【Objective】The study was carried out to explore the effects of different concentrations of uniconazole in plug media on the growth and development of different varieties of lettuce seedlings.【Method】Five lettuce varieties in southern China were used to study the effects of different concentrations (0-50 mg/L) of uniconazole on seedling growth, leaf shape parameters and soluble solids (TSS) of lettuce.【Result】With the increase of uniconazole concentration, the root fresh weight, root dry weight, shoot fresh weight and shoot dry weight of seedlings of various lettuce varieties increased first and then decreased. The root fresh weight and dry weight of bolting-tolerant lettuce and Roman upright lettuce were the highest under 10 mg/L uniconazole treatment, and those of other varieties were the highest under 5 mg/L uniconazole treatment. The total leaf width, maximum functional leaf width and total leaf area of seedlings also reached the maximum under 5 mg/L uniconazole treatment. The total leaf width and total leaf area of butter lettuce seedlings were larger than those of other varieties. The root-shoot ratio of iceberg lettuce, butter lettuce and bolting-tolerant lettuce increased with the increase of uniconazole concentration, while the root-shoot ratio of Hong Kong soft-tail lettuce and Roman upright lettuce increased first and then decreased. In addition, under the treatment of 50 mg/L uniconazole, SPAD values of lettuce seedlings of all varieties increased significantly, while plant height, total leaf area and TSS accumulation were severely inhibited.【Conclusion】Strong seedlings of lettuce could be cultivated by the medium with suitable concentration (5 mg/L) of uniconazole. The growth and development of lettuce seedlings would be inhibited by higher concentration of uniconazole.

为探究江西省赣州设施菜地土壤全硒(Se)的含量及其分布特征,于2021年对赣南地区设施蔬菜大棚采集0～20 cm耕层土壤样235件,测定了土壤采样点的经纬度、海拔及土壤中全硒含量和理化性质.结果表明,赣南地区设施菜地土壤全硒质量分数平均为0.31 mg/kg,变化范围为0.03～1.25 mg/kg,全硒含量分布频率符合正态分布.研究区域设施菜地富硒土壤资源较为丰富,85.1％的样点数土壤全硒含量处于足硒及以上水平(>0.175 mg/kg),其中有22.1％的样点数土壤属于富硒水平标准(>0.400～3.000 mg/kg),而富硒土壤主要集中在赣南地区的正西部及东北部等部分区域;7.2％和7.7％的样点数土壤全硒质量分数分别达硒不足(>0.125～0.175 mg/kg)和潜在硒不足水平(≤0.125 mg/kg),二者主要集中在赣南地区西南角部分区域,不存在硒中毒区域.海拔每增加1 m,设施土壤全硒质量分数降低5.35×10-4 mg/kg;纬度每增加1°和pH值每增加一个单位,土壤全硒质量分数分别增加0.090和0.049 mg/kg.综上,赣南地区设施菜地土壤硒资源具有较大利用潜力,并可依据研究区域全硒含量分布特征开展具有针对性的设施富硒蔬菜发展策略.

以5种生菜为试材,使用穴盘基质拌施多效唑育苗来模拟土壤多效唑残留的方法,其中多效唑浓度(以有效成分计)设置A1(0 mg·L-1)、A2(2.5 mg·L-1)、A3(5.0 mg·L-1)、A4(10.0 mg·L-1)、A5(20.0 mg·L-1)、A6(40.0 mg·L-1)和A7(80.0mg·L-1)共7种残留水平,研究了多效唑残留对生菜幼苗质量、叶型及地上部可溶性固形物含量的影响,以期探明生菜育苗生长对多效唑残留浓度的响应机制.结果表明:随多效唑浓度增加,各生菜株高、地上部鲜质量、地上部干质量、总叶面积、总叶长、总叶宽、最大功能叶叶长、最大功能叶叶宽及可溶性固形物均降低,SPAD值及根冠比均增加,而根鲜质量及根干质量先增后降.其中A5、A6和A7处理株高、地上部鲜质量、地上部干质量、总叶面积及可溶性固形物等指标均显著低于A1处理,SPAD值和根冠比等指标却均显著高于A1处理.随菜地多效唑残留浓度增加,各生菜苗期生长发育受抑制程度增加,其中多效唑残留浓度为A5(20 mg·L-1)及其以上时其抑制效果均达显著水平,对生菜育苗质量极为不利.

