Effects of dwarfing genes on yield and yield components under irrigated and rainfed conditions in wheat (Triticum aestivum L.)

Summary Near-isogenic tall (no dwarfing gene), semidwarf (Rht1 or Rht2) and dwarf (Rht1 + Rht2 or Rht3) spring wheat lines were evaluated for yield and yield components under irrigated and rainfed conditions. Under irrigated conditions, the dwarf and the semidwarf lines exhibited a significant yield advantage over the tall lines. Under rainfed conditions, the semidwarf lines outyielded the tall as well as the dwarf lines. Percent yield reduction in response to drought stress was highest with the dwarfs and lowest with the tall lines. Dry matter production of the tall lines and that of the semidwarf lines did not differ significantly and both produced significantly more dry matter than the dwarf lines under irrigated as well as rainfed conditions. Plant height and kernel weight decreased with increasing degree of dwarfness while number of kernels per spikelet, harvest index and days to heading increased under both moisture regimes. The dwarfing genes did not have any significant influence on number of tillers/m² and spikelets per spike in either moisture regime.     

Chemical composition and methane yield of maize hybrids with contrasting maturity

Maize (Zea mays L.) is the most important substrate for biogas production in Germany. This study was conducted to determine the influence of harvest date and hybrid maturity on the yield and quality of maize biomass for anaerobic methane production. In 2004 and 2005, maize hybrids of widely contrasting maturity were grown on a loamy sand soil (Haplic Luvisol) near Braunschweig, Germany. Whole-plant yield was determined several times after female flowering and the biomass analysed for nutrient composition. The specific methane yield (SMY) was measured using 20 l batch digesters. In both experimental years, the late energy maize prototypes had a lower concentration of fat and protein, but higher concentration of ash, detergent fibre, and lignin as compared with the climatically adapted medium-early hybrids. Despite substantially different nutrient concentration among the maize hybrids, no clear-cut association existed between chemical composition and specific methane yield. Contrary to the medium-early hybrids, the late hybrids attained both maximum specific methane yield and maximum methane hectare yields at the final harvest date. In the very long growing season of 2004, the highest individual methane yield of 9370 N m³ ha⁻¹ was obtained by the hybrid with the latest maturity used in the study. It appears that late energy maize, which can take full advantage of the growing season, is better suited for biogas production, provided that the whole-plant dry matter concentration is high enough to produce good quality silage.     

Effects of biogas digestion of clover/grass-leys, cover crops and crop residues on nitrogen cycle and crop yield in organic stockless farming systems

The trend towards specialization in conventional farming led to large agricultural areas in Germany and in Europe lacking livestock. Also stockless organic farming has increased during recent years. In organic farming clover/grass-ley (CG) provides nitrogen (N) to the whole cropping system via symbiotic N₂ fixation and also controls certain weeds. A common practice in organic farming, when ruminants are not present, is to leave the biomass from CG in the field for their residual fertility effect. CG biomass, crop residues (CR) and cover crops (CC) represent a large unexploited energy potential. It could be used by anaerobic digestion to produce biogas. A field experiment was carried out by implementing a whole cropping system with a typical crop rotation for such farming systems on the research station Gladbacherhof from 2002 to 2005. The crop rotation consisted of six crops (two legumes and four non-legume crops). The aim was to evaluate whether the use of N could be improved by processing biomass from CG, CR and CC in a biogas digester and using the effluents as a fertilizer, compared to common practice. In the control treatment, represented by the usual stockless system, the CG, CR and CC biomass were left on the ground for green manure purposes. In the biogas systems these substrates were harvested for digestion in a biogas plant. The effluents of digestion were used to manure the non-legumes in the same crop rotation. Results indicate that digestion of CG, CR and CC can increase the crop dry matter and N yields and the N content of wheat grains in organic stockless systems. Harvesting and digestion of residues and their reallocation after digestion resulted in a better and more even allocation of N within the whole crop rotation, in a higher N input via N₂ fixation and lower N losses due to emissions and probably in a higher N availability of digested manures in comparison to the same amounts of undigested biomass.     

