Effect of non-lethal low phytic acid mutations on grain yield and seed viability in rice

Low phytic acid (LPA) crops have recently been considered as a potential way to combat nutritional and environmental issues related to seed phytic acid phosphorus (PA-P). Although, a number of LPA mutant lines have been developed in various crops, they are often featured with lower grain yield and seed viability compared with wild type (WT) parents. We recently developed several LPA mutant lines in rice with PA-P reductions varying from 33.8% to 63.6%. In this study, the performance of grain yield and seed viability of these mutants were investigated. Four of the five mutant lines had 12.5–25.6% reductions in grain yield compared to the corresponding WT parental lines. The reduction in grain weight, varying from 5.4% to 10.7%, was found to be the main causative factor of yield reduction. Similarly, LPA mutants had inferior seed viability to their corresponding WT parent varieties; all mutant lines had a significantly lower simplified vigour index (seed germination rate × seedling dry weight) than their parents, with reductions of 7.8–26.3%, although some mutant lines had similar germination rates as their WT parents. The two mutant lines, which had similar germination rates as their WT parent, however, had significantly lower field emergence rates. More pronounced differences of simplified vigour index were observed after artificial aging treatments between four LPA lines from their WT parents, implying that LPA rice seeds were more susceptible to storage than WT. The yield and yield-related traits of F₂ plants and F₃ lines from three crosses were evaluated; the results showed that while LPA was associated with significantly lower grain yield and grain weight than WT sibs, there were also LPA plants and lines that out-performed WT controls. These results implied that the negative effect of LPA mutations on grain yield might be reduced or minimized through cross and selection breeding. The implications of these findings were discussed with regard to LPA rice breeding and potential commercial production.     

圭亚那柱花草花粉活力的测定方法

采用蔗糖萌发、无机酸测定、TTC染色、碘－碘化钾染色、红墨水染色和联苯胺染色等6种方法,测定了圭亚那柱花草[Stylosanthes guianensis(Aublet)Swartz]的花粉活力,并比较了各方法的优缺点、试验效果。结果发现,前4种方法的测定效果较好,且二者配合使用测定结果较为准确。试验结果同时表明,F137号柱花草种质的花粉活力最低,有望成为圭亚那柱花草雄性不育研究工作的育种材料。     

Is the Organic System Economically Viable? The Case of Pineapple in India’s Northeast

This study intends to fill the gaps in the organic agriculture literature emerging from infrequent use of farm budget-related data, overlooking the imputed costs and non-existence of long-run return and profitability estimates. The results suggest that the organic system is economically unviable as the growers fail to recover their total production cost. However, growers’ returns exceed their ‘perceived’ production cost, which excludes their imputed expenses. Temporal, spatial, and size-based analysis also attests to this. On the contrary, cultivation in two sample villages where the household’s size, its head’s age, percentage of land, and yield are significantly higher, remain economically viable.     

不同贮藏年限敖汉苜蓿种子活力及生理特性的研究

种子在贮藏过程中随着贮藏时间的延长出现老化现象,使种子活力下降、生理特性发生变化,从而降低种用价值.为探讨不同贮藏年限紫花苜蓿种子的活力变化,选择室温贮藏0～3年的敖汉苜蓿种子,比较分析种子劣变规律及生理特性的差异.结果表明:收获当年的敖汉苜蓿种子具有较高的硬实率,其抗逆性强,SOD、POD、CAT、MDA和脯氨酸含量最高,而发芽势和可溶性蛋白含量最低.贮藏起初2年,种子硬实率、不正常种苗数、死种子数、SOD、POD、CAT、MDA和脯氨酸含量降低,发芽率、发芽势和可溶性蛋白含量增加.随着贮藏时间的延长,种子可溶性蛋白含量降低,SOD、POD、CAT、脯氨酸和MDA积累量增加,种子质量下降,不正常种苗数和死种子数增多,种子活力下降.综合试验结果,贮藏2年有利于打破种子休眠,其种子质量最佳,种子发芽能力最强,但是种子抗逆性不高;贮藏1年存在轻度休眠,应进行打破硬实处理;贮藏3年的种子活力下降,其种用价值降低,不利于在人工草地建植中使用,生产中应贮藏2年后再播种效果较好.研究结果能较好地说明苜蓿种子在贮藏期间的活力变化,为我国人工草地建设中合理使用苜蓿种子提供理论依据.     

多花野牡丹传粉生物学特性研究

多花野牡丹花期从5月初至6月末,单朵花开放1 d。异型雄蕊,5枚黄色花药位于柱头的上方,5枚紫红色花药位于柱头的下方两侧。花粉为扁球形,极面观为六裂圆形,黄色花药中花粉的三假沟连接到两极,紫红色花药花粉的三假沟未连接到两极。黄色和紫红色花药的花粉活力不同,并随开花进程有下降趋势。该物种存在无融合生殖现象。异花授粉单果饱满种子数显著高于自花授粉,两种传粉方式中,黄色花药中的花粉授粉效果好于紫红色花药。传粉昆虫有圆花熊蜂、红光熊蜂、鞋斑无垫蜂等,9:00~10:30昆虫访花频率最高,11:40以后见不到昆虫访花。杂交指数为4,繁育系统为部分自交亲和,异交,需要传粉者。花粉与胚珠比为601.54,繁育系统为兼性异交。     

莴苣种子贮藏条件研究

运用适当的种子起始含水量、贮藏温度和包装方式,可经济有效地保持种子的发芽率。种子的生活力与超氧化物歧化酶、酸性磷酸酶的活性呈正相关。     

不同温度对东北红豆杉种子活力的影响

对在不同温度下保存一段时间的东北红豆杉种子进行了活力测定。结果表明,低温环境比常温环境更利于东北红豆杉种子的长期保存,其中,-25℃环境中保存的种子活力最高。     

玉米花粉和花丝活力研究

探讨了在不同温度条件下离体玉米花粉生活力和花丝受粉结实活力保持的时间。结果表明,不同环境下不同基因型材料花粉活力存在显著差异。在低温条件下花粉寿命没有延长;常温条件下花粉寿命在24~48 h。花丝活力能持续到开花期结束后7 d,结实率可达80%以上。     

不育紫薇花粉活力及柱头可授性研究

以4年生"不育紫薇"和普通"可育紫薇"为研究对象,进行杂交育性分析,并利用液体培养法和荧光显微技术测定了两个紫薇品种的花粉活力和柱头可授性。结果表明:"不育紫薇"的花药表面较光滑湿润,难以释放花粉;花粉粒畸形,不能萌发,没有生活力;雌蕊的柱头对正常成熟的花粉有亲和力,具有可授性,但结实率仅4.0%。"不育紫薇"的不育性状由雄性不育和雌性不育共同作用所致。     

云南高海拔地区甜樱桃花粉生活力的研究

采用花粉离体萌发法和染色法测定甜樱桃的生活力,目的在于选择花粉生活力强的品种作为授粉品种,以提高坐果率,确保产量和品质。结果表明:拉宾斯花粉的生活力最高,达70%以上,98-1A和南阳红的花粉发芽率最低,分别为10%~15%,其他品种的花粉发芽率在30%~60%,因此,拉宾斯可以作为其他甜樱桃的理想授粉树;南阳红和98-1A由于花粉生活力较低,一般不建议用做授粉树。