密度是影响产量的关键因素。以半紧凑型品种金海5号和紧凑型品种郑单958为材料，研究了种 植密度对不同株型的玉米农艺、根系性状及产量的影响。结果表明：随群体密度的增加植株高度增高、茎粗、穗粗变细，果穗变短，秃尖长度、穗位节数和穗位高度 呈现增加的趋势；气生根与总根数减少，耕层根系干重比例增加。群体干物质积累量随密度增加而增加，单株干物质积累量呈相反的趋势；穗行数、穗粒数、百粒 重、双穗率、单株产量均随密度的增加而减低，群体产量先增后降。金海5号产量与密度的关系为Y=-625．67x^2＋9044．5x-18530，适宜 种植密度为7．0万～7．5万株／hm^2；郑单958产量与密度的关系为y=-375．67x^2＋6410x～13043，适宜种植密度为8．5 万～9．0万株/hm^2。分析表明，气生根数量和总根数量可作为衡量单株干物质积累量大小和产量高低的指标。

以两种不同耐密性的4个玉米品种为材料,探讨在不同密度压力下茎秆性状的变化,重点研究了地面上第三节茎秆形态及内部中央大维管束生理结构的变化,并分析了各性状与倒伏的关系。结果表明,不同类型间和同类型不同品种间对密度的反应存在明显差异。郑单958和辽单526对密度变化更加敏感。4个品种的田间倒伏率与种植密度、茎秆第三节的长粗比、茎秆中央大维管束单位视野个数呈显著正相关;与第三节茎粗、中央大维管束的平均面积呈负相关。

以秋冬季塑料大棚中盆栽西瓜幼苗为材料，研究了50～200mg／L 5-氨基乙酰丙酸（ALA）处理对低温弱光条件下西瓜植株光合特性、碳水化合物积累、抗氧化酶活性和丙二醛（MDA）含量的影响。结果表明，外源ALA处理显著提高了西瓜幼苗叶片净光合速率（Pn）、气孔导度（Gs）和蒸腾速率（Tr）。ALA处理还显著提高了叶片SOD和POD等抗氧化酶活性，但对CAT及APX活性影响不大，暗示ALA处理可能主要通过提高植株SOD和POD活性来促进西瓜幼苗活性氧代谢，从而保护细胞光合性能。处理后30d分析表明，ALA处理植株干物质重量比对照高出42％～54％，淀粉含量增加62．2％～207．0％，可溶性糖含量也增加32．0％～87．1％。以上结果说明，ALA处理可以增强低温弱光条件下西瓜幼苗抗氧化系统活性，促进光合作用与光合产物积累，并促进植株生长。

The role of 5-aminolevulinic acid (5-ALA) as a precursor of chlorophyll and a herbicide is well documented. 5-ALA as a Plant Growth substance is also proven in recent times. In the present report, to elucidate the physiological effects of 5-ALA, the compound was used in in vitro studies using MS medium supplemented with 5-ALA at 2, 5 and 10 mg l -1 . Leaf and cotyledonary node were used as the explants. In vitro studies confirmed the hormonal role of 5-ALA by striking proliferation of callus paripassu induction of rooting and shooting with a profound effect of the former than the latter. Thus, 5-ALA has the dual properties of auxin and cytokinin in the induction of callusing and rhizogenesis, and shooting respectively.

In order to utility ALA in summer squash, we need a better understanding of the mechanism of ALA to photosynthetic and physiological characteristic of summer squash. Using ‘Zaoqingyidai’ as experiment material, an experiment was conducted to examine the effects of 5-aminolevulinic acid (ALA) on photosynthetic characteristics of leaves of summer squash seedlings under chilling stress. The results were as follows: Under chilling stress，the chlorophyll contents decreased, net photosynthesis rate (Pn), leaf area and dry matter of per seedling decreased greatly. ALA of 60 mg/L could relieve the effects of chilling on summer squash seedlings by increasing chlorophyll contents, photosynthesis rate, the leaf area and dry matter with 29.96%, 52.96%, 39.80% and 43.75% respectively. Because of increasing the chlorophyll contents and decreasing nonstomatal limitation effects, ALA of 60 mg/L could relieve some of the effects of chilling stress on summer squash seedlings.