Modelling potential growth and yield of olive (Olea europaea L.) canopies

The wide variability and complexity of olive orchards makes it difficult to provide solutions to the numerous management questions using a pure experimental approach. In this paper we calibrate and validate a simple model of olive orchard productivity based on the Radiation-Use Efficiency (RUE) concept of Monteith. A calibration experiment was performed in Cordoba from 1998 to 2001 with drip-irrigated olive trees cv. ‘Arbequina’. Destructive samples of 18 trees and non-destructive measurements on 80 trees were used to determine RUE and dry matter partitioning coefficients. Validation experiments were performed in 18 drip-irrigated orchards of seven locations in Southern Spain, including two cultivars (‘Arbequina’ and ‘Picual’). Average RUE was 0.86 g dry matter (MJ PAR)⁻¹ which is equivalent to 1.56 g glucose (MJ PAR)⁻¹. Aboveground accumulated biomass was allocated equally to fruits and vegetative growth, which in turn was partitioned into 30% for leaves and 70% for stems, branches and trunk. The fraction of oil in fruits was 0.38 which implies that the average ratio oil yield/intercepted PAR, which is an equivalent RUE for oil production (_o), is 0.17 g oil (MJ PAR)⁻¹. The prediction of oil yield as the product of 0.17 and total intercepted PAR was tested successfully in the validation experiments (relative RMSE = 0.26). Errors of this simple model were partly due to alternate bearing and partly to a decrease in _o as canopy size increases, which deserves further research. The concept of _o may be also useful for the evaluation of alternate bearing in olive trees.

Estimated potential carbon sequestration by intensive irrigated olive orchards in Southern Spain was 7 t CO₂ ha⁻¹ year⁻¹ which is much higher than that of other agricultural systems in Europe.

The simple model of growth and yield presented herein is the core of a complete model of olive growth and yield and may be useful not only for evaluating productivity at different scales but also for solving different management problems (nutrient requirements, plant protection, etc.)     

Adaptation and yield stability of selected lines of Lathyrus spp. under rainfed conditions in West Asia

Summary Sixteen promising lines (selections) of Lathyrus spp. (chicklings), comprising 11 L. sativus, four L. ochrus, and one L. cicera, were evaluated under rainfed conditions in Syria. Two locations in each of four years were treated as separate environments, to give eight environments altogether. Genotype x environment (G×E) interactions were analysed using linear regression.There was considerable variation in herbage and seed yields within both lines and environments. Genotype x environment interactions were present for both herbage and seed yields; a little over half was accounted for by the linear regression. The non-linear component was also significant, although it was smaller than that of the linear component.The most stable herbage and seed yields were obtained from L. sativus. Two selections, 347 and 311, origmating from Syria and Turkey respectively, combined both high herbage and seed yields with wide adaptation and stability, and could be considered the most widely adapted lines. Other lines were identified as suitable for favourable and unfavourable environments; in particular, all four lines of L. ochrus have great potential in frost-free climates. The importance of genotype x environment interactions in future breeding strategies is discussed.     

Effects of green manure herbage management and its digestate from biogas production on barley yield,N recovery,soil structure and earthworm populations

In repeatedly mown and mulched green manure leys, the mulched herbage contains substantial amounts of nitrogen (N), which may only slightly contribute to the following crops’ nutrient demand. The objective of the present work was to evaluate the effect of alternative strategies for green manure management on the yield and N recovery of a subsequent spring barley crop, and their short term effects on soil structure and earthworm populations. A field trial was run from 2008 to 2011 at four sites with contrasting soils under cold climate conditions. We compared several options for on-site herbage management and the application of anaerobically digested green manure herbage. Depending on the site, removal of green manure herbage reduced the barley grain yield by 0% to 33% compared to leaving it on-site. Applying digestate, containing 45% of the N in harvested herbage, as fertilizer for barley gave the same yields as when all herbage was mulched the preceding season. Overall, the apparent N recovery was enhanced from 7% when all herbage was mulched, to 16% when returned as digestate. A positive effect on earthworm density and biomass was seen after one season of retaining mulch material, rather than removing it. Digestate did not affect the earthworm population, but contributed to higher soil aggregate stability. In conclusion, for spring barley production after green manure ley, the digestate strategy increased N recovery and reduced the risk of N losses. The yield of the succeeding barley crop yield was reduced when N in herbage was not returned as mulch or digestate.     

