Using morphological characteristics for assessing seedling vitality in small-scale tree nurseries in Kenya

Small-scale tree nurseries are important in fulfilling the goals of reforestation and agroforestry implementation schemes in Kenya and other developing countries. The focus in seedling production has been on quantity, instead of quality, but a change can be seen in recent tree nursery manuals. These manuals are emphasising morphological characteristics as tools for assessing potential field performance of seedlings. However, morphological criteria are debatable and their value is questioned. A survey was carried out among tree nursery operators in the Meru area, in the Eastern province of Kenya, to determine how operators perceived seedling vitality, and how they separated acceptable seedlings from those of poor vitality. Based on the survey, 3 pairs of criteria were chosen, size (tall versus small), colour (green versus yellowish), and sturdiness quotient (sturdy versus lanky). These criteria were tested on survival and growth in a field trial, a controlled bench trial, and in a root growth potential test. The results showed that the nursery operators were aware of quality differences in seedlings, but they did not cull accordingly. The results from the field trial showed that mango (Mangifera indica L.) performed poorly compared to grevillea (Grevillea robusta A. Cunn. ex. R. Br.), probably due to the high altitude. The altitudinal range for mango and grevillea are 0-1,200 m and 0-2,300 m, respectively, and the trial site was located on an altitude of 1,725 m. In grevillea, small seedlings grew better than tall in the field trial, but no differences could be found in the other trials. In mango, sturdy seedlings grew better than lanky ones in the field trial, while in the controlled trials tall seedlings grew better than small ones. The results showed that morphological characteristics as seedling quality assessment criteria could be unreliable as the effect differs with species and planting site.     

李树不同品种花粉生活力研究

采集盖县大李、澳洲琥珀、长里15号、龙园秋里、大石早生、黑宝石等6个李树品种成年树木花粉,用附加不同浓度蔗糖和硼酸的培养基培养花粉,测定花粉生活力,比较不同品种间花粉生活力差异。结果表明,花粉均在5%蔗糖浓度下发芽率最高,为18.4%,黑宝石发芽率最高。     

不同核桃品种花粉生活力的比较研究

用TTC染色法和培养基法测定了香玲、上宋、中林1号、岱香4个核桃品种花粉生活力和萌发率。结果表明,核桃不同品种花粉生活力存在显著差异,岱香和上宋花粉生活力极显著高于香玲,显著高于中林1号;各品种花粉发芽率在同一种培养基上,以岱香最高,其次是上宋和中林1号,香玲最低;4个品种均以在低糖、高硼酸培养基中即“5%蔗糖 0.5%硼酸”上花粉发芽率最高,显著或极显著高于其他培养基上的发芽率;在“10%蔗糖 0.5%硼酸”和“15%蔗糖 0.5%硼酸”培养基上花粉发芽率均为0。     

木聚糖酶酶活测定条件的优化

采用DNS法,探讨了不同测定条件对1株欧文氏杆菌变异菌株CXJZ11-01所产木聚糖酶活性的影响及其产酶规律。研究结果表明,该木聚糖酶活性测定的最佳条件为:采用0.1mol/L柠檬酸—柠檬酸钠缓冲体系,pH值为5.2￣5.8,木聚糖质量分数为0.8%,温度为60℃,DNS用量为2.0￣2.5mL。在适宜测定下,该菌株发酵液酶活最高达344U/mL。     

磁粉包衣丸粒化蔬菜种子活力性能试验

为了满足磁吸式精密播种需要,提出了一种以滑石粉和细铁粉为填料的磁粉包衣剂。通过对白菜和甘蓝2种蔬菜种子的磁粉包衣丸粒化和磁化处理,试验研究了不同铁粉含量的磁粉剂在外磁场磁化作用下,对白菜、甘蓝种子发芽率、发芽势、活力指数的综合影响。试验结果表明：磁粉包衣丸粒化对种子早期萌发有抑制作用,但磁粉剂中铁粉质量分数控制在20%以内时,在磁场综合作用下,能明显提高种子后期的发芽率和活力指数,改善幼苗素质,促进幼苗根茎生长,根据试验得出的发芽率、发芽势、活力指数和幼苗素质,得到丸粒化用磁粉剂铁粉最佳质量分数：白菜种子为20%,甘蓝种子为10%,2种种子的磁化磁场强度为100 mT,研究结果为推动磁吸式精密播种技术的应用提供了试验依据。     

