播种时期与密度对关中灌区夏玉米群体生理指标的影响

采用二次饱和D最优试验设计,运用作物群体生理学方法,研究了关中灌区玉米密度、播期与群体生理指标的关系及其影响效应.结果表明,关中灌区夏播条件下,在6月13日—7月22日,播期与玉米籽粒产量、干物质积累量(DMA)、吐丝期叶面积指数(LAImax)、总光合势(LAD)、群体净同化率(NAR)、作物生长率(CGR)呈负相关,播期对CGR、LAD的影响较大,对LAImax和NAR的影响较小;在45000～65918株·hm-2范围内,密度与玉米籽粒产量、DMA、LAImax、LAD、CGR呈正相关,而与NAR呈负相关,密度对CGR、LAImax和LAD的影响较大,而对NAR的影响较小.播期对玉米群体生理指标的总影响效应显著大于密度,实际生产中应力争早播.对密度和播期与玉米群体生理指标建立的回归模型表明,陕单8806玉米在关中灌区夏播中实现高产的适宜播期为6月10—20日,密度应控制在57767～71706株·hm-2.     

密度与氮肥对关中灌区夏玉米（Zea mays L.）群体光合生理指标的影响

合理的密度是玉米构建良好群体结构、优化群体光合生理功能的基础,适宜的氮肥施用量是玉米进行光合生产的营养物质保障。运用作物群体生理学的方法,采用二次饱和D试验设计,研究了关中灌区夏玉米密度与氮肥耦合和群体光合生理指标的关系及其效应,明确了在关中灌区夏播条件下,在45000～75000株/hm2的密度范围内,密度与玉米籽粒产量、总干物质积累量（DMA）、吐丝期叶面积指数（MLAI）、总光合势（LAD）、平均作物生长率（CGR）为正相关,在45000～60000株/hm2的密度范围内,密度与玉米叶片平均净同化率（NAR）为正相关,而在60000～75000株/hm2的密度范围内,密度与玉米NAR为负相关;在氮素施用量≤600.0 kg/hm2的范围内,氮素施用量与玉米籽粒产量、DMA、CGR为正相关,在氮素施用量≤260.55 kg/hm2的范围内,氮素施用量与玉米MLAI、LAD为正相关,与玉米NAR为负相关,而在氮素施用量260.55～600.0kg/hm2的范围内,氮素施用量与玉米MLAI、LAD为负相关,与玉米NAR为正相关。密度对其影响较大的指标为:籽粒产量、DMA、LAD、CGR和MLAI , 影响较小的指标为:NAR;氮肥对其影响较大的指标为:DMA、CGR、籽粒产量、NAR,影响较小的指标为:LAD和MLAI 。对籽粒产量和群体生理指标的综合影响效应,密度显著大于氮肥,玉米生产中,尤其要重视合理密植。通过对回归模型的解析,筛选确定了陕单8806玉米在关中灌区夏播中,实现高产的密度与氮肥耦合优化技术方案:合理密度为61713～66177株/hm2,适宜纯氮施用量为309.88～569.02kg/hm2。     

开放式空气CO2浓度增高条件下C3作物(水稻)与C4杂草(稗草)的竞争关系

通过田间试验,研究了FACE（开放式空气CO2浓度升高）条件下C3作物水稻（Oryza sativa）和C4杂草稗草（Echinochloa crusgalli）的生长和竞争关系,结果表明,FACE条件下C3植物水稻生物量和产量增加,吉片数增加,分蘖数增加,叶面积系数（LAI）增大;而C4植物稗草相反,FACE条件下水稻和稗草中面积均减少,而净同化率（NAR）均增加;FACE条件下水稻-稗草比例为1：1时,水稻与稗草的生物量比率、产量比率、LAI比率、茎蘖比率和NAR比率均增加,水稻-稗草的竞争关系发生变化,水稻（C3植物）竞争能力增加,稗草（C4植物）竞争能力下降。     