Carbon isotope discrimination and water use efficiency relationships of alfalfa genotypes under irrigated and rain-fed organic farming

Carbon isotope discrimination (Δ) has been proposed as a method for evaluating water use efficiency (WUE) in C₃ plants and as a precise technique for screening plants with higer tolerance under water deficit conditions. In this research, 18 alfalfa genotypes from different geographical origins were evaluated under irrigated and rain-fed conditions in organically managed fields in Austria. Significant differences were found amongst harvests for Δ-shoot under both conditions while genotype by harvest interaction was only significant under irrigated condition. Drought stress under rain-fed condition reduced the overall mean of water use efficiency and carbon isotope discrimination responses(up to 34%), but the ratios of reduction differed for characters and genotypes. Narrow ranges were found for all traits especially for WUE-TBY (total biomass yield) (0.78 kg m⁻³) and Δ-shoot (0.53‰) based on genotype means over locations and years, although variation and ranges were higher under irrigated condition. Regarding the variable and low correlations, simultaneous assessment of genotypes for Δ-shoot and biomass production can ensure the selection of superior genotypes and minimize potential biomass reductions that may result from using Δ-shoot as the only selection criterion to improve WUE. Sitel was the most water use efficient genotype(2.79 and 4.48 kg m⁻³ based on shoot dry matter and total biomass,respectively) across two condition (widely adapted genotype) followed by Mohajeran, Fix232 and Verko under irrigated condition (as specific adapted genotypes) and Vlasta, Sanditi, Ghara-aghaj under rain-fed condition.     

Water use efficiency of crops cultivated in the Mediterranean region: Review and analysis

Improvement of water use efficiency (WUE) of field crops in the Mediterranean region is an imperative imposed by the critical situation of water resources of the region, as well as by the demographical increment. This review reports the experimental data concerning WUE of 16 species cultivated in the region. The species include cereals, leguminous, horticultural and industrial crops. This review however underlines that WUE data of fruit trees are lacking, despite they represent one of the main productions of the Mediterranean agriculture.

In this region, the large range of WUE values observed, for the same species, can be ascribed mainly to: (i) fertilizers and water management (water regime, mineral supply and water quality); (ii) plant factors (species, variety and sensitivity of growth stage to the stress); and (iii) environmental factors (climate, atmospheric pollution, soil texture and climate change). The conclusion highlights the actual gap concerning WUE in the Mediterranean region. This gap will constitute a field of research designated to ameliorate WUE of agriculture in this region.     

Effect of biogas digestate,animal manure and mineral fertilizer application on nitrogen flows in biogas feedstock production

The expansion of biogas feedstock cultivation may affect a number of ecosystem processes and ecosystem services, and temporal and spatial dimensions of its environmental impact are subject to a critical debate. However, there are hardly any comprehensive studies available on the impact of biogas feedstock production on the different components of nitrogen (N) balance. The objectives of the current study were (i) to investigate the short-term effects of crop substrate cultivation on the N flows in terms of a N balance and its components (N fertilization, N deposition, N leaching, NH₃ emission, N₂O emission, N recovery in harvested product) for different cropping systems, N fertilizer types and a wide range of N rate, and (ii) to quantify the N footprint of feedstock production in terms of potential N loss per unit of methane produced. In 2007/08 and 2008/09, two field experiments were conducted at two sites in Northern Germany differing in soil quality, where continuous maize (R1), maize–whole crop wheat followed by Italian ryegrass as a double crop (R2), and maize–grain wheat followed by mustard as a catch crop (R3) were grown on Site 1 (sandy loam), and R1 and a perennial ryegrass ley (R4) at Site 2 (sandy soil rich in organic matter). Crops were supplied with varying amounts of N (0–360 kg N ha⁻¹, ryegrass: 0–480 kg N ha⁻¹) supplied as biogas digestate, cattle slurry, pig slurry or calcium-ammonium nitrate (CAN).Mineral-N fertilization of maize-based rotations resulted in negative N balances at N input for maximum yield (Nopt), with R2 having slightly less negative balances than R1 and R3. In contrast, N balances were close to zero for cattle slurry or digestate treatments. Thus, trade-offs between substrate feedstock production and changes of soil organic matter stocks have to be taken into consideration when evaluating biogas production systems. Nitrogen losses were generally dominated by N leaching, whereas for the organically fertilized perennial ryegrass ley the ammonia emission accounted for the largest proportion. Nitrogen balance of the ryegrass ley at Nopt was close to zero (CAN) or highly positive (cattle slurry, digestate). Nitrogen footprint (NFP) was applied as an eco-efficiency measure of N-loss potential (difference of N input and N recovery) related to the unit methane produced. NFP ranged between −11 and +6 kg N per 1000 m³ methane at Nopt for maize-based rotations, without a significant impact of cropping system or N fertilizer type. However, for perennial ryegrass ley, NFP increased up to 65 kg N per 1000 m³. The loose relation between NFP and observed N losses suggests only limited suitability for NFP.     

Productivity and water use efficiency of sweet sorghum as affected by soil water deficit occurring at different vegetative growth stages

The growth and production of sweet sorghum [Sorghum bicolor (L.) Moench] crops under semi-arid conditions in the Mediterranean environment of southern Italy are constrained by water stress. The effects of temporary water stress on growth and productivity of sweet sorghum were studied during three seasons at Rutigliano (Bari, Italy). The aim of this research was to evaluate the sensitivity of phenological stages subjected to the same water deficit. In a preliminary study it was observed that stomata closed when pre-dawn leaf water potential (Ψ_b) became lower than −0.4 MPa. This criterion was used in monitoring plant water status in three different plots: one never stressed and two stressed at different phenological stages (‘leaf’ and ‘stem’) when mainly leaves or stems were growing, respectively. An evaluation of the sensitivity of phenological stages subjected to identical water stress was obtained by comparing the above-ground biomass and WUE of drought crops with those of the well-irrigated crop (up to 32.5 t ha⁻¹ of dry matter and 5.7 g kg⁻¹). The sensitivity was greatest at the early stage (‘leaf’), when a temporary soil water stress reduced the biomass production by up to 30% with respect to the control and WUE was 4.8 g kg⁻¹ (average of three seasons). These results help quantify the effects of water constraints on sweet sorghum productivity. An irrigation strategy based on phenological stage sensitivity is suggested.     

Yield and water-use efficiency of water- and nitrogen-stressed wheat crops increase with degree of co-limitation

Availability of water and nitrogen are key constraints to primary productivity in arid and semiarid ecosystems. Theoretically, plant growth is maximised when all resources are equally limiting. This paper tested the hypothesis that for a given amount of available water, the gap between actual and attainable yield of dryland crops in semiarid southern Australia is inversely proportional to the degree of nitrogen and water co-limitation.

Field and simulation experiments were combined in an analysis involving three steps. Step 1 assessed the capacity of a crop simulation model to estimate yield and its responses to water and nitrogen inputs in the semiarid Mallee region. Step 2 derived a boundary function relating grain yield and water availability using simulations with long-term weather records. Step 3 explored the link between degree of co-limitation and deviations between actual yield and the boundary function. Degree of co-limitation (C_WN) was calculated as a function of model-derived nitrogen (NSI) and water stress indices (WSI), i.e. C_WN = 1 − |NSI − WSI|. Stress indices range from zero (no stress) to 1 (maximum stress), and C_WN tends to 1 when both resources impose constraints of similar magnitude to crop growth.

The field experiment combining locations, seasons and management practices generated a range of grain yield from 0.6 to 3.8 t ha⁻¹. Water availability, i.e. seasonal rainfall plus change in soil water content from sowing to harvest, ranged from 127 to 370 mm. Nitrogen fertiliser varied from nil to 36 kg N ha⁻¹ and inorganic nitrogen in the soil profile at sowing ranged from 29 to 497 kg ha⁻¹. For these ranges of conditions, the relationship between simulated and measured yield was statistically undistinguishable from the y = x function.

