缺素对小麦冠层反射光谱的影响

为给小麦缺素症早期诊断提供依据,以太湖地区典型稻麦轮作区的长期定位施肥实验为研究对象,分析了氮磷钾单一营养元素缺乏和两种或两种以上元素同时缺乏时的小麦叶绿素含量（SPAD值）及冠层反射光谱特性的变化规律。结果表明,缺素造成了叶片叶绿素含量的下降。缺氮使小麦冠层光谱反射率在可见光波段（460～710nm）和1480～1650nm波段增加,在近红外波段（760～1220nm）下降,红光波段对胁迫表现最为敏感．其次为黄光波段和1480nm左右的水分吸收波段;缺磷降低了近红外波段反射率,对可见光波段反射率的影响则受生育阶段和其他肥料互作的影响;缺钾处理对冠层反射光谱的影响较小,差异不显著。氮胁迫对可见光波段的影响程度显著高于磷胁迫,近红外波段两者持平。光谱对养分胁迫的响应程度随生育进程的推进而逐渐减小。缺素均使冠层光谱的红边位置向短波方向移动即发生蓝移,位移大小依元素缺乏种类及数量而定,最大位移可达10nm左右。     

玉米叶片高光谱特征及与叶绿素、类胡萝卜素相关性的研究

测定了不同品种类型、不同株型、不同发育期的春玉米叶片及其它器官、不同叶位叶片及叶片不同部位的高光谱反射率和叶片的叶绿素、类胡萝卜素含量。结果表明,玉米不同鲜器官的反射率随波长的变化趋势相似,但数值存在较大差异;不同叶位的叶片、不同品种同一叶位的叶片、叶片的不同部位的光谱反射率有差异;叶片光谱反射率随含水率减少而升高,它们的变化趋势相似;叶片叶绿素和类胡萝卜素浓度与光谱植被指数R800/R550、R673/R640、PSSRa、PSNDa、RCh、CARI、λred、Dλred和Sred具有极显著相关。说明可以通过光谱方法来监测玉米长势和估算叶绿素、类胡萝卜素含量。     

不同施氮条件下小麦冠层的高光谱和多光谱反射特征

为了更好地利用冠层反射光谱特征监测小麦生长及氮素营养状况。以宁麦9号、淮麦20、徐麦26和扬麦10号四个小麦品种为材料,通过田间小区试验,研究了不同小麦品种在不同生育时期和不同氮素水平下冠层反射光谱的变化规律。结果表明,相同氮素水平下不同小麦品种冠层反射光谱的反射率有差异,且近红外部分差异较明显。小麦从拔节开始,随生育期的推进,冠层反射光谱在可见光波段的反射率先降低然后升高,以孕穗期反射率最低。随着叶片的逐渐变黄。反射率又增大,并且绿光波段的反射峰也逐渐消失。而近红外区反射率则表现出相反的趋势,以开花期为分界,先上升然后下降,直到成熟前降为最低。随着施氮水平的提高,冠层反射光谱在近红外反射平台（750-1300nm）的反射率呈上升趋势,而可见光部分反射率则下降,并且反射光谱的绿峰和红边位置也随着施氮水平的提高分别向蓝光方向（波长变短）和红光方向（波长变长）移动。     

小麦叠加叶片的叶绿素含量光谱反演研究

为了给田间冠层水平叶绿素含量高光谱反演研究提供参考,研究了小麦单层及叠加叶片不同波长光谱反射率及几种常用植被指数对叶绿素含量的响应特征。结果表明,可见光波段的绿光到红光波段范围内叶片光谱反射率与叶绿素含量存在良好的相关关系,其中在绿光反射峰550 nm附近和红边区域的705 nm附近反射率都可以用来预测叶绿素含量。红谷吸收表现为随叶绿素含量提高而蓝移的特征。常用植被指数NDVI在本研究中对小麦叶片的叶绿素含量的监测效果并不理想。SR705虽然与单层叶片叶绿素含量相关性较好,但是对叠加多层叶片的叶绿素含量反演效果不好。光谱参数中TCARI对单层叶片和不同叠加层数的叶片均有最好的预测能力,因此可以利用TCARI监测小麦叶绿素含量,进而用于评价其光合特性。     

