马齿苋中草酸钙晶体形态及积累特征

马齿苋(Portulaca oleracea L.)是营养价值较高的常用野生蔬菜,含有丰富的矿质元素,但目前人们对其钙养分的存在状态还缺乏认识,因此本研究对马齿苋茎和叶进行了显微观察,以了解马齿苋是否含有固定钙的草酸钙晶体以及晶体的积累特征。结果表明,马齿苋积累的草酸钙晶体,属于簇晶类型,直径为25~50μm;分布于茎的髓部和叶的叶肉组织中,叶中晶体多,每1 mm²叶片约含有287个晶体,而茎中含晶体少,每1 mm²茎横切面上只含有26多个晶体。叶中的草酸总含量、可溶性草酸和不溶性草酸含量均高于茎中,草酸分布模式与草酸钙晶体分布模式一致。显然,由于草酸钙晶体的积累,马齿苋中的钙相当一部分以难溶状态存在。     

碎甘薯秧离散元仿真参数测量与标定*

针对甘薯秧蔓机械化回收过程中离散元仿真研究缺乏准确参数值的问题,采用直接测量和虚拟标定相结合的方法对碎甘薯茎秆和叶片离散元仿真参数进行研究。采用物理试验法获得碎甘薯秧的本征参数、碰撞恢复系数等参数值及碎甘薯秧颗粒的静摩擦系数参数范围,并为离散元法仿真设计了不同的参数组合。通过堆积角优化仿真试验确定甘薯叶片本征参数及其他不易直接测量的离散元仿真参数。Plackett-Burman试验表明,甘薯茎秆—甘薯茎秆和甘薯茎秆—45钢的静摩擦系数、甘薯茎秆—甘薯茎秆和甘薯茎秆—甘薯叶的滚动摩擦系数均显著影响堆积角。运用最陡爬坡试验和Box-Behnken优化试验标定了对碎甘薯秧堆积角有显著影响的参数值,以得到的参数进行颗粒堆积仿真试验,测得堆积角平均值为40.51°,与实测值相对误差为0.972%,说明物理试验加优化仿真试验来标定离散元参数是可行的,标定所得的参数可作为甘薯秧茎叶离散元仿真参数。     

Potassium accumulation,partitioning, and remobilization in high-yield spring maize in Northeast China

Potassium (K) plays an important role in maize yield, but K accumulation characteristics in high yielding maize is still not well documented. A two-year field experiment was conducted to investigate the K accumulation characteristics of high yield (HY)（>15 t ha^?1）spring maize compared with medium yield (MY)（10–15 t ha^?1), and low yield (LY)（<10 t ha^?1). The maximum K accumulation stage in maize appeared between V6 and V12 stage (LY, MY, and HY was 125.46, 138.05, and 146.22?kg ha^?1, respectively). Most of the K (94.27–97.13%) was accumulated during vegetative stages. HY exhibited a significantly higher K accumulation than either MY or LY. For different organs, the K remobilization amount of leaf was the highest, and the remobilization amount of stalk was the lowest, the K remobilization amount of leaf and stalk showed as HY?<?MY?<?LY, same as the total K remobilization amount, but the K remobilization amount of sheath and husk plus cob showed the opposite order. These results indicated that sufficient nutrient supply for maize can not only accumulate more K but also delay leaf senescence and maintain high photosynthetic activity, resulting in reduced K remobilization from vegetative organs, and reduced K loss in whole plant.     

施肥对春青稞干物质积累、分配及产量的影响

为研究施肥对青稞干物质积累、分配及产量的调节作用,以‘藏青27’、‘QTB13’和‘QTB25’为试验材料,比较分析不同施肥处理下干物质积累、分配及产量的变化规律。结果表明：增加施肥量促进青稞分蘖期—成熟期的干物质积累及开花期和成熟期干物质向营养器官和籽粒的分配,提高了花前营养器官贮藏同化物转运量及对籽粒贡献率,降低了花后同化物输入籽粒量对籽粒贡献率。‘QTB13’和‘QTB25’在F₂条件下,更有利于干物质积累及向营养器官和穗部的分配,花后同化物输入籽粒量最大,产量也最大。‘藏青27’在F₃条件下,更有利于干物质积累及向营养器官和穗部的分配,花后同化物输入籽粒量和对籽粒贡献率最大,产量也最大。说明合理施肥有利于青稞干物质积累分配及产量提高。     