以盆栽萝卜为材料,研究了叶面喷布100～300mg/LALA对萝卜植株生长、光合作用以及叶绿素荧光特性的影响.结果表明,ALA促进萝卜植株生长与其促进植株中下部叶片的光合作用有关.ALA处理提高了叶片光合表观量子效率,并降低了光补偿点.叶绿素荧光动力学资料显示,ALA处理不仅降低了叶绿素初始荧光Fo、稳态荧光Fs以及两者的差值ΔFo,还降低了暗适应以及光照下的最大荧光(Fm和Fm′)和可变荧光(Fv和Fv′),但是不影响PSⅡ最大光化学效率(Fv/Fm),对于中下部叶片PSⅡ实际光化学效率(ΦPSⅡ)还有明显的促进作用.ALA处理植株叶片光合非循环电子传递速率ETR显著提高,300mg/LALA处理还降低了光合相对限制值L(PFD).ALA具有促进叶绿素荧光光化学猝灭和非光化学猝灭的双重特性,其中,前者提高了叶片光化学速率,后者增加热耗散量以及提高热耗散速率.另外,本试验结果显示,ALA处理提高了植株基部叶片的叶绿素含量以及中下部叶片类萝卜素含量.以上参数变化说明ALA通过诱导光抑制保护机制来提高叶片光合效率.

为探究外源5-氨基乙酰丙酸（ALA）对低温胁迫下玉米幼苗生长及光合特性的调控效应,以绥玉13（低温敏感型）和郑单958（耐低温型）为试验材料,于三叶一心期叶面喷施20mg/L ALA,在昼/夜温度为14℃/5℃的低温条件下培养48h,恢复常温48h后取样,分析外源ALA对玉米幼苗生长、叶绿素含量、光合作用参数及叶绿素荧光特性的影响。结果表明：低温胁迫显著抑制两个玉米品种幼苗的株高、叶面积、鲜重和干重。低温处理导致幼苗SPAD值下降,叶片净光合速率（P_n）、蒸腾速率（T_r）、气孔导度（G_s）、胞间CO_2浓度（C_i）、最大荧光（F_m）、最大光化学效率（F_v/F_m）、潜在光化学效率（F_v/F_o）及光化学猝灭系数（q_P）水平降低,初始荧光（F_o）和非光化学猝灭系数（NPQ）升高。外源ALA能够促进低温胁迫下玉米幼苗形态建成与物质积累,叶片SPAD值增加。外源ALA能够缓解由低温胁迫导致的叶片P_n、T_r、G_s和C_i下降,提高F_m、F_v/F_m、F_v/F_o及q_P水平,降低F_o和NPQ水平。由此可见,外源ALA能够促进叶片光合作用,提高PSⅡ反应活性,促进物质积累,增强玉米苗期的抗低温能力,且对低温敏感型玉米品种的缓解低温伤害效果更好。

【目的】为了探讨5-氨基乙酰丙酸(ALA)在苹果生产上应用的可能性,【方法】以‘红星’和‘富士’苹果为材料,研究了生长季节喷施低质量浓度(0.05~5 mg·L-1)外源ALA对苹果叶片叶绿素相对含量(SPAD)、气体交换参数、叶绿素荧光快速诱导曲线(OJIP)、820 nm光吸收曲线以及果实品质的影响。【结果】0.05~5 mg·L-1ALA均能不同程度地提高苹果叶片SPAD,增加叶片净光合速率(P n)、瞬时羧化效率(P n/Ci)。M-PEA测定结果表明,ALA处理叶片单位面积吸收(ABS/CS)、捕获(TR0/CS)和传递(ET0/CS)的能量以及光合性能指数(PI ABS和PI CS)均有不同程度升高,PSI反应中心的氧化和再还原速率上升,同时以热形式耗散的能量(DI o/CS和DI o/RC)下降,表明低浓度ALA可以显著促进苹果叶片光合电子传递和能量转换。另外,果实成熟时,ALA处理果实的硬度、花青素、可溶性固形物、可溶性糖、可溶性蛋白和维生素C含量显著高于对照,而可滴定酸含量则低于对照。【结论】生长季节喷施低浓度ALA可以提高苹果叶片光合性能,改善果实内外品质。

