水分胁迫对荔枝幼树根系与梢生长的影响

以盆栽沙培1年生荔枝空中压条苗为试材,研究了水分胁迫对荔枝幼树根系和梢生长的影响以及二者的相互关系。3个处理为:沙体积含水量为7.5%(严重缺水),15.0%(一般缺水),22.5%(充分供水)。结果表明:水分胁迫严重抑制荔枝幼树地上部分和各级侧根的生长,使地上部枝梢生长严重受阻,叶片数量、平均叶面积、叶片厚度均显著变小;根总干重、侧根长度、根表面积显著减少。水分胁迫下促进须根的生长,须根的长度、根表面积比水分充足时显著增加。水分胁迫时叶片淀粉含量下降,而根系积累更多的淀粉。比较不同处理的根梢比发现,干旱对根系生长的抑制作用比枝梢更显著。     

糖和氮对山楂组织培养新梢生根的影响

采用敞口山楂组培新梢研究糖和无机氮源对不定根形成的影响,含有高水平蔗糖的培养基比低水平蔗糖的培养基新梢生根率高。新梢对糖的这种反应与糖代谢和物理渗透都有关,用甘露醇作为渗透代替剂在低浓度蔗糖存在下无作用,当蔗糖浓度达到一定程度时(86.64mmol·1~(-1))能影响新梢的生根率。在培养基中分别加入NO_3~(-)-N或NH_4~(+)-N作为唯一氮源,或是在MS培养基中加入NO_3~-/NH_4~+比率为标准的混合氮源,在测试范围(0～120mmol·1~(-1))内均降低新梢的生根率,三者对生根的抑制作用大小顺序依次为NH_4~+>NO_3~(-)-NH_4~(+)-N>NO_3~(-)-N.NO_3~-/NH_4~+的比率影响生根。NO_3~-/NH_4~+比率与生根之间呈直线正相关。糖/氮比值高有利于生根。插穗中碳、氮的绝对量及碳/氮比率可作为山楂新梢生根的指标。     

稻属植物21个种颖花稃尖的比较研究

用扫描电镜对稻属植物２１个种颖花稃尖进行观察,看到外稃尖的两侧各个一个突起或折痕。根据其形状不同,将２１个稻种的外稃尖分为“乳突型”、“钝角型”、“折痕型”和“融合型”４种型。     

几种抗生素对梨叶片愈伤组织和不定梢诱导的影响

研究了氨苄青霉素(Amp)、羧苄青霉素(Carb)、头孢霉素(Cef)和卡那霉素(Km)对梨叶片愈伤组织和不定梢诱导的影响。结果表明,Amp对巴梨叶片分化影响较小,当浓度达500mg/L时,其出愈率和不定梢再生率分别为96.48%和56.17%,与对照差异不显著;Cef浓度在50-300mg/L时对巴梨和身不知叶片再生均无显著影响,只有当Cef浓度高于400mg/L时,巴梨的不定梢再生率才受到显著抑制;巴梨和身不知叶片对Carb的反应不相同,低浓度(≤200mg/L)的Carb对巴梨的出愈率和不定梢再生率影响较小,却显著抑制身不知的不定梢再生率,高浓度(≥300mg/L)的Carb不仅极显著抑制巴梨和身不知的出愈率,而且完全抑制了2者的不定梢再生;Km浓度大于10mg/L时,明显抑制愈伤组织的生长,且随着浓度的增加,死亡率逐渐增大,当Km浓度达100mg/L时,巴梨和身不知叶片死亡率达100%和96.30%。     

培养条件对酸枣叶片不定梢再生率的影响

以酸枣无菌苗叶片为外植体,选用基本培养基ＮＮ６９和ＷＰＭ,外源激素包括ＴＤＺ、ＩＡＡ、ＩＢＡ和ＮＡＡ,暗培养时间为２、３、４周。采用正交实验设计方法,研究了基本培养基、外源激素及暗培养时间对叶片不定梢再生的影响。结果表明在附加ＴＤＺ１~３ｍｇ/Ｌ的ＷＰＭ和ＮＮ６９上都可诱导不定梢再生,但ＷＰＭ比ＮＮ６９更有效。暗培养时间对不定梢再生也有影响,暗培养３周比２、４周更有利于提高叶片的不定梢再生率。在附加ＴＤＺ１ｍｇ/Ｌ、ＩＡＡ０．１ｍｇ/Ｌ的ＷＰＭ培养基上,暗培养３周后转到光下培养,获得的不定梢再生率达８７．５%。     