低氮胁迫对不同基因型夏玉米源库性状和灌浆特性的影响

2007和2008年连续2年在低氮（105 kg·hm^-2）和正常施氮（337.5 kg·hm^-2）两种施肥水平下,分析了6个不同基因型玉米品种的群体源库关系及籽粒灌浆特性间的差异.结果表明：低氮胁迫对不同基因型玉米品种的群体产量、叶面积指数（LAI）、群体源库性状和籽粒灌浆特性影响明显,在低氮胁迫下,先玉335、郑单958等耐低氮能力较好品种的籽粒活跃灌浆期较长、最大灌浆速率高、最大叶面积指数持续期较长,群体库源关系比较协调;陕单902和豫玉22等耐低氮能力较差品种吐丝后的籽粒活跃灌浆时数、最大灌浆速率、灌浆速率最大时的生长量及LAI较低,源的供应能力显著下降;低氮胁迫明显加剧了不同基因型玉米品种间的产量差异.     

密度与氮肥对关中灌区夏玉米(Zea mays L.)群体光合生理指标的影响

合理的密度是玉米构建良好群体结构、优化群体光合生理功能的基础,适宜的氮肥施用量是玉米进行光合生产的营养物质保障.运用作物群体生理学的方法,采用二次饱和D试验设计,研究了关中灌区夏玉米密度与氮肥耦合和群体光合生理指标的关系及其效应,明确了在关中灌区夏播条件下,在45000～75000株/hm2的密度范围内,密度与玉米籽粒产量、总干物质积累量(DMA)、吐丝期叶面积指数(MLAI)、总光合势(LAD)、平均作物生长率(CGR)为正相关,在45000～60000株/hm2的密度范围内,密度与玉米叶片平均净同化率(NAR)为正相关,而在60000～75000株/hm2的密度范围内,密度与玉米NAR为负相关;在氮素施用量≤600.0 kg/hm2的范围内,氮素施用量与玉米籽粒产量、DMA、CGR为正相关,在氮素施用量≤260.55 kg/hm2的范围内,氮素施用量与玉米MLAI、LAD为正相关,与玉米NAR为负相关,而在氮素施用量260.55～600.0kg/hm2的范围内,氮素施用量与玉米MLAI、LAD为负相关,与玉米NAR为正相关.密度对其影响较大的指标为:籽粒产量、DMA、LAD、CGR和MLAI , 影响较小的指标为:NAR;氮肥对其影响较大的指标为:DMA、CGR、籽粒产量、NAR,影响较小的指标为:LAD和MLAI .对籽粒产量和群体生理指标的综合影响效应,密度显著大于氮肥,玉米生产中,尤其要重视合理密植.通过对回归模型的解析,筛选确定了陕单8806玉米在关中灌区夏播中,实现高产的密度与氮肥耦合优化技术方案:合理密度为61713～66177株/hm2,适宜纯氮施用量为309.88～569.02kg/hm2.     

不同类型饲用玉米群体光合生理特性的研究

对两种类型饲用玉米的群体生理特性进行了研究,结果表明：青贮型玉米的叶面积和叶面积系数较大,吐丝前叶面积增长快,吐丝后叶片衰老略快,拔节至吐丝25d期间作物生长率较高,光合势和干物质积累量大,是决定生物学产量的关键时期,青贮型玉米科多8号的适宜密度在67500株／hm^2左右;粮饲兼用型玉米叶面积和叶面积系数较小,吐丝前叶面积增长较快,吐丝后叶片衰亡较慢,吐丝后至成熟期期间干物质积累量和光合势大,作物生长率高,是决定其生物学产量和籽粒产量的关键时期,粮饲兼用型玉米陕单310的耐密性较好。     

开放式空气CO2浓度增高条件下C3作物(水稻)与C4杂草(稗草)的竞争关系

通过田间试验,研究了FACE(开放式空气CO₂浓度升高)条件下C₃作物水稻(Oryza sativa)和C₄杂草稗草(Echinochloa crusgalli)的生长和竞争关系.结果表明,FACE条件下C₃植物水稻生物量和产量增加,叶片数增加,分蘖数增加,叶面积系数(LAI)增大;而C₄植物稗草相反.FACE条件下水稻和稗草叶面积均减少,而净同化率(NAR)均增加.FACE条件下水稻稗草比例为1:1时,水稻与稗草的生物量比率、产量比率、LAI比率、茎蘖比率和NAR比率均增加,水稻稗草的竞争关系发生变化,水稻(C₃植物)竞争能力增加,稗草(C₄植物)竞争能力下降.     

