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1.
甘蓝型油菜双显性细胞核雄性不育系Shaan-GMS雄配子发育观察 总被引：1，自引：0，他引：1
采用常规压片与冰冻切片两种方法,观察甘蓝型油菜不育系Shaan-GMS的不育株与可育株小孢子母细胞减数分裂和小孢子发育过程,以阐明小孢子败育时期和细胞学特征。植株表型上,花期可育株与不育株花器官差异较大:不育株花丝较短,花药小且干瘪,微粉或无粉,淡黄色;细胞学观察结果显示不育株的花粉母细胞能够进行正常的减数分裂,形成四分体,但在单核期开始发生异常。主要表现为小孢子从四分体中释放后无法形成正常的小孢子外壁,随后小孢子外壁、内容物和绒毡层均提早降解,只剩下空壳与残渣,药室也随之萎缩变形,最终导致花粉败育。上述结果说明Shaan-GMS为单核败育类型,可能是一个细胞核雄性不育新材料。 相似文献
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温敏雄性不育小麦BNS366花粉败育的细胞学观察 总被引：1，自引：0，他引：1
为了明确温敏雄性不育小麦BNS366雄性败育的细胞学机理,采用醋酸洋红染色法观察减数分裂和小孢子发育过程,用1%I2-KI溶液染色进行花粉育性统计;以温敏不育系BNS和常规品种扬麦13作为对照。结果表明,BNS366的减数分裂和小孢子发育过程与BNS完全一致,即:在减数分裂过程中,中期Ⅰ染色体出现滞后现象,在形成二分体和四分体时细胞质分裂不均匀,出现三孢现象;小孢子发育过程中,只观察到单核靠边期,最后核物质解体出现空孢现象。而扬麦13在减数分裂过程中染色体表现正常,小孢子发育过程中,观察到单核期→双核期→三核期。开花期,BNS366和BNS花粉均表现典败和圆败,扬麦13可育。减数分裂表现出的异常行为是导致BNS366花粉败育的原因之一,单核靠边期是其败育的关键时期。 相似文献
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通过光学显微镜观察泰玉D2不育系的花药发育进程,探明新型细胞质雄性不育材料泰玉D2花粉败育的细胞学机理。研究发现,花药绒粘层在二分体时期发生异常,小孢子在单核前期开始败育,至单核后期完全解体,花药发育后期不育系药腔中只观察到少量的小孢子残体,花药壁的4层细胞依然存在,绒粘层细胞已经彻底液泡化, 占据了药腔的整个空间,花粉成熟期不育系花药维管束消失。泰玉D2不育系花药绒粘层在二分体时期成辐射状膨大,小孢子在单核期败育,花粉败育完全,属无花粉类型。 相似文献
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F型小麦雄性不育系小孢子发育的细胞学观察 总被引：3，自引：0，他引：3
为明确F型小麦雄性不育系雄性败育的细胞学机理,以西农979为对照,采用醋酸洋红染色制片等方法观察花粉母细胞减数分裂、小孢子发育过程及成熟花粉粒育性表现,并套袋自交,于成熟期统计结实率。结果发现,F型小麦雄性不育系仅有2.15%的花粉母细胞减数分裂Ⅱ异常,其余绝大多数花粉母细胞减数分裂正常,但小孢子由单核期进入二核期后,生殖核和营养核先后降解,导致无核小孢子的出现,其比率为77.04%。成熟花粉粒经1% I2-KI染色后显示异常的花粉粒比率高达94.8%,其中包括圆败、典败和染败类型,但以染败型为主。F型小麦雄性不育系套袋自交结实率为2.5%。上述三方面的研究结果彼此相符,据此认为,小孢子由单核期进入二核期后,生殖核和营养核先后降解导致无核小孢子的产生是F型小麦雄性不育系雄性败育的主要细胞学原因。 相似文献
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同源四倍体水稻花粉的发育特征 总被引：7，自引：0，他引：7
利用激光扫描共聚焦显微技术观察了同源四倍体水稻紫粳 4x花粉的发育过程及其败育时期和方式。在成熟花粉中正常花粉只占45.5％,还有54.5％的花粉在发育过程中发生败育。在小孢子母细胞减数分裂过程中出现了一些异常现象,如染色体不能正常配对、形成异常二分体及二分体分裂不同步等现象。绝大部分花粉败育发生在单核小孢子期和二胞花粉晚期。在败育花粉中典败花粉粒占21.4％,圆败花粉粒占5.0％,染败花粉粒占28.1％。导致紫粳 4x花粉败育的原因可能是由于其染色体数目加倍,在减数分裂过程中有些染色体不能正常配对,从而进行异常分裂造成的。 相似文献
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本研究结果表明，新发现的大麦雄性不育材料小孢子母细胞的减数分裂，四分体之前表现正常，此后出现四分体小孢子形成不同步，单核期的小孢子，因无淀粉等必要的营养合成与积累而发生饥饿败育。主要表现为，细胞皱缩，胞壁逐渐解体，I－KI不染色等。自小孢子母细胞减数分裂四分体开始，经单核小孢了列双核小孢子期，雄性不育株的雌、雄蕊及其单核小孢子期的旗叶、旗下叶和倒3号，过氧化物酶同酶谱与其等基因可育株的相比，或酶带数增多或颜色加深，酶活性显著增强。可能是造成内源IAA氧化分解，导致小孢子发生饥饿败育的重要原因。在不育和可有株雄蕊中，分别发现染色很深的过氧化酶同工酶带POD－1、POD－9和POD－14、POD－15及POD－16等，可能是该雄性不育的特征带。 相似文献
