生长调节剂对降香黄檀营养生长与生殖生长的影响

【目的】研究生长调节剂对降香黄檀Dalbergia odorifera营养生长与生殖生长的影响,为不同经营目标的降香黄檀人工林生产提供技术支撑。【方法】以10年生降香黄檀为研究材料,采用随机区组试验设计,通过叶面喷施3种不同浓度的赤霉素(GA3)、多效唑(PP333)和6-苄氨基嘌呤(6-BA),测定盛花期内一年生新梢、花、叶的形态生长和干质量变化,再运用统计分析软件,对各种生长调节剂处理后营养生长和生殖生长的变化规律进行分析。【结果】不同种类和不同浓度的生长调节剂对降香黄檀营养生长和生殖生长的影响差异均达显著水平(P0.05)。叶面喷施200、100 mg·L~(-1)的GA3和500 mg·L~(-1)的6-BA均能显著促进降香黄檀的营养生长,抑制其生殖生长;其中,200 mg·L~(-1)的GA3对生殖生长的抑制效果最理想,施用后其营养枝率比对照显著提高140.84%,花序数显著降低79.41%;100 mg·L~(-1)的GA3对营养生长效果显著,施用后其营养枝枝长、直径、复叶数和单叶干质量分别比对照提高218.08%、120.70%、132.38%和217.33%,且均达显著水平。1 500、2 000 mg·L~(-1)的PP333和50 mg·L~(-1)的6-BA均能显著促进降香黄檀的生殖生长,以2 000 mg·L~(-1)的PP333作用效果较好,处理后其花枝率、花序数量和花序径依次比对照提高73.50%、50.37%和31.30%,且均达显著水平。【结论】降香黄檀人工林培育中,叶面喷施200或100 mg·L~(-1) GA3能显著抑制生殖生长、促进营养生长,有利于大径级木材培育,2 000 mg·L~(-1)的PP333则有利于生殖生长,有利于良种壮苗生产。     

The positive function of selenium supplementation on reducing nitrate accumulation in hydroponic lettuce (Lactuca sativa L.)

High nitrate(NO_3~- ) in vegetables, especially in leaf vegetables poses threaten to human health. Selenium(Se) is an important element for maintaining human health, and exogenous Se application during vegetable and crop production is an effective way to prevent Se deficiency in human bodies. Exogenous Se shows positive function on plant growth and nutrition uptake under abiotic and/or biotic stresses. However, the influence of exogenous Se on NO_3~- accumulation in hydroponic vegetables is still not clear. In the present study, hydroponic lettuce plants were subjected to six different concentrations(0, 0.1, 0.5, 5, 10 and 50 μmol L–1) of Se as Na2 Se O3. The effects of Se on NO_3~- content, plant growth, and photosynthetic capacity of lettuce(Lactuca sativa L.) were investigated. The results showed that exogenous Se positively decreased NO_3~- content and this effect was concentration-dependent. The lowest NO_3~- content was obtained under 0.5 μmol L–1 Se treatment. The application of Se enhanced photosynthetic capacity by increasing the photosynthesis rate(Pn), stomatal conductance(Cs) and the transpiration efficiency(Tr) of lettuce. The transportation and assimilation of NO_3~- and activities of nitrogen metabolism enzymes in lettuce were also analysed. The NO_3~- efflux in the lettuce roots was markedly increased, but the efflux of NO_3~- from the root to the shoot was decreased after treated with exogenous Se. Moreover, Se application stimulated NO_3~- assimilation by enhancing nitrate reductase(NR), nitrite reductase(Ni R), glutamine synthetase(GS) and glutamate synthase enzyme(GOGAT) activities. These results provide direct evidence that exogenous Se shows positive function on decreasing NO_3~- accumulation via regulating the transport and enhancing activities of nitrogen metabolism enzyme in lettuce. We suggested that 0.5 μmol L–1 Se can be used to reduce NO_3~- content and increase hydroponic lettuce yield.     