One-time fertilization at first flowering improves lint yield and dry matter partitioning in late planted short-season cotton

Cotton producers have substantially reduced their inputs(labor, nutrients, and management) mainly by adopting a shortseason cropping management that is characterized by late sowing, high density, and reduced fertilization with one-time application at the first bloom stage without lint yield reduction. However, it has been hypothesized that one-time fertilization at an earlier growth stage could be a more effective and economic management practice. A two-year field experiment was conducted by applying five fertilizer one-time fertilization at 0(FT1), 5(FT2), 10(FT3), 15(FT4), and 20(FT5) days after the first flower appeared in the field and one three-split fertilizer application taken as the conventional control(FT6), making six treatments altogether. Cotton growth period, biomass accumulation, yield, and its formation were quantified. The results showed that the one-time fertilization did not affect the cotton growth progress as compared to FT6, however, the total crop cycles for FT3–FT5 were 3 days shorter. FT1 produced the highest cotton lint yield(1 396 kg ha–1), which was similar to the FT6 but higher than the other treatments, and could be attributed to more bolls per unit area and higher lint percentage. Cotton yield was positively correlated with cotton plant biomass accumulated. FT1 had both the highest average(VT)(193.7 kg ha–1 d–1) and the highest maximum(VM)(220.9 kg ha–1 d–1) rates during the fast biomass accumulation period. These results suggest that one-time fertilizer application at the first flower stage might be an adjustment that is more effective than at first bloom, and allowed for easier decision making for application date due to non counting of plants with flowers is needed.     

Effects of post-silking water deficit on the leaf photosynthesis and senescence of waxy maize

Waxy maize is widely cultivated under rainfed conditions and frequently suffers water shortage during the late growth stage. In this study, a pot trial was conducted to examine the effects of post-silking drought on leaf photosynthesis and senescence and its influence on grain yield. Two waxy maize hybrids, Suyunuo 5(SYN5) and Yunuo 7(YN7), were grown under the control and drought(soil moisture content was 70–80% and 50–60%, respectively) conditions after silking in 2016 and 2017. The decrease in yield was 11.1 and 15.4% for YN7 and SYN5, respectively, owing to the decreased grain weight and number. Post-silking dry matter accumulation was reduced by 27.2% in YN7 and 26.3% in SYN5. The contribution rate of pre-silking photoassimilates transferred to grain yield was increased by 15.6% in YN7 and 10.2% in SYN5, respectively. Post-silking drought increased the malondialdehyde content, but decreased the contents of water, soluble protein, chlorophyll, and carotenoid in the leaves. The weakened activities of enzymes involved in photosynthesis(ribulose-1,5-bisphosphate carboxylase and phosphoenolpyruvate carboxylase) and antioxidant system(catalase, superoxide dismutase and peroxidase) reduced the photosynthetic rate(P_n) and accelerated leaf senescence. The correlation results indicated that reduced Pn and catalase activity and increased malondialdehyde content under drought conditions induced the decrease of post-silking photoassimilates deposition, ultimately resulted in the grain yield loss.     

Dietary α‐linolenic acid affects lipid metabolism and tissue fatty acid profile and induces apoptosis in intraperitoneal adipose tissue of juvenile grass carp (Ctenopharyngodon idella)

A 56‐day feeding trial was conducted to elucidate the effects and mechanism action of dietary α‐linolenic acid (ALA, 18:3n‐3) on lipid accumulation and fatty acid profile of muscle, hepatopancreas and intraperitoneal fat (IPF) in juvenile grass carp using three isonitrogenous and isoenergetic semi‐purified diets containing 0.0% (control group), 1.0% and 2.0% ALA, respectively. The lowest intraperitoneal fat (IPF) ratio was found in 2.0% group. In the muscle, hepatopancreas and IPF, docosahexaenoic acid (DHA, 22:6n‐3) and eicosapentaenoic acid (EPA, 20:5n‐3) contents increased with the increase in dietary ALA. In the IPF, caspase 3, caspase 8 and caspase 9 showed the highest activities in 2.0% group, while the value of Bcl‐2/Bax (B‐cell leukaemia 2/Bcl‐2‐associated X protein) reached the lowest. Meanwhile, swelling of the IPF mitochondria was observed in 2.0% group. The gene expressions of fatty acid desaturase (FAD) and fatty acid elongase (ELO) in the hepatopancreas and muscle showed significantly higher levels in the treatment groups, whereas an opposite trend was existed in the IPF. Fatty acid synthase (FAS), sterol regulatory element binding protein‐1c (SREBP‐1c) in the IPF and hepatopancreas reached the lowest in 2.0% group. Overall, dietary ALA could promote n‐3 highly unsaturated fatty acids (HUFAs) synthesis and suppress the accumulation of lipid by decreasing the expression of related genes and promoting the apoptosis in IPF.     

