拟南芥种子的脱水耐性和长寿命获得的研究

ABA在种子的发育和成熟过程中起重要作用、是诱导种于休闲必不可少的激素，并且和种子发育期间脱水位性的获得相联系。利用ABA缺乏和对ABA不敏感的突变体进行研究，有利于了解影响脱水耐性获得的因素．对ABA不敏感的三个位点称为：abi1、abi2、abi3．abi1和abi2突变体表现为在营养生长时期．在水分协迫下美艺。abi3突变主要影响种于发育。缺乏ABA以及对ABA不敏感的突变体种子能获得脱水耐性，但缺乏ABA以及对AnA不敏感的双突变体Aha、abi3的种子失去脱水时性。这种对脱水田惠的基因到可以对种子的脱水同住进行详细的分析。在有关…     

种子脱水耐性的成因及其研究进展

成熟脱水是正常种子发育的末端事件,种子在成熟时,胚的脱水耐性增加,在种子萌发时变得不耐脱水.正常型种子脱水耐性与发育阶段有关,并与种子成熟后期富集LEA蛋白、可溶性糖、ABA调控及其抗氧化系统有一定的相关性.脱水耐性是一种复杂的数量性状,各种影响因子协同调节脱水耐性.本文综述了种子发育、LEA蛋白、可溶性糖、ABA和抗氧化防御系统在种子脱水耐性方面的研究进展.     

脱水敏感的黄皮种子在发育过程中的碳水化合物变化研究

脱水敏感的黄皮种子发育至生理成熟时淀粉积累达最大值,但其胚轴中淀粉含量远低于子叶且在种子成熟以后明显下降。花后65d子叶中可溶性糖含量最高而胚轴中可溶性糖随种子发育而一直上升。还原性葡萄糖和麦芽糖含量随种子发育而逐渐降低．非还原性果糖和蔗糖则逐渐增加。生理成熟期子叶中还含有较多的水苏糖和棉籽糖。外源ABA可提高成熟林子子叶中蔗糖的含量和未成熟种子的淀粉含量、但不能提高种子的耐脱水能力。因此我们认为黄皮种子的碳水化合物变化与其所在组织（子叶和胚轴）的不同代谢模式有关,而不是与种子的脱水敏感性有关。     

强迫休眠对几种顽拗性种子的贮藏效果

黄皮(Clausena lansium),荔枝(Litchi chinesis)和龙眼(Euphoria tongan)种子在离开未十分成熟的果实后,有1—2天的休眠期。在休眠期进行强迫休眠处理,即用密封、隔氧、保湿处理。黄皮再进入休眠,12个月后种子发芽率能达90％以上,但胚芽不伸长,胚根伸长;24个月后休眠解除,幼苗正常生长。荔枝能贮藏6个月。木棉(Bombax malabaricum)不耐低温而耐脱水,在休眠期进行密封隔氧快速脱水,15℃可贮一年。龙眼能贮5个月。蒲桃种子(Averrhoa carambola)在休眠期隔氧贮藏15℃能贮一年。     

顽拗性种子的发育特性与脱水耐性

顽拗性种子不经过成熟脱水，在整个发育过程中保持代谢活性，没有明显的静止期，对脱水高度敏感。主要的贮藏物质是可溶性的糖，淀粉是碳水化合物贮藏物的唯一复杂形式。顽拗性种子在发育后期，胚中的ABA含量下降，胚缺乏LEA蛋白，在贮藏物积累阶段获得发芽能力。脱水耐性的影响因子主要有ABA、寡糖和LEA蛋白等。     

种子脱水耐性与保护性系统的关系

正常性种子组织分化后通过成熟，维管分离后、预脱水、脱水和静止五个阶段获得充分的脱水耐性；顽拗性种子是一种缩短的ＰＶＳ阶段拉物或者是一种发育的早期中断事件，在整个发育过程中保持水合状态和代谢活性。     

龙脑香科植物种子特性的研究进展

大部分龙脑香科植物的种子在发育末期不经历成熟脱水,脱落时有较高的含水量,并且对低温和脱水非常敏感,在贮藏特性上属于顽拗性种子.而影响种子脱水耐性的因素,有种子本身的生理生化物质基础,也有种子在母株上所经受的外界环境的影响.目前,龙脑香科种子在脱水过程中种子的生理生化变化、贮藏条件对种子活力的影响以及种质资源保存技术等方面研究得较多.此外,对顽拗性的龙脑香科种子脱水敏感性的机制也有研究.本文对龙脑香科种子研究的现状作一综述.     