光强对两种入侵植物生物量分配、叶片形态和相对生长速率的影响

 比较研究了不同光强下生长的（透光率分别为12.5%、36%、50%、100%）两种入侵性不同的外来种——紫茎泽兰（Eupatorium adenophorum）和兰花菊三七（Gynura sp.）的生物量分配、叶片形态和生长特性。结果表明: 1）两种植物叶片形态对光环境的反应相似。弱光下比叶面积（SLA）、平均单叶面积（MLS）和叶面积比（LAR）较大,随着光强的升高,SLA、MLS、LAR和叶根比（LARMR）降低。2）100%光强下紫茎泽兰叶生物量比（LMR）、叶重分数（LMF）和叶面积指数高于低光强下的值,也高于兰花菊三七,支持结构生物量比（SBR）则相反。强光下紫茎泽兰叶片自遮荫严重,这可能是其表现入侵性的重要原因之一;兰花菊三七分枝较多,避免了叶片自遮荫,较多的分枝利于种子形成对其入侵有利。3）随生长环境光强的升高,两种植物的净同化速率（NAR）、相对生长速率（RGR）和生长对NAR的响应系数均升高（但100%光强下兰花菊三七RGR降低）,平均叶面积比（LARm）和生长对LARm的响应系数均降低,但不同光强下LARm对生长的影响始终大于NAR。4）随着光强的减弱,两种植物都增加高度以截获更多光能,但它们的生物量分配策略不同,紫茎泽兰根生物量比（RMR）降低,SBR增大,而兰花菊三七SBR降低,RMR增大。紫茎泽兰的生物量分配策略更好的反应了弱光环境中的资源变化情况。结论：紫茎泽兰对光环境的适应能力强于兰花菊三七。     

不同生态环境下水稻基因型产量形成与源库特性的比较研究

以日本和IRRI的9个水稻品种为材料,分别以武香粳9号和两优培九为对照,在江苏南京和云南丽江研究了不同水稻基因型干物质积累与源库形成特征及其在不同生态环境下的差异.结果表明,生态环境对水稻产量和干物质积累量影响显著.高产水稻品种积累了高额干物质量,且干物质生产优势在中后期.高产品种的总颖花量、LAI及群体生长速率(CGR)都较高.稻谷产量随干物质积累总量的增加而提高,与齐穗后干物质积累量、总颖花量和LAI呈极显著正相关,与粒叶比呈显著正相关.与云南丽江点相比,群体LAI、单位面积颖花量和抽穗后干物质积累量少及生长速率(CGR)低是南京点稻谷产量低的关键因素.     

水稻主茎节位分蘖及生产力补偿能力

本研究选用两个籼稻杂交品种西农优1号和冈优725,采用人工去蘖形成分蘖初期的早发、中发、迟发三个处理,在群体条件下研究分蘖和生产力的补偿能力。本研究发现,迟发处理高节位群的分蘖补偿能力最明显,但绝对补偿量小。迟发处理高节位群的生长势、有效分蘖倍数增加,抽穗期单茎叶面积有增加的趋势,但抽穗期有效穗数、叶面积系数降低;迟发处理冠层光分布增加,叶绿素、蛋白质含量提高,叶片细胞内保护酶类(Superoxide dismutase, SOD、catalase,CAT)活性下降慢,叶片衰老慢,但是漏光率增加,截光率下降;迟发处理净光合生产率（Net assimulation rate, NAR）增加,同化物分配合理,经济系数有增加的趋势,但物质积累速度（Crop growth rate ,CGR）和干物质生产量减少。在本实验条件下,早发与中发处理的经济产量差异不显著,但早发与迟发处理的经济产量差异达极显著。本研究结果表明大苗秧对生物、非生物因素胁迫,如本田前期一定程度的人工去蘖,具有一定的分蘖补偿能力。     