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采用染色体压片法研究甘蔗属热带种与滇蔗茅远缘杂交F1代花粉母细胞减数分裂过程及染色体行为,显微观察结果显示:在终变期观察到单价体、二价体和四价体;分裂中期Ⅰ、后期Ⅰ、中期Ⅱ和后期Ⅱ均出现落后染色体;中期Ⅱ形成"八"字形纺锤丝、后期Ⅱ二分体2个子细胞染色体不同步分离;四分体时期观察到三分体、微核、大小不等的四分体以及多面体等异常细胞;同一小花的3个花药中几个不同时期的分裂相同时存在。进一步应用DAPI荧光染料进行染色观察,结果表明,大多数小孢子在单核时期就发生皱缩变形。该结果说明减数分裂过程异常染色体行为和异常细胞分裂是导致杂交F1代花粉完全败育的主要原因。花粉败育时期为小孢子母细胞时期、四分体时期和单核小孢子时期。 相似文献
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为了明确YS型小麦温敏不育系雄性败育发生的具体时期和败育的细胞学机理,以温敏不育系A731和其同型保持系731B为供试材料,采用花粉粒制片和石蜡切片法,对其花药形态特征及小孢子形成和发育过程进行细胞学观察。结果表明,不育系和保持系均能进行正常的减数分裂形成小孢子;保持系731B的花药和小孢子发育正常,只有极少数后期发育不正常;不育系A731花粉不育类型为典败和圆败;单核期小孢子可正常形成核,二核期正常形成营养核和精核,但有些营养核不清晰,三核期花粉粒染色后精核呈圆形,不能形成梭形精子;二核期花药中绒毡层提前解离侵入药室,造成小孢子败育。表明该温敏不育系的败育主要发生在二核期到三核期,推测二核期是其雄性败育发生的关键时期,败育的原因可能与绒毡层结构的异常有关。 相似文献
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系统研究了茉莉花双瓣品的小孢子发生与雄配子体发育过程。观察结果表明：茉莉花双瓣品种药壁发育为基本型，中层在小孢子减数分裂时期逐渐解体，绒毡层是异常细胞绒毡层，解体迟，不利于小孢子发育，药室内壁纤维层加厚不明显。小孢子从减数分裂中期1开始走向败育，胞质分裂为同时型，正常四分体为正四面体形。雄配子体发育大多为不正常，其发育早期有花粉管萌发的异常现象。空瘪、异形花粉多，正常与不正常比例为100：324。成熟花粉粒为2－细胞型，具三个萌发孔。 相似文献
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Four levels of nitrogen, 188, 285, 358 and 392 kgJ.ha (150, 225, 285 and 350 units/ac) supplied as anhydrous ammonia were injected on each of four occasions, 18 Dec, 5 Feb., 12 Mar. and 16 Apr. DM and CP yields were estimated at each of three harvests taken on 4 June, 19 July and 28 Sept Total DM yields showed only a 10% difference between the highest yielding injection date, 12 Mar., which yielded 12270 kg/ha (10946 Ib/ac) and the lowest, 16 Apr., which yielded 11169 kgJ.ha (9963 Ib/ac). Early injection of ammonia promoted growth during the late spring and later injections resulted in increased yields at the two later harvests. The responses per kg fertilizer N were 11.9 kg DM (10.8 lb/unit) and 3.6 kg CP (3–3 Ib/unit). It was concluded that ammonia should be applied to grassland before April and, preferably, during March, for maximum yields of DM and CP. 相似文献
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Considerable improvement has been achieved in rough grazings by fairly frequent close mowing with the forage harvester or flail mower, particularly when combined with manuring and surface seeding.