一个黄麻矮秆种质株高性状对外源激素的敏感性

【目的】探索黄麻矮秆种质爱店野黄麻株高对不同外源激素的敏感性,进而确定该种质属于哪种激素敏感型,为后续利用该矮秆种质剖析黄麻株高的遗传基础与激素调控的关系提供依据。【方法】首先,比较分析爱店野黄麻与正常株高的栽培品种黄麻179株高等重要农艺性状。其次,以爱店野黄麻为材料,用不同浓度的赤霉素（GA₃）、油菜素类固醇（BR）和生长素（IAA）处理,比较分析MS培养基条件下不同处理间下胚轴的长度和叶面喷施大田条件下不同处理间株高的变化;同时,比较分析爱店野黄麻与黄麻179在MS培养基条件下GA₃处理间下胚轴的长度。再次,每隔3 d,叶面喷施一次浓度100 mg·L^-1GA₃,分析连续喷施GA₃对爱店野黄麻株高的恢复程度。继而,分析爱店野黄麻在一次喷施GA₃处理后α-淀粉酶活性的变化。【结果】没有用激素处理条件下,爱店野黄麻和黄麻179株高分别为1.89 和4.28 m,两者之间差异达极显著水平,表明爱店野黄麻是一份典型的矮秆种质。在0.1 mg·L^-1外源IAA和BR的MS培养基条件下,爱店野黄麻下胚轴与未处理的爱店野黄麻相比,差异不显著;但在0.1 mg·L^-1外源GA₃的MS培养基条件下,爱店野黄麻下胚轴长度明显高于未处理的爱店野黄麻,差异达到极显著水平,而且未处理的黄麻179与外源GA₃处理的爱店野黄麻、黄麻179的下胚轴长度相当,初步表明爱店野黄麻为植株体内赤霉素敏感型,外施GA₃后爱店野黄麻下胚轴有显著的增长,黄麻179没有明显的变化。在不同浓度外源激素大田的叶面喷施条件下,高浓度（100 mg·L^-1）的GA₃ 处理的爱店野黄麻株高变化量均显著高于另2个较低浓度GA₃;但不同浓度IAA和BR处理后,爱店野黄麻株高与未处理的爱店野黄麻对照相比,差异不显著,进一步表明爱店野黄麻为赤霉素敏感型植株。在大田叶面喷施条件下,100 mg·L^-1的外源GA₃连续处理后,爱店野黄麻的株高明显高于未处理的爱店野黄麻,差异达到极显著水平,而且其株高接近黄麻179水平,表明外源赤霉素GA₃连续处理可以使该矮秆种质植株的株高恢复到正常栽培种的株高水平。酶活性分析试验中,一次喷施100 mg·L^-1 GA₃激素处理后,第3天α-淀粉酶活性与处理前相比开始升高,直到第6天,α-淀粉酶活性显著增强,表明GA₃能诱导爱店野黄麻的α-淀粉酶活性提高。【结论】爱店野黄麻是一份典型的黄麻矮秆种质,该种质对外源IAA和BR不敏感,对外源GA3敏感;连续用GA₃处理可以恢复其株高,外源GA₃可以诱导其α-淀粉酶活性增强,该种质是GA₃敏感型的矮秆种质资源。     

化学药剂处理对蕹菜种子发芽的影响

采用培养皿发芽法,研究了化学药剂处理对蕹菜种子发芽的影响。结果表明,GA3 Ca2 混合液处理蕹菜种子,对促进种子发芽和提高种子活力表现加成作用,以50 g/L GA3 5mmol/L Ca2 处理较为适宜。蕹菜种子经稀盐酸预处理1 h后,以100 mg/L GA3浸种处理,可明显提高种子发芽势和活力指数,促进种子发芽。用30~50 mmol/L的低浓度NaCl胁迫处理蕹菜种子,能提高种子发芽率,但随着NaCl胁迫浓度的增大,对发芽抑制作用明显增强。低浓度(0.05%~0.07%)ZnSO4浸种可促进种子发芽,高浓度(>0.09%)则抑制种子发芽。     

Study on Agrobacterium-Mediated Transformation of Pepper with Barnase and Cre Gene