荔枝环剥时期对新梢生长及碳素储备的影响

 枝梢环剥显著抑制了‘怀枝’荔枝新梢的生长，并导致射线细胞和髓部大量积累淀粉。梢芽萌发或伸长前环剥可完全抑制新梢生长，而新梢快速伸长期环剥对其抑制效应最弱。秋季环剥对新梢的抑制和对淀粉积累的促进效应明显高于春季环剥。环剥口以上的老叶面积和环剥位置并不影响环剥对新梢生长的抑制效应和促进淀粉的积累效应，但环剥口以上单位枝梢长度的叶面积与淀粉含量呈显著正相关。     

Estimation of phenotypic variability in symbiotic nitrogen fixation ability of common bean under drought stress using 15N natural abundance in grain

Common bean (Phaseolus vulgaris L.) is the most important food legume, cultivated by small farmers and is usually exposed to unfavorable conditions with minimum use of inputs. Drought and low soil fertility, especially phosphorus and nitrogen (N) deficiencies, are major limitations to bean yield in smallholder systems. Beans can derive part of their required N from the atmosphere through symbiotic nitrogen fixation (SNF). Drought stress severely limits SNF ability of plants. The main objectives of this study were to: (i) test and validate the use of ¹⁵N natural abundance in grain to quantify phenotypic differences in SNF ability for its implementation in breeding programs of common bean with bush growth habit aiming to improve SNF, and (ii) quantify phenotypic differences in SNF under drought to identify superior genotypes that could serve as parents. Field studies were conducted at CIAT-Palmira, Colombia using a set of 36 bean genotypes belonging to the Middle American gene pool for evaluation in two seasons with two levels of water supply (irrigated and drought stress). We used ¹⁵N natural abundance method to compare SNF ability estimated from shoot tissue sampled at mid-pod filling growth stage vs. grain tissue sampled at harvest. Our results showed positive and significant correlation between nitrogen derived from the atmosphere (%Ndfa) estimated using shoot tissue at mid-pod filling and %Ndfa estimated using grain tissue at harvest. Both methods showed phenotypic variability in SNF ability under both drought and irrigated conditions and a significant reduction in SNF ability was observed under drought stress. We suggest that the method of estimating Ndfa using grain tissue (Ndfa-G) could be applied in bean breeding programs to improve SNF ability. Using this method of Ndfa-G, we identified four bean lines (RCB 593, SEA 15, NCB 226 and BFS 29) that combine greater SNF ability with greater grain yield under drought stress and these could serve as potential parents to further improve SNF ability of common bean.     

广西葡萄良种脱毒研究进展

建立葡萄脱毒技术并繁育和推广葡萄良种脱毒苗木,对于广西葡萄产业的健康可持续发展极为重要。本研究团队在广西最先开展了葡萄脱毒技术研究。目前已建立了10种葡萄主要病毒的RT-PCR检测方法,并建立了热处理结合茎尖培养的葡萄脱毒技术,且已成功对‘阳光玫瑰’葡萄、‘夏黑’葡萄和‘巨峰’葡萄三个优良品种的带毒单株进行了脱毒。研究成果有助于进一步推动广西葡萄产业的健康可持续发展。     

糜子愈伤诱导及再分化最适条件研究

研究旨在应用组织培养技术探究愈伤诱导及再分化的最适条件,以期为糜子建立遗传转化体系奠定基础。采用5种不同类型的糜子品种研究愈伤诱导及再分化的最适条件。利用植物激素2,4-二氯苯氧乙酸(2,4-D)诱导茎尖愈伤组织,筛选出发芽率高,愈伤组织诱导率高,染菌率低的品种,并对诱导愈伤最适激素浓度及配比进行了鉴定。结果显示,冀黍2号出芽率高、愈伤组织诱导率高、染菌率低,适宜进行组织培养;2,4-D对冀黍2号愈伤诱导效果最好,最适浓度为2.5mg/L,诱导率达86.67%,淡黄色块状,结构紧密,质地较硬,继代培养后形成的胚性愈伤组织状态更好。再分化过程中,2,4-D浓度为2.5mg/L+TDZ浓度为3.5mg/L时出现明显的嫩芽。该试验获得冀黍2号愈伤诱导及再分化的最适条件,可为糜子再生体系的构建提供参考。     

辣木的染色体制片优化及核型分析

以辣木分生组织为材料,采用酶解去壁低渗法制片,探讨不同取材部位、预处理方式和酶解时间对辣木染色体制片的影响,并对其进行核型分析,以期为辣木的起源、演化及遗传育种提供一定理论依据。结果表明:以辣木新枝茎尖为最佳取材部位,用饱和对二氯苯预处理2 h,再用4%纤维素酶和5%果胶酶混合物酶解4 h,制片所得染色体效果最佳。核型分析表明,辣木染色体属于小染色体,有28条,核型公式为2n=2x=2n=28m,属于1B类型,核型不对称系数60.29%,核型对称程度较高,这表明辣木在进化中可能处于比较原始类型。