植物生长调节剂对薄壳山核桃品种‘波尼’枝条生长和叶片碳氮代谢物积累的影响

以5年生薄壳山核桃品种‘波尼’(Carya illinoinensis‘Pawnee’)幼树为实验材料,根据L_9(3~3)正交试验设计进行3因子(包括植物生长调节剂的种类、质量浓度和喷施次数)3水平(植物生长调节剂分别为GA_3、PP_(333)和6-BA,植物生长调节剂质量浓度分别为100、200和300 mg·L~(-1),植物生长调节剂喷施次数分别为1、2和3)叶面喷施实验,研究不同处理对薄壳山核桃品种‘波尼’枝条生长和叶片碳氮代谢物积累的影响。结果表明:GA_3处理组薄壳山核桃品种‘波尼’枝条长度较CK(对照,蒸馏水喷施3次)组显著增加,其中,T2(200 mg·L~(-1)GA_3喷施2次)处理组的枝条长度最大,较CK组增加了35.7%;PP_(333)处理组的枝条粗度总体上较CK组显著增加,其中,T5(200mg·L~(-1)PP_(333)喷施1次)处理组的枝条粗度最大,较CK组增加了23.8%。处理后30~90 d,所有处理组薄壳山核桃品种‘波尼’枝条叶片中可溶性糖含量均呈逐渐升高的变化趋势,而叶片中淀粉和可溶性蛋白质含量以及C/N比总体上呈先升高后降低的变化趋势。PP_(333)和6-BA处理组叶片中可溶性糖、淀粉和可溶性蛋白质含量以及C/N比总体上显著高于CK组,其中,T5和T6(300 mg·L~(-1)PP_(333)喷施2次)处理组对叶片中可溶性糖和淀粉含量以及C/N比的促进效果较佳,而T4(100 mg·L~(-1)PP_(333)喷施3次)和T8(200 mg·L~(-1)6-BA喷施3次)处理组对叶片中可溶性蛋白质含量的促进效果较佳。极差分析结果表明:植物生长调节剂种类对薄壳山核桃品种‘波尼’枝条长度、叶片中可溶性糖和淀粉含量以及叶片C/N比的影响最大,植物生长调节剂喷施次数对枝条粗度和叶片中可溶性蛋白质含量的影响最大。研究结果显示:叶面喷施200 mg·L~(-1)GA_3对薄壳山核桃品种‘波尼’枝条伸长的促进效果最佳,喷施200 mg·L~(-1)PP_(333)对枝条增粗及叶片碳氮代谢物积累的促进效果最佳。     

氮素形态对小白菜生长和碳氮积累的影响

水培条件下,研究不同氮素形态(硝态氮、铵态氮、甘氨酸、谷氨酰胺、丙氨酸、牛血清蛋白,以及甘氨酸与硝态氮、牛血清蛋白与硝态氮的混合氮源)对小白菜生长和碳氮积累的影响.结果表明:不同氮素形态对小白菜质量、碳氮积累量、可溶性蛋白质含量、可溶性糖含量和游离氨基酸含量的影响不同;硝态氮处理下小白菜地上部分和根的干质量与鲜质量均最大;甘氨酸对小白菜根系的生长及碳氮积累具有明显的促进作用;在3种氨基酸中,谷氨酰胺更有利于小白菜地上部分的生长和氮积累.聚类分析表明,9种氮素形态处理按营养效应大小分为:硝态氮、谷氨酰胺＞甘氨酸与硝态氮混合氮源、牛血清蛋白与硝态氮混合氮源、甘氨酸、铵态氮＞丙氨酸、牛血清蛋白、对照.有机氮源可以作为小白菜生长的氮源,不同的氮素形态对植物产生的生理效应不同.     