A factorial modelling experiment combining sites, seasons, initial soil water content and dose of nitrogen fertiliser was used to derive a boundary function which provided an objective and independent upper limit for the field data. Actual yield was below the boundary function in most cases. The difference between actual and attainable yield was inversely proportional to C_WN. This study thus supported the hypothesis that yield and water-use efficiency of water- and nitrogen-stressed crops increase with increasing degree of co-limitation.     

化肥有机肥配合对水稻产量和氮素利用的影响

摘要：通过对不同施肥与水稻产量和氮肥利用率连续4年定位观测研究,结果表明：在红壤丘陵区稻田上,土壤氮素来源以施肥带入为主,占土壤氮素总收入95%以上,氮素带出以作物吸收和氨挥发损失为主要途径;水稻对氮素吸收利用与氮素形态关系密切,早稻对无机氮吸收利用好于有机氮,晚稻对有机氮利用优于无机氮;对水稻4年产量统计分析,单施有机肥（M）处理与化肥（NPK）处理具有同等的产量效果,但有机肥料处理提高土壤有机质含量,提升了土壤生产力;单施有机肥（M）处理氮肥利用率达37.8%,化肥有机肥配施（NPKM）处理氮肥利用率为35.1%,而单施化肥（NPK）处理氮肥利用率仅为25.7%。     

不同栽培管理条件下夏玉米产量与肥料利用效率的差异解析

于2017—2018年在泰安、淄博和烟台,根据生产调研和各地夏玉米高产经验,在同一地块综合设置了超高产栽培、高产高效栽培和农户栽培3种栽培模式,分别模拟超高产生产水平(SH)、高产高效生产水平(HH)和农户生产水平(FP) 3个层次。并分别设置不施氮(SHN_0、HHN_0、FPN_0)、不施磷(SHP_0、HHP_0、FPP_0)和不施钾(SHK_0、HHK_0、FPK_0)的肥料空白处理。定量分析不同产量层次之间产量差及肥料利用效率差,探究产量差和效率差的影响因素及缩差增效途径。结果显示,当前山东省夏玉米SH、HH和FP的籽粒产量分别实现了光温潜力产量的68.13%、63.71%、53.22%。随着产量差距的增大,肥料利用效率降低。FP的N、P、K肥料利用效率分别为4.23、5.83、4.94 kg kg~(–1), SH的分别为3.84、4.64、2.97 kg kg~(–1)。通过优化栽培措施后,高产高效管理模式能够较FP籽粒产量提升10.49%, N、P、K的肥料利用效率分别提高67.07%、101.35%、57.65%,是实现产量与肥料利用效率协同提升的有效技术途径。对各产量水平进行产量性能分析发现,随着产量水平的提高,平均叶面积指数和单位面积穗数明显提高,而穗粒数、平均净同化率和粒重则有所下降。随着产量水平的提高,吐丝后干物质和N、P、K元素积累比例有增加的趋势。因此,在保持现有功能性参数不降低情况下,优化结构性参数是当前产量与资源利用效率协同提升的有效措施,今后高产高效应更加注重生育后期群体结构性能的优化。     

Agronomic performance of winter wheat grown under highly divergent soil moisture conditions in rainfed and water‐managed environments

Even in the temperate climates of Europe, increasing early season drought and rising air temperature are presenting new challenges to farmers and wheat breeders. Sixteen winter wheat (Triticum aestivum L.) genotypes consisting of three hybrids, six line cultivars and two breeding lines from Germany as well as five line cultivars from France, Austria, Slovakia, Hungary and the Ukraine (referred to as “exotic” lines) have been included in this study. The genetic materials were evaluated over three growing seasons under a range of soil moisture regimes at the three North German sites Braunschweig (irrigated and drought‐stressed), Warmse (rainfed) and Söllingen (rainfed). The average grain yields in the twelve growth environments (water regime × season combinations) ranged from 6.1 to 13.5 t ha^?1. The exotic lines showed little evidence of specific phenological adaptation to drought although they are frequently faced with water scarcity in their countries of origin. The hybrids and German lines exhibited higher regression coefficients (b_i) to environmental means than the exotic lines, indicating particular adaptation to favourable growing conditions. The phenotypical correlations of grain yield between the various environments were high, ranging for instance from 0.6 to 0.8 for the irrigated and drought‐stressed environments at Braunschweig. It is thus expected that in the foreseeable future continued selection aiming at high yield potential will suffice as a means to counter the expected increase in droughts.     