枇杷种子脱水敏感性的初步研究

枇杷（EriobotryajaponicaL.）种子成熟采收时含水量高达58.7％，其中子叶含水量为55.3％，胚轴的含水量为73.2％。新鲜种子的发芽率和活力指数分别为90％和0.81。轻度脱水能较大幅度地提高发芽率和活力指数。但随着脱水程度的不断加深，子叶和胚轴的超氧物歧化酶（SOD）活性下降，丙二醛（MDA）含量和种子浸泡液的电导率增加，种子活力迅速降低。当子叶和胚轴的含水量分别降至35.5％和28.0％时，种子发芽力完全丧失。枇杷种子脱水敏感的一个重要原因就是在脱水劣变过程中，发生了膜脂过氧化作用，从而使膜脂含量下降，膜结构和功能受损，最终导至种子活力丧失。     

樟树种子的脱水耐性和贮藏特性研究

樟树种子的生育期约210d.在发育过程中,樟树种子的生物学性状(果皮颜色、种子鲜重和干重、含水量等)发生了显著变化:果实体积在150 DAA(DAA表示花后天数,下同)时达最大值,直径约为0.98 cm,但种子仍在继续生长,直到210DAA左右达到生理成熟,此时果实黑而发亮.成熟种子每1 000粒的鲜、干重分别为186.42g和138.90g,含水量约为0.33 g/g(DW).新鲜种子萌发率很低,只有2.4%左右;种皮有抑制种子萌发的作用,去种皮后,种子萌发率可达到21.0%.干燥脱水处理时,无论硅胶脱水(快干)或室内自然风干(慢干),都使种子电导率呈上升趋势;但脱水程度使种子萌发率呈现不同的变化:最初的轻度脱水都使种子的萌发率上升,分别达到90.0%和67.0%;随着脱水程度加大,种子萌发率呈下降趋势,但在种子脱水至趋于稳定的含水量之前,种子萌发率仍高于未脱水前的水平.结果表明:樟树种子具一定的脱水耐性,但较大程度的脱水会对种子造成伤害,而且慢干比快干对种子的伤害更大.0℃以上低温湿藏是解除樟树种子休眠的有效途径;温度较高时,种子达到最高萌发率的时间较短,但此后种子活力下降的速度也较快;0℃以下低温贮藏时,种子迅速死亡.     

顽拗性种子的脱水敏感性与萌发的关系

产生顽拗性种子的植物通常生存在易于比较迅速形成幼苗的生境。须拗性种子在发育中期获得萌发能力，不经历成熟脱水，脱落后能继续萌发。种子中的贮藏物质和植物生长调节物质的变化有利于种子萌发。     

黄皮种子在萌发过程中脱水敏感性变化的研究

在萌发过程中，黄皮完整种子的干、鲜重变化，干燥处理时的脱水速度和脱水敏感性变化都与其离体胚轴明显不同，子叶树于延缓胚轴耐水性的丧失可能起重要作用，胚根突破种皮的时期不是其耐脱水性丧失的时期，而与正常性种子在萌发过程中的耐脱水性变化模式相区别。     

Relationship Between Storage and Germinability of Cardamom (Elatteria cardamomum Maton)

Cardamom seeds are considered recalcitrant, with relatively low retention of germinability during storage. Thus, a study tested the effects of drying temperatures on moisture loss and reduction in germinability of cardamom seeds. In addition, the effect of storage material and temperatures on retention of germinability was evaluated. The mature seeds of cardamom contained a high percentage of water at harvest, and germinability at harvest was around 62 %, confirming the recalcitrant nature of the seeds. Seed germinability was completely lost at moisture levels below 50 % (dry wt. basis) and higher temperatures reduced moisture levels and germinability faster. Drying at 20°C retained some degree of germinability for 7 days. In terms of storage, sealed polythene containers and low temperature (5°C) was optimal for maintaining some degree of germinability of cardamom seeds during storage for approximately 15 days.     

氧气浓度对杧果种子贮藏寿命的影响

杧果种子在所试各氧浓度中密闭贮藏时，含水量变化不大，但在21．0％和17．5％O2中贮藏20天后，颜色由白完全变黑，生活力完全丧失；在10．5％。。中贮藏100天，颜色保持白色，生活力达40％；在7．0％和3．5％O2中贮藏100天，种子颜色虽保持白色，但生活力已降至20％以下。推论除脱水损伤外，种子氧化变黑也是杧果种子表现顽拗性的一个主要原因。     

Effect of Time of Harvest and Storage Conditions on Germination of Nutmeg (Myristica fragrans Houtt)

Nutmeg ( Myristica fragrans ) is a valuable tropical spice crop, which is not easily propagated vegetatively. As the seeds of this species lose viability soon after harvest, storage for research causes problems, especially due to the seasonality of production. Thus, a study evaluated the characteristics of nutmeg seeds, and the relationship between time of harvest, drying temperature, and storage condition on germinability. Seeds were picked at full maturity, full ripeness or were collected within 2 hours after falling from the tree. Seed moisture contents, germination characters and germination indices were determined soon after harvest. The freshly fallen seeds were used for the drying and storage due to their better germination characters and higher germination index.
Seed moisture contents were high in the seeds. These values decreased and germinability increased with increasing seed maturity. Germination percentages were lost at higher moisture contents at a faster rate when dried at higher temperatures. All seeds lost germinability at moisture contents below 45 % (dry wt basis) when dried at the selected temperatures. Germination of stored seed were maintained for a longer period of time when stored at 5 °C in sealed transparent polythene packs, in contrast to when stored at room temperature. The results suggest the recalcitrant nature of nutmeg seeds and present possible methods of storage for short period of time while maintaining some degree of germinability.     

