Maintenance Respiration of Oryza sativa Leaves at Different Growth Stages as Influenced by Nitrogen Supply

Maintenance respiration rate, R_M, irrespective of growth stages, increased with increase in nitrogen supply. The R_M increased almost in proportion with net photosynthetic rate, P_N, and biomass production during early growth stages, while it declined after anthesis. Significant positive correlation was observed between biomass production and P_N at all growth stages except tillering. Though R_M was positively correlated with biomass production during early growth stages, it was negatively correlated with the rate of increase in shoot biomass after flowering, which could indicate a possibility to identify certain cultivars endowed with low maintenance expenses despite building up biomass.     

杏品种一年生休眠枝,花,幼果抗寒的相关分析

用电导法并配以Ｌｏｇｉｓｔｉｃ方法对２５个杏品种的抗寒性进行鉴定,结果表明,杏１年生枝的抗守则测试在－２８．５℃～－４０℃,花蕾的抗寒温度在－７．０℃～－１９．０℃,盛开花朵的抗寒温度在－３．０℃～－６．９℃,幼果的抗寒温度在－１．１℃～－２．２℃,枝、花枝和幼果彼此间抗寒性呈显著相关,其抗寒性强弱的顺序为枝〉花〉幼果,同一朵花器官的抗寒性为：花瓣〉雄蕊〉雌蕊。     

杏愈伤组织的超低温保存

杏茎段在附加１．０ｍｇ／Ｌ ２,４－Ｄ和０．１ｍｇ／Ｌ ＢＡ的改良ＭＳ培养基中诱导出愈伤组织,放入１０％ＤＭＳＯ＋０．５ｍｏｌ／Ｌ山梨醇或葡萄糖的冰冻保护剂中,以１Ｃ／ｍｉｎ的降温速度降至－４０℃,停留２ｈ后投入液氮保存,在４０℃水浴中化冻。继代培养８次生长１５－２０ｄ的愈伤组织保存后的相对存活率最高,不同品种基因型保存效果差异很大,保存后的愈伤组织生长量比对照减少,但经过２次继代培养后不再表现差     

紫外线诱导小麦条锈菌毒性突变及突变体的RAPD分析

以夏孢子相对致死率90%左右作为紫外线处理最适时间,发现8min为小麦条锈菌条中29号单孢菌系(CY29-3)最适处理时间,其夏孢子相对致死率达88.97%。CY29-3的夏孢子经紫外线处理、扩繁、筛选品种筛选及4代的稳定选择后,获得了两个毒性变异的突变菌株。毒性突变产生的Jubi菌株对尤皮Ⅱ号的毒性增强,反应型由野生菌系的0型变为4型;非毒性突变产生的Funo菌株在阿夫上的反应型由野生菌系的4型变为2型。研究结果表明两突变菌株在鉴别寄主上的反应型和毒性范围也明显不同于野生菌系,说明紫外线诱导的小麦条锈菌变异是不定向和复杂的。对野生菌系和两个突变菌株进行RAPD分析后发现,两突变菌株与野生菌系之间的DNA多态性存在显著差异,多态率分别为10.58%和11.57%,说明紫外线可使小麦条锈菌基因组DNA发生较大的变化且突变位点比较复杂。     

Fungi pathogenic to ryegrass seedlings

Summary Fungi borne on or in ryegrass (Lolium spp.) seeds or invading ryegrass seedlings grown on field soils were isolated and identified. Selected isolates were tested to determine their pathogenicity to ryegrass seedlings. Seed-borne fungi were generally weakly virulent or non-pathogenic to ryegrass seedlings. Pathogenic seed-borne fungi includedChaetomium globosum Kunze: Fr.,Curvularia trifolii (Kauffm.) Boedijn, and species ofPenicillium Link andAspergillus Mich. ex Link. Species of fungi isolated from seedlings grown on field soils de pended on soil and temperature. Soil-borne fungi pathogenic to seedlings includedFusarium avenaceum (Fr.) Sacc.,F. culmorum (W. G. Smith) Sacc.,F. equiseti (Corda) Sacc.,F. oxysporum Schlecht.: Fr.,F. solani (Mart.) Sacc.,Pythium afertile Kanouse and Humphrey,P. debaryanum auct. non Hesse,P. irregulare Buisman,P. ultimum Trow, a sphaerosporangiatePythium sp.,Chaetomium globosum, Thanatephorus cucumeris (Frank) Donk,Trichoderma koningii Oudem., and aPhomopsis sp. Individual isolates of fungi differed in virulence to ryegrass seedlings, and ryegrass cultivars differed in susceptibility to seedling pathogens.     

Salt tolerance of rice cultivars

Summary The dry matter production and the concentration of nutrients in rice (Oryza sativa L.) cultivars from soil adjusted to different levels of salinity were evaluated under a greenhouse conditions. Soil salinity levels were produced by applying 0.34 mol l^–1 solution of NaCl which resulted in the following levels, control (0.29), 5, 10 and 15 dS m^–1 conductivity of saturation extract. The effect of salinity on dry matter production varied from cultivar to cultivar.The concentrations of P and K in the tops of rice cultivars decreased with increasing soil salinity. But the concentrations of Na, Zn, Cu and Mn increased.Significant varietal differences were found in relation to salinity tolerance. Based on dry matter yield reduction, rice cultivars were classified as tolerant, moderately tolerant, moderately susceptible or susceptible.     

碗莲新品种选育研究

本文阐述了作者1982—1987年选育碗莲新品种的试验方法和研究结果。通过实生苗选种和杂交育种,1982—1983年获得碗莲F_1代种子,分别在次年将其直接栽植于钵、碗中,从中选育出12个花型新颖、花色艳丽、适宜家庭种植的优良碗莲新品种。几年的试验证明:实生种苗具有方法简便,有利于发展推广的特点。