甘菊种子萌发特性及自然条件下生长发育规律

对甘菊[Chrysanthemum lavandulifolium(Fisch.ex Trautv.)Makino]种子萌发特性和自然条件下生长发育规律进行了试验观察,发现不同栽培基质及不同储藏时间对甘菊种子萌发率均有影响,在MS培养基上播种甘菊种子萌发率最高,可达90%左右。甘菊种子无休眠现象,采收后立即播种和次年春季播种萌发率均可达90%左右。甘菊种子不耐储藏,储藏至第3年秋季播种,萌发率仅为30%。自然条件下,5月至8月底是甘菊植株的营养生长时期,在此期间,甘菊株高、茎粗、冠幅、叶片数及分枝数一直处于增长状态;9月份当日照长度缩短至13 h时,甘菊开始现蕾,这表明13 h光照/11 h黑暗可能为甘菊现蕾的临界日长。     

整地方式对杂种落叶松生长的影响

以4种整地方式下杂种落叶松试验林为研究对象,建立固定观测样地48块,连续观测地径、苗高和胸径生长,采用方差分析等研究方法,研究整地方式对杂种落叶松生长的影响,结果表明:杂种落叶松幼龄期间的地径及苗高生长,高台和穴状两种整地方式较好,另外两种整地方式差些;揭草皮方式在杂种落叶松幼龄时对其苗高生长及地径的作用不明显,但随着幼树的生长,效果越来越显著;在杂种落叶松11龄时,穴状与揭草皮两种整地方式下的平均胸径较大;杂种落叶松4种整地方式对生长的作用效果穴状揭草皮高台现整现造。     

重庆市石宝镇马尾松单木生长模型研究

为了更加科学地保护和利用马尾松森林资源并为其可持续经营提供参考依据,利用多模型选优法对重庆市忠县石宝镇马尾松的单木胸径生长模型进行了探讨与分析,结果表明：对竞争优势木和竞争劣势木的拟合效果最好的均是Richards函数,其次是Schumacher函数,而Gauss函数和Logistic函数的拟合效果较差.考虑到模型运算的简便性和结构的清晰性,结合研究区马尾松胸径生长量的预测情况,选取了模型参数相对较少的Schumacher 函数作为描述重庆市忠县石宝镇马尾松生长过程的最佳模型.     

越橘Elliot组培苗生长高度影响因素的研究

[目的]探讨影响越橘Elliot组培苗生长高度的因素。[方法]采用3因素3水平进行正交试验,研究pH值、2ip、NAA对越橘Elliot组培苗苗高生长的影响。[结果]pH值对越橘组培苗高的影响在0.01水平显著。经多重检验,最优水平是A1。[结论]影响Elliot苗高因素的顺序为：pH值〉2ip〉NAA,最佳条件为A1B3C1。     

播种期对薏苡生长及产量的影响

[目的]探究不同播种期对薏苡生长及产量的影响,选出适宜播种期。[方法]采用5个不同播种期、实行田间小区试验的方法。种植方式以窝行距60 cm×60 cm进行种植,每种种植期设3个小区,随机区组排列,小区面积80 m2。苗期以每穴4苗进行定苗。根据生长期进行两次追肥和除草,以及有关生长数据采集,测产验收。[结果]种植期对薏苡产量和生长都有很大的影响。播种期晚,将导致无效分蘖增多,侧枝减少,穗粒数降低,空瘪率高,千粒重减小,大籽粒所占百分率逐渐降低,最终产量降低,质量差。[结论]为了获得高产,播种期应选在清明节之前。     

泡泡树不同品种果实性状差异及生长动态分析

对引种的泡泡树4个品种果实单果重、纵径、横径、果形指数及生长动态进行了初步研究，结果表明不同品种间单株结果量存在较大差异。根据当前单株结果量和果实性状表现，筛选出Mary Foos Johnson和Overleese两个早期丰产的优良品种；同时发现各品种之间果实横径和纵径大小存在差异。4个泡泡树品种的纵横径变化在泡泡果实成熟前期都随着时间的增加而增大。     

Effects of stocking density and algal concentration on the survival,growth and metamorphosis of Bobu Ivory shell,Babylonia formosae habei (Neogastropoda: Buccinidae) larvae