Pod, Seed and Germination Characteristics of Selected Cardamom (Elettaria cardamomum (Linn.) Maton) Varieties

Cardamom is a popular and important tropical spice, traditionally propagated by rhizomes, although seeds which are considered recalcitrant are being increasingly used in planting programmes. Thus a study evaluated the effects of pod maturity on pod, seed and germination characteristics of three popular varieties, along with the influence of drying on seed germinability.
Green and yellow mature pods and seeds of all varieties had a high moisture content. The variety Mysore, which is considered high yielding, had larger pods with a greater number of heavy seeds. Although the pods of Vazukka were heavier than the Malabar variety due to greater seed weights, seed numbers were similar in both varieties. Seed moisture contents declined with increasing pod maturity, while seed weights and germinability increased.
The germinability of Mysore seeds were greater, while that of the other varieties were lower. The larger seeds of all varieties germinated 15–20 days earlier, giving rise to a greater percentage (20–25 %) of seedlings. Desiccation at 20 °C maintained germinability for a longer period (5–9 days) in all varieties, than when dried at 30 °C. The seeds of the variety Mysore was more tolerant to desiccation than other varieties. The study illustrated the importance of selecting large seeds from yellow mature pods of cardamom for propagation and the value of establishment immediately after harvest to obtain a greater number of seedlings.     

水稻种子耐干性机理的研究

以籼稻C38、粳稻京21、杂交稻秋优3为材料,进行种子超干储藏特性的研究,进而探讨种子耐干性的机理。通过超干水稻种子生活力和活力的比较,发现籼稻C38耐干性较强。超干有利于保持种子抗氧化酶系统的完整性,因此超干能提高种子的耐储性。对超干种子可溶性糖含量与组分进行分析,结果表明随着种子含水量的降低,蔗糖含量增高,多糖和葡萄糖含量降低,籼稻C38的蔗糖含量明显低于粳稻京21和杂交稻秋优3。用热重仪测定的种子含水量与烘干法得到的数据相吻合,用差示热量扫描仪测定束缚水/自由水的比例和玻璃化转变温度Tg,发现籼稻C38的Tg高于粳稻京21和杂交稻秋优3,籼稻C38束缚水/自由水比例大于粳稻京21和杂交稻秋优3,而束缚水/自由水的比例与耐干性成正相关。由此表明,耐干性在不同的水稻品种间有明显的差异,籼稻C38的耐干性较强。     

How does the harvest index affect water‐use efficiency and nutrient‐utilization efficiency of sunflowers (Helianthus annuus L.)?

Besides oilseed rape and soybean, sunflower is one of the most important annual oilcrops. Apart from seed yield, which is the most important trait in many crops, oil yield is of utmost interest for sunflower breeders and farmers. Compared to the seed yield of sunflowers, their total biomass is often very high, and it is of great agronomic interest to increase the ratio of both parameters, which is defined as harvest index. With an increase in harvest index, improvements of resource‐use efficiencies can be expected. To generate an adequate seed yield, water and nutrients are key factors and their efficient use becomes increasingly important under conditions of aridity and higher production goals. A pot experiment was conducted in summer 2017 to determine differences in harvest index of various sunflower genotypes which could have an influence on the use efficiencies of water and nutrients (N, P, K). In total, 25 genotypes of different origin and with various morphological traits were investigated under optimal growth conditions. The harvest index varied from 29% to 47% and showed significant differences among some genotypes. The harvest index was less affected by the total biomass of the plants but more by the seed yield. The seed yield itself was mainly determined by the single seed weight rather than by the number of seeds. The experiment also confirmed significant positive correlations between harvest indices and all use efficiencies. Genotypes with high harvest indices were characterized by high oil concentrations in the seeds and particularly by high oil yields. In conclusion, cultivation of sunflower genotypes with high harvest indices most likely results in high water‐use efficiency and high nutrient‐utilization efficiencies as well as in high oil yields.     

冰菜种子采后处理技术和萌发温度的研究

探寻冰菜蒴果的采收期、烘干温度、种子大小及催芽温度，为冰菜的种苗繁育提供技术支持。选用冰菜蒴果和种子为试验材料，研究蒴果不同采收期、蒴果烘干温度、种子大小及催芽温度对种子萌发的影响。结果表明，在冰菜蒴果变为黄色，含水量低于20%时，采收的种子发芽率最高，褐果发芽率次之，青果最差；0.7-0.9mm大小的种子萌发率最高，为82.3%；对蒴果进行烘干处理发现，40℃烘干5.5h的蒴果易碾碎脱粒，种子含水量7%以下，种子发芽率89%以上；25℃催芽处理种子萌发率最高，为83%。当冰菜蒴果变为黄色时及时采收，然后经过40℃烘干5.5h后进行碾碎处理，再经0.7-0.9mm网筛处理后种子的种子发芽率最高，种子最适催芽温度为25℃。