梨杂种后代亲本性状遗传倾向的研究

通过对49个杂交组合2542株梨杂种实生苗亲本性状遗传倾向的观察研究看出,在河南郑州地区,梨杂种后代的童期为4～5年,6年生杂种一般开花株率可达70%以上;童期的长短主要受亲本遗传特性的制约;梨杂种后代果实重量一般较亲中值小27%,但有些组合超亲现象明显,一般超亲19.2%;果形遗传似表现为圆或扁圆对卵圆或圆锥为显性;皮色遗传表现为黄对褐为显性;肉质的遗传表现为细脆、紧脆和粗脆对细嫩占优势,细嫩型所占比重约为30%;在品质遗传方面,鸭梨、麻梨、库尔勒香梨易将其优良品质传给后代,在鸭梨×金花梨的后代中,果实大小和风味品质超亲现象明显。     

小麦苗期抗纹枯病鉴定方法的改良及抗病品种筛选

Wheat sharp eyespot, caused by Rhizoctonia cerealis and R. solani, is a soil-borne fungal disease, which poses a great threat to wheat yield. In order to increase the identification efficiency of wheat sharp eyespot resistance, an improved method of rapidly identifying wheat sharp eyespot resistance was established by inoculating wheat seedlings with diseased wheat grains in greenhouse. To verify its reliability, four standard materials and 96 wheat varieties from Huanghuai wheat region were used for resistance assessment to sharp eyespot. Meanwhile, the resistance to Rhizoctonia solani of aforementioned materials in the field was identified by traditional methods. The results showed that the correlation coefficient between the four repetitions of the improved method ranged from 0.735 to 0.825, and the correlation coefficient between the average number of repetitions and the traditional method was 0.630. The results of wheat sharp eyespot resistance identification in Huanghuai wheat area showed that 66 wheat varieties were susceptible, accounting for 68.8% of tested materials. This indicated that the resistance of wheat varieties in Huanghuai wheat area to sharp eyespot was poor on the whole and needed to be improved urgently. At the same time, eleven wheat varieties which showed resistance to sharp eyespot at seedling and adult stages were screened, which include Zhengzhou 8998, Beijing 841, Handan 94-5316, Jimai 32, Jinmai 50, Jinmai 54, Longmai 157, Lumai 23, Shanhe 6, Shi 02-1 and Xinmai 18. Therefore, this study provides a method for identification of wheat sharp eyespot resistance at seedling stage, by which the resistance of wheat varieties to sharp eyespot can be quickly and efficiently identified. Furthermore, selected resistant materials provide important material resources for wheat sharp eyespot resistance breeding in Huanghuai wheat region and even in China.     

Growth and Yield Responses to Plant Density and Stage of Transplanting in Winter Oilseed Rape (Brassica napus L.)

Growth and yield responses to plant density (6.75 × 10⁴, 9.75 × 10⁴ and 12.75 × 10⁴ plants ha^–1) and stage of transplanting (30, 35 and 40 days after sowing) of winter oilseed rape cultivar HO 605 were investigated in two field trials in the 1996/97 and 1997/98 growing seasons at Zhejiang University Farm, Huajiachi Campus, China. Results revealed a progressive decrease in leaf area per plant in response to increasing plant density and delayed transplanting, though leaf area m^–2 and leaf area index were higher in high-density plants. Number of effective branches and pod per branch decreased with increasing plant density and delayed transplanting. There were no significant differences in the mean seed weight among treatments. Although the average number of seeds per pod was significantly lower for high-density plants and delayed transplanting, the economically highest seed yields were realized in relatively high-density plants. Seed oil content was negatively affected by increasing plant density, but no significant differences were observed with delayed transplanting. The highest seed yields of 1730.7 and 1748.1 kg ha^–1 with no significant differences were observed for plant densities of 9.75 × 10⁴ and 12.75 × 10⁴ plants ha^–1, respectively, transplanted at 35 and 30 days after sowing.     

