome from L. secundiflorum. For both species, high viability percentage (ranging from 55% to 100%) were observed for small and medium suckers planted in shaded nursery and greenhouse, against less than 49% for sucker planted in open nursery. The mean seedling emergence times were estimated to 84, 77 and 75 days after planting (DAP) for small, medium and large sucker of L. secundiflorum, respectively under open nursery condition, and 76, 75, 95 DAP for small, medium and large suckers of the same species, respectively in shaded condition. Greenhouse has a significant positive effect on E. macrocarpa seedlings emergence time. For this species, the mean seedling emergence times were estimated to 43 DAP for small sucker and 76, 93 DAP for medium and large suckers. No seedling was obtained from rhizome planted in all the growing conditions tested. Concerning seed dormancy breaking, germination percentages and rates were determined for 13 treatments. The best treatments were pre-soaking unscarified seeds for 4 days in 1.01 g l⁻¹ and 0.10 g l⁻¹ KNO₃, with 79% and 68% of germination, respectively and in 3.46 × 10⁻³ g l⁻¹ GA₃ for 68% of germination. These methods are suggested to improve germination of L. secundiflorum seeds. Successful and recommended methods for E. macrocarpa are pre-soaking scarified seeds in 3.46 × 10⁻³ g l⁻¹ and 3.46 × 10⁻⁴ g l⁻¹ GA₃, 96% and 94% of germination, respectively. Dormancy, probably a combination of mechanical and chemical dormancy, is present in the two species.     

野菊嫩茎的组织培养

在适宜的培养条件下,利用野菊花的嫩茎作为外植体,用组织培养的方法,在MS培养基上生长良好,获得再生植株.练苗后,成活率达100%,生长势强,茎粗壮叶色浓绿.结果表明:利用组织培养的方式对野菊花进行扩繁,简便易行.     

Response of Vitis vinifera cv. ‘Tempranillo’ to partial rootzone drying in the field: Water relations, growth, yield and fruit and wine quality

This paper reports the effects of irrigation amount and partial rootzone drying (PRD) on water relations, growth, yield and wine quality of Vitis vinifera cv. ‘Tempranillo’ during two consecutive years in a commercial vineyard with a deep, light-clay soil located in Requena, Valencia, Spain. Partial rootzone drying applied at two amounts (100% and 50% of the estimated crop evapotranspiration), was compared to conventional drip irrigation, and also to rainfed vines. Results showed that the effects of irrigation amount on yield and wine quality were different between years. In 2003 with low yield values (around 6.3 t ha⁻¹) irrigation did neither affect grape production nor wine quality. However, in the following year, with much higher general yield (17 t ha⁻¹), the high irrigation dose increased yield by 30% compared to rainfed vines and it also increased must total soluble solids and wine alcohol content. In both seasons, PRD did not significantly affect physiological parameters, nor growth, yield or fruit and wine quality, when compared to the same amount of water applied by conventional drip irrigation. Overall these results suggest that, under our experimental conditions, it was the irrigation amount rather than the system of application what affected vine performance, indicating the difficulties of successfully employing the PRD type of irrigation with a drip system in heavy and deep soils.     

Determining reference values for stem water potential and maximum daily trunk shrinkage in young apple trees based on plant responses to water deficit

The use of plant water status indicators such as midday stem water potential (Ψ_stem) and maximum daily trunk shrinkage (MDS) in irrigation scheduling requires the definition of a reference or threshold value, beyond which irrigation is necessary. These reference values are generally obtained by comparing the seasonal variation of plant water status with the environmental conditions under non-limiting soil water availability. In the present study an alternative approach is presented based on the plant’s response to water deficit. A drought experiment was carried out on two apple cultivars (Malus domestica Borkh. ‘Mutsu’ and ‘Cox Orange’) in which both indicators (Ψ_stem and MDS) were related to several plant physiological responses. Sap flow rates, maximum net photosynthesis rates and daily radial stem growth (DRSG) (derived from continuous stem diameter variation measurements) were considered in the assessment of the approach. Depending on the chosen plant response in relationship with Ψ_stem or MDS, the obtained reference values varied between −1.04 and −1.46 MPa for Ψ_stem and between 0.17 and 0.28 mm for MDS. In both cultivars, the approach based on maximum photosynthesis rates resulted in less negative Ψ_stem values and smaller MDS values, compared to the approaches with sap flow and daily radial stem growth. In the well-irrigated apple trees, day-to-day variations in midday Ψ_stem and MDS were related to the evaporative demand. These variations were more substantial for MDS than for midday Ψ_stem.     

芦笋种质苗期对茎枯病的抗性评价

为了解不同芦笋种质对茎枯病的抗性差异,采用孢子喷雾法对其幼苗进行喷雾后48 h保湿处理,7 d后统计分析各种质的发病情况并计算病情指数。结果表明：野生型大理天门冬和B7/TX-4病情指数均为0,为免疫种质;井冈701、TC山东、井冈全雄(2)、B4-a/B20-a(紫)、B19-c(H)、B2-a/SD、B3/TX-6,病情指数均小于20,为中抗种质;太平洋2000病情指数为81.25,为感病种质。