Morphological and phenological comparisons of two Hopi maize varieties conserved in situ and ex situ

Over the last twenty-five years, crop genetic resources (CGR) have been preserved in genebanks around the world for use by formal plant breeders. Recently conservation of folk crop varieties for direct use by the farmer-breeders of traditional agricultural communities has been suggested as another purpose for CGR conservation. While both in and ex situ CGR conservation programs have been proposed to meet the needs of formal plant breeders and farming communities, the needs and goals of the two groups are different. Formal breeders seek maximum allelic diversity while farmer-breeders are interested in both diversity and population structure that provide local adaptation. Based on the morphological and phenological data analyzed for this study of two Hopi maize varieties conserved in and ex situ, it appears that both genetic shift and genetic drift have occurred ex situ, and that populations conserved ex situ are different from those maintained in situ. These findings suggest that CGR conservation strategies must be re-evaluated in light of the specific conservation goals that are sought.     

Genetic variation,heritability, divergence and biomass accumulation of rice genotypes resistant to bacterial blight revealed by quantitative traits and ISSR markers

A field experiment was carried out in order to evaluate genetic diversity of 41 rice genotypes using physiological traits and molecular markers. All the genotypes unveiled variations for crop growth rate (CGR), relative growth rate (RGR), net assimilation rate (NAR), yield per hill (Yhill^?1), total dry matter (TDM), harvest index (HI), photosynthetic rate (PR), leaf area index (LAI), chlorophyll‐a and chlorophyll‐b at maximum tillering stage. The CGR values varied from 0.23 to 0.76 gm cm^?2 day^?1. The Yhill^?1 ranged from 15.91 to 92.26 g, while TDM value was in the range of 7.49 to 20.45 g hill^?1. PR was found to vary from 9.40 to 22.34 µmol m^?2 s^?1. PR expressed positive relation with Yhill^?1. Significant positive relation was found between CGR and TDM (r = 0.61**), NAR and CGR (r = 0.62**) and between TDM and NAR (r = 0.31**). High heritability was found in RGR and Yhill^?1. Cluster analysis based on the traits grouped 41 rice genotypes into seven clusters. A total of 310 polymorphic loci were detected across the 20 inter‐simple sequence repeats (ISSR) markers. The UPGMA dendrogram grouped 41 rice genotypes into 11 clusters including several sub‐clusters. The Mantel test revealed positive correlation between quantitative traits and molecular markers (r = 0.41). On the basis of quantitative traits and molecular marker analyses parental genotypes, IRBB54 with MR84, IRBB60 with MR84, Purbachi with MR263, IRBB65 with BR29, IRBB65 with Pulut Siding and MRQ74 with Purbachi could be hybridized for future breeding program.     

Biomass accumulation and energy conversion efficiency in aromatic rice genotypes

A field experiment was conducted to evaluate photosynthetic efficiency along with different growth parameters of aromatic rice genotypes. Forty genotypes including three non-aromatic checks exhibited enormous variations for leaf area index (LAI), crop growth rate (CGR), relative growth rate (RGR), net assimilation rate (NAR), grain yield, total dry matter, harvest index and photosynthetic efficiency or energy use efficiency (Eμ) at panicle initiation and heading stages. Minimum LAI-value was 0.52 in Khazar at PI stage and maximum was 4.91 in Sakkor khora at heading stage. The CGR-value was in the range of 4.80−24.11 g m⁻² per day. The best yielder BR39 produced grain of 4.21 t ha⁻¹ and the worst yielder Khazar gave 1.42 t ha⁻¹. Total dry matter (TDM) yield varied from 4.04 to 12.26 t ha⁻¹ where genotypes proved their energy use efficiency a range between 0.58 to 1.65%. Eμ showed a significant positive relation with TDM (r = 0.80^**), CGR (r = 0.72^**) and grain yield (r = 0.66^**). A negative correlation was established between TDM and harvest index and LAI and RGR. Path analysis result showed that NAR at heading stage exerted highest positive direct effect (0.70) on Eμ.     

