灌浆后期6-BA灌根对玉米衰老和产量形成的影响

以郑单958为材料,用浓度为10 mg/L的6-苄基腺嘌呤(6-BA)溶液在玉米灌浆期(花后40 d)浇灌根系,研究6-BA对玉米根系与叶片衰老及产量形成的影响。结果表明,花后6-BA灌根处理能延缓玉米根系的衰老,使收获期单株总根长显著高于对照,增长48%,其中,轴根长与对照相比差异不显著,侧根长显著高于对照。6-BA灌根处理同样延缓叶片衰老,使成熟期绿叶面积增加。6-BA灌根处理显著增加吐丝期-成熟期植株吸氮量和植株干物质积累量,不影响营养器官中氮素与干物质的转运。6-BA灌根处理显著提高单株子粒产量,与对照相比增产16%,其中,主要是百粒重的增加,同时保持子粒中氮浓度不变。通过细胞分裂素延缓后期根系衰老,可能是协调玉米后期氮素吸收与转运、提高玉米子粒产量的一条途径。     

干旱条件下不同种茎材料对木薯成活率及产量性状的影响

在干旱条件下,比较4种不同种茎材料对木薯成活率、农艺及产量性状的影响。结果表明：成活率(survival rate,SR)呈现SR1年生种茎(100.0%)＞SR2年生种茎(92.2%)＞SR60 d嫩茎(78.9%)＞SR老茎头(30.0%);鲜薯和薯干产量(root yield,RY)呈现RY1年生种茎＞RY60 d嫩茎＞RY老茎头＞RY2年生种茎;淀粉产量(starch yield,SY)呈现SY60 d嫩茎＞SY1年生种茎＞SY老茎头＞SY2年生种茎;薯干率和鲜薯淀粉含量呈现老茎头＞60 d嫩茎＞2年生种茎＞1年生种茎,且植株密度越小,则薯干率和鲜薯淀粉含量越高。     

Variation in qualitative and quantitative traits of cassava germplasm from selected national breeding programmes in sub-Saharan Africa

An improved understanding of phenotypic variation within cassava germplasm in southern, eastern and central Africa will help to formulate knowledge-based breeding strategies. Thus, the overall objective of this study was to examine the phenotypic variation in cassava germplasm available within six breeding programmes in Africa, namely Uganda, Kenya, Tanzania, Rwanda, Democratic Republic of Congo and Madagascar. In each country, single-row plots were used for assessment of 29 qualitative traits and evaluation of four quantitative traits: root dry matter content (DMC), harvest index (HI), leaf retention (LR) and root cortex thickness. Qualitative traits provided limited discrimination of cassava germplasm. However, differences in DMC, HI, LR and root cortex thickness were observed among the germplasm indicating scope for genetic improvement. Highest average DMC was registered in Uganda (39.3%) and lowest in Tanzania (30.1%), with the elite genotypes having a relatively higher DMC than local genotypes. Highest average HI was observed in Uganda (0.60) and lowest in Kenya (0.32). Cassava genotypes displayed varied root peel thickness (0.34-4.89 mm). This study highlights variation in agronomic traits that could be exploited to increase cassava productivity.     

紫肉甘薯新品种渝苏紫43的产量表现及主要经济性状

对紫肉甘薯新品种渝苏紫43的生产力和主要经济性状的鉴定结果进行介绍。分别于2007—2008年参加重庆市甘薯品种区域试验和生产试验,并对渝苏紫43鲜薯产量、藤叶产量、薯干产量、淀粉产量、薯块干物率、淀粉含量进行测定;2008年经江苏省农业科学院食品质量安全与检测研究所测定鲜薯薯块总花色苷含量,薯块萌芽性好,上薯率85%以上。该品种可作色素、淀粉、保健综合利用型甘薯品种。     

种植种茎的芽眼朝向对华南8号木薯产量性状的影响

以华南8号木薯为材料,通过试验比较了在水平种植时,种茎芽眼的4个朝向（芽向）在木薯产量性状上的效应。结果表明,芽向对木薯产量性状有较大影响,鲜薯、薯干和淀粉的产量排序依次为向南＞向西＞向北＞向东（CK）,最高产的芽眼向南处理比最低产的芽眼向东处理（CK）,提高鲜薯产量38.8％、薯干产量36.3％和淀粉产量34.8％;次高产的种茎芽眼向西处理比芽眼向东处理（CK）提高鲜薯产量24.9％、薯干产量24.5％和淀粉产量24.6％。我国在种植木薯时,建议采用种茎芽眼朝南、朝西或朝西南的水平摆种方式。     