DPC~+化学封顶对不同施氮量下棉花叶片光合生理特性的影响

在北疆气候条件下,为明确棉花对不同施氮量下增效缩节胺[DPC+,25%甲哌鎓(1,1-dimethylpiperidinium chloride, DPC)水剂]化学封顶效应的响应,以新陆早53号为试验材料,在150(N1)、300(N2)和450(N3) kg hm~(–2)施氮水平下,以人工打顶(P0)为对照,研究DPC+剂量[450(P1)、750(P2)和1050(P3) mL hm~(–2)]对棉花叶绿素含量(Chl)、叶面积(LA)、气体交换参数、叶绿素荧光参数及干物质累积与分配的影响。结果表明,同一DPC+剂量下,随施氮量增加, Chl、LA、气体交换参数、叶绿素荧光参数和生殖器官干物质(RODM)均呈现先上升后下降的趋势;同一施氮量下,上述参数因DPC+剂量不同呈不同变化趋势,其中N1水平下以P1处理、N2水平下以P2处理、N3水平下以P3处理表现出较高的RODM、Chl、净光合速率(Pn)、实际光化学效率(ФPSII)、电子传递速率(ETR),较低的非光化学淬灭(NPQ)。DPC+与施氮量互作表现为,与其他处理相比, Chl、Pn、蒸腾速率(Tr)、气孔导度(Gs)、ФPSII、ETR、RODM在N2P2处理下分别提高了15.52%、29.39%、27.97%、36.77%、23.28%、23.55%、8.41%～22.24%, NPQ降低了34.54%。相关分析表明,干物质累积和Chl、LA、Pn、Gs、ФPSII均呈显著正相关,与NPQ呈极显著负相关。因此,在喷施DPC+(750 mL hm~(–2))条件下,适量追施氮肥(300kghm~(–2))能改善棉花光合性能,在增加干物质累积的基础上,促进了光合产物向生殖器官分配。     

鸡粪的施用对薄皮甜瓜果实糖积累及糖代谢相关酶活性的影响

为了探讨鸡粪以及鸡粪与尿素配施对薄皮甜瓜果实糖积累及糖代谢相关酶活性的影响,本试验以薄皮甜瓜DX108为试验材料,以尿素为氮源的处理为对照(CK),研究了相同施氮量条件下,鸡粪与尿素配施(A)以及鸡粪(B)对甜瓜果实葡萄糖、果糖和蔗糖含量的影响,分析了蔗糖磷酸合成酶(SPS)、蔗糖合成酶(SS,蔗糖合成与分解方向)、酸性转化酶(AI)和中性转化酶(NI)的活性。结果表明,与CK相比,B、A明显促进了果实中果糖、蔗糖及葡萄糖积累,尤其是显著增加了成熟果实中这3种糖的含量。相关性分析表明,CK的甜瓜果实蔗糖积累与AI活性呈显著负相关,葡萄糖与SPS和SS(蔗糖合成酶)合成方向酶活性呈显著正相关;A和B果实中蔗糖、葡萄糖和果糖积累(除B中葡萄糖积累)与SPS、NI活性呈显著或极显著正相关,与SS分解方向酶活性呈极显著负相关,而A果实中葡萄糖积累与SPS和NI活性呈极显著正相关。综上所述,A和B提高了果实中SPS、NI活性,降低了SS分解方向酶活性,进而促进了糖的积累。本研究结果为有机肥替代化学氮肥在甜瓜生产上的应用提供了理论依据。