基于高光谱指数的叶片尺度叶绿素荧光参数反演

在叶片尺度上,基于高光谱植被指数反演实际光合速率(Phi2)、非调节的光能耗散(PhiNO)、非光化学淬灭(PhiNPQ)、相对叶绿素含量(RC)4个叶绿素荧光参数,分析不同氮素处理下叶片光谱反射率和4个叶绿素荧光参数在不同时期的变化特征。结果表明,可见光波段在过量施氮下叶片反射率低于不施氮处理;在近红外波段,叶片光谱反射率随着施氮量的增大而增大。随着玉米的生长,不施氮处理下Phi2逐渐减少,PhiNPQ逐渐增加;过量施氮下Phi2先增加后减少,PhiNO和PhiNPQ先降低后增加。RC在不同施氮条件下均随着生育时期发展先增加后减少。Phi2和PhiNPQ与归一化植被指数(NDVI)的相关性最好,PhiNO与改进型叶绿素吸收比值指数(MCARI)的相关性最好,RC与红边植被指数(CIred edge)的相关性最好。     

根腐病胁迫对大豆光谱特征和叶绿素荧光特性的影响

为探讨根腐病胁迫下光谱特征指数和叶绿素荧光参数与光合色素的相关性,以大豆植株为研究对象,分析了不同程度根腐病胁迫下大豆叶片光合色素、叶绿素荧光特性以及冠层光谱特征的差异性。结果表明:随大豆根腐病病情的加重叶绿素a、叶绿素b、总叶绿素、类胡萝卜素以及叶绿素/类胡萝卜素降低。同时,光系统II最大光化学效率、光系统II光化学效率、非光化学淬灭系数以及PSII的量子产额等荧光参数显著低于正常植株。光谱反射率在近红外区域(700～1 000 nm)随病害程度的加重而降低,归一化深度变浅。通过对原始光谱进行微分变换,病害植株红边幅值降低,红边位置出现蓝移现象。除绿峰位置、幅值以及修正叶绿素吸收反射率指数外,红边幅值、红边位置、结构不敏感色素指数、光化学植被指数、简单植被指数、归一化差异指数、修正归一化差异指数、绿度指数以及荧光参数与根腐病胁迫下叶片光合色素相关性均达到显著水平。因此,选择适宜的光谱特征指数和叶绿素荧光参数,借助光合色素变化,可为利用高光谱遥感技术和荧光成像技术对大豆根腐病危害诊断提供理论支持。     

用高光谱植被指数估算水稻乳熟后叶片和穗的色素含量

 分析测定了大田条件下2个水稻品种在3个氮素水平下的剑叶和穗从乳熟期至收割的光谱反射率(350~2500 nm)及对应剑叶和穗的叶绿素（Chl）、类胡萝卜素（Car）含量,并利用相关分析研究了11个植被指数与剑叶、穗的叶绿素含量之间的关系。mSR705、mND705在试验范围各叶绿素含量水平下，都表现极显著的相关性。mSR705、mND705与叶片、穗叶绿素含量进行线性回归，两者拟合R2分别为0.9319和0.9488（n＝48）。植被指数与类胡萝卜素、Car/Chl间的相关性分析表明，光化学反射指数（PRI）与剑叶、穗Car/Chl都有很好的负相关（R2=0.7745，n=48）, 可以用来预测不同植被结构的Car/Chl;R760/R500与剑叶Car/Chl和穗Car含量也具有较好的相关性。结果表明，mSR705、mND705和PRI等指数可用于估算叶片、穗的色素含量，作为水稻成熟度的监测指标。     