Abstract BACKGROUND: Children with acute lymphoblastic leukemia (ALL) are at risk for developing musculoskeletal complications during and after their medical treatment. The objective of this study was to examine the feasibility of an in-hospital physical therapy- and home exercise program during the first four phases of medical treatment, for children with newly diagnosed ALL. PROCEDURE: Nine patients, between the ages of 2-14 years old were enrolled within 2 weeks of diagnosis in the study. Each patient was evaluated at study entry, after each of the first four phases of therapy and each time patients were re-admitted to the hospital. Following the initial physical therapy evaluation an individualized home exercise program was developed, consisting of stretching, strengthening, and aerobic exercises. The following end points were measured at each evaluation: gross motor assessment as measured by gross motor function measure (GMFM), health-related quality of life as measured by the PedsQL and parent satisfaction questionnaire. RESULTS: This study was feasible with 98% of the evaluation sessions completed. The GMFM and PedsQL improved steadily throughout the study; however, the PedsQL slightly decreased from interim maintenance to delayed intensification. The parents reported being satisfied with the physical therapy program. CONCLUSION: We demonstrated that an in-hospital- and home exercise physical therapy program during the first four phases of medical treatments is feasible for children with ALL. Future randomized studies are needed to confirm whether an initial physical therapy program at diagnosis in children with ALL will limit functional impairments, improve overall fitness and increase health-related quality of life. Copyright 2011 Wiley-Liss, Inc.

5-氨基乙酰丙酸(ALA)作为一种新型植物生长调节剂,同五大类植物激素一样,能对植物生长发育起重要调节作用。近10多年来,关于ALA的研究取得了很大的进展。与五大类植物激素相比,ALA具有一些新的功能及其生理作用,综述了其在蔬菜作物上的应用。

为了弄清外源5 - 氨基乙酰丙酸(ALA) 提高亚适宜温光下黄瓜幼苗光合作用的效果, 以‘津优1号’黄瓜为试材, 用0.5 mg·L - 1 ALA喷洒幼苗, 利用光照培养箱模拟亚适宜温光条件(昼/夜温度18 ℃/12 ℃, 光量子通量密度300μmol·m <SUP>- 2</SUP> ·s<SUP>- 1</SUP> ) , 研究ALA对幼苗气体交换参数、叶绿素荧光参数及光合酶活性的影响。结果表明: 亚适宜温光下, 黄瓜幼苗叶片的净光合速率( <EM>P</EM><SUB>n</SUB> ) 和气孔导度(<EM>G</EM><SUB>s </SUB>) 、羧化效率(<EM>CE</EM>) 、表观量子效率(<EM>AQY</EM>) 、光下实际光化学效(<EM>Φ</EM><SUB>PⅡ</SUB> ) 、光化学猝灭系数( <EM>q</EM><SUB>P </SUB>) 、天线转化效率(<EM>F</EM><SUB>v</SUB> ′/<EM>F</EM><SUB>m </SUB>′) 及核酮糖- 1, 5 - 二磷酸羧化酶(RuBPCase) 、果糖- 1, 6 - 二磷酸酶( FDPase) 活性等均明显降低, 胞间CO2浓度(<EM>C</EM><SUB>i </SUB>) 升高, 光补偿点(<EM>LCP</EM>) 、CO2补偿点(<EM>CCP</EM>) 显著下降。与水处理相比, ALA处理的<EM>P</EM><SUB>n</SUB>、<EM>G</EM><SUB>s</SUB>、CE、<EM>AQY</EM>、<EM>Φ</EM><SUB>PSⅡ</SUB>、<EM>q</EM><SUB>P</SUB>、<EM>F</EM><SUB>v</SUB> ′/<EM>F</EM><SUB>m </SUB>′及RuBPCase和FDPase活性等有不同程度提高,<EM>C</EM><SUB>i</SUB>、<EM>LCP</EM>和<EM>CCP</EM>有所降低。亚适宜温光下, 黄瓜幼苗光合速率下降的主要原因是非气孔限制, 外源ALA能明显提高其光合作用。