[目的]南丰蜜桔作为江西省四大特色柑桔产业之一,加快南丰蜜桔品质提升对促进江西柑桔产业高质量发展具有重要作用.2007年笔者发现一棵(4年树龄)砧木为枳、接穗来源于南丰蜜桔"杨小2-6"的芽变优株,并经连续10余年高接鉴定表明该变异品种遗传稳定性较好,品质及耐贮特性也较佳,该变异优株被命名为"南丰蜜桔芽变优株ZZL-03".为评价南丰蜜桔芽变优株"ZZL-03"(突变体)果实采后品质变化特征,客观探讨其商品性.[方法]以普通南丰蜜桔为对照,采收后每隔10 d测定其果实耐贮特性、内在品质及果皮果汁的色差指数等指标,并于采摘期对果实外在品质进行测定.[结果]研究表明,随贮藏期延长(采后4～34 d内),突变体及对照组的果实硬度、可滴定酸、果皮L、h0值均逐渐降低,果实可溶性固形物含量、腐烂率、浮皮率、可溶性糖、糖酸比、固酸比、果皮a、c值及果汁L、a、b、c值均逐渐增加,而维生素C、果皮b值及果汁h0值均先增后降.在贮藏各时期,突变体果实硬度、可溶性固形物含量、可溶性糖、糖酸比、固酸比和维生素C均显著高于对照(P<0.05),分别平均高48.7％、53.7％、35.2％、66.9％、89.9％和25.3％;而腐烂率、浮皮率、可滴定酸均显著低于对照,平均低于45.0％、71.0％和18.9％.突变体果皮及果汁L、a、b及c值均高于对照,但h0值有所降低.突变体果实皮薄而硬,外在品质显著优于对照.[结论]综上,与对照相比突变体果实采后具有更好的耐贮特性及果实品质,研究得出的贮藏期品质的变化规律可为蜜桔采后加工利用提供理论指导.

[目的]增施氮肥是实现水稻高产最为重要的措施之一,但过量施用氮肥会降低氮肥吸收利用率并造成氮素面源污染.合理的每穴苗数通过调节稻田基本苗数构建高产群体起点,但通过增加每穴苗数降低施氮量能否同步实现水稻高产及氮素高效利用目前还不清楚.旨在探索每穴苗数及氮肥用量对构建晚籼稻高产氮高效群体的协同调控效果.[方法]于2017—2018年,选用五优308及天优华占为晚籼稻材料,设CK(每穴2苗和N 180 kg/hm2)、T1(每穴3苗和N 144 kg/hm2)及T2(每穴4苗和N 126 kg/hm2)等3个处理,测定了水稻干物质生产、叶面积指数、产量及氮素吸收利用.[结果]随着增苗减氮调控程度增加,两品种产量均先增后降.与CK处理相比,五优308及天优华占品种T1处理产量分别增加0.36％～0.38％及8.73％～10.01％,其中天优华占T1处理与CK处理产量间差异达显著水平;天优华占T2处理产量增加0.95％～1.72％,而五优308品种T2处理产量却显著降低7.46％～7.96％.增苗减氮促进晚籼稻有效穗数增加,每穗粒数降低,结实率先增后降,千粒质量无显著变化.两品种抽穗期及成熟期的叶面积指数及幼穗分化期至成熟期的光合势均先增后降,五优308作物生长速率、总干物质量降低,而天优华占作物生长速率、总干物质量却均先增后降.总吸氮量降低,氮素偏生产力增加、氮素吸收利用率、生理利用率及农学利用率均先增后降.[结论]T1处理可同步协调"增苗"与"减氮"二者关系,可有效构建晚籼稻高产氮高效群体,但具体调控效果因品种而异.