基于高光谱遥感的小麦叶片含氮量监测模型研究

为了在作物氮素管理中实现叶片氮含量的实时无损估测,以不同类型小麦品种在不同施氮水平下连续3年田间试验为基础,研究了小麦叶片氮含量与冠层高光谱参数的定量关系.结果表明,叶片氮含量随着施氮水平的增加而提高,冠层光谱反射率在不同叶片氮含量水平下存在明显差异.叶片氮含量的敏感波段主要存在于近红外平台和可见光区,其中,红边区域最为显著.红边及面积类参数REPIE、SDr-SDb和FD729与叶片氮含量关系密切,方程拟合决定系数R2分别为0.829、0.806和0.856,估计标准误差SE分别为0.278、0.295和0.271;模拟宽光谱波段组合类参数方程拟合精度较低,标准误差较大,以AVHRR-GVI为变量模拟方程,R2 和SE分别为0.786和0.315;多波段组合类参数方程拟合效果较好,以mND705为变量建立方程,其R2 和SE分别为0.836和0.275.经不同年际独立数据检验,红边及面积类参数表现最好,以REPIE、SDr-SDb和FD729三个参数为变量,模型预测的RMSE分别为0.418、0.380和0.395,相对误差RE分别为14.4%、15.1%和15.2%;模拟宽光谱波段组合类参数与多波段组合类参数比较,模拟宽光谱波段组合模型预测效果更好,以AVHRR-GVI 和mND705为变量建立模型,RMSE分别为0.436和0.408,RE分别为17.3%和16.7%.以上结果表明,红边及面积类参数与叶片氮含量关系密切且表现稳定,利用REPIE、SDr-SDb和FD729三个参数可以对小麦叶片氮含量进行可靠的监测.     

基于冠层反射光谱的夏玉米叶片色素含量估算模型研究

通过分析不同施氮水平下夏玉米叶片色素含量与冠层光谱反射率及其衍生的比值植被指数(RVI)、归一化植被指数(NDVI)、正交植被指数(MTVI2、MCARI2、SAVI、MSAVI)以及叶绿素吸收比值指数(CARI)之间的关系,建立夏玉米叶片叶绿素a(Chla)、叶绿素b(Chlb)、叶绿素a+b(Chl a+b)和类胡萝卜素(Car)含量估算模型。结果表明:NDVI与夏玉米叶片色素含量的相关性最好,RVI、RVI、CARI位居其次。通过逐步回归分析确立的夏玉米叶片Chla、Chlb、Chl a+b及Car含量的估算模型R2分别为0.790 8、0.832 4、0.808 8和0.761 7,说明利用冠层NDVI可以对夏玉米叶片Chla、Chlb、Chl a+b和Car含量进行可靠的监测。     

关中冬小麦叶片氮素含量高光谱遥感监测模型

为给黄土高原大范围的冬小麦氮素营养遥感监测提供理论依据,通过田间试验,研究了冬小麦叶片氮素含量遥感监测的最佳生育时期、最敏感波段及其他最优光谱参量。结果表明,灌浆期是利用高光谱遥感监测冬小麦叶片氮素营养状况的最佳生育时期;在拔节、抽穗和灌浆期680nm波段光谱反射率R680均能较好地反映冬小麦叶片氮素含量,基于光谱位置以及叶面积指数的光谱参量也能较好地反映冬小麦叶片氮素含量。拔节期、抽穗期和灌浆期分别以680nm波段光谱反射率R680、绿峰反射率Rg和植被指数(SDr-SDb)/(SDr+SDb)对小麦叶片氮素含量的拟合效果最佳,其回归方程分别为Y=27.54-280.247 X+1456.245 X2、Y=8.632 X-0.24和Y=25.83 X1.012。     

