杉木全同胞家系的遗传分析及重要树冠因子的筛选

通过对5年生杉木6×6全双列杂交(Griffing Ⅲ)试验林的调查与分析，研究杉木若干性状的遗传与变异规律，并筛选决定理想株型的重要树冠结构因子，为杂交育种和杉木理想株型无性系选育提供科学依据。运用转化分析法来处理不平衡试验数据，结合配合力分析法、相关分析法和通径分析法,研究杉木遗传变异、基因作用方式和重要树冠因子的选择。通过对杉木若干性状进行研究，获得了不同性状遗传变异大小。结果表明，杉木材积、枝下高和饱满度等性状具有中度遗传变性，树高、胸径具有窄的遗传变异性，同时杉木改良性状具有中度以上的遗传力，因此杉木生长形质性状宜采用连续多世代改良；在杉木生长、形质性状和树冠结构性状中，12个研究性状有8个重要性状的基因作用方式以非加性遗传基因效应为主，杉木高世代育种亲本是多世代与高强度选择的产物,杂合体居多,杉木的多性状、高世代遗传改良以杂交育种为主；生长、形质和树冠结构性状间具有明显的遗传相关性，通径分析揭示:决定杉木理想株型育种中重要树冠结构性状是冠形率和树冠表面积大小。由此可见:杉木多性状、多世代连续改良以杂交育种为主，杉木无性系理想株型选择时，应注重冠形率和树冠表面积的作用。     

Source of mycorrhizal inoculum influences growth of Faidherbia albida seedlings

Poor land use management and practice inhibit the growth and establishment of tree seedlings in dryland areas.We assessed arbuscular mycorrhizal fungi(AM)status of Faidherbia albida(Del.)A.Chev.trees grown on different land uses.We quantified the growth and nutrient uptake of F.albida seedlings inoculated with AM from different sources.These efforts were based on soil and fine root samples from the rhizosphere soils of F.albida trees.AM root colonization was determined using the gridline intersect method.Spores were extracted by the wet sieving and decanting method and identified to genus level.The seedling experiment had a completely randomized onefactorial design with four treatments and five replications.Faidherbida albida seedlings were grown in a greenhouse.All in situ F.albida trees were colonized by AM fungi.AM root colonization of F.albida trees was significantly higher(P<0.0086)in area exclosures than on lands used for grazing or cultivation.Spore abundance was significantly higher(P<0.0014)in area exclosures followed by cultivated land and grazing land.Glomus was the dominant genus in all land-uses.AM-inoculated F.albida seedlings grew better(P<0.05)than non-inoculated controls.Seedlings inoculated with AM from area exclosure had significantly(P<0.05)higher growth and nutrient uptake than those inoculated with AM from grazing and cultivated land.This emphasizes the importance of the native soil AM potential for better establishment of seedlings to achieve optimum plant growth improvement and assist in rehabilitation of degraded arid lands.     

Genetic variation of seedling traits responded to brassinosteroid and gibberellin inhibitors in maize (Zea mays) doubled haploid lines

The purpose of this study was to examine the genotypic variation in maize doubled haploid (DH) lines response to brassinosteroid and gibberellin inhibitors. Plant responses to hormone inhibitors were determined in growth chamber experiments using germination paper for three different seedling treatments: application of propiconazole (Pcz), uniconazole (Ucz) or water (control). Mesocotyl length (ML) was more sensitive to hormone inhibitors, especially to the Ucz treatment, than other seedling traits. ML was significantly correlated with other traits in the Ucz treatment. All the seedling traits showed moderate-to-high broad sense heritability values, ranging from 0.39 to 0.82. The Euclidian genetic distances of inbred line pairs ranged from 1.27 to 19.94, indicating there was a high level of variability across the maize DH lines used in this study. DH lines with extreme MLs were identified, which can provide valuable breeding resources for improving abiotic stress tolerance, and for further genetic studies.     

氟节胺抑制枇杷嫁接成苗砧木萌蘖相关机理初探

为寻找更长效、无害的化学控蘖剂以减轻田间管理劳动强度,以枇杷(Eriobotrya japonica)嫁接成苗为材料,喷施有效成分浓度为0.050%,0.071%和0.125%的氟节胺,于不同时期取样观察控蘖效果,并尝试探究相关机理。结果表明,氟节胺减少了叶片单位面积光能的吸收量、抑制了光化学转换,但叶片的热耗散量并无明显变化。进一步测定植株氧化还原状态发现,氟节胺能够快速促进细胞内超氧阴离子(O₂^.-)积累并延缓或抑制H₂O₂的转化,从而诱发氧化胁迫。由此可见,氟节胺可能通过抑制叶片光化学转换和热耗散来破坏新生萌蘖的光合性能,进而抑制其萌发生长,而成熟叶片则通过提升自身抗氧化系统活性耐受氟节胺造成的轻度胁迫。在本试验中,各浓度的氟节胺对控制砧木萌蘖有不同程度的效果,其中浓度为0.125%的氟节胺控蘖效果相对最佳,且基本不会对砧木和嫁接成苗造成持续伤害,其作为化学控蘖剂有一定的应用潜力。     