This study was designed to control plant fertility by cell lethal gene Barnase expressing at specific developmental stage and in specific tissue of male organ under the control of Cre/lox system, for heterosis breeding of chili pepper （Capsicum annuum L.）. Chili pepper inbred lines （A, D, E, and I） were transformed with Cre gene and Barnase gene situated between loxp, separately, by means of Agrobacterium co-culture. In this study, we had established a high transformation system by extensive study of affecting factors including genotype, selection of marker, and lethal dose. Cotyledon with petiole from 9-11-day-old seeding was pre-cultured on media MR[MB（MS mineral＋vitamine B5）＋BA（6-Benzyladenine） 5.0 mg·L^-1 ＋IAA（indoleacetic acid） 1.0 mg·L^-1＋GA3（gibberellic acid） 1.0mg·L^-1＋sucrose 3%＋agar 6.5g·L^-1] for 2d. The explants were infected by Agrobacterium tumefaciens when their OD600（optical density at 600 nm）reached 0.6-0.9. After co-cultured for 4-5 d on media MC [MB＋BA5.0 mg·L^-1＋IAA 1.0 mg·L^-1 ＋GA3 1.0 mg·L^-1＋sucrose 3% ＋agar 6.5 g·L^-1＋AS （acetosyringone） 200μmol·L^-1, these cotyledons with petiole were cultured on selective differentiation medium in the media MT[MB medium supplemented with BA [5.0 mg·L^-1＋ IAA 1.0 mg·L^-1＋ GA3 1.0 mg·L^-1＋ AgNO3 5.0 mg·L^-1＋ CW （coconut water） 5% ＋ Km （kanamycin） 65 mg·L^-1＋ Cb （carbenicillin） 500 mg·L^-1＋ 3% sucrose ＋ agar 6.5 g·L^-1].The Kmr （kanamycin resistant） bud rosettes were elongated on selective elongation medium and rooted on rooting medium. PCR and Southern blotting analysis of Kmr plantlet indicated that the foreign genes had been integrated into the genome of pepper. The transgenic plants with Cre gene developed well, blossomed out, and set fruit normally. The transgenic plants with Barnase gene grew well with normal appearance of flower, but they showed different fertility from complete sterility, partial sterility to complete fertility, and similar results were obtained from in vitro pollen germination experiments.     

Physiological and Biochemical Changes of IrlVHA-c gene Transgenic Tobacco Seedlings and Self-crossed Progeny Under NaHCO3 Stress

In order to study the alkali resistivity of VHA-c in Iris lacteal. (IrlVHA-c), the transgenic tobacco seedlings harboring IrlVHA-c gene from Iris lactea (T0), the self-crossed progeny (T1), and the non-transgenic lines of tobacco seedlings were grown in Hoagland nutrient solutions supplemented with 0, 100, 200, 300, 400 mmol·L-1 NaHCO3 . The MDA content, CAT, POD and SOD activity, electrical conductivity, chlorophyll content, soluble sugar content, proline content and polyphenol oxidase activity of the seedlings were determined. The results showed that the transgenic lines of tobacco maintained a high activity up to 200 mmol·L-1 NaHCO3 , and activity was slightly lower at 300 mmol·L-1 NaHCO3 . When the concentration of NaHCO3 was as high as 400 mmol·L-1 the seedlings were badly hurt. In addition, the activity of T0 and T1 transgentic tobacoo was maintained more or less. While the non-transgenic lines of tobacco could maintain viably up to 100 mmol·L-1 NaHCO3 , and they could not survive at 400 mmol·L-1 NaHCO3 . The conclusion was drawn that the alkali resistance of the tobacoo transformed IrlVHA-c was noticeably improved.     

喷施外源激素对苦荞籽粒产量和黄酮含量的影响

以2份苦荞材料威苦1号和黔苦6号为试验材料,在花蕾期进行不同浓度的外源激素全株喷施处理,测定了其产量和品质的变化。结果表明,不同浓度外源激素处理对苦荞的产量和品质有一定影响。适宜浓度的外源GA₃、IAA喷施荞麦均可提高其产量,其中GA₃、IAA的最适浓度分别为80和110 mg·L^-1。喷施外源GA₃威苦1号籽粒黄酮含量比不施用降低,而低浓度GA₃处理黔苦6号时,其籽粒黄酮含量升高;喷施低浓度外源IAA时,威苦1号籽粒黄酮含量升高,而喷施外源IAA黔苦6号籽粒黄酮含量比不施用降低。     

