Chilling Tolerance and Physiological Parameters as Influenced by Grafting in Watermelon Seedlings

The influences of different rootstocks on chilling tolerance and physiological parameters in wa-termelon seedlings have been studied. The results showed that grafting improved the chilling tolerance. Com-pared with own-rooted watermelon seedlings, the grafted watermelon seedlings had lower chilling injury index,lower electrolytic leakage (%), lower malondialdehyde (MDA) content, higher chlorophyll and proline con-tent, and higher activities of superoxide dismutase (SOD), ascorbate peroxidase (AsA-POD) and de-hydroascorbate reductase (DR) in the leaves under iow temperature stress. There was a considerable differenceof chilling tolerance among different grafted watermelon seedlings due to the difference of rootstock chillingtolerance. After low temperature treatment, the grafted seedling with higher chilling tolerance had lower elec-trolytic leakage ( %), lower MDA content, higher proline content and higher activities of SOD, AsA-POD andDR in the leaves compared with the grafted seedling with weaker chilling tolerance. From these, we could con-clude that chilling tolerance of watermelon seedlings may be related to higher antioxidative ability and mem-brane stability in the plants. The chilling tolerance of grafted seedling could be properly evaluated by compre-hensive physiological indexes but not a single physiological index.     

海南香蕉花叶病病毒分离物的研究

对海南产区感染花叶病的香蕉病株进行生物学分离获得一种直径为28—30nm的球形病毒分离物,该分离物汁液接种可引起香蕉花叶症状,并侵染一些黄瓜花叶病毒(CMV)的诊断寄主植物,提纯病毒外壳蛋白由一种分子量约为3.2×10~6道尔顿的亚基构成,琼脂免疫双扩散试验表明,该病毒分离物和CMV有血清学关系,根据这些性质该病毒分离物被鉴定为黄瓜花叶病毒。     

水分胁迫对番茄幼苗生长影响的研究

水分胁迫对番茄幼苗的生长有严重的抑制作用。幼苗根、茎、叶干重及株高、茎粗、叶面积等形态指标同土壤水分张力(PF值)呈极显著负相关。幼苗叶片水势有明显的日变化,春季日变化呈三次曲线(S型)。叶片水势同土壤PF值呈极显著负相关。这是利用土壤PF值进行番茄苗期水分管理的依据。叶片相对含水量、水分饱和亏、自由水、束缚水含量,细胞汁液浓度也同土壤PF值显著相关。土壤水分亏缺增加,叶片净光合率下降,游离氨基酸含量升高,硝酸还原酶活力降低。根据本试验结果认为,番茄幼苗从分苗到定植,土壤PF值维持在1.9—2.2范围内,幼苗生长健壮。     

脱落酸对甜菜幼苗抗冻性的影响

试验筛选出脱落酸(ABA)用于提高甜菜幼苗抗冻力的有效浓度为5×10~(-6)～5×10~(-5)mol/L,最佳浓度为10~(-5)mol/L;处理有效作用期为24～96小时,36～72小时效果最佳;正常的光照和生长温度是提高ABA有效作用的必要条件,ABA用于较抗冻的品种比冷敏感品种效果更好;试验表明,调节脯氨酸代谢和糖代谢是ABA提高甜菜幼苗抗冻性的实质。     

桃叶卫矛种子休眠、催芽及芽苗移栽技术的探讨

桃叶卫矛是优良的观赏树种。作者揭示了它的种子休眠主要是由于种皮、胚乳含有抑制物。通过试验得出结论,低温层积30d或混雪层积40d,再转入高温催芽,效果最好。同时探讨了利用间苗时的芽苗移栽技术,以求经济、合理的利用种子,降低苗木成本。     

Seedbed Characteristics and Seeding Depth Effects on Emergence and Seedling Vigour of Upland Rice

Effects of seedbed condition and seeding depth on the emergence and seedling vigour of upland rice was studied. Regardless of aggregate size distribution, seeds sown at 2 cm depth gave the maximum emergence rate (80-90 %) which was reduced to 47 % for sowing at 5 cm depth. Seeding at 10 cm depth caused total failure in emergence. When planted at 2 cm depth, aggregate size produced considerable variation in the speed of emergence but caused no significant differences in final emergence count. For seeds sown at 5 cm depth, seedbed with aggregate size < 2 mm resulted in poor emergence (12 %) while with aggregates > 8 mm reduced emergence by 34 % compared with balanced proportion of larger, moderate and smaller aggregates. Neither the seedbed condition nor seeding depth caused significant variation in seedling height or seedling dry weight.     

珍稀树种的种苗繁殖研究

本文对１０种珍稀树种的采种期、采种方法、种子处理、贮藏方法、育苗方法以及幼苗形态特征等进行了较为系统的介绍。     

辣椒黄绿苗突变体的选育及遗传分析

磁带 椒黄绿苗突变体是辣椒叶色隐性突变体。该突变体黄绿色遗传性状稳定，苗期遗传标记性状明显，抗苗期疫病等，在杂交育种及品种纯度鉴定上有极大的利用价值。     

光肥在针叶树育苗中的应用研究

为提高针叶树苗木质量，促进针叶树生长，对光肥在针叶树种育苗中的应用进行大量实验研究。结果表明：不同浓度光肥对不同针叶树种苗木苗高、地径生长有促进作用；对种子的萌发亦有一定的影响。光肥适用范围广，应用方法简单，成本低，在针叶树种育苗中可推广应用。