基于优化光谱指数的新疆春小麦冠层叶绿素含量估算

为筛选可用于干旱半干旱区春小麦冠层叶绿素含量估算的高光谱植被指数,2017年通过测定春小麦关键生育时期冠层的田间高光谱与叶绿素含量,利用光谱指数波段优化算法分别计算400～1 300 nm光谱波段中不同波段两两组合的比值光谱指数(ration spectral index,RSI)、归一化光谱指数(normalized difference spectral index,NDSI)、叶绿素指数(chlorophyll index,CI)、简化光谱指数(CI/NDSI,NPDI),并将这些参数及其他17个不同高光谱植被指数分别与实测冠层叶绿素含量进行Pearson相关分析,通过变量重要性准则筛选最优光谱参数,使用偏最小二乘回归法建立冠层叶绿素含量的预测模型。结果表明:(1)RSIs、NDSIs、CIs和NPDIs与冠层叶绿素含量的相关性都优于前人研究中定义的17种高光谱植被指数,并且冠层叶绿素含量与NDSI(R_(849),R_(850))、RSI(R_(849),R_(850)),CI(R_(849),R_(850))和NPDI(R_(849),R_(850))表现出强相关性。(2)用此4个优化光谱指数分别建模时,以CI(R_(849),R_(850))、 CI(R_(539),R_(553))、 CI(R_(540),R_(553))、 CI(R_(536),R_(553))为自变量的X-3模型预测精度最高(r~2=0.74,RMSE=0.272 mg·g~(-1))。(3)结合4个优化光谱指数构建的组合模型预测精度,其r~2=0.83,RMSE=0.187 mg·g~(-1)。     

Leaf nitrogen distribution to maximize the canopy photosynthesis in rice

The optimum distribution of leaf nitrogen (N) in the canopy of rice plants (Oryza sativa L.) for maximum daily canopy photosynthesis (DCP) and the optimization effects on DCP were estimated during the grain filling period. The low- and high-density canopies (28.3 and 47.5 plants m⁻²) and isolated plants were established at heading using plants in pots grown up at the low density until heading to make the same canopy architecture except plant density and the same leaf N distribution at the start of treatment among the two canopies and the isolated plants. The simulation was conducted under two conditions of the upper limit of leaf N. Under condition 1, upper limit of leaf N content was 1.80 g m⁻². Under condition 2, upper limits were measured leaf N content in each leaf position at heading. The model indicates that if leaf N content in the upper leaves can be increased with reduction of N in the lower leaves, DCP will increase in any of the plant density, light conditions and under conditions 1 and 2. On a clear day, the estimated increase in DCP was 19–45 and 38–70% in the low- and high-density canopies under condition 1, respectively. Even under condition 2, which is more realistic than condition 1, the increase was up to 21 and 25% in the low- and high-density canopies. These estimates obtained by the present model that incorporates the shading effects of panicles and stems on DCP were higher than the previous reports which did not consider the effects of shading by panicles and stems. In the observed leaf N distribution, the higher the plant density was, the steeper the gradient of the leaf N remained. The gradient in the high-density canopy was closer to that of the predicted optimum leaf N distribution, and likely to contribute to maintaining higher DCP in the canopies. Compared with the hypothetical case in which gradient of leaf N distribution would be more gentle as observed in the isolated plants, the maintained steeper gradient of observed leaf N content in the canopies was estimated to increase DCP by 13 and 5% in the high- and low-density canopy, respectively.     

开放式空气CO2浓度增高和施氮量对水稻结实期叶片内肽酶活力的影响

 利用农田开放式空气CO2浓度增高 (free air CO2 enrichment,FACE) 系统,CO2浓度设正常CO2 (ambient, AMB) 和高CO2 (FACE,AMB + 200 μmol/mol) 2个水平,施N量设低氮 (LN,15 g/m2,以纯氮计)、中氮 (NN,25 g/m2)和高氮 (HN,35 g / m2) 3个水平,对水稻品种武香粳14结实期剑叶和倒2叶的内肽酶活力变化情况进行了研究。结果表明: 1) 同AMB相比,FACE处理使剑叶抽穗后10 d、20 d以及倒2叶抽穗到抽穗后20 d内肽酶活力明显提高,但使剑叶成熟期内肽酶活力明显下降;使剑叶抽穗后10 d、20 d和成熟期以及倒2叶抽穗到成熟期内肽酶比活力明显提高;FACE对抽穗后10 d、20 d叶片内肽酶活力和比活力影响较大,而对抽穗期和成熟期的影响较小。同LN相比,HN使灌浆前期叶片内肽酶活力明显降低,灌浆中后期则呈增加趋势;HN降低了叶片各期内肽酶比活力,灌浆前期降幅大于后期。 2) 同AMB相比,FACE使叶片抽穗后10 d至成熟期可溶性蛋白含量明显降低;同LN相比,HN明显减缓FACE处理对抽穗后10 d至成熟期功能叶片可溶性蛋白含量的影响。 3）除成熟期叶片可溶性蛋白含量与内肽酶活力呈正相关外,结实期剑叶及倒2叶可溶性蛋白含量与对应时期内肽酶活力呈显著负相关。上述结果说明,FACE处理下水稻剑叶及倒2叶结实中后期可溶性蛋白含量明显下降与结实期叶片内肽酶活力的变化关系密切。     