适宜氮水平下冬油菜苗期不同叶位叶片光合氮分配特征

【目的】探讨适宜氮水平下冬油菜苗期不同叶位叶片的光合速率及其内部光合氮素利用特征,并分析氮素营养影响光合氮利用效率的限制因子,为合理施用氮肥提供理论依据。【方法】采用田间试验,设置4个施氮水平(0、45、180和360 kg·hm~(-2),分别用N_0、N_(45)、N_(180)和N_(360)表示),测定苗期干物质积累及成熟期产量。选取N_0(对照)和N_(180)(适宜氮水平)处理,将植株绿叶从上而下平均分为上部、中部和下部,测定不同叶位叶片最大净光合速率(P_n max)、氮含量(N_A)、叶绿素含量(Cc)以及可溶性蛋白氮含量(N_S)等相关生理、光合参数,并计算叶片氮素在光合组织系统(羧化系统、生物力能学组分和捕光系统)的分配比例,分析叶片氮素利用特征。【结果】施氮对冬油菜增产效果显著,N_(45)、N_(180)和N_(360)较N_0处理增产幅度分别达170.0%、505.6%和604.1%,其中,N_(180)与N_(360)处理产量差异不显著;苗期干物质积累与产量表现一致。与N_0处理相比,N_(180)处理冬油菜不同叶位叶片N_A、Cc和P_n max均显著升高,上部和中部叶片光合氮利用效率(P_NUE)有所下降。光合组织系统氮分配结果表明,N_(180)处理上部、中部叶片,氮素在光合组织系统中羧化系统(P_C)、生物力能学组分(P_B)及捕光系统(P_L)的分配比例均低于N_0处理,但各组分氮含量较N_0处理平均增加幅度分别达到20.6%、11.8%和28.8%。施氮与否对相同叶位叶片可溶性蛋白氮(N_S)与非可溶性蛋白氮(N_(non-S))的比例影响不大,但显著影响光合组织系统在N_S和N_(non-S)中的分配,其中N_0处理各部叶片的羧化系统氮含量(NC)占N_S的比例平均为83.4%,N_(180)处理比例为60.3%。基于边界线分析法定量各光合组织系统分配对P_NUE的影响结果表明,P_C和P_B对P_NUE的影响大小分别为26.8%和42.6%,显著高于P_L的影响。氮素营养对P_NUE的影响以P_C和P_B限制为主,平均所占比例达77.8%。上部叶P_NUE主要受P_C限制,所占比例达83.3%;而下部叶片P_NUE主要受P_B和P_L限制。【结论】施氮对冬油菜增产效果显著,施氮量为180 kg·hm~(-2)时较为适宜。缺氮条件下,植株将有限的氮尽可能地向光合器官中分配,且下部叶片光合氮素较早发生降解,而适宜氮水平下能维持光合蛋白在各自蛋白类型内的分配比例。氮素营养限制光合氮素利用效率提高的主要因子是羧化系统和生物力能学组分氮分配;随着叶位的降低光合氮素利用效率的主要限制因子由羧化系统氮分配逐渐转变为捕光系统及生物力能学组分氮分配。     

Interactive effects of elevated carbon dioxide and nitrogen availability on fruit quality of cucumber (Cucumis sativus L.)

Elevated CO_2 and high N promote the yield of vegetables interactively, whilst their interactive effects on fruit quality of cucumber(Cucumis sativus L.) are unclear. We studied the effects of three CO_2 concentrations(400 μmol mol–1(ambient), 625 μmol mol–1(moderate) and 1 200 μmol mol–1(high)) and nitrate levels(2 mmol L~(–1)(low), 7 mmol L~(–1)(moderate) and 14 mmol L~(–1)(high)) on fruit quality of cucumber in open top chambers. Compared with ambient CO_2, high CO_2 increased the concentrations of fructose and glucose in fruits and maintained the titratable acidity, resulting in the greater ratio of sugar to acid in moderate N, whilst it had no significant effects on these parameters in high N. Moderate and high CO_2 had no significant effect on starch concentration and decreased dietary fiber concentration by 13 and 18%, nitrate by 31 and 84% and crude protein by 19 and 20% averagely, without interactions with N levels. The decreases in amino acids under high CO_2 were similar, ranging from 10–18%, except for tyrosine(50%). High CO_2 also increased the concentrations of P, K, Ca and Mg but decreased the concentrations of Fe and Zn in low N, whilst high CO_2 maintained the concentrations of P, K, Ca, Mg, Fe, Mn, Cu and Zn in moderate and high N. In conclusion, high CO_2 and moderate N availability can be the best combination for improving the fruit quality of cucumber. The fruit enlargement, carbon transformation and N assimilation are probably the main processes affecting fruit quality under CO_2 enrichment.     

Optimizing nitrogen levels combined with gibberellic acid for enhanced yield, photosynthetic attributes, enzyme activities, and artemisinin content of Artemisia annua

Artemisia annua L. is an aromatic-antibacterial herb that destroys malarial parasites, lowers fever, and checks bleeding, and from which the secondary compound of interest is artemisinin. It has become increasingly popular as an effective and safe alternative therapy against malaria, and its derivatives are effective against multidrug resistant Plasmodium falciparum strains. Nitrogen is required by the plants in the largest quantity and is most limiting where biomass production is desired. On the other hand, gibberellic acid plays an important role in flowering, growth, and development and also in other physiological and biochemical processes. The feasibility of foliar GA₃ (75 mg·L⁻¹) alone or with varying levels of soil applied nitrogen (40, 80, and 120 mg·kg⁻¹ soil) was tested on A. annua in the present study. The application of GA₃ proved effective in alleviating the growth, photosynthesis, and enzyme activities of A. annua. However, N levels combined with GA₃ showed better responses, and further improvement in these parameters was observed. Furthermore, the most important task we were interested in was to increase the artemisinin content and its yield on a per plant basis. The N combination (80 mg·kg⁻¹ soil) together with GA₃ augmented the content (21.8% more) and yield (55.8% more); this is true for both the treated plants, which were more than the control.     

Exogenous Hydrogen Sulfide Enhanced Antioxidant Capacity,Amylase Activities and Salt Tolerance of Cucumber Hypocotyls and Radicles

In the present experiment, effects of sodium hydrosulfide (NaHS), a H₂S donor, on the oxidative damage, antioxidant capacity and the growth of cucumber hypocotyls and radicles were studied under 100 mmol L^?1 NaCl stress. NaCl treatment significantly induced accumulation of H₂O₂ and thiobarbituric acid-reactive substances (TBARS) in cucumber hypocotyls and radicles, and application of NaHS dramatically reduced the accumulation of H₂O₂ and lipid peroxidation. However, the alleviating effects greatly depended on the concentrations of NaHS, and 400 μmol L^?1 NaHS treatment showed the most significant effects. Corresponding to the change of lipid peroxidation, higher activities of antioxidant enzymes as well as the antioxidant capacity indicated as DPPH scavenging activity, chelating activity of ferrous ions and hydroxyl radical (·OH) scavenging activity were induced by NaHS treatment under NaCl stress, especially by 400 μmol L^?1 NaHS treatment. With the alleviating lipid peroxidation, the amylase activities in cotyledons were increased, and the length of cucumber hypocotyls and radicles were significantly promoted by NaHS treatment under NaCl stress. Unlike the effects of NaHS, pretreatment with other sodium salts including Na₂S, Na₂SO₄, NaHSO₄, Na₂SO₃, NaHSO₃ and NaAc did not show significant effects on the growth of cucumber hypocotyls and radicles. These salts do not release H₂S. Based on above results, it can be concluded that the effects of NaHS in the experiment depended on the H₂S rather than other compounds derived from NaHS, and the alleviating effects might related with its function in modulating antioxidant capacity and amylase activities.     

Effects of Chlorine Dioxide Gas on Postharvest Physiology and Storage Quality of Green Bell Pepper （Capsicum frutescens L. var. Longrum）

The effects of treatment of chlorine dioxide (ClO2) gas on postharvest physiology and preservation quality of green bell peppers were studied. Green bell peppers were collected in bags and treated with 0, 5, 10, 20, and 50 mg L-1 ClO2 gas at 10 ± 0.5℃ for over 40 d, and the changes in postharvest physiology and preservation quality of the peppers were evaluated during the storage. The inhibition of rot of the peppers was observed for all the tested ClO2 gas treatments. The rot rates of the treated samples were 50% lesser than those of the control after day 40 of storage. The highest inhibitory effect was obtained after 50 mg L-1 ClO2 gas treatment, where the peppers did not decay until day 30 and showed only one-fourth of the rot rate of the control at day 40 of storage. The respiratory activity of the peppers was significantly (P ＜ 0.05) inhibited by 20 and 50 mg L-1 ClO2 treatments, whereas no significant effects on respiratory activity were observed with 5 and 10 mg L-1ClO2 treatments (P＞ 0.05). Except for 50 mg L-1 ClO2, malondialdenyde (MDA) contents in the peppers treated with 5,10, or 20 mg L-1 ClO2 were not significantly (P＞0.05) different from those in the control. Degradation of chlorophyll in the peppers was delayed by 5 mg L-1 ClO2, but promoted by 10, 20, or 50 mg L-1 ClO2. The vitamin C content, titratable acidity,and total soluble solids of the peppers treated by all the tested ClO2 gas did not significantly change during the storage.The results suggested that ClO2 gas treatment effectively delayed the postharvest physiological transformation of green peppers, inhibited decay and respiration, maintained some nutritional and sensory quality, and retarded MDA accumulation.     

采用均匀设计法优化西选二号培养基配比

以西选二号为试材,运用均匀试验设计方法调整植物生长调节剂的浓度和种类,通过建立回归模型筛选出适宜于西选二号植株愈伤组织形成、不定芽诱导和植株生根的最佳配方.结果表明:以MS+0.5 mg·L-16-BA+0.1 mg·L-1NAA作为愈伤组织的诱导培养基,可以获得92%的愈伤组织诱导率.MS+3.0 mg·L-16-BA +0.1 mg·L-1NAA可作为芽诱导培养基,其芽分化率为90%.使用芽诱导培养基,附加0.6 mg·L-1GA3作为增殖继代培养基为宜.在1/2MS+1.0 mg·L-1 IBA+0.2 mg·L-1NAA培养基中,芽苗诱导生根效果较佳.小植株炼苗移栽成活率达85%.     

Response of axillary bud development in garlic(Allium sativum L.) to seed cloves soaked in gibberellic acid(GA_3) solution

Gibberellins(GAs) are important phytohormones that regulate many developmental processes in plants. Clove, as the reproductive organ of garlic, dramatically affected garlic bulb development. Considering the potential of gibberellins in plant development and our previous studies, we investigated the effect of soaking two types of seed cloves(seed clove-I: without root/shoot sprouting; seed clove-II: with root/shoot sprouting) in GA_3 solution on axillary bud development and examined the effect of soaking seed cloves in GA_3 solution on bulb development, phytohormone level and sugar content in this study.Results indicated seed clove types, soaking liquids and their interaction significantly affected the number of cloves per bulb and the rate of single-clove bulb. Moreover, soaking seed cloves in 1 mmol L~(–1) GA_3 solution for 24 h not only promoted axillary bud formation and secondary plant growth(equal to tillering or branching), but also slightly increased the number of cloves per bulb and changed bulb structure with a low yield and marketable quality. On the 40 th day after GA_3 treatment(at axillary bud outgrowth stage), zeatin riboside(ZR) and soluble protein in stem were sharply increased with the increase of GA_3, sucrose, fructose and soluble protein in leaf. However, GA_3, indole~(-3)-acetic acid(IAA), soluble sugar and sucrose in stem(3.52 ng g~(–1) fresh weight(FW), 19.88 ng g~(–1) FW, 237.3 mg g~(–1) FW, and 8.24 mg g~(–1) FW, respectively) were significantly decreased on the 40 th day after GA_3 treatment, compared to the control of water treatment(5.56 ng g~(–1) FW, 32.96 ng g~(–1) FW, 263.6 mg g~(–1) FW, and 10.37 mg g~(–1) FW, respectively). To our knowledge, these novel results indicate seed cloves soaked in GA_3 solution promotes axillary bud formation and outgrowth that caused the changes in plant architecture and bulb structure. Meanwhile, our findings suggest that the level of endogenous plant hormone(GA_3, IAA and ZR) cooperates with the content of sugar(sucrose and fructose) in leaf and stem to regulate axillary bud outgrowth in garlic.     

Variety-specific responses of lettuce grown in a gravel-film technique closed hydroponic system to N supply on yield,morphology, phytochemicals,mineral content and safety

Utilization of nitrogen(N) element is a common practice used to reach profitable yields in horticultural crops and N supply can be used as a tool to manipulate the enhancement of phytochemicals and minerals in vegetable crops to address consumeroriented quality production. Hence the study was aimed to investigate the effect of N application on leaf morphology, ascorbic acid content, phenolic acids, flavonoids, mineral content, and nitrate residues in three lettuce varieties(two green leafy lettuce, Multigreen 1 and Multigreen 3; one red leafy lettuce, Multired 4) grown in a closed hydroponic system(gravel-film) at harvest. Nitrogen was applied as ammonium nitrate(NH_4 NO_3) at six different concentrations of 0, 60, 90, 120, 150 and 180 mg L~(–1). The results obtained during 2015 and 2016 seasons were similar and demonstrated variety dependent responses with respect to different N application rates. Multigreen 3 was more sensitive to N supply and showed higher amount of nitrate residue at harvest. Variety Multired 4 was less sensitive to N supply followed by Multigreen 1. Although N supply at 120 mg L~(–1) improved the yield and the number of leaves in Multigreen 3, overall 90 mg L~(–1) can be recommended for these lettuce varieties to improve the yield and the accumulation of ascorbic acid content, phenolic acids mainly caffeic, caftaric acids, quercetin(the important flavonoid in lettuce), and Fe and Mn contents. Furthermore, the concentration of 90 mg L~(–1) improved the antioxidant property(FRAP and ABTS~+) and reduced the nitrate accumulation, ensuring safe food for consumers.     

添加生物黑炭对茶园土壤CO2、N2O排放的影响

采用室内培养试验,研究了不同生物黑炭施用量对两种茶园土壤(红壤和黄壤)CO₂、N₂O排放特征的影响。生物黑炭用量设5个水平:H0(0 g·kg^-1)、H1(3.56 g·kg^-1)、H2(7.11 g·kg^-1)、H3(14.22 g·kg^-1)、H4(28.44 g·kg^-1).结果表明:红壤茶园土壤CO₂排放量显着高于黄壤,N₂O排放总量则低于黄壤;与H0处理相比,施用低量的生物黑炭(H1)对两种茶园土壤CO₂排放无显着影响;高量的生物黑炭处理(H3、H4)则显着增加土壤CO₂排放量,增幅为20%~47%(P<0.05).生物黑炭施用后(H2、H3、H4)明显降低两种茶园土壤N₂O释放速率及反硝化损失率,土壤N₂O排放总量降幅为37%~63%(P<0.05),反硝化损失量降幅22%~54%(P<0.05),且均随着生物黑炭施用量增加而增大。此外,从土壤pH值、无机氮含量和硝化率角度,探讨了生物黑炭影响茶园土壤CO₂和N₂O排放的因素。     