Growth Rate, Photosynthesis and Respiration in Relation to Leaf Area Index

This work examined three possible explanations of growth rateresponses to leaf area index (LAI) in which growth rate perunit of ground area (crop growth rate, CGR) increased to a plateaurather than decreasing above an optimum LAI at which all lightwas intercepted. Single leaf photosynthetic measurements, andwhole plant 24 h photosynthesis and respiration measurementswere made for isolated plants and plants in stands using Amaranlhushybridus, Chenopodium album, and two cultivars of Glycine maxgrown at 500 and 1000 µimol m^–2 S^–1 photosyntheticphoton flux density at 25 °C. CGR, relative growth rate(RGR), and LAI were determined from 24 h carbon dioxide exchangeand leaf area and biomass measurements. Respiration increasedrelative to photosynthesis with crowding in A. hybridus andthere was an optimum LAI for CGR. In contrast, the ratio ofrespiration to photosynthesis was constant across plant arrangementin the other species and they had a plateau response of CGRto LAI. Neither increased leaf photosynthetic capacity at highLAI nor a large change in biomass compared to the change inLAI could account for the plateau responses. It was calculatedthat maintenance respiration per unit of biomass decreased withdecreasing RGR in C. album and G. max, but not A. hybridus,and accounted for the plateau response of CGR to LAI. Sincesimilar decreases in maintenance respiration per biomass atlow RGR have been reported for several other species, a constantratio of respiration to photosynthesis may occur in more speciesthan constant maintenance respiration per unit of biomass. Amaranlhus hybridus L., Chenopodium album L., Glycine max L Merr, soybean, photosynthesis, respiration, growth, leaf area index     

氮磷用量对杂种小麦C6-38/Py85-1群体生长及产量的影响

在大田条件下研究了不同氮、磷用量对杂种小麦群体生长及产量的影响.结果表明,在试验供肥范围内 (N112.5～337.5 kg·hm^-2,P₂O₅ 90～270 kg·hm^-2),杂种的群体总茎数(PS)、群体干物重（PDW）、叶面积指数（LAI）、光合势（PP）和作物生长率（CGR）均以低肥处理低.高肥处理的PS和PDW高于中肥处理,高肥处理的LAI、PP和CGR分别于挑旗、拔节和开花期之前高于中肥处理,之后低于中肥处理.在低、中肥处理下,杂种各生育时期PS的离中优势（H_m）为负值,高肥处理冬前期、拔节期、开花期和成熟期分别为6.3％、49.7％、4.2％和10.8％;LAI的H_m除灌浆期中肥处理比高肥处理高3.8％、PDW的H_m除成熟期中、高肥处理间差异不显著外,其余各时期两性状的优势值高肥处理均极显著高于中肥处理;PP和CGR的Hm均以低肥处理最低,分别于拔节至挑旗期和挑旗至开花期之前高肥处理高于中肥处理,之后中肥处理高于高肥处理.杂种的籽粒产量及其H_m均以低肥处理最低,中肥处理的产量比高肥处理高216.2 kg·hm^-2;中肥与高肥处理之间产量的H_m差异不显著.     

海岸带复合梨园的光能分布与利用规律

采用方格法和分层法相结合的技术对江苏省如东县棉花原种场林网保护区内13年生梨园的树冠结构特征和光能分布与利用规律进行了系统研究。结果表明:梨树叶幕光能分布状况直接受叶面积系数、树冠结构、太阳位置及光强的影响。各层叶幕中的光合有效辐射(PAR)分布随自然光照条件的变化而改变,其日平均透光率大小和PAR日变化范围均从叶幕外围向内膛随累积叶面积系数(LAI)的增加而减弱;不同生长时期及不同天气变化下树冠光能分布存在明显的差异性;树冠结构与累积LAI对PAR的分布及利用率具有决定性的影响。在生产实践中,通过密度调控、整形修剪等农业技术措施,维持成年梨园盛果期高效光合生产的叶幕厚度在2.5m以上,有效LAI为4左右,是增强梨树光合生产能力、提高产量和品质的有效措施。