5 -氨基乙酰丙酸 (ALA) 10mg·L-1处理能够明显提高弱光下生长的甜瓜幼苗叶片净光合速率 (Pn) ,而低温胁迫明显降低甜瓜幼苗叶片光合能力。经ALA处理过的甜瓜幼苗光合表观量子效率、羧化效率、气孔开度、叶片叶绿素 (特别是叶绿素b)和可溶性糖含量均显著增加。在ALA处理 3d之后 ,将幼苗转移到 8℃低温条件下 4h ,对照叶片光合能力基本丧失 ,而ALA处理叶片仍能维持一定的光合能力 ,并在 2 0h内基本恢复至对照水平。若幼苗在低温下处理 6h ,对照植株完全死亡 ,而ALA预处理植株仅出现少量伤害症状。本研究结果表明 ,ALA处理可以提高植物耐弱光性和抗冷性

以辣椒品种超越5号为试材,利用加温玻璃温室模拟大棚的生产方法,探讨低温胁迫期间及常温恢 复过程中叶面喷施25 mg/L5-氨基乙酰丙酸（ALA）对辣椒花期植株生长及光合特性的影响。结果表明：叶面喷施25mg/L ALA提高了低温胁迫下植株的株高、茎粗、干鲜重、叶绿素含量以及净光合速率（Pn）、胞间CO2浓度（Ci）、气孔导度（Gs）和蒸腾速率（Tr）等光 合参数,降低了气孔限制值（Ls）和水分利用率（WUE）;常温恢复后,低温＋ALA处理的植株生长量和叶片中的叶绿素含量仍明显高于低温处理;低温处理 的叶片Pn、Gs和Tr显著低于常温对照,而低温＋ALA处理的较低温度处理有明显提高,但仍低于常温对照。表明叶面喷施ALA能提高植株叶片中叶绿素的 含量,缓解低温胁迫对辣椒叶片气孔的限制,从而提高叶片的光合作用,促进植株生长。

以油菜品种沪油15为材料，叶面喷施30mg／L5-氨基乙酰丙酸（ALA）4d，再置于 4oC低温条件下处理8d，分析测定了低温处理0．4、8d及恢复4d后光合色素含量及SOD、CAT、APX、POD等抗氧化酶活性、脯氨酸含量、超氧 阴离子（O2-·）生成速率及MDA含量等生理指标，研究了ALA对油菜幼苗抗冷性的影响及作用机制。结果表明，低温胁迫下，喷施ALA明显缓解了油菜叶 片叶绿素a（Chla）、叶绿素b（Chla）和总叶绿素（Chl）含量的下降程度，增加了类胡萝卜素（Car）的含量，显著提高了SOD、CAT、 APX和POD的活性和脯氨酸的含量，降低了O2-·生成速率和MDA含量的上升幅度。低温胁迫时间越长，ALA的作用效果越明显，说明喷施ALA通过促 进叶绿素的合成，提高油菜植株的抗氧化能力，降低活性氧的产生，减少膜脂过氧化的伤害程度，从而提高了油菜幼苗的抗冷性。另外，喷施ALA可以促进油菜幼 苗在受到低温伤害后迅速恢复。

以‘超越五号'辣椒品种为试材,研究了低温胁迫期间及随后的常温恢复过程中5-氨基乙酰丙酸(ALA 25 mg·L-1)处理对始花期辣椒植株生长量,叶片中脯氨酸、可溶性糖、可溶性蛋白含量,超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶 (CAT)、抗坏血酸过氧化物酶(APX)活性和电解质渗透率及丙二醛(MDA)含量的影响,以探讨ALA提高辣椒抗寒性的生理机制.结果表明,低温胁迫 下叶面喷施25 mg·L-1的ALA可显著提高辣椒植株生长量,增加叶片中脯氨酸、可溶性糖及可溶性蛋白含量,增强其POD、CAT及APX活性,并显著降低辣椒叶片中 SOD活性、电解质渗透率和MDA含量.叶面喷施ALA也显著降低了恢复过程中辣椒叶片中的渗透调节物质含量和抗氧化酶活性,使膜伤害基本恢复到对照水 平.可见,外源ALA处理可通过提高低温胁迫下辣椒叶片的渗透调节能力和抗氧化能力,促进植株生长,缓解低温胁迫对植株的伤害.