The implement has proved capable of tackling very tough vegetation and converting it into grazing swards of fair value and good botanical composition. Undesirable species have been largely eliminated by treatment over two growing seasons.
The method is believed to compare favourably in cost with sward renovation by cultivation or by herbicides. 相似文献
The implement has proved capable of tackling very tough vegetation and converting it into grazing swards of fair value and good botanical composition. Undesirable species have been largely eliminated by treatment over two growing seasons.
The method is believed to compare favourably in cost with sward renovation by cultivation or by herbicides. 相似文献
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With modern machinery and modem techniques of grass production, mechanical-or zero-grazing offers a means of utilizing the crop to perfection. Whether this results in enhanced profits depends largely upon the farm and the specific circumstances. It may, it may not. What is evident is that the health of the cows is not affected by an unnatural manner of summer feeding; the sward, per se, may be improved by the regular and uniform defoliation; and under conditions of intensive production and the vital need to use profitably every blade of grass, as for instance on small, highly-rented farms, the practice of zero-grazing merits the most careful consideration. It cannot lightly be dismissed as merely a new fad. 相似文献
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THE USE OF THE IN VITRO TECHNIQUE IN THE DETERMINATION OF THE DIGESTIBILITY OF GRASS/LEGUME MIXTURES
The in vitro dry-matter digestibility was determined of two samples of Digitaria decumbens , one sample of Medicago sativa , and one sample of Trifolium repens and nine mixtures prepared from these samples.
When the results were compared with in vivo digestibilities the standard errors of the regressions for the three combinations of legume, grass and legume/grass mixtures were ±0.6, ±0.6 and ±1.5 percentage units, respectively.
It is considered that in vivo digestibility of mixtures of grasses and legumes can be estimated by the in vitro technique, provided that suitable grass and legume standards are included. 相似文献
When the results were compared with in vivo digestibilities the standard errors of the regressions for the three combinations of legume, grass and legume/grass mixtures were ±0.6, ±0.6 and ±1.5 percentage units, respectively.
It is considered that in vivo digestibility of mixtures of grasses and legumes can be estimated by the in vitro technique, provided that suitable grass and legume standards are included. 相似文献
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The effect of temperature on silage quality was investigated in a series of trials over a period of three years.
The results indicated that when conditions in the silage were favourable for the formation of lactic acid, either through treatment or because of the herbage itself, low temperatures in the mass had no adverse effect on silage quality.
Some results suggest that, with chopped or lacerated silage, low maximum temperatures are associated with better quality silage. The results, however, were not entirely consistent.
There appeared to be little or no advantage in allowing unchopped silage to heat to 100°F. 相似文献
The results indicated that when conditions in the silage were favourable for the formation of lactic acid, either through treatment or because of the herbage itself, low temperatures in the mass had no adverse effect on silage quality.
Some results suggest that, with chopped or lacerated silage, low maximum temperatures are associated with better quality silage. The results, however, were not entirely consistent.
There appeared to be little or no advantage in allowing unchopped silage to heat to 100°F. 相似文献
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The effect of dalapon is described on pastures of Agrostis/Festuca, Festuca ovinal Deschampsia flexuosa and related Nardus- or Molinia -rich hill grasslands. The results are discussed in relation to the technique of surface sowing and the choice of vegetation types suitable for treatment. 相似文献