Effects of Nitrogen Fertilizer Level on Chlorophyll Fluorescence Characteristics in Flag Leaf of Super Hybrid Rice at Late Growth Stage

To compare the effects of slow-release nitrogen fertilizer at six different levels on the flag leaf chlorophyll fluorescence characteristics of super hybrid rice,a field fertilization experiment was conducted with super hybrid rice Y Liangyou 1 as a test material.The photosynthetic electron transport rate (ETR),effective quantum yield (EQY),photochemical quenching coefficient (q P),and non-photochemical quenching coefficient (NPQ) of flag leaves were measured at the initial heading,full heading,10 d after full heading and 20 d after full heading stages.Results showed that the values of ETR,EQY and q P increased with rice development from initial heading to 20 d after full heading,whereas the NPQ decreased.During the measured stages,ETR,EQY and q P increased initially and then decreased as nitrogen application amount increased,but they peaked at different nitrogen fertilizer levels.The maximum ETR and EQY values appeared at the treatment of 135 kg/hm 2 N.In conclusion,the optimum nitrogen amount for chlorophyll fluorescence characteristics of super hybrid rice was 135 180 kg/hm 2.     

不同施肥水平对杂交水稻氮、磷、钾吸收积累的影响

为探索不同施肥量下2个杂交水稻植株氮、磷、钾的吸收积累特性,采用田间小区试验研究了两个杂交稻品种抽穗期和成熟期的植株氮、磷、钾吸收积累。结果表明,2个杂交水稻品种在不同施肥水平下,抽穗期和成熟期茎＋叶鞘、叶、穗各器官内的氮、磷、钾的含量无显著差异;抽穗期,叶的氮含量最高,茎＋叶鞘的磷、钾含量最高;成熟期,叶的氮含量、茎＋叶鞘的磷含量、穗的钾含量均下降。抽穗期,氮、钾吸收量及干物质量红泰优996高于粤优589,磷吸收量粤优589高于红泰优996;成熟期,氮、钾吸收量及干物质量粤优589高于红泰优996,磷吸收量2品种差异不明显。2个杂交水稻品种地上部植株对氮、磷、钾积累量比例的变幅范围均在高产水稻积累变幅范围内。     

杂交稻旗叶衰老过程中超氧自由基与超氧物岐化酶活性的变化

The O₂^- production, scavenging capacity, photooxidation, protein content, and SOD activity were studied in leaves of Yayou 2 (indica-japonica hybrid rice) and Shanyou 63 (indica hybrid rice) at filling stage. It was shown that protein content decreased gradually with days of heading in two varieties in natural condition, and the decrease in Shanyou 63 was more than that in Yayou 2. The rate of O₂^- production and SOD activity increased from heading to 20 days after heading, then decreases but still maintained certain levels until 30 days after heading in two varieties. O₂^- production rate in Shanyou 63 was more than that of Yayou 2, but SOD activity was contrary in two varieties. In addition, the change of O₂^- and SOD under photooxidation condition was consistent with the tendency above under natural condition. It was also shown that there was negative correlation between protein degradation and O₂^- / SOD in the process of senescence in flag leaves after 20 days of heading. It is suggested that O₂^-/SOD could be used as an index of scavenging ability for O₂^- during senescence in rice.     