<div style="line-height: 150%">为探讨5-氨基乙酰丙酸（ALA）对NaCl胁迫下番茄光合特性的调控作用，以&lsquo;金鹏一号&rsquo;番茄幼苗为试材，研究叶面喷施50 mg&middot;L^-1或根施10 mg&middot;L^-1 ALA对100 mmol&middot;L^-1 NaCl胁迫下番茄幼苗光合及叶绿素荧光参数的影响.结果表明： NaCl胁迫下，番茄幼苗光合气体交换参数（净光合速率<em>P</em>_n、气孔导度<em>g</em>_s、胞间CO₂浓度<em>C</em>_i、蒸腾速率<em>T</em>_r）及叶绿素荧光参数（实际光化学量子产量<em>F</em>_v&prime;/<em>F</em>_m&prime;、<em>F</em>_m&prime;、PSⅡ反应中心实际光化学效率<em>&Phi;</em>_PSⅡ、表观光合电子传递效率ETR、光化学淬灭<em>q</em>_P、光化学反应<em>Pc</em>）均显著降低，根施或叶施ALA均可以提高NaCl胁迫下番茄叶片的光合能力，但两种处理方式之间存在一定差异.叶面喷施50 mg&middot;L^-1ALA或根施10 mg&middot;L^-1ALA处理均显著提高了番茄叶片<em>P</em>_n、<em>T</em>_r、<em>g</em>_s和<em>C</em>_i，提高了水分利用效率（WUE），显著增加了NaCl胁迫下叶片的最大净光合速率，减轻了光抑制.根施ALA对叶绿素含量的作用效果较好，而叶施ALA对光合参数的作用效果较好，两处理叶绿素荧光参数差异不显著.叶面喷施或根施ALA可以提高番茄幼苗的耐盐性，其调控作用与促进叶绿素合成与稳定、维持正常气孔开闭、降低气孔限制，进而提高NaCl胁迫下番茄叶片的光合能力和PSⅡ光化学效率有关.</div><div style="line-height: 150%"></br>&nbsp;</div>

In this study, the possibility of enhancing chilling stress tolerance of pepper ( Capsicum annuum L.) during early growth stages by exogenous application of 5-aminolevulinic acid (ALA) was investigated. To improve chilling tolerance during seedling stage, ALA was applied in various concentrations (0, 1, 10, 25 and 50 ppm) through three different methods (seed soaking, foliar spray, or soil drench). After ALA applications, the plants were subjected to chilling stress at 3 C for 2 days. Although all ALA application methods improved chilling stress tolerance in pepper seedlings, seed soaking and foliar spray provided better protection against chilling stress compared to soil drench. Exogenous application of ALA provided significant protection against chilling stress compared to non-ALA-treated seedlings, significantly enhancing plant mass and chlorophyll, sucrose, and proline contents. ALA pre-treatment also increased relative water content, stomatal conductance and superoxide dismutase (SOD) enzyme activity and reduced membrane permeability. Of the ALA concentrations, the highest chilling tolerance was obtained with 25 ppm ALA pre-treatment. Results indicate that ALA which is considered as an endogenous plant growth regulator could be used effectively to protect pepper seedlings from damaging effects of chilling stress without any adverse effect on seedling growth.

以4个杂交晚稻为材料,研究了齐穗期叶面喷施1 mg/L的5-氨基乙酰丙酸叶面肥对杂交晚稻生育后期叶片SPAD值、光合作用、干物质积累和经济产量的影响。结果表明:5-氨基乙酰丙酸叶面肥能提高水稻功能叶SPAD值、光合作用,增加干物质积累量,产量增加3.2%～4.0%。

以水稻品种豫粳6号为试验材 料,研究了在孕穗期喷施不同浓度(0、10、30、50、70mg/L)的ALA对水稻干物质积累、运转及产量的影响。结果表明,叶面喷施ALA后,能够 促进干物质的积累和运转;提高水稻的结实率和粒重;使产量增加0.37%～10.19%,其中以喷施30mg/L的ALA效果较好。

