锯缘青蟹苗池微生态环境影响因素的初步探讨

通过对锯缘青蟹苗池微生态环境和水质环境的全过程检测,探讨了总菌数、弧菌数及弧菌数/总菌数的消长规律,并对苗种培育阶段涉及的各种外源因素及控制苗池微生态环境的相关手段的有效性作了初步的探讨。结果表明:苗池水体中总菌数在Z1~Z2少量添加水不换水阶段,呈相对稳定状态,进入Z3后总菌数逐渐增加,最高达3.5×106cfu/m l;弧菌数在Z1培育阶段出现2×102cfu/m l激增至5×104cfu/m l的峰值,第二峰值出现在Z5阶段,达6×105cfu/m l;弧菌数/总菌数比值在育苗起始时仅为0.4%,之后迅速升至30%~40%,在Z5阶段,由于弧菌数量急剧上升,达到50%的高比值;NH4-N与COD检测值在育苗过程中变动较大,两者与弧菌数/总菌数比值呈正相关关系。现行育苗方式中对苗池微生态环境产生影响的主要因素是苗种培育密度,海水、饵料的处理方式和抗生素;净化功能菌和蛭弧菌应用于育苗水体具有抑制弧菌繁殖的效果。     

Mitigating nitrous oxide emissions from agricultural soils by precision management

Nitrous oxide (N₂O) emissions make up a significant part of agricultural greenhouse gas emissions. There is an urgent need to identify new approaches to the mitigation of these emissions with emerging technology. In this short review four approaches to precision managements of agricultural systems are described based on examples of work being undertaken in the UK and New Zealand. They offer the opportunity for N₂O mitigation without any reduction in productivity. These approaches depend upon new sensor technology, modeling and spatial information with which to make management decisions and interventions that can both improve agricultural productivity and environmental protection.     

山东地区夏玉米的高产种植技术

随着我国市场经济的不断发展和农业供给侧的不断改革,玉米价格呈现出大幅度下降趋势, 玉米种植面积也急剧下降。为了提高玉米的产量和效益,科学推广和应用玉米高产种植技术是当务 之急,同时也是玉米产业快速发展的必然趋势。基于以上情况,本文从精细播种、苗期管理、玉米穗期 管理、花粒期管理五个方面入手,研究了夏玉米高产种植技术。希望通过这次研究,为相关种植人员 提供有效的参考。     

Screening of antagonistic Trichoderma strains and their application for controlling stalk rot in maize

Maize is one of the major crops in China, but maize stalk rot occurs nationwide and has become one of the major challenges in maize production in China. In order to find an environment-friendly and feasible technology to control this disease, a Trichoderma-based biocontrol agent was selected. Forty-eight strains with various inhibition activities to Fusarium graminearum, and Fusarium verticillioides were tested. A group of Trichoderma strains(DLY31, SG3403, DLY1303 and GDFS1009) were found to provide an inhibition rate to pathogen growth in vitro of over 70%. These strains also prevented pathogen infection over 65% and promoted the maize seedling growth for the main root in vivo by over 50%. Due to its advantage in antifungal activity against pathogens and promotion activity to maize, Trichoderma asperellum GDSF1009 was selected as the most promising strain of the biocontrol agent in the Trichoderma spectrum. Pot experiments showed that the Trichoderma agent at 2–3 g/pot could achieve the best control of seedling stalk rot and promotion of maize seedling growth. In the field experiments, 8–10 g/hole was able to achieve over 65% control to stalk rot, and yield increased by 2–11%. In the case of natural morbidity, the control efficiency ranged from 27.23 to 48.84%, and the rate of yield increase reached 11.70%, with a dosage of Trichoderma granules at 75 kg ha~(-1). Based on these results, we concluded that the Trichoderma agent is a promising biocontrol approach to stalk rot in maize.     