不同葡萄糖浓度下海洋纤毛虫种群生长对水体氨积累的影响

为揭示纤毛虫种群增长在不同碳 -氮比下对水体氨氮积累的影响 ,本文利用实验生态学方法 ,对海水养殖水体中 2种常见的纤毛虫扇形游仆虫和海洋尾丝虫在牛肉浸膏及梯度浓度葡萄糖培养基中的种群增长过程与氨氮积累之间的关系进行了探讨。结果表明 ,在葡萄糖浓度为 0 0 1 - 0 2 g/L的牛肉浸膏培养液中 ,氨积累在纤毛虫种群生长平衡期高于对照组 ;在衰退期扇形游仆虫组显著低于对照组 ,而海洋尾丝虫组仅在 0 0 5 - 0 2g/L葡萄糖浓度范围内显著较低。在浓度为 0 4 g/L时 ,纤毛虫生长受到高度抑制 ,氨浓度也显著低于对照组 ,但保持上升趋势。本工作揭示出 :在一个趋于稳定的养殖体系 (如封闭的养殖 /育苗水体 )中 ,由于纤毛虫的存在 ,氨积累过程是按照一个通常的模式进行的 ,即越过一个短暂峰值后迅速降低并从此维持在一个较低的水平 ;同时 ,水体中营养物质的碳 -氮比的变动会影响氨积累过程中的峰值及峰值持续的时间 ,即适宜的碳 -氮比可缩短降氮的进程。同时 ,本结果也证实了纤毛虫对改良水质中所具有的贡献     

基于作物生长监测诊断仪的双季稻叶片氮含量和氮积累量监测

为了验证作物生长监测诊断仪(CGMD)监测双季稻氮素营养指标的准确性和适用性,构建基于CGMD的双季稻叶片氮含量(LNC)和氮积累量(LNA)的监测模型。选用8个不同早、晚稻品种,设置4个不同施氮水平,利用CGMD采集冠层差值植被指数(DVI)、归一化植被指数(NDVI)和比值植被指数(RVI),同步利用ASD FH2高光谱仪采集冠层光谱反射率,并计算DVI、NDVI和RVI;通过比较CGMD和ASD FH2采集的冠层植被指数变化特征,验证CGMD的测量精度,构建基于CGMD的LNC和LNA监测模型,并利用独立试验数据对模型进行检验。结果表明: 早、晚稻LNC、LNA、DVI、NDVI和RVI随施氮水平的增加而增大,随生育进程的推进呈先升后降的趋势;CGMD与ASD FH2采集的DVI、NDVI和RVI间拟合的决定系数(R²)分别为0.9350、0.9436和0.9433,表明CGMD的测量精度较高,可替代ASD FH2采集冠层植被指数。基于CGMD的3个冠层植被指数相比,NDVI_CGMD与LNC的相关性最高,RVI_CGMD与LNA的相关性最高;基于NDVI_CGMD的指数模型可较准确地预测LNC,模型R²为0.8581～0.9318,模型检验的均方根误差(RMSE)、相对均方根误差(RRMSE)和相关系数(r)分别为0.1%～0.2%、4.0%～8.5%和0.9041～0.9854;基于RVI_CGMD的幂函数模型可较准确地预测LNA,模型R²为0.8684～0.9577,模型检验的RMSE、RRMSE和r分别为0.37～0.89 g·m^-2、6.7%～20.4%和0.9191～0.9851。与化学分析方法相比,利用CGMD可便捷准确地获取早、晚稻的LNC和LNA,在双季稻丰产高效栽培和氮肥精确管理中具有应用价值。     

低温和GA3对凤丹种子萌发及碳氮代谢物和内源激素含量的影响

研究了低温(4℃)和300 mg·L-1GA3对凤丹(Paeonia suffruticosa‘Fengdan’)种子萌发过程中子叶、上胚轴和叶原基形态及种胚中碳氮代谢物(包括淀粉、可溶性糖和可溶性蛋白质)和内源激素(包括ZR、IAA、ABA和GA)含量的影响。结果表明:GA3处理后第11天凤丹种子上胚轴萌发,且形态细长;经低温处理后第27天上胚轴萌发,且形态较粗壮。低温处理后种子萌发的幼苗叶片较大、株高居中、根系发育较好、须根多且长,生长状况总体上优于对照和GA3处理组。与处理后第3天相比,对照和低温处理后第27天以及GA3处理后第11天,种胚中淀粉、可溶性糖、ZR、IAA和GA含量升高,ABA含量降低;而对照和低温处理后第27天种胚中可溶性蛋白质含量降低,GA3处理后第11天可溶性蛋白质含量无显著变化。各处理组凤丹种子蛋白质电泳条带的相对分子质量多集中在12 000~80 000,在对照和低温处理后第27天蛋白质条带颜色均较处理后第11天略深,但条带数量不变。研究结果显示:低温及GA3处理均可导致凤丹种胚中碳氮代谢物和内源激素含量变化,促进种胚发育及上胚轴生长,但低温处理更有利于上胚轴萌发及幼苗生长。     

氮输入和水淹对短叶茳芏生长、养分及固碳的影响

外源氮输入显著改变河口湿地植物生长和固碳能力,进而影响河口湿地生态系统碳、氮循环过程。以闽江口湿地土著种短叶茳芏(Cyperus malaccensis)为研究对象,通过15个月的中型生态系实验,分析不同氮输入水平(CK,0 g N m~(-2)a~(-1);N8,8 g N m~(-2)a~(-1);N16,16 g N m~(-2)a~(-1))和2种水淹(T1,每天水淹时长2—3 h;T2,每天水淹时长11—12 h)处理对短叶茳芏生长、养分和固碳的影响,探讨短叶茳芏在环境变化下的生长、固碳特征。结果表明:T2处理株高极显著高于T1处理,N8、N16处理的植物株高显著高于CK处理,植物成熟季节的株高也极显著最高(P0.001)。水淹状况和植物生长期对短叶茳芏的密度有显著影响:T1处理密度极显著高于T2处理,植物成熟季节的密度也极显著最高(P0.001),但是氮输入没有显著提高植物密度。植物碳含量较为稳定,T2处理地上碳含量显著高于T1处理(P0.05),但是氮输入和植物生长期对地上碳含量影响不显著。氮输入水平、水淹状况和植物生长期则对植物地上氮含量都有显著影响(P0.05)。N8处理的植物地上生物量和固碳量极显著最高,CK处理极显著最低,植物成熟期的地上生物量和固碳量也极显著最大(P0.001),但是不同水淹处理植物生物量和固碳量无显著差异。闽江口湿地短叶茳芏具有较强的环境适应能力,在持续氮输入环境下,闽江口湿地的短叶茳芏可能向高潮滩拓展。     

水土流失治理措施对小流域土壤有机碳和全氮的影响

明确综合治理条件下小流域土壤有机碳(Soil organic carbon,SOC)和全氮(Total nitrogen,TN)的空间分布特征及其影响因素,对科学评价水土流失区土壤固碳潜力具有重要意义。以黄土高原丘陵沟壑区典型小流域(砖窑沟流域)为对象,基于流域内3种典型地貌类型(梁峁坡、沟坡、沟谷)和3种典型水土流失治理措施(水平梯田、林地和草地措施,坡耕地为对照),采集土壤样品737个,研究地貌类型和水土流失治理措施对小流域SOC和TN变化的影响。结果表明,同一地貌类型上,水平梯田、林地和草地措施的SOC和TN(0—10 cm土层)含量均显著高于坡耕地(P<0.1)。梁峁坡上,水平梯田、林地和草地措施条件下的SOC和TN含量较坡耕地依次提高了18%和24%、70%和59%、25%和21%;沟坡上,林地和草地措施的SOC和TN较坡耕地依次提高了76%和54%、25%和27%。同一治理措施在不同地貌类型间对0—10 cm土层SOC和TN的影响存在显著差异(P<0.1)。水平梯田条件下,沟谷的SOC和TN含量比峁坡提高了46%和43%;林地措施条件下,沟坡的SOC和TN含量比峁坡提高了18%和6%;草地措施条件下,沟坡的SOC和TN含量比峁坡提高了14%和18%。0—100 cm土层的SOC或TN在不同地貌类型或不同治理措施间的差异与土壤水分含量(Soil moisture,SM)的变化趋势基本一致,并且SOC或TN与SM呈指数关系y=aebx(y为SOC或TN,x为SM)。     

光质对韭菜碳氮代谢、生长和品质的影响

以‘平韭2号’为试材,以白光(W)处理为对照(CK),研究白+红(WR)、白+蓝(WB)、白+绿(WG)、白+紫(WP)4种不同光质处理对韭菜碳氮代谢、生长和品质的影响.结果表明: WR处理韭菜的光合速率(P_n)显著高于CK,而WB、WG和WP与CK无显著差异,但RuBP羧化酶(RuBPCase)活性均显著高于CK.各处理相比,总糖含量以WR最高,WP其次,WB和WG最低.WR下韭菜蔗糖磷酸合成酶(SPS)活性显著高于CK,其余三者均显著低于CK,其中以WB最低,但蔗糖合成酶(SS)和淀粉酶(AMS)活性均以WB最高,WR最低,WG和WP的SS活性与CK无差异,但AMS活性显著低于CK.可见,增加红、紫光比例可促进韭菜碳的同化和转化,加速糖的积累.总氮、蛋白氮含量、硝酸还原酶(NR)、谷氨酰胺酶(GS)和谷氨酸合成酶(GOGAT)活性以WB最高,显著高于CK,但WB下谷氨酸脱氢酶(GDH)活性最低,显著低于CK;WR的蛋白氮和非蛋白氮含量、NR和GS活性最低,显著低于CK,GOGAT和GDH活性显著高于CK,且GDH在所有处理中最高;WG的全氮、非蛋白氮含量及GDH活性均显著低于CK,但蛋白氮含量、NR和GOGAT活性显著高于CK,WP的氮含量及相关酶活性呈现出与WG相同的趋势,且GS活性亦同样高于CK.说明增加蓝光、紫光和绿光可使韭菜氮代谢增强,而增加红光对蛋白质的合成有一定的抑制作用.红光和紫光下韭菜生长较好,而蓝光则抑制其加粗生长,叶片较薄,单株生长量较低.紫光下韭菜的粗纤维含量最低,营养品质最优,因此,紫光对韭菜的生长最有利.     

不同氮形态对AM真菌孢子萌发和菌丝生长的影响

以Long-Ashton培养基为基础,采用NH4+-N、NO3--N和NH4+-NO3--N 3种氮源,研究了不同氮形态对AM真菌孢子萌发和菌丝生长的影响。结果表明,孢子的萌发速度在NO3--N和NH4+-NO3--N培养基上先快后慢,而NH4+-N培养基上先慢后快,但最终三者的萌发率没有差异,均达到50%左右;菌丝生长对3种氮形态的反应存在显著差异,NO3--N和NH4+-NO3--N培养基上的菌丝生长速率和长度大于NH4+-N培养基上的相应值。本试验表明,与NO3--N和NH4+-NO3--N 相比,NH4+-N虽然没有降低AM真菌孢子的萌发率,但是能够抑制萌发菌丝的生长。     

Cd对不同种类植物生长和养分积累的影响

溶液培养法研究了不同活度Cd2 对4种植物卷心菜、黑麦草、玉米和白三叶草生长和养分积累的影响．结果表明,随Cd2 活度增加,4种植物的生长速率和干物质产量均下降．白三叶草对Cd2 最敏感;黑麦草和玉米耐性较强;卷心菜在高ACd2 时敏感．Cd2 对Fe、Mn、Cu、Zn、Ca、Mg、P、S等养分积累的影响因植物种类而异．Cd2 降低Fe、Mn、Cu、Zn、Ca、Mg等的积累．P在4种植物中和S在除卷心菜外的3种植物中的积累比对照增加．卷心菜和白三叶草对Cd毒敏感性差异与Fe、Mn、Ca、Mg的积累受Cd2 影响程度不同密切相关．     

激素浸种对薄壳山核桃种子萌发的影响及其种子吸胀过程中SOD和POD活性变化

薄壳山核桃﹝Carya illinoinensis ( Wangenh.) K. Koch﹞为胡桃科( Juglandaceae)山核桃属( Carya Nutt.)植物,又名美国山核桃、长山核桃,是世界上著名的经济树种之一[1-2]。目前,主要采用本砧嫁接的方法培育薄壳山核桃良种嫁接苗,而培育优质实生苗作为砧木是该技术的关键环节之一,因此,了解其种子萌发特性极为重要。目前,对薄壳山核桃种子萌发特性的研究主要集中在植物激素催芽方面[3-5],而有关激素催芽过程中的适宜浸泡天数、种子吸胀过程中相关的酶活性变化等问题尚不明确。     

不同分枝数对桑树幼苗生长发育的影响

以我国常见经济林木桑树(Morus alba)为试验材料,从气体交换、形态变化和地上生物量方面研究5种分枝模式(1、2、3、4和5枝)对幼苗生长发育的影响。结果显示:(1)分枝数为1的植株的净光合速率(P n)最高,达到8.6μmol·m-2·s-1。随着分枝数增加,P n显著下降,直至分枝数达到3枝及其以上时,净光合速率保持相对稳定,为4.3μmol·m-2·s-1。而气孔导度(g s)、胞间CO2浓度(C i)和蒸腾速率(E)则不受分枝数的影响。(2)随着分枝数增加,总叶片数量、总叶面积和总枝长都显著增加,最终分别达到114.3,10481.1 cm2和457.1 cm,而平均单枝叶片数、平均单枝基径、平均单叶面积和比叶面积则显著减少。(3)随着分枝数的增加,植株的总叶生物量和总枝生物量无显著变化,但平均每枝叶干重、平均每枝枝干重和平均每枝总生物量随分枝数的增加而逐渐减少。研究结果表明了分枝数增加可能导致叶片间对光资源的竞争强度增大,引起净光合速率下降,叶片面积变小,单枝长度和生物量减小。另一方面,植株则通过生长出更多的叶片数量,以及更大的总叶片面积来尽可能地消除竞争带来的不利影响,提高对光环境资源的利用。     

Influence of magnesium deficiency on rates of leaf expansion, starch and sucrose accumulation, and net assimilation in Phaseolus vulgaris

Twenty one-day-old Phaseolus vulgaris 'Saxa'plants were cultured in a growth chamber and the plants supplied with either a complete or a Mg-free nutrient solution. From 6 days after transfer to the Mg-free solution, the rate of increase of the area of the second trifoliate leaf was considerably reduced; by day 11 the sucrose concentration in the first trifoliate leaf had increased 6. 2-fold at the end of the dark period and 4. 6-fold after the light period as compared with the control plants. Corresponding starch concentrations increased 6. 6-fold and 2. 9-fold respectively. After days 5 to 6 the assimilation rates declined in the first trifoliate leaf of the plants showing deficiency, in comparison with the plants fully supplied with nutrients; respiration increased during darkness. The reduction in net assimilation rate was to a great extent reversible after resupply of magnesium.
The reduction of magnesium concentration in the deficient plants was much more marked in the expanding leaves than in the mature primary leaves and roots. Sucrose and starch accumulation did not occur when the first trifoliate leaf was partially shaded, although magnesium concentration, as in the unshaded leaves, was reduced to 13% of that of the control plants. The consequences of magnesium deficiency in the expanding first trifoliate leaf are discussed in terms of the possibility of sink limitation.     

胡杨枝芽生长特征及其展叶物候特征

以5个不同发育阶段的胡杨(Populus euphratica Oliv.)个体为研究对象,观测记录了枝芽展叶物候、枝芽生长特征和叶形变化的空间分布规律。结果表明:不同发育阶段的胡杨个体以及同一个体树冠的不同层次,其枝芽生长及其展叶物候期表现出不同的时空特征。随着树龄的增加和树冠层次的增高(由基向顶),当年新生枝条长度、枝条叶片数和叶形指数逐渐减小,但叶面积和叶片干重逐渐增大。5个不同发育阶段胡杨个体均表现出展叶物候始于树冠顶层,依次向下结束于树冠基部;展叶物候期共性表现在枝芽萌动期均在4月上旬,起始展叶期集中在4月中旬,展叶终期则在5月上旬到下旬;树龄较大的个体其枝芽萌动期、起始展叶期、展叶终期较树龄较小的个体早;其枝芽萌动期到展叶终期的时间进程较树龄较小的个体短;不同发育阶段的个体枝芽萌动期出现的时间较为离散,起始展叶期和展叶终期出现的时间较为集中。相关分析表明,出叶周期与枝条长度、枝条叶片数量和叶形指数呈极显著正相关,与叶面积和叶片干重呈显著负相关。     

多效唑和缩节胺对现蕾前忍冬枝叶生长及花蕾性状和有效成分含量的影响

以忍冬品种‘九丰一号’(Lonicera japonica‘Jiufeng 1’)为实验材料,采用叶面喷施方法研究了不同质量浓度多效唑和缩节胺对现蕾前(抽枝生长初期)枝叶生长和叶片叶绿素含量以及花蕾性状和花蕾中绿原酸和总黄酮含量的影响。结果显示:分别喷施100、400、700和1 000 mg·L-1多效唑和50、100、150和200 mg·L-1缩节胺后,多数处理组的开花枝条数、着花节数和叶绿素含量较对照CK1(水)有不同程度提高,但叶面积差异不明显。随处理时间延长,各处理组枝条节间长度总体上呈逐渐增加的趋势,其中多数处理组枝条节间长度增长缓慢。各处理的花蕾长度、百蕾鲜质量和干质量总体上小于CK1,而花蕾折干率、总黄酮含量和绿原酸含量显著或不显著高于CK1。此外,在喷施多效唑和缩节胺的同时喷施质量体积分数1.0%尿素和质量体积分数0.1%硼砂,忍冬的叶面积、着花节数、花蕾长度、折干率、百蕾鲜质量和干质量总体上有所提高,而绿原酸含量降低,但各指标的差异总体较小。研究结果表明:喷施适量多效唑和缩节胺可调控忍冬枝条生长,并能提高花蕾中总黄酮和绿原酸含量。     

Spatial distribution of growth rates and of epidermal cell lengths in the elongation zone during leaf development in Lolium perenne L.

Relative elemental growth rates (REGR) and lengths of epidermal cells along the elongation zone of Lolium perenne L. leaves were determined at four developmental stages ranging from shortly after emergence of the leaf tip to shortly before cessation of leaf growth. Plants were grown at constant light and temperature. At all developmental stages the length of epidermal cells in the elongation zone of both the blade and sheath increased from 12 m at the leaf base to about 550 m at the distal end of the elongation zone, whereas the length of epidermal cells within the joint region only increased from 12 to 40 m. Throughout the developmental stages elongation was confined to the basal 20 to 30 mm of the leaf with maximum REGR occurring near the center of the elongation zone. Leaf elongation rate (LER) and the spatial distributions of REGR and epidermal cell lengths were steady to a first approximation between emergence of the leaf tip and transition from blade to sheath growth. Elongation of epidermal cells in the sheath started immediately after the onset of elongation of the most proximal blade epidermal cells. During transition from blade to sheath growth the length of the blade and sheath portion of the elongation zone decreased and increased, respectively, with the total length of the elongation zone and the spatial distribution of REGR staying near constant, with exception of the joint region which elongated little during displacement through the elongation zone. Leaf elongation rate decreased rapidly during the phase when only the sheath was growing. This was associated with decreasing REGR and only a small decrease in the length of the elongation zone. Data on the spatial distributions of growth rates and of epidermal cell lengths during blade elongation were used to derive the temporal pattern of epidermal cell elongation. These data demonstrate that the elongation rate of an epidermal cell increased for days and that cessation of epidermal cell elongation was an abrupt event with cell elongation rate declining from maximum to zero within less than 10 h.Abbreviations LER leaf elongation rate - REGR relative elemental growth rates     

Root influence on in vitro growth of hyphae of the mycorrhizal mushroom Cantharellus cibarius replaced by carbon dioxide

The presence of a living root of tomato ( Lycopersicon esculentum Mill. cv. Panase F) had a strong positive effect on growth in vitro of hyphal fragments of Cantharellus cibarius Fr. This was observed for 12 out of 14 fungal strains tested. Initial re-growth of hyphae was independent of the presence of a root, but for the further development of strong mycelial growth 7 strains completely depended on the presence of a root. Five strains showed a considerably prolonged lag phase in the absence of a root and only 2 strains were independent. The presence of a root had no influence on the specific growth rates. Hyphal fragments of the totally root-dependent strain S1 grew strongly in the absence of a root if they were brought into intimate mutual contact. Factor(s) stimulating growth were apparently produced by both roots and fungus. Volatiles from donor cultures of tomato roots of C. cibarius, Boletus edulis , and Tylopilus felleus stimulated growth of hyphal fragments in root-less receiver cultures. This effect was prevented by the presence of a KOH solution. Donor cultures could be replaced by 0.5% CO₂.     

盐胁迫对2种珍贵速生树种种子萌发及幼苗生长的影响

以1/2Hoagland营养液为基础培养液,研究了在0.1%、0.2%、0.4%和0.6%NaCl胁迫条件下,毛红椿〔Toona ciliata Roem. var. pubescens(Franch.)Hand.-Mazz.〕和水松〔Glyptostrobus pensilis(Staunt.ex D.Don)K.Koch〕的种子萌发和幼苗生长情况。结果表明,随着NaCl浓度的增加,2个树种的种子萌发率和简化苗木活力指数均明显下降,在0.1%、0.2%、0.4%和0.6%NaCl胁迫条件下,毛红椿和水松种子的最终萌发率分别为89.3%、87.3%、62.7%、32.0%和26.0%、16.7%、6.0%、3.3%,简化苗木活力指数分别为1.39~0.08和1.52~0.07,且毛红椿的种子萌发率和简化苗木活力指数均明显高于水松。萌发恢复实验结果表明,高浓度NaCl处理后的种子具有较高的萌发恢复率。根据实验结果初步判定毛红椿种子具有较强的耐盐性。     

Effects of exogenously applied growth regulators on shoot growth of inbred lines of Plantago major differing in relative growth rate: differential response to gibberellic acid and (2-chloroethyl)-trimethyl-ammonium chloride

The possibility of modulating shoot growth charaeteristics of seedlings of two inbred lines of Plantago major L., differing in relative growth rate (RGR), by exogenously applied 6-benzylaminopurine (BA), α-naphthalene acetic acid (NAA), (gibberellic acid (GA₃) and (2-chloroethyl)-trimethyl-ammonium chloride (CCC) was investigated. BA completely inhibited growth of the shoot at a concentration of 1 m M , while lower concentrations had no effect. NAA reduced growth of the shoot at 10 ü M , while 1 m M completely inhibited growth. Addition of 10 μ M GA₃ or higher stimulated shoot fresh weight up to 20% and leaf area up to 30% for the slow growing inbred line (W9), but less for the fast growing line (A4). Application of 1 m M CCC, an inhibitor of gibberellin metabolism, reduced growth of both inbred lines, but to a larger extent in the fast growing seedlings.
The lower shoot growth of W9 was associated with a lower specific leaf area (SLA) and a higher dry matter percentage of the shoot, as compared with A4. NAA reduced growth by reducing SLA and increasing leaf thickness, but the percentage dry matter of the leaves was unaffected. Stimulation of the shoot growth by GA₃ application was associated with higher SLA and lower dry matter percentage. Application of CCC had opposite effects on SLA and dry matter percentage as compared with GA₃. GA seems to be involved in the regulation of at least part of the genetic difference in RGR in Plantago major .     

Effect of mycorrhizal-enhanced leaf phosphate status on carbon partitioning, translocation and photosynthesis in cucumber

An assessment of the effects of arbuscular mycorrhizal (AM) infection on photosynthesis, carbon (C) allocation, translocation and biomass production of cucumber, grown in sand culture, was made using a previously determined phosphorus (P) supply (0·13 mol m^?3 P) which had a significant impact on AM infection. Separation of a direct effect of AM infection from an indirect one due to an enhanced leaf P status was achieved using a comparable non‐mycorrhizal treatment (NAM + P) supplemented with extra P (0·19 mol m^?3 P). Total leaf P concentration, specific leaf mass, photosynthetic capacity, and incorporation of ¹⁴C into non‐structural carbohydrate pools were dependent on leaf age. Both maximum and ambient photosynthetic rates were significantly higher in the youngest fully expanded leaves from AM and NAM + P plants which also had the higher leaf P concentrations. There were no differences in the total concentrations of starch, sucrose, raffinose or stachyose in young or old leaves among AM, non‐mycorrhizal (NAM) and NAM + P treatments. However, younger leaves of NAM plants showed a shift in ¹⁴C‐partitioning from stachyose and raffinose synthesis to starch accumulation. Determination of ADP‐glucose pyrophosphorylase (AGPase), sucrose synthase and sucrose phosphate synthase enzyme activities revealed that only AGPase activity was correlated with the increased incorporation rate of ¹⁴C into starch in young leaves of NAM plants. Although there were significant AM‐specific effects on C translocation to the root system, AM plants had similar rate of photosynthesis to NAM + P plants. These results suggest that the increase in photosynthetic rate in leaves of AM‐infected cucumber was due to an increased P status, rather than a consequence of a mycorrhizal ‘sink’ for assimilates.