以耐盐性不同的番茄品种金鹏超冠(耐盐性较强)和中杂9号(耐盐性较弱)为材料,研究了叶面喷施5-氨基乙酰丙酸(ALA)对150 mmol/L,250 mmol/L NaCl胁迫下番茄光合作用、保护酶系统及产量的影响。结果表明,ALA能使NaCl胁迫下番茄叶片的叶绿素含量、净光合速率(Pn)、蒸腾速率(Tr)、气孔导度(Gs)升高,胞间二氧化碳浓度(Ci)降低;ALA处理显著提高了高盐胁迫下的SOD、POD和CAT活性,且降低了丙二醛含量,尤其是中杂9号更为显著,ALA处理可能是通过促进保护酶系统活性,保护细胞的光合性能,促进光合作用,从而促进番茄的生长发育,提高产量,缓解盐胁迫对番茄的抑制作用。

以2个耐盐性不同的西葫芦品种翡翠二号（耐盐性较强）和新早青一代（耐盐性较弱）为材料,研究了叶面喷布5-氨基乙酰丙酸（ALA）对200 mmol/L,400 mmol/L NaCl胁迫下西葫芦生长某些生理特性及果实产量的影响。结果表明,外源ALA对200 mmol/L NaCl胁迫下盐敏感品种的生长及生理特性的缓解作用较好,而在400 mmol/LNaCl胁迫下ALA对耐盐性较强的翡翠二号的缓解作用显著。ALA处理可提高NaCl胁迫下西葫芦叶片的叶绿素、可溶性蛋白及脯氨酸含量,降低细胞膜透性,抑制MDA产生,增加西葫芦植株对盐胁迫的抵抗能力,显著提高盐胁迫下西葫芦产量。

为外源5-氨基乙酰丙酸(ALA)在荒漠地区设施园艺中的推广和应用,以番茄和辣椒为材料,设置清水、叶面肥和外源ALA(5-氨基乙酰丙酸)3个处理,研究外源ALA和叶面肥处理对荒漠区番茄和辣椒生长及产量品质的影响.结果表明,外源ALA和叶面肥均可促进荒漠区番茄和辣椒的生长,并显著改善果实相关品质.其中ALA处理的番茄株高、茎粗、叶片数和冠径与对照相比分别提高15.45％、8.33％、13.69％和8.58％,辣椒叶片数提高22.79％;番茄果实固酸比提高8.86％,辣椒可溶性固形物质量分数提高8.59％,并且还能够提高番茄和辣椒的产量.可见,ALA和叶面肥对荒漠区设施番茄和辣椒的生长都表现一定的促进作用,对品质有不同程度的改善,同时也提高了产量.

[Objective] This study aimed to investigate the influence of illumination intensity, 5-aminolevulinic acid (ALA) concentration and their interaction on chlorophyll fluorescence parameters and yield of summer maize. [Method] Two illumination intensity levels and five ALA concentrations were applied in the experiment using 2 5 completely balanced program. The two illumination intensity levels were natural light (S0 ) and 60% shade (S1 ), and five ALA concentrations were0, 1, 10, 25 and 50 mg/L. [Result] The relative chlorophyll content of leaf (SPAD), the optimal/maximal quantum yield of PS (Fv/Fm), the photochemical quenching coefficient (qP), electron transport rate (ETR), grain number per cob and grain weight per cob in S1 treatment were significantly reduced compared with that in S0 . However, the non-photochemical quenching coefficient (qN) was significantly increased. The responses of these parameters to ALA were different under S0 and S1 treatments. The SPAD, Fv/Fm, qP, ETR, grain number and grain weight per cob were firstly increased, but then decreased following the raise of ALA concentration, ranging from0 to 50 mg/L, whereas qN showed opposite trend. The effect of the interaction of illumination intensity and ALA concentration on these parameters was significant (P0.05). Under natural light, summer maize could obtain higher SPAD, Fv/Fm, qP and ETR and lower qN combined with low concentration of ALA. However, high concentration of ALA was needed under shading to get the same results. [Conclusion] Soaking seed in suitable concentration of ALA can reduce the yield loss of summer maize caused by short-term shading in seedling stage.