不同发育阶段干旱胁迫对玉米株高、果穗性状及产量的影响

摘要：为研究同一品种不同发育阶段干旱胁迫对玉米植株高度、果穗性状以及产量的影响程度,设置全生育期供水充足、大田自然干旱、拔节期控水、抽雄期控水、拔节期控水-复水、抽雄期控水-复水6种处理的对比试验,用对比分析的方法比较不同处理下玉米的株高、果穗性状以及产量之间的差异。结果表明：干旱胁迫使玉米植株矮小,果穗长减小7.88%~54.55%,果穗粗减小14.58%~52.08%,秃尖长度增大66.67%~258.33%,百粒重减小0.99%~41.36%,单株产量减少15.03%~94.41%,最终导致减产23.57%~90.03%。不同发育阶段干旱胁迫对产量的影响差异显著,全生育期干旱最为严重,几乎无产量,拔节期次之,抽雄期干旱胁迫影响最小,复水后由于部分补偿了前期干旱胁迫所减少的生物量,果穗性状、百粒重均有好转,减产幅度减轻。     

覆膜方式对雨养饲用玉米生长、产量及水分利用效率的影响

为促进冀西北坝上高寒半干旱区旱地饲用玉米稳产、高产和提高水分利用效率,于2016—2017年在农业部张北农业资源与生态环境重点野外观测试验站,进行了露地平作(ck),双垄沟覆膜、微垄覆膜、土下覆膜处理对饲用玉米叶面积指数、干物质积累、土壤水分、产量和水分利用效率影响的试验研究。结果表明,在丰水年,双垄沟覆膜处理效果最好,与露地相比叶面积指数、干物质积累量、土壤蓄水量分别提高36.45%、70.24%、13.25%,产量和水分利用效率提高了67.24%和87.66%;在欠水年,土下覆膜处理效果最佳,较露地增产71.31%,水分利用效率提高81.69%。双垄沟覆膜是寒旱区提高饲用玉米产量和高效利用降水的有效技术,土下覆膜则更适用于土壤贮水丰富农田的高水效生产。     

Functional polymorphism among members of abscisic acid receptor family(ZmPYL) in maize

Pyrabactin resistance 1-like proteins(PYLs) are direct receptors of abscisic acid(ABA). For the redundant and polymorphic functions, some members of the PYL family interact with components of other signaling pathways. Here, 253 positive colonies from a maize cDNA library were screened as interacting proteins with the members of ZmPYL family. After sequencing and function annotation, 17 of 28 interaction combinations were verified by yeast two-hybrid(Y2 H). The germination potential, taproot length and proline content of a quartet mutant of Arabidopsis PYL genes were significantly deceased comparing to the wild type(WT) under alkaline stress(pH 8.5) and 100 μmol L–1 methyl jasmonate(MeJA) induction. The malondialdehyde(MDA) content was significantly increased. After germinating in darkness, the characteristics of dark morphogenesis of the quartet mutant seedlings were more obvious than those of the WT. The differential expression of the related genes of photomorphogenesis in the mutant was much more than that in the WT. Three light and two JA responsive cis-affecting elements were identified during the promoter sequences of the AtPYL1 and AtPYL2 genes. These results suggested that functional polymorphism has evolved among the members of ZmPYL family. In response to developmental and environmental stimuli, they not only function as direct ABA receptors but also interact with components of other signaling pathways mediated JA, brassinosteroid(BR), auxin, etc., and even directly regulate downstream stress-related proteins. These signaling pathways can interact at various crosstalk points and different levels of gene expression within a sophisticated network.     

Effect of three insect-resistant maizes expressing Cry1Ie,Cry1Ab/Cry2Aj and Cry1Ab on the growth and development of armyworm Mythimna separata(Walker)

Three transgenic maize events(IE09 S034, Shuangkang 12–5 and C0030.3.5) produced Cry1 Ie, Cry1 Ab/Cry2 Aj and G10-EPSPS, Cry1 Ab and EPSPS, respectively, all of which target the Asian corn borer. The oriental armyworm Mythimna separata(Walker) is the secondary target. In this study, the effects of the three Bt maizes on the development and survival of armyworm were studied. The results showed that IE09 S034 had insecticidal activity against 1 st instar larvae, and the survival rate of armyworm fed with Bt maize for 10 days was 46.2%, significantly lower than that of the control. The larvae at 3 rd–6 th instar were more tolerant of the Bt toxin than the early instar larvae. However, Shuangkang 12-5 had good insecticidal activity against 1 st–5 th instar larvae. The mortality was nearly 100% when the larvae were fed with Shuangkang 12-5 before 3 rd instar, and the toxin had quick-acting efficacy. This event significantly inhibited the development of armyworm; that is, the larval duration of the 3 rd and 4 th instar larvae fed with Shuangkang 12-5 was prolonged by 4.5 and 3.0 days, respectively. The pupal weight and egg number were also significantly lower than those of the control. For C0030.3.5, it could control 1 st–5 th instar larvae effectively. The mortality rates were all over 50% if 1 st–3 rd larvae were fed with this event. The pupal weight of 4 th–6 th instar larvae fed with Bt maize were only 53.9, 56.8 and 54.6%, respectively, compared to that of the control. The number of eggs laid was significantly less than the control. The results indicate that all three transgenic maize events exhibit the potential to provide effective control of early instar larvae of armyworm, which can be commercialized in future to control lepidoptera pests such as Asian corn borer and armyworm.     