Phenotypic indicators for cultured pearl size improvement in the black‐lipped pearl oyster (Pinctada margaritifera): towards selection for the recipient growth performance

The black‐lipped pearl oyster, Pinctada margaritifera, is the most important farmed species in French Polynesia and the basis of the most valuable export industry. Mass production of black pearls relies on a surgical operation requiring tissue from a donor pearl oyster to be grafted, together with a nucleus made of shell, into the gonad of a recipient oyster. Improving pearl size through family selection remains one of the main challenges for future aquaculture development. This study analyses the relative contribution of donor and recipient oysters to pearl size. To this end, hatchery‐produced donor oysters of two batches, large and small (based on shell height), were used to supply grafts for recipients, which were then monitored individually for their growth performance by recording shell height, width, and thickness, and total live weight (flesh + shells) every 6 months (four biometric measurement times) over 20 months of culture. Pearls issued from the two batches of donors showed no significant differences in nacre weight or thickness. In contrast, recipient oyster shell height and total weight were increasingly positively correlated with these pearl size parameters over the culture period, becoming significant at 8 months post‐grafting. Potential therefore exists to use shell height and oyster weight as phenotypic indicators for selective breeding of recipient oysters with high growth performance to increase pearl size in P. margaritifera.     

Zinc biofortification of maize (Zea mays L.): Status and challenges

Zn deficiency is one of the leading health problems in children and women of developing countries. Different interventions could be used to overcome malnutrition, but biofortification is most impactful, convenient, sustainable and acceptable intervention. Maize is one of the major crops grown and consumed in the regions with prevalent Zn malnutrition; therefore, this is suitable target for Zn biofortification. Zn biofortification of maize could be achieved through agronomic and genetic approaches. Discussion of agronomic approaches with genetic approaches is prerequisite because soils in developing countries are deficit of Zn and availability of Zn in soils is mandatory for estimating the genetic responses of maize genotypes through genetic approaches. Seed priming, foliar and soil applications are agronomic tools for biofortification, but solo and combined applications of these treatments have different effects on Zn enrichment. Genetic approaches include the increase of Zn bioavailability or increase of kernel Zn concentration. Zn bioavailability could be increased by reducing the anti‐nutritional factors or by increasing the bioavailability enhancers. Kernel Zn concentration could be improved through hybridization and selections, whereas genetically engineered attempts for improving Zn uptake from soil, loading in xylem, remobilization in grains and sequestration in endosperm can further improve the kernel Zn concentration. Key challenges associated with dissemination of Zn biofortified maize are also under discussion in this draft. Current review emphasized all of above‐mentioned contents to provide roadmap for the development of Zn biofortified maize genotypes to curb the global Zn malnutrition.     

覆盖栽培模式对冬小麦花后旗叶 光合特性及产量的影响

为探究旱地小麦秸秆带状覆盖栽培增产的光合特性和干物质积累转运的特征，在甘肃省半干旱雨养农业区以“陇中2号”为材料，研究了秸秆带状覆盖栽培（BS）、地膜覆盖栽培 （PF）和无覆盖露地栽培（CK）3种栽培模式下冬小麦花后旗叶光合特征、叶绿素荧光动力参数、干物质积累转运及产量的差异。结果表明：与CK相比，BS和PF显著提高了花后旗叶光合势、叶绿素和类胡萝卜素含量及叶绿素/类胡萝卜素比率，且BS在生育后期优于PF。BS整个生育期的净光合速率、气孔导度均高于CK，而PF仅生育前期发挥正效应，生育中、后期出现了负效应。BS生育前中期胞间CO₂浓度、生育中后期旗叶瞬时水分利用效率均高于PF和CK，前者分别高出2.8%~8.2%和6.7%~11.3%，后者分别高出30.3%~44.8%和27.5%~39.3%。PF在灌浆中期以前，BS在整个花后生育期显著提高了小麦花后旗叶F_v/F_m、F′_v/F′_m、ΦPSⅡ、qP、ETR，降低了NPQ。BS较PF和CK显著提高了花后干物质输入籽粒量和对籽粒粒重的贡献率，2个指标分别增加2.6%、1.0%和14.2%、8.6%。BS显著增加了单位面积穗数，提高了产量，较CK增产35.4%。说明秸秆带状覆盖能显著改善旱地冬小麦花后光合效率，促进干物质积累转运，从而达到增产的效果。