5-Aminolevulinic acid (ALA) promoted the growth and yield of several crops and vegetables at concentrations lower than those eliciting herbicidal responses, i.e., less than 1.8 mm by foliar spray and 60 0204m by root soaking. To evaluate the physiological action of ALA, the effects of ALA on plants were examined by several bioassay systems at 0.0006090009600 0204m. ALA at 0.060900096 0204m by root soaking increased the growth of rice seedlings in light, but did not affect this in darkness. In horseradish shoot primordia, promotion by ALA was not proportional among total chlorophyll content, chlorophyll concentration, and fresh weight. In the test using pothos, ALA at 0.06 0204m elicited the accumulation of chlorophyll, but the photosynthesis of the plants was promoted by treatment together with ALA and nutrients. These results suggest that ALA have a variety of plant physiological effects on chlorophyll synthesis, photosynthesis, and plant growth, and ALA acts as a growth regulator in plants at low concentrations. These effects of ALA were also assumed to be linked to light irradiation and an uptake of fertilizer by plants. However, excess ALA suppressed these effects.

The role of 5-aminolevulinic acid (ALA) as a precursor of chlorophyll or a herbicide is well documented. In the present report, to elucidate the physiological effects of ALA, this compound was applied to the foliage of radish at 0.06, 0.18, 0.6, 1.8 and 6 mM. ALA at 0.06ndash;1.8 mM increased the dry weight of radish root (underground part), but injured radish seedlings at 6 mM. Also, the application of ALA at 0.18 and 0.6 mM increased fixation of CO 2 in light and decreased release of CO 2 in darkness. Furthermore, the effects of foliar treatment of ALA on the yield of several crops were also evaluated. The results showed that an application of ALA at low concentrations increased the growth and yield by 10ndash;60percnt; over the control on kidney bean, barley, potato and garlic. These results suggest that ALA has plant growth regulating properties at low concentrations and may enhance agricultural productivity.

有效的氮肥管理一直是农业可持续发展面临的重大挑战.通过田间试 验,采用裂区-裂区设计,研究了不同密度、不同氮肥用量和有机肥施用的不同措施对春玉米抽雄期穗位叶叶绿素含量(SPAD值)的影响.结果表明:种植密度 (60000,90000株/hm2)、氮肥施用量(N0,N225,N300)及有机肥的施用与否均显著影响玉米抽雄期的SPAD值；施用有机肥有助于 提高玉米SPAD值；种植密度增加,玉米SPAD值呈下降趋势；施氮量对玉米SPAD值的影响,在不施有机肥情况下呈直线型,而在施有机肥条件下呈抛物线 型.

The effects were examined of 5-aminolevulinic acid (ALA) on the accumulation of Chl and apoproteins of light-harvesting Chl a/b-protein complex of photosystem II (LHCII) in cucumber cotyledons under intermittent light. A supply of ALA preferentially increased the accumulation of Chl a during intermittent illumination. However, when cotyledons were pretreated with a brief exposure to light or benzyladenine (BA), the stimulatory effect of ALA on the increase in the level of Chl b was greater than that in the level of Chl a, resulting in decreased ratios of Chl a/b. Time-course experiments with preilluminated cotyledons revealed that LHCII apoproteins accumulated rapidly within the first 30 min of intermittent illumination with a decline during sub-sequent incubation in darkness. A supply of ALA did not affect the accumulation of LHCII apoproteins during the intermittent light period, but it efficiently inhibited the decline in their levels during the subsequent darkness. After exposure to a single pulse of light of BA-treated cotyledons, the prompt increase in levels of LHCII apoproteins was not accompanied by the formation of Chl b, which began to accumulate later. The pattern of changes in levels of LHCII apoproteins was quite similar to that in levels of Chl a. These results suggest that LHCII apoproteins are first stabilized by binding with Chl a and that an increased supply of Chl a and the accumulation of LHCII apoproteins are prerequisites for the formation of Chl b.

Photosynthetic activity in terms of O 2 evolution and the growth of Spirulina platensis was stimulated by adding 5-aminolevulinic acid (ALA, 500 mg/ l ) to photoautotrophically growing cells. After ALA was added to the medium, intracellular accumulations of phycocyanin and chlorophyll were stimulated simultaneously, followed by enhancement of the photosynthetic activities of photosystems I and II, and lastly, growth was promoted. ALA did not directly activate the photosynthetic electron transport system. However, during a 3-h incubation of intact cells with ALA, photosynthetic activity was enhanced.