磷素对甘薯生长前期源库关系建立和平衡的影响

通过2年盆栽试验研究不施磷P₀（P₂O₅ 0 g/kg）、适量施磷P_0.04（P₂O₅ 0.04 g/kg）和过量施磷P_0.08（P₂O₅ 0.08 g/kg）对鲜食型甘薯‘烟薯25’和‘普薯32’生长前期（栽后0~40 d）根系活力、根系形态分化、潜在块根重量、结薯数、薯块重量、根生物量、叶面积、茎叶生物量、根干物质分配比例、茎叶干物质分配比例及根冠比的影响。结果表明,在块根形成期（栽后0~30 d）,与不施磷处理相比,适量施磷显著提高了甘薯总根条数、根尖数、总根长、根系表面积、根系平均直径、根系体积和总根鲜重,并显著提高了根系活力,提高了潜在块根鲜重;显著提高叶面积、叶鲜重、茎鲜重、地上部总鲜重;显著提高甘薯茎叶干重、根干重和植株干重,显著增加干物质根分配比例,降低干物质茎叶分配比,显著提高根冠比,为块根形成提供良好的物质基础。而过量施磷抑制干物质在根中的分配比例,导致根冠比降低,不利于块根的形成。在封垄期（栽后40 d）,与不施磷处理相比,适量施磷可以显著增加单株结薯数（主要提高直径5 mm以上的块根数量）、单薯重和单株薯重,若继续增加施磷量将导致单株结薯数和单薯重显著降低。因此,适量施磷可以促进甘薯根系和茎叶发育,增加干物质根分配比例,降低干物质茎叶分配比,显著提高根冠比,增加甘薯单株结薯数和单薯重,提高单株薯重,促进甘薯生长前期源库关系建立和平衡,为甘薯丰产奠定基础。     

种植密度和施氮水平对华南8号木薯产量形成的影响

在不同种植密度和施氮水平条件下探讨华南8号木薯干物质积累、分配的规律及其对产量形成的影响。结果表明,低密度低施氮水平处理的产量显著高于高密度高施氮水平处理;低密度低施氮水平处理的单条薯重显著高于高密度高施氮水平处理,并且交互作用显著;低密度和低施氮水平处理虽然前期干物质生产速率较低,但后期干物质生产速率及其向块根的分配比例明显高于高密度和高施氮水平。     

超高产水稻的干物质生产特性研究

 以我国近年育成的超高产水稻品种为材料, 在福建龙海和云南涛源研究分析了超高产水稻品种的高产生理特性。结果表明超高产水稻品种积累了高额的生物量。 稻谷产量随干物质积累总量的增加而提高，产量主要取决于生物产量的高低，而收获指数对稻谷产量的贡献较小。超高产水稻干物质生产优势在中期和后期，产量随中期和后期干物质净积累量的增加而提高。中期和后期的群体生长率(CGR)与产量呈高度正相关，而前期CGR与产量的关系不密切。茎叶干物质输出量构成籽粒产量平均为24％（福建龙海）和33％（云南涛源），茎叶干物质输出量和抽穗后干物质积累量均与稻谷产量呈极显著正相关。在同一地点，对干物质积累的作用，CGR显著大于生长日数。     

Growth of sugarcane under high input conditions in tropical Australia. II. Sucrose accumulation and commercial yield

Information on the processes controlling the accumulation of sucrose over time can be used to assess the physiological basis of yield variation and consequently the scope for yield improvement in sugarcane. As commercial yield is commonly expressed on a fresh weight basis, and dry weight measures of sucrose accumulation aid biological interpretation, there is a need to study yield accumulation on both a fresh and dry weight basis. This study analysed the pattern of sucrose accumulation in the stalk in relation to crop biomass, and the concentration of sucrose in the stalk on a fresh and dry weight basis of two contrasting cultivars (Q117 and Q138) of sugarcane during the same season in tropical Australia, with irrigation and under plant and ratoon crop conditions. Over the 15 month season, 11 crop samplings were conducted. The key findings were that (1) greater than 95% of the aboveground sucrose accumulation is in the stalk; (2) a logistic relationship described the time trend in stalk sucrose accumulation, with maximum sucrose yield occurