Ammonia Emission from Leaves of Different Rice (Oryza sativa L.) Cultivars

Abstract

NH₃ emission from leaves of three rice (Oryza sativa L.) cultivars, Akenohoshi, Shirobeniya and Kasalath, was examined using a simple open chamber system.　In the three cultivars, NH₃ emission rate (AER) and NH₄⁺ content of leaves decreased with decreasing NH₄⁺ concentration in the root medium, but these values differed significantly with the cultivar. In the daytime, AER, NH₄⁺ content and glutamine synthetase (GS) activity in leaves changed similarly with maximum values around midday. Akenohoshi showed significantly lower AER and NH₄⁺ content but higher GS activity than Kasalath. The difference in AER among the rice cultivars may be related to the activity of GS involved in photorespiratory NH₃ recycling. Akenohoshi can be a breeding material useful for improving N recycling.     

小麦光合强度的日变化及其产生的原因

用Ll—6200便携式光合作用分析系统测定了小麦光合强度的日变化和单叶在不同环境条件下的光合强度。通常小麦的光合强度随光强的变化而变化,光强升高,光合强度提高。干热条件下,小麦光合强度在中午下降,即出现“午睡”现象。产生“午睡”的主要原因有:1.中午前后相对湿度下降,引起气孔关闭;2.强光、高温增加了光呼吸的消耗。田间浇水,可降温增湿,缓解小麦的“午睡”现象。     

短枝型与普通型苹果叶片光合特性比较研究

采用红外线CO#-2气体分析仪对短枝型和普通型苹果树新梢叶片光合特性进行比较研究。结果表明：年周期和日周期中,短枝型苹果树新梢叶片的光合速率（Pn）分别高于普通型苹果树12.8%-19.1%、9.5%-13.2%;年周期中,短枝型苹果树新梢叶片的叶绿素含量、SLW分别高于普通型苹果树4.3%-55.5%、3.8%-15.1%;光呼吸速率（Pr）、暗呼吸速率（Dr）、Pr/Pn分别低于普通型苹果树24.2%-25.6%、11.4%-12.0%、27.8%-44.5%。与普通型苹果树相比,短枝型苹果树具有较高的光饱和点和较低的光补偿点。因而,短枝型苹果树光能利用率高,呼吸消耗少,光合强度高,能够积累较多的光合产物,有利于早果、丰产。     

提高作物光合作用途径的研究现状

光合作用是重要的生物合成过程,也是栽培作物产量形成的基础.C3作物光呼吸高,光合速率低.如何提高光合效率,一直是植物学界研究的重大课题,对喷施亚硫酸氢钠、碳肥、钾营养、遗传改造等途径采提高C3作物光合作用的研究现状进行了综述.以期为提高C3作物光合作用研究提供参考.     

亚硫酸氢钠对蚕豆光合生产和蛋白含量的影响

在蚕豆(Vicia fabaL.)灌浆期对其叶面喷施50 mg.L-1和100 mg.L-1的亚硫酸氢钠溶液,结果表明:两种浓度的亚硫酸氢钠均可提高叶片净光合速率,增加籽粒产量,其中50 mg.L-1的促进效果明显。同时研究表明,亚硫酸氢钠虽然可以增加籽粒产量,但却降低了籽粒的蛋白质含量,其中100mg.L-1处理后的降低幅度较大。此外,试验还测定了各处理组的叶绿素含量,结果表明,亚硫酸氢钠对促进叶绿素含量增加与光合产量增加呈正相关。     

环境因子对C3植物光呼吸生态学效应研究进展

光呼吸是C3植物体内重要的代谢过程.本文阐述了人类经济发展的同时对自然环境所产生的种种影响后果,包括CO:浓度升高、紫外辐射增加、温度变化、强光等环境因子对植物光呼吸所产生的影响,如直接或间接导致植物光呼吸速率的变化,进而在植物生理和生态上产生相关的效应.C3植物在受到环境胁迫时,可以通过光呼吸协调代谢功能,在一定程度上发挥规避环境、尤其是极端环境胁迫的效应.因此,可通过调节C3植物的光呼吸规避环境胁迫,这为光呼吸研究在环境生态学领域的拓展指出新的方向.     

