基于Voronoi图的单粒播玉米产量效果的蒙特卡罗模拟

为了明确在单粒播种条件下田间出苗率对玉米产量的影响,以蒙特卡罗二项分布作缺苗模拟,以Voronoi图分配缺苗土地,通过对产量-密度方程进行数学恒等变换计算产量补偿,模拟了2种单粒播策略的玉米产量随出苗率(75%~95%)的变化。结果表明,缺苗斑数目与出苗率呈单峰曲线关系,缺苗斑大小随出苗率呈负指数下降;单粒播造成0.06%~16.78%的减产,且减产率随出苗率下降而增加;两种单粒播策略的产量大小和产量稳定性均有差异,且差异随出苗率下降而扩大。该研究推荐的玉米单粒播策略是:在千方百计提高出苗率基础上,播种的种子数目应当等于目标种植密度除以出苗率、保证出苗的植株数目达到推荐种植密度。该结论对于在玉米生产上广泛采用单粒精量播种具有重要参考价值。     

Corn Genotypic Variation Effects on Seedling Emergence and Leaf Appearance for Short-Season Areas

Identifying corn ( Zea mays L.) genotypes with faster rates of seedling emergence and leaf appearance is important in developing a corn crop with earlier canopy closure and better seasonal light interception. A greenhouse experiment was conducted twice to investigate whether corn genotypes known to vary in canopy architecture and yield potential differed in rates of seedling emergence and leaf appearance. The experiment was arranged in a randomized complete block design utilizing seven genotypes: five of the newly developed Leafy reduced-stature (LRS) types (LRS1, LRS2, LRS3, LRS4 and LRS5), one conventional type [Pioneer 3979 (P3979)], and one late-maturing big-leaf (LMBL) type. Five seeds were planted in each pot and seedling emergence was recorded every day until all seeds emerged. Leaf appearance was recorded from seedling emergence until the plants reached anthesis. There was variability among the genotypes for both seedling emergence and leaf appearance rate. Mean seedling emergence values of greater than 90 % were achieved by four of the five LRS genotypes, and the LRS types generally emerged more rapidly than the others. Leaf appearance rate showed linear increases over time; however, LRS genotypes (in particular LRS3, LRS4 and LRS5) had more rapid leaf appearance rates than the others. The LMBL hybrid ranked last for both seedling emergence (<80 %) and leaf appearance rate. Rapid seedling emergence and leaf appearance by early-maturing genotypes (LRS and P3979, especially LRS) may help these types of genotypes achieve earlier canopy closure and better use of the light available during the growing season, which is critical in a short growing season environment.     

Effect of Seed Pre-sowing Hardening on Physiological Behaviour and Seed Yield of Berseem (Trifolium alexandrinum L.) Crop

A field experiment was conducted at Central Research Farm, Indian Grassland and Fodder Research Institute, Jhansi to study the effect of seed pre-sowing hardening on seed emergence, physiological behaviour — and seed yield of berseem ( Trifolium alexandrinum L. Var. S-99-1) crop. For this purpose, seed pre-sowing hardening were made by soaking of seeds in tap water for 24 and 36 hours separately and later dried back to their original weight or left undried. These seeds were sown at two depths (5 and 3 cm) and judged against control (no soaking). Results demonstrated that augmented effect of seed hardening on seed emergence and physiological process responsible for seed yield was recorded in descending order of harden seeds (of 24 hours soaking) > non harden seeds (of 24 hours soaking) > harden seeds (of 36 hours soaking); while non-harden seeds of 36 hours soaking adversely affect the plant growth because of leaching of sugar during excess soaking — an element for reduced seed vigour potential. Seed hardening system developed the strength of seed emergence on account of efficient catabolic process releasing high water soluble sugars needed for efficient germination process. Further this process augmented the absorption mechanism of mineral nutrients (particularly phosphorus and nitrogen with marginal variation in calcium) was quite evident at bloom stage — indicating a high metabolic activity during this period. Performance of seed hardening was effective at 5 cm deep sowing.     

山东泰安地区小麦禾谷孢囊线虫幼虫孵化特性初步研究

为大量获得研究所需的小麦禾谷孢囊线虫2龄幼虫,在室内离体条件下研究了预处理条件、孵化温度、低温预处理时间以及田间采样时期对山东泰安地区小麦禾谷孢囊线虫幼虫孵出量的影响.结果表明:5℃低温预处理条件下,孢囊浸水处理有利于幼虫孵出;低温预处理后,孵化温度为15℃处理的2龄幼虫孵出率高于20℃处理的孵出率;低温预处理时间为8周的2龄幼虫孵出率最高;6月和8月田间采集的孢囊幼虫孵出率显著高于7月和9月,其中8月采集的孢囊幼虫孵出率最高,为最佳采集时间.     