棉蚜对棉花生育期及温度条件的生态适应性

测定了不同温度、棉花不同生育期及棉株不同部位上棉蚜的体型大小,结果表明,在２０～３２℃下随温度的升高,棉蚜个体变小,且高温胁近促使棉蚜往下部老叶转移;棉花顶芽下１～２叶片上蚜体显著大于其它叶位;１９９９年江苏南京在棉花苗、蕾和铃期,棉蚜体型大小无显著差异,但到吐絮期后则显著变小。温度与棉蚜累积产仔量间的二次函数模拟结果表明,棉花不同生育期,棉蚜的最大累积产仔量和最知道仔温度存在差异。不同温度下缺蚜日最大产仔量表现为苗、铃期小于花、蕾期;但高于２８℃后差异缩小,并且高温使棉蚜的死亡高峰日提前。     

绿豆花荚期施活力素的效应研究

在绿豆（Ｐｈａｓｅｏｌｕｓ Ｒａｄｉａｔｕｓ）花荚期根外喷施不同浓度的复合微肥“活力素”,结果表明,以５００倍稀释液处理的株高增量低于对照,差异极显著,产量高于对照,差异达显著水平;１０００倍稀释液处理的株高增量高于对照,差异达显著水平,产量与对照差异不显著。     

立冬本龙眼结果母枝性状与开花结果的关系

通过两年的观测统计,分析了晚熟龙眼立冬本秋、冬梢不同抽生期及结果母枝生长状况对开花结果的影响;提出立冬本龙眼初结果树两个最佳放梢时期分别为８月中旬至９月上旬、１０月上旬至１０月下旬;优良结果母枝应选择粗度０．７０～１．０９ｃｍ的枝梢为宜;统计分析表明,结果母枝粗度与穗坐果数呈极显著正相关,而结果母枝长度、复叶数与穗坐果数的相关不显著,说明结果母枝的粗度对坐果的影响最大,是立冬本优良结果母枝的主要衡量指标;立冬本初结果树在１２月上旬之前抽发的枝梢仍可开发结果,但８月上旬、１２月上旬两个时期所抽枝梢的结果性能差,生产上应予疏除。     

应用二阶适应性整群抽样估计害虫密度

在农作物害虫管理中人们需要得到准确的田间数据.本文提出了一种简便的抽样方法——二阶适应性整群抽样.给出了害虫密度的无偏估计,并举例说明.     

拔节水对春玉米氮磷钾吸收动态模型及肥料利用率影响的研究

通过田间试验结合化学分析和生物统计,查明了拔节水增产的营养基础包括显著地提高N、P、K在体内的浓度,促进各个生育时期N、P、K的累积吸收量,使N、P、K的最大吸收量分别提高11%,12%,6%;N、P、K最快吸收速率分别提高8%,25%,14%.最快吸收速率出现时间分别提前4d,5d,15d;使N、P、K的生产效率分别提高2.5%,1.9%,7.3%;使N、P、K化肥利用率分别提高5.0,5.0,12.7个百分点.     

穗肥施用时期对水稻产量及群体质量的影响

采用迟熟中粳稻品种和杂交中籼稻汕优组合 ,进行穗肥施用时期试验。结果表明 :合理施用穗肥 ,利于控制抽穗期群体干物质适宜值、提高抽穗至成熟期的干物质生产量 ,利于提高有效、高效叶面积率 ,增加根系活力 ,提高颖花根活量 ,最终提高结实率和实粒数 ,获得高产。在当前推广品种中 ,在取得适宜穗数条件下 ,迟熟中粳稻在倒 3叶 1次施肥或倒 4倒 3叶分次施肥 ,确保提高群体质量而获得高产。     

水稻有效分蘖叶龄期的株型特征及其与产量关系初探

以汕优 63和 951 6为材料 ,通过密肥措施 ,培育不同产量的群体 ,研究水稻有效分蘖叶龄期 ( N-n)的株型特征及其与产量关系。结果表明 :高产群体 N-n期叶开角较大 ,叶长适中而稍长 ,叶片的松散度较大 ;叶片较厚 ,叶绿素含量高 ;叶面积增长缓慢 ,叶面积指数较小 ;叶鞘积累快 ,单位叶鞘重量承载的叶面积小等