Independent and combined effects of stocking density and algal concentration on the survival, growth and metamorphosis of the Bobu Ivory shell Babylonia formosae habei larvae were assessed using a 5 × 5 factorial design with densities of 0.25, 0.5, 0.75, 1.00 and 1.50 larvae mL⁻¹ and algal concentrations of 5, 10, 15, 20 and 25 × 10⁴ cells mL⁻¹ in the laboratory. Larval growth, survival and metamorphosis were significantly affected by both the independent effects of stocking density and algal concentration and by their interaction. The highest per cent survival (72.5%) and metamorphosis (49.5%), fastest growth (41.57 μm day⁻¹) and shortest time to initial metamorphosis (10 days) all occurred at the lowest stocking density and the highest algal concentration. Both crowding and food limitation had independently negative impacts on the survival, growth and metamorphosis of larvae, and these negative impacts were further strengthened by the interaction of a higher stocking density and a lower algal concentration. Moreover, the results suggest that stocking density and algal concentration obviously played different roles in determining larval survival and growth. To maximize survival and growth, B. formosae habei larvae should be reared at a lower stoking density of 0.25 larvae mL⁻¹ and fed a higher algal concentration of 25 × 10⁴ cells mL⁻¹ in large-scale hatchery seed culture.     

The effect of nearly closed RAS on the feed intake and growth of Nile tilapia (Oreochromis niloticus), African catfish (Clarias gariepinus) and European eel (Anguilla anguilla)

One of the challenges that Recirculating Aquaculture Systems (RAS) are still facing is the risk that in RAS fish grow less than in flow-through systems due to the accumulation of substances originating from feed, fish or bacteria associated with the water re-use. The present study investigated whether RAS with high and low accumulation levels of these substances affect feed intake and growth of Nile tilapia Oreochromis niloticus, African catfish Clarias gariepinus, and European eel Anguilla Anguilla. One-hundred and twenty individuals of each species were used (start body weights: Nile tilapia 264.8 ± 8.3 g; African catfish 253.2 ± 2.1 g and European eel 66.6 ± 1.3 g). For a period of 39 days, growth and feed intake were compared between high and low accumulation RAS. HIGH accumulation RAS was designed for maximal accumulation of substances in the water by operating the system at nearly-closed conditions (30 L/kg feed/d), using mature biofilters and high feed loads; and (2) LOW accumulation RAS was designed to be a proxy for flow-through systems by operating at high water exchange rates (1500 L/kg feed/d), new biofilters and low feed load. HIGH accumulation RAS induced a reduction in feed intake (42%) and growth (83%) of Nile tilapia, as compared to systems that are a proxy for flow-through conditions. This effect was not observed in European eel and African catfish. The cause of this reduced feed intake and growth rate of Nile tilapia is still unclear and should be addressed in further studies.     

根土空间对花生生长发育和产量的影响

为明确花生生长过程中是否存在生长冗余,探讨花生高产的适宜生长度,以高产花生品种青花7号为试材,设长×宽×深分别为40 cm×20 cm×20 cm、40 cm×20 cm×40 cm、40 cm×20 cm×60 cm、40 cm×20 cm×80 cm4种规格不等的根土空间,采用网袋法,研究了根系生长空间对花生生长发育和产量的影响。结果表明,随着根土空间增大,株高逐渐增高,分枝数逐渐增多,根系干质量和茎叶干质量逐渐增大,其生育进程的推进差异越来越大。根土空间过小显著影响各时间段花生开花数、下针和结果;根土空间过大则中前期开花数、下针和结果少,中后期开花数、下针和结果多;适当的根土空间(如限根深度60 cm)则中前期开花数、下针和结果多,中后期开花数、下针少。说明根土空间过小影响产量提高的主要原因是生长量不足,而根土空间过大影响产量提高的主要原因是冗余生长。适当空间则既能保证足够的生长量,产生的冗余生长又少,从而提高荚果产量和籽仁产量,为花生高产新品种的选育和栽培提供理论依据。     

不同肥料处理对盆栽红豆杉生长的影响

研究了不同肥料处理对盆栽红豆杉的茎高、新枝、根长和鲜重的影响。结果表明:每周对红豆杉叶面喷施3‰磷酸二氢钾,对红豆杉的生长效果最好。