荒漠绿洲不同种植方式对青贮玉米产量及水肥利用效率的影响

合理的种植方式可以在不增加灌溉耗水量的前提下,利用植物个体间的正相互作用关系和群体适应特点来达到提高作物产量和水分利用效率的目的。通过田间试验,研究了河西走廊黑河中游边缘绿洲区1穴1株、1穴2株和1穴3株种植方式对青贮玉米产量及水肥利用效率的影响。结果表明,1穴2株和1穴3株的地上生物产量均高于1穴1株,1穴2株最高,鲜重为102.9 t/hm~2,比1穴1株提高了29.4%;1穴2株与1穴1株之间存在显著差异(P0.05),1穴3株与1穴1株之间差异不显著(P0.05)。同样,1穴2株和1穴3株的地上生物产量水肥利用效率也均高于1穴1株,1穴2株的水分和氮肥利用效率也均最高,分别为9.3 kg/m~3和342.9 kg/kg;1穴2株与1穴1株之间存在显著差异(P0.05),1穴3株与1穴1株之间差异不显著(P0.05)。在河西走廊边缘绿洲区,采用1穴2株的种植方式能显著提高青贮玉米的地上生物产量和水肥利用效率,可在生产中推广应用。     

基因型和环境对小麦产量、品质和氮素效率的影响

以不同基因型的小麦品种(13个强筋小麦品种和2个中筋小麦品种),不同试验地点(馆陶、宁晋、藁城)和不同施氮水平(0、180、240和300 kg hm^–2)的田间试验,综合分析基因型、环境对小麦产量、品质、氮肥利用率的影响,以期为优质强筋小麦品种选育、栽培调控及高产提质增效的协同目标提供科学依据。研究表明,不同小麦品种产量在9289～10,088 kg hm^–2之间,强筋小麦品种平均产量9548 kg hm^–2,比中筋小麦品种减产3.1%。藁城、宁晋、馆陶三地的产量分别达9932、9433和9223kghm^–2。不同小麦品种籽粒蛋白质均值14.5%,湿面筋28.5%,沉淀指数39.5mL,稳定时间15.4 min,拉伸能量87.5 cm2,最大拉伸阻力428.8 BU。藁优5218、藁优5766、冀麦738、科农2009、师栾02-1、藁优2018、冀麦867综合品质表现较好。馆陶和宁晋的小麦品质性状相对较好,藁城的品质较差。氮肥利用率随施氮量增加呈降低趋势, N180处理的氮肥农学效率、氮肥吸收利用效率、氮肥生理利用率最高,依次为4.3 kg kg^–1、26.2%、16.6 kg kg^–1。兼顾产量、品质、效率三方面,藁城适宜种植品种有冀麦738、冀麦867、师栾02-1;宁晋有师栾02-1、科农2009、冀麦738;馆陶有藁优5766、藁优2018、师栾02-1。综合考虑小麦产量、籽粒品质和氮素利用率, 180 kg hm^–2为本研究条件下的最佳施氮量。     

新疆石河子棉区高密条件下冠层结构和光分布特征

对新疆石河子5个棉花主栽品种全生育期的干物质积累、生长参数、产量和盛铃期的冠层结构、光渗透能力和光分布等进行了测量分析。结果表明,作物生长速率、铃生长率以及子棉产量等均与总受光量呈正相关关系,净同化率则与单位叶面积受光量呈正相关关系,说明受光量是决定干物质生产和产量的重要因素;单位叶面积受光量即光的渗透能力与单位土地面积总受光量呈正相关关系、而与LAI呈负相关关系,说明冠层结构也是影响冠层受光量的主要因素;总受光量与LAI呈显著的正相关关系,说明LAI最大值并未达到最适宜水平。新疆地区棉花高产棉田的主要特征可以总结为叶数少、叶片大、冠层结构为椭圆形。由于叶面积指数尚未达到最适宜水平,增加种植密度可能是提高产量的一个途径。     

The intercropping common bean with maize improves the rhizobial efficiency,resource use and grain yield under low phosphorus availability