马尾松花粉萌发性状和不同林分马尾松花粉生活力的初步研究

通过对马尾松花粉萌发性状的观测及不同林分花粉生活力的测试,结果表明:花粉在培养液里萌发时首先是花粉萌发沟呈透明状,然后萌发沟两端突起,继而其中一端伸长成为花粉管。成熟花粉采后立即测定,染色率达90.6%、萌发率达77.2%;在低温(约6℃)贮藏120 d后测定,染色率与萌发率分别为85.2%与89.9%。不同林分中以全同胞无性系幼林的染色率与萌发率最高,分别为95.6%与93.8%;其次是半同胞无性系幼林,分别为91.2%与79%。说明马尾松无性系幼林的花粉是高生活力的花粉。     

吸涨损伤对绿蒙古锦鸡儿种子生活力测定的影响

德国巴伐利亚种子检验站在检验一批绿蒙古锦鸡儿（Ｃａｒａｇａｎａａｒｂｏｒｅｓｃｅｓ）种子的生活力时，出现了较大的误差。笔者重新检验，采用不同的处理方法，找出了产生误差的原因。即：种子猛烈吸水后，吸水不均匀，产生局部坏死，这就是所谓的吸涨损伤。并由此找到了一种合理的检验方法，即低温缓慢湿润法，避免直接将种子浸泡在水中而产生吸涨损伤。     

扁桃的开花结实特性

新疆3个扁桃品种在河北省保定生长正常,以毛桃为砧木的2年生树即能形成花芽并结果;花器发育正常,花药内花粉数量多,有正常的发育能力;供试品种自花结实率为0或极低,属异花结实类型;新疆扁桃能在各类结果枝上形成花芽熏但以中、短结果枝结果为主,3月下旬至4月上旬开花,有两次落花落果高峰,结果初期坐果率低,均在10%以下;果实及种子发育正常,果实8月下旬到9月上旬成熟,平均果实干重3.54g,种子(包括内果皮和种仁)干重2.05g,种仁干重0.91g,出仁率为44.4%。     

氯虫苯甲酰胺拌种对玉米种子活力及幼苗生长的影响

为研究氯虫苯甲酰胺拌种对玉米种子萌发、幼苗生长及生理生化指标的影响,采用平皿法和盆栽法研究氯虫苯甲酰胺不同剂量(0.5、1、2、3、4 g/kg)拌种处理对玉米种子萌发、幼苗生长量（株高、根长、根冠比等）以及生理生化指标（保护酶、根系活力、叶绿素含量等）的影响。结果表明：氯虫苯甲酰胺在0.5~3 g/kg剂量下拌种处理能明显提高玉米种子发芽势、发芽率、发芽指数和活力指数;增加幼苗期生长量;诱导幼苗叶片中CAT、POD、SOD、PAL、PPO活性升高;提高根系活力、叶绿素含量、还原糖含量及可溶性蛋白含量。氯虫苯甲酰胺在4 mg/kg剂量时对玉米植株的生长有一定的抑制作用,但各项指标仍高于空白对照。结果表明：合适剂量的氯虫苯甲酰胺拌种可以显著促进玉米种子萌发和幼苗生长。     

79个铁线莲品种花粉育性分析

铁线莲享有"藤本皇后"的美誉,是优异的垂直绿化材料。本研究以79个铁线莲栽培品种为试材,通过0.5%TTC法和I2-KI法两种方法测定铁线莲品种的花粉量和花粉活力,并比较栽培品种之间的差异。结果表明:两种方法测定花粉量差异不显著,测定花粉活力差异显著,TTC法测量花粉活性均值高于I2-KI法并成为铁线莲栽培品种花粉活力检测的最佳方法。铁线莲品种间花粉量差异显著,品种间变幅为0~241粒,平均花粉量为118粒,以48粒花粉量为级差,栽培品种可分为5类群。铁线莲品种花粉均具活力,其花粉活力变幅为2.8%~78.4%,萌发率最高为78.4%(C.’Doctor Ruppel’),最低为2.8%(C.’Purpurea Plena Elegans’),铁线莲品种群间花粉活力排序为早花大花组>晚花大花组>其他基因型,本研究可为铁线莲杂交育种亲本选配等研究提供科学依据。