氮钾配施下施磷对冬小麦群体发育特性、冠层光截获及产量的影响

【目的】明确一定氮钾配施条件下不同施磷水平对冬小麦群体发育特性、冠层截获光合有效辐射(IPAR)及产量的影响,同时分析IPAR与LAI之间的相关性,为在一定氮钾配施下筛选出适宜的磷肥用量提供理论依据。【方法】以郑麦7698为试验材料,设低氮低钾N_1K_1(N 225 kg·hm~(-2)、K_2O 150 kg·hm~(-2))、低氮高钾N_1K2(N 225 kg·hm~(-2)、K_2O 225 kg·hm~(-2))、高氮低钾N_2K_1(N 300 kg·hm~(-2)、K_2O 150 kg·hm~(-2))、高氮高钾N_2K_2(N 300 kg·hm~(-2)、K_2O 225 kg·hm~(-2))4个氮钾配施比例,每个氮钾配施设置5个施磷水平:P0(不施磷)、P1(P_2O_5 150 kg·hm~(-2))、P_2(P_2O_5 225 kg·hm~(-2))、P~(-2)3(P_2O_5 300 kg·hm2)、P4(P_2O_5 375 kg·hm-),共20个处理。对小麦群体动态、叶面积指数(LAI)、开花后干物质积累、冠层截获光合有效辐射(IPAR)、产量等指标进行测定分析。【结果】(1)在4种氮钾配施下,施P_2O_5 0—225 kg·hm~(-2)时,随施磷量的增加,总茎蘖数、开花后干物质积累及LAI均增加,施P_2O_5超过225 kg·hm~(-2)时,各指标均有所下降,以施P_2O_5 225 kg·hm~(-2)水平群体指标最佳。(2)氮钾配施固定条件下,不同施磷水平小麦冠层截获光合有效辐射值(IPAR)的大小顺序均为P_2P1P3P4P0,且P_2水平IPAR值最高,增幅最大。不同氮钾配施下以N_1K_1条件IPAR增幅最多。(3)4种氮钾配施条件下IPAR与LAI均呈指数正相关关系,N_1K_1、N_1K2、N_2K_1、N_2K_2条件下不同施磷水平小麦IPAR与LAI的拟合系数分别为0.8492、0.8363、0.7321、0.8081。产量与LAI在二阶多项式函数关系上拟合度较好,拟合系数为0.7145。(4)从3个年度各处理产量来看,适当增施磷肥有利于提高小麦的籽粒产量,但磷肥增加到一定程度小麦产量又呈下降趋势,不同氮钾配施下N_1K_1处理产量水平最高,氮钾配施固定条件下,不同施磷水平的产量及增产率均为P_2(P_2O_5 225 kg·hm~-2))时最高。【结论】本研究条件下,N_1K_1P_2(N_225 kg·hm~(-2)、K_2O 150 kg·hm~(-2)、P_2O_5 225 kg·hm~(-2))处理可以优化小麦群体结构,提高LAI,增加开花后干物质积累,提高IPAR和籽粒产量。     

Short Response of Spring Wheat to Tillage,Residue Management and Split Nitrogen Application in a Rice-Wheat System

A field experiment was conducted to study the impact of tillage, crop residue management and nitrogen (N) splitting on spring wheat (Triticum aestivum L.) yield over 2 yr (2010-2012) in a rice (Oryza sativa L.)-wheat system in northwestern Pakistan. The experiment was conducted as split plot arranged in randomized complete blocks design with three replications. Treatments comprised six tillage and residue managements: zero tillage straw retained (ZTsr), zero tillage straw burnt (ZTsb), reduced tillage straw incorporated (RTsi), reduced tillage straw burnt (RTsb), conventional tillage straw incorporated (CTsi), and conventional tillage straw burnt (CTsb) as main plots and N (200 kg ha⁻¹) was applied as split form viz., control (no nitrogen & no splitting, N₀S₀); 2 splits of total N, half at sowing and half at the 1st irrigation (i.e., 20 d after sowing (DAS)) (NS₁); 3 splits of total N, 1/3 at sowing, 1/3 at the 1st irrigation, and 1/3 at the 2nd irrigation (NS₂); 4 splits of total N, 1/4 at sowing, 1/4 at the 1st irrigation, 1/4 at the 2nd irrigation (45 DAS), and 1/4 at the 3rd irrigation (70 DAS) (NS₃); and 4 splits of total N, 1/4 at the 1st irrigation, 1/4 at the 2nd irrigation, 1/4 at the 3rd irrigation, and 1/4 at the 4th irrigation (95DAS) (NS₄) as sub plots. The results showed that the most pikes m⁻², grains/spike, 1000-grain weight, grain yield, and N use efficiency (NUE) were obtained at zero tillage, straw retained and 4 splits application of total N (i.e., at sowing 20, 45 and 70 d after sowing). The results indicated that ZTsr with application of 200 kg N ha⁻¹ in 4 equal splits viz. at sowing 20, 45 and 70 d after sowing is an appropriate strategy that enhanced wheat yield (7436-7634 kg ha⁻¹) and N efficiency (28.6-29.5 kg kg⁻¹) in rice-wheat system.