Effects of post-silking water deficit on the leaf photosynthesis and senescence of waxy maize

Waxy maize is widely cultivated under rainfed conditions and frequently suffers water shortage during the late growth stage. In this study, a pot trial was conducted to examine the effects of post-silking drought on leaf photosynthesis and senescence and its influence on grain yield. Two waxy maize hybrids, Suyunuo 5(SYN5) and Yunuo 7(YN7), were grown under the control and drought(soil moisture content was 70–80% and 50–60%, respectively) conditions after silking in 2016 and 2017. The decrease in yield was 11.1 and 15.4% for YN7 and SYN5, respectively, owing to the decreased grain weight and number. Post-silking dry matter accumulation was reduced by 27.2% in YN7 and 26.3% in SYN5. The contribution rate of pre-silking photoassimilates transferred to grain yield was increased by 15.6% in YN7 and 10.2% in SYN5, respectively. Post-silking drought increased the malondialdehyde content, but decreased the contents of water, soluble protein, chlorophyll, and carotenoid in the leaves. The weakened activities of enzymes involved in photosynthesis(ribulose-1,5-bisphosphate carboxylase and phosphoenolpyruvate carboxylase) and antioxidant system(catalase, superoxide dismutase and peroxidase) reduced the photosynthetic rate(P_n) and accelerated leaf senescence. The correlation results indicated that reduced Pn and catalase activity and increased malondialdehyde content under drought conditions induced the decrease of post-silking photoassimilates deposition, ultimately resulted in the grain yield loss.     

杂交稻低播量精量播种育秧及机插取秧特性

【目的】明确杂交稻70 g以下低播量精量穴播和条播对育秧效果及机插特性的影响,突破生产中杂交稻机插的技术瓶颈。【方法】以中浙优1号和甬优1540两个杂交稻品种为材料,利用机插标准9寸盘,设置机械穴播和条播两个精量播种方式,并以机械流水线撒播为对照,穴播规格为16(纵向)×34(横向)穴,条播为纵向16条,以穴播5粒、3粒及2粒的播种量进行播种试验。考查了低播量下不同播种方式对秧苗生长影响及配套取秧效果【结果】1)低播量下不同播种方式对秧苗成苗率的影响不大。2)降低播种量提高秧苗生长一致性,且穴播和条播秧苗生长一致性好于撒播。3)与撒播相比,精量穴播和条播能够在低播量下提高秧苗根系盘结力和成毯性,中浙优1号和甬优1540根系盘结力比撒播平均高75.4%和81.0%,播量每穴3粒时即能有效成毯,穴播和条播差异不大。4)精量穴播和条播能够显著降低低播量下机插漏秧率,中浙优1号和甬优1540机插漏秧率平均分别比撒播低76.3%和74.6%,穴播和条播下,两个品种每穴播量3粒的漏秧率均在1%以下,与撒播相比降幅在10个百分点以上。5)精量穴播和条播机插取秧苗数均匀度比撒播要好,两个品种预期取秧2~5苗(5粒)、1~3苗(3粒)和1~2苗(2粒)比例均达80%以上,中浙优1号和甬优1540机插苗数均匀度平均比撒播高121.2%和67.0%,其中,穴播机插取秧苗数均匀度及预期取秧苗数比例高于条播。【结论】精量穴播和条播可以解决目前杂交稻机插用种量大、漏秧率高和机插取秧苗数均匀度差的问题。