小粒种咖啡光合特性的研究

自然状况下,小粒种咖啡树冠外围向阳叶的叶绿素a/b值及其光谱吸收能力都较树冠内层荫蔽叶以及同龄的人工遮荫叶大,且其叶绿体的DCPIP光还原活性和乙醇酸氧化酶活性也都较强,呼吸速率较高,但其叶绿素含量(mg/g)却较低。小粒种咖啡树冠外围向阳叶光合作用的光饱和点约为40klx,内层荫蔽叶和用3层纱布遮荫1.5个月左右的人工遮荫叶部约为15klx。向阳叶在其光饱和点时的光合速率高于荫蔽叶光饱和点时的光合速率;当光照强度处于荫蔽叶的光饱和点时,荫蔽叶的光合速率高于向阳叶;当光照强度超过各自的光饱和点时,向阳叶和荫蔽叶的光合速率都明显下降,即都出现明显的光抑制现象,但这时向阳叶的光合速率仍高于荫蔽叶。小粒种咖啡光合作用的低温界限约比5℃稍高,在本实验高CO_2浓度条件下,温度高达40℃时,其光合速率仍未降低。     

小麦旗叶光呼吸对光强和CO2浓度的响应

为给C₃作物光呼吸等光合参数以及光响应模型和CO₂响应模型的研究提供参考,定量研究了小麦花期旗叶光呼吸速率对光强和CO₂浓度的响应。结果表明,在21%和2%O₂下小麦旗叶光饱和点分别为1 960.629和2 030.120 μmol·m^-2·s^-1。在较弱光强(小于800 μmol·m^-2·s^-1)下,小麦的总光呼吸速率(R_pt)与表观光呼吸(R_pa)均随着光强的升高而增大;当光强大于800 μmol·m^-2·s^-1时,R_pt和R_pa趋于稳定;整体上,不同光强下R_pt与R_pa之间差异较小(P>0.05),这主要是由于在380 μmol·mol^-1 CO₂下,光呼吸的CO₂回收利用率较低。饱和光强下,R_pa随着CO₂浓度的增加呈先上升后下降的趋势,R_pa最大值(Rpmax)所对应的外界CO₂浓度为600 μmol·mol^-1,而R_pt则随着CO₂浓度的升高而降低;在低浓度CO₂(小于380 μmol·mol^-1)条件下,R_pt与R_pa之间差异显著(P<0.05)。R_pt与羧化速率的比值(R_pt /Vc)随着胞间CO₂浓度的升高而呈下降的趋势,而不同光强下R_pt /Vc相对稳定,整体上未达到显著水平(P>0.05)。     

光呼吸与硝酸还原关系研究——光呼吸抑制剂与代谢物对黄化小麦硝酸还原酶光诱导的影响

 用黄化小麦为材料研究了多种光呼吸抑制剂与光呼吸代谢物对硝酸还原酶光诱导及叶片亚硝酸盐含量的影响。结果表明,光呼吸抑制剂NaHSO3、INH、HPMS与光呼吸代谢物乙醇酸、乙醛酸对硝酸还原酶光诱导有显著的抑制作用,而乙醇酸和乙醛酸处理可以提高叶片的亚硝酸盐含量,说明光呼吸与氮代谢有密切的关系,光呼吸的正常进行有利于硝态氮的还原。乙醇酸和乙醛酸对硝酸还原酶的抑制可能与亚硝酸盐在叶片中的积累有关。     

Production of Raphanus sativus (C3)-Moricandia arvensis (C3-C4 intermediate) Monosomic and Disomic Addition Lines with Each Parentl Cytoplasmic Background and their Photorespiratory Characteristics

Abstract

We are maintaining five Moricandia arvensis monosomic addition lines of Raphanus sativus carrying R. sativus cytoplasm (autoplasmic MALs) and twelve M. arvensis MALs of R. sativus carrying M. arvensis cytoplasm (alloplasmic MALs) from BC₆ to BC₈ generation, and newly produced five M. arvensis disomic addition lines of R. sativus (autoplasmic DALs) and seven M. arvensis DALs of R. sativus carrying M. arvensis cytoplasm (alloplasmic DALs) from selfing and sib-crossing of the MALs and DALs in S₃BC₅ and S₂BC₆ generations. The structural, biochemical and physiological characteristics related to photorespiration of these MALs and DALs were compared to study the genetic mechanisms of the C₃-C₄ intermediate photosynthesis in the individual chromosomes of M. arvensis. The CO₂ compensation point of the autoplasmic and alloplasmic DALs (RMa-b and MaR-b DALs) with one pair of M. arvensis ‘b’ chromosome were 29.4 and 30.1 μmol mol-¹, respectively, which were significantly lower than that of other DALs and MALs as well as R. sativus (34.5 𰂼mol mol-¹). An immunogold electron microscopic study of the P-protein of glycine decarboxylase (GDC) in photosynthetic cells of the RMa-b DAL revealed that the bundle sheath cell (BSC) mitochondria were more intensively labeled for the protein than the mesophyll cell (MC) mitochondria. The ratio of the labeling density of the BSC mitochondria to that of the MC mitochondria was 1.13, which lies between values in M. arvensis (2.66) and R. sativus (0.76). These data suggest that the ‘b’ chromosome of M. arvensis genome controls the expression of C₃-C₄ intermediate characteristics.