高静水压诱变水稻突变株系的叶绿素荧光特性变化

以经75 MPa高静水压处理后筛选得到的3个水稻突变株系及其亲本粤香占为材料,测定了田间生长条件下不同生育时期水稻剑叶的叶绿素荧光动力学参数。与对照亲本相比较,3个突变株系的Fv/Fm在分蘖期和抽穗期均增加,除抽穗期突变2的ΦPSⅡ略低外,其余的ΦPSⅡ都表现为增加,说明光系统Ⅱ的功能得到改善。在抽穗期,突变株系与亲本在中午高光强下受到的抑制相比,突变株系受到的抑制较小,而且在18:00以后几乎能恢复到早上6:00的水平;在灌浆期,突变株系受到的光抑制增加,但能够快速恢复。突变1、突变2和粤压1号单株产量比对照亲本分别提高268%、279%和188%。结果显示,高静水压处理萌动的水稻种子后筛选得到的突变株系叶片的叶绿素荧光特性及田间光抑制发生了改变,产量也明显提高。高静水压诱变可能成为一种筛选高产水稻品种的新途径之一。     

Effects of Flag Leaves and Panicles on Light Interception and Canopy Photosynthesis in High-Yielding Rice Cultivars

Abstract

The effects of flag leaves and panicles on canopy photosynthesis in a leading cultivar (Nipponbare) and two high-yielding rice cultivars (Takanari and Ghugoku 117) bred in Japan were compared. The total dry matter production was in the order of Takanari > Ghugoku 117 > Nipponbare. Canopy photosynthesis was highest in Takanari throughout the growth season, and was higher in Chugoku 117 than in Nipponbare during the ripening period. The photosynthetic rate in the flag leaf was in the order of Nipponbare > Takanari > Chugoku 117. The light extinction coefficient of canopy was higher in Takanari than in the others. At the middle ripening stage, canopy photosynthesis increased 35 and 17% in Nipponbare and Takanari, respectively, by the removal of panicles and decreased 37 and 48%, respectively, by the removal of flag leaves. In Chugoku 117, canopy photosynthesis was hardly influenced by these treatments. Clearly, the panicles intercept more radiation at the upper layer of the canopy in Nipponbare than in Takanari and flag leaves contribute more to canopy photosynthesis in Takanari than in Nipponbare. However, these effects were small in Chugoku 117. In conclusion, Takanari produces more dry matter than the others due to larger, wider, longer and more erect 1st (flag) and 2nd leaves above the panicles, which intercept more radiation. Chugoku 117 had erect panicles which allowed more radiation to penetrate into the deeper layer of the canopy, resulting in a high dry matter production. The lower panicle height relative to leaf layer and erect panicles are important characteristics for higher yield in rice.     

高浓度CO2条件下水稻叶片氮含量下降与氮代谢关键酶活性的关系

利用FACE（Free Air Carbon Dioxide Enrichment）平台技术,研究了低氮（125 kg/hm2,以纯N计）和常氮（250 kg/hm2）水平下,高浓度CO2（周围大气CO2浓度+200 μmol/mol）对水稻不同生育期功能叶N代谢关键酶活性的影响。结果表明,高浓度CO2提高了叶片硝酸还原酶和蛋白水解酶的活性,两者在常N下的响应程度大于在低N下的响应程度;高浓度CO2降低了低N下叶片谷氨酰胺合成酶和谷氨酸脱氢酶（NADH GDH）活性,常N水平下酶活性的下降趋势得到改变或缓解。由此可见,高浓度CO2条件下NO3-转化为NH4+加速,而NH4+进一步同化为有机N却受阻,而且,由于后期蛋白水解加速,将进一步加剧叶片N含量的下降。这是水稻叶片N含量下降的内在因素。而增施N肥,有利于同化酶的表达,降低叶片蛋白水解酶活力,从而缓解叶片N含量的下降。