黑条帕寄蝇成虫生物学特性初步研究

黑条帕寄蝇(Palesisa nudioculla Villeneuve)是草地螟(Loxostege sticticalis L.)及其他许多鳞翅目害虫的重要寄生性天敌,国内外对其研究报道较少。通过田间调查和室内试验研究了黑条帕寄蝇成虫主要的生物学特性,为该蝇种的保护利用奠定基础。结果表明:黑条帕寄蝇的寄生方式属微卵生型,羽化时间主要集中在每天的08:00-10:00,16:00-18:00,羽化性比为1.13∶1(雌∶雄),且雄蝇比雌蝇先羽化;在条件为(23±1)℃、L∥D=16h∥8h、RH 60%～70%的光照培养箱中饲养,成虫的寿命最长,可达34d;以含糖物质补充营养能延长成虫的寿命,特别是20%的蜂蜜水补充可显著延长其寿命,且雌蝇比雄蝇的寿命长;被寄生的草地螟虫茧低温(4℃)储存20d后的羽化率没有显著变化,但随着储存时间的增加羽化率显著降低。     

黑龙江省高粱出苗不全的原因与对策

高粱出苗不全给农民造成巨大的损失,导致农民与种子公司的纠纷不断发生,给农业安全生产和社会和谐带来隐患。根据对黑龙江省高粱生产情况的掌握,以及对高粱出苗不全地块的调查及相关农民的走访可知,黑龙江省高粱出苗不全的原因虽多,但可归结为4类:商品种子自身因素、自然因素、土壤因素和人为因素。现对其提出防治对策,以促进黑龙江高粱产业的健康发展。     

海南桉树枝瘿姬小蜂成虫羽化量的研究

通过对桉树枝瘿姬小蜂野外黄板调查以及室内羽化量的统计,调查桉树枝瘿姬小蜂在海南发生危害规律,评价海南省5个地点的桉树周年受害情况和种群动态,从而得出不同季节和不同桉树品种受到桉树枝瘿姬小蜂的危害程度和种群发生存在显著差异。不同桉树品种感虫程度存在显著的差异性,感虫程度由重到轻依次为:尾赤桉DH201无性系=小叶桉>桉树混合林>广林9号。     

鳢肠种子萌发及出苗条件的研究

通过萌发试验研究了温度、光照、pH、水势、盐分对鳢肠种子萌发以及埋土深度对其出苗的影响。结果表明:鳢肠种子萌发适宜温度为25～40℃,最适35℃;鳢肠为光敏感性种子,在光照条件下才能萌发,在黑暗中萌发受到抑制,但不同光照周期对种子萌发率没有明显影响;鳢肠种子对pH具有广泛的适应性,在pH为4～10范围内均可萌发;鳢肠种子对水势非常敏感,随着溶液水势从0下降至-0.5 MPa,萌发率从97.78%降低为4.44%;对盐分不敏感,当NaCl浓度为0.15mol.L-1时,萌发率为42.22%。表土层的鳢肠种子出苗率最高,当埋土深度大于0.5 cm时不能出苗。该研究表明:耕作将种子带入土层,可有效治理鳢肠的危害。     

冷藏处理对烟蚜茧蜂羽化率及寿命的影响

该研究是为了弄清不同温度、不同僵化天数以及冷藏时间对烟蚜茧蜂羽化率及寿命的影响.目的在于找出烟蚜茧蜂最适冷藏条件.实验在不同温度(2,3,4,5,6℃)下冷藏不同僵化程度(僵化1,2,3,4,5d)的烟蚜茧蜂僵蚜5,15,25d.结果显示:随冷藏时间的延长烟蚜茧蜂的羽化率逐渐降低.僵化3d的僵蚜更耐冷藏,5℃较适合烟蚜茧蜂低温冷藏.6℃时有部分虫体在冷藏过程中羽化.冷藏期为5,15,25d时,最长可分别存活9.43～9.92,7.97～8.45和5.08～5.85d.结果表明:烟蚜茧蜂最适宜在僵化3d时,于5℃冷藏.     

持续低温阴雨寡照天气对甘蔗出苗的影响及控制对策

对广西上思县长时间低温阴雨寡照天气对甘蔗出苗的影响进行了调查与分析。结果表明,由于长时间低温阴雨寡照天气的严重影响,造成2011年上思县甘蔗出苗迟、出苗少、苗势弱,甚至烂芽烂种,若及时采取补救措施和加强前期管理工作,可有效降低受灾率并可挽回经济损失。