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排序方式: 共有292条查询结果,搜索用时 15 毫秒
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茉莉3品种叶肉细胞超微结构的季节变化研究 总被引:2,自引:0,他引:2
应用透射电镜对地栽3茉莉品种叶肉细胞超微结构的季节变化进行详细观察和比较研究。结果显示,3茉莉品种春季和秋季叶肉细胞的超微结构完整,但夏季和冬季3茉莉品种叶肉细胞超微结构变化明显且品种间的变化有差异。茉莉遭受高温(夏季)或低温(冬季)胁迫时,叶肉细胞超微结构的变化具有适应意义,但随着胁迫时间的延长,细胞亚显微结构会受伤害。比较研究结果表明,双瓣茉莉比单、多瓣茉莉抗低温和高温能力更强,有细胞超微结构基础,在高温和低温胁迫下,双瓣茉莉细胞超微结构更稳定。 相似文献
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对31个柚类品种主要果实性状的变异情况及性状间的相关性进行了分析研究。结果显示,主要果实性状变异系数的分布范围很广,在9.18% ̄82.59%之间。单果重和果实横径、果实纵径呈极显著正相关,与果汁率呈显著正相关,与正常种子数、风味呈显著负相关;维生素C与果实横径、果汁率和可滴定酸呈显著负相关;风味与维生素C、固酸比、糖酸比呈极显著正相关,与可滴定酸呈极显著负相关,与果汁率、可食率、单果重和果实横径呈显著负相关。 相似文献
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《Plant Production Science》2013,16(1):75-82
SummaryDrought is a major production constraint of rainfed lowland rice grown in Thailand and Laos. Adverse soil conditions also reduce yield. In an attempt to increase rainfed lowland rice production in these countries, a major collaborative international project was conducted during a 6-year period in the region. The objectives of the project were to quantify production constraints, determine genotypic variation in yield, and identify an effective breeding strategy. A rice simulation model was developed also and used to investigate the potential impact of strategies for genetic improvement and agronomic management.Four major physical or biological constraints to higher production levels of rainfed lowland rice were identified, (1) the lack of standing water at the appropriate time of transplanting, (2) severe water stress that often develops at the end of the growing season, (3) low yield potential of the present cultivars, particularly in Thailand, and (4) adverse soil conditions including low pH and low soil fertility. The results of the field experiments and simulation modelling exercises showed that the influence of these constraints can be reduced and yield increased by several methods : in particular, choice of appropriate cultivars and time of sowing to match crop phenology with water availability, application of appropriate fertilizer, adoption of high yielding cultivars, adoption of direct seeding in place of the traditional transplanting system, and reduction of percolation water loss from the paddies.A technology package currendy being investigated for the rainfed lowland rice is direct seeding early in the season, using cultivars that flower by the end of the rainy season, with application of organic or chemical fertilizer. The appropriate cultivars are early flowering and short-intermediate statured, possess high yield potential and ability to maintain favourable plant water status at flowering, and have the ability to establish well and compete against weed under direct seeding. 相似文献
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三倍体葡萄胚培养、倍性鉴定及育种进展 总被引:6,自引:0,他引:6
综述了胚培养技术在三倍体育种上的应用 ,包括不同杂交组合、培养基的种类、培养时期及激素等的影响以及三倍体的鉴定方法和已育成三倍体无核葡萄新品种的特征特性。 相似文献
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The study investigated rumen dry matter (DM) degradability characteristics in a completely randomized design and the effects of milk, sweet potato foliage (SPF) from three cultivars (A = TIS-87/0087; B = TIS-8164; C = TIS-2532.OP.1.13), dried brewers' grains (DBG) and cottonseed meal (CSM) as supplements to Panicum maximum (Panicum) for pre-weaned calves in randomized complete block designs. Diet 1 = milk + SPF-A foliage + Panicum, Diet 2 = milk + SPF-B foliage + Panicum, Diet 3 = milk + SPF-C foliage + Panicum, and Diet 4 = milk + DBG & CSM + Panicum (as control). Dry matter (130 ± 0.4 to 864 ± 3.9 g kg− 1), ash (54 ± 4.2 to 173 ± 2.8 g kg− 1 DM), OM (827 ± 4.2 to 946 ± 5.7 g kg− 1 DM), N (7.4 ± 0.6 to 38.6 ± 1.4 g kg− 1 DM), and NDF (439 ± 1.4 to 774 ± 8.5 g kg− 1 DM) contents were highly significant (P < 0.01). In Trial I, 16 pre-weaned calves were used over 70 d with milk intake (34.8 ± 4.4 ml kg W− 0.75 d− 1), Panicum DMI (22.3 ± 2.77 g kg W− 0.75 d− 1), total DMI (35.7 ± 2.83 g kg W− 0.75 d− 1), and LWG (198 ± 44.6 g d− 1) not significantly different (P > 0.05). Supplement DMI varied (P < 0.05) from 11.6 g kg W− 0.75 d− 1 in Diet 3 to 16.6 g kg W− 0.75 d− 1 in Diet 4. In Trial II, 16 pre-weaned local and crossbred calves were involved over 77 d with initial age of calves, Panicum intake, metabolic DMI, and LWG similar (P > 0.05) among crosses. Birthweight varied (P < 0.05) from 17.3 kg for N'Dama × Jersey crosses to 21.2 kg for White Fulani × Brown Swiss crosses. Supplement and total DMI ranged (P < 0.05) from 172 to 483 g d− 1 for N'Dama × Jersey crosses to 233 and 674 g d− 1 for non-inseminate or purebred calves, respectively. The LWG in the White Fulani × Brown Swiss and the N'Dama × Jersey calves were respectively 30% and 24% better, though not significantly, than purebred calves. In Trial III, rumen DM degradability characteristics of feeds in three N'Dama steers showed no significant differences (P > 0.05) in slowly degradable fraction (b) and rate of degradation of b (c). Soluble fraction (a), 48-h degradation, potential degradability (PD) and effective degradability (ED) varied significantly (P < 0.05) and were lowest in Panicum, but similar for foliage among the three sweet potato cultivars. Panicum fodder showed improvements in degradation characteristics with supplementation. 相似文献
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以华北地区自50年代开始至今各年代大面积推广的冬小麦代表品种为材料,对其旗叶的光合性能进行了比较研究。结果表明,按品种的更替顺序,旗叶的叶绿素含量和光合速率在衰老过程中下降较慢,表现为光合速率高值持续期逐渐延长,叶片功能期有所延长,平均光合速率有所提高,因此,反应叶片一生中碳同化能力的叶源量逐渐增大。进一步的分析表明:平均光合速率的提高、叶面积的增大和高光合持续期的延长都是品种更替过程中光合性能优化的因素;光合性能的优化具有内部解剖结构的基础;光合性能的优化与产量构成因素的优化是相一致的。 相似文献