In order to better understand how mixed crop cultures mitigate stressful conditions, this study aims to highlight the beneficial effect of the intercropping legume-cereal in enhancing soil phosphorus (P) availability for plant growth and productivity in a P-deficient soil of a northern Algerian agroecosystem. To address this question, common bean (Phaseolus vulgaris L. cv. El Djadida) and maize (Zea mays L. cv. Filou), were grown as sole- and inter-crops in two experimental sites; S1 (P-deficient) and S2 (P-sufficient) during two growing seasons (2011 and 2012). Growth, nodulation and grain yield were assessed and correlated with the rhizosphere soil P availability. Results showed that P availability significantly increased in the rhizosphere of both species, especially in intercropping under the P-deficient soil conditions. This increase was associated with high efficiency in use of the rhizobial symbiosis (high correlation between plant biomass and nodulation), plant growth and resource (nitrogen (N) and P) use efficiency as indicated by higher land equivalent ratio (LER > 1) and N nutrition index (for maize) in intercropping over sole cropping treatments. Moreover, the rhizosphere P availability and nodule biomass were positively correlated (r² = 0.71, p < 0.01 and r² = 0.62, p < 0.01) in the intercropped common bean grown in the P-deficient soil during 2011 and 2012. The increased P availability presumably improved biomass and grain yield in intercropping, though it mainly enhanced grain yield in intercropped maize. Our findings suggest that modification in the intercropped common bean rhizosphere-induced parameters facilitated P uptake, plant biomass and grain yield for the intercropped maize under P-deficiency conditions.     

甘蔗CIPK23基因克隆及对低钾、干旱、盐胁迫的响应

本研究采用RT-PCR技术从低钾胁迫的甘蔗根系中克隆得到一个长度为1 749 bp的与CBL互作的丝氨酸/苏氨酸蛋白激酶基因,命名为Ss CIPK23(Gen Bank登录号为KM981737),包含1 350 bp的开放阅读框(ORF),可编码一个449氨基酸残基的多肽。Ss CIPK23具有CIPK基因家族典型的蛋白激酶结构域和NAF调控结构域。进化树分析显示Ss CIPK23与其他作物的CIPK23关系较近,具有较高的保守性。q PCR分析结果表明,在低钾、干旱和盐胁迫下,Ss CIPK23的表达都发生改变。在低钾胁迫24 h后Ss CIPK23相对表达量开始上升,而且随着胁迫时间的延长,相对表达量持续增加;而在干旱和盐胁迫下,相对表达量最高出现在48 h,随后表达量开始下降,暗示了该基因在低钾、干旱和盐胁迫下发挥重要的调控作用,可为深入研究Ss CIPK23基因功能奠定坚实的基础。     

Transpiration efficiencies of indica and improved tropical japonica rice grown under irrigated conditions

A study of the genetic diversity in coconut by RFLP analysis was performed in 100 individuals representing 10 Tall and seven Dwarf local populations or 'ecotypes' from various geographical origins. Nine cDNA clones from rice, one mitochondrial DNA clone (CoxI) and one genomic clone (rDNA) from wheat were used as probe for southern hybridization. The distribution of the 40 polymorphic bands revealed by rice cDNA clones was studied using a multivariate analysis and allowed to identify two main genetical groups. The first one includes the ecotypes from the Far East and from the South Pacific, whereas the other one comprises the ecotypes from India, Sri Lanka and Western Africa. The rDNA and the CoxI probes confirm this distinction. The Far East and the Pacific regions which were the most likely center of origin also exhibit the widest polymorphism. The associations between the Panama Tall and the Pacific group and between the West African Tall and the Indian Ocean group reflect their likely origin. The Comoro Tall appears to be intermediate between the two main groups, and could reflect the old migration route between Indonesia and Madagascar. All Dwarf varieties belong to the first group, even those collected in West Africa. Those were probably introduced from Asia and Pacific at the beginning of the century. The cross-pollinating Tall ecotypes were generally more polymorphic than the self pollinating Dwarf ecotypes. The legitimacy of two hybrids between ecotypes was confirmed and maternal inheritance of mitochondrial genome was observed. This revised version was published online in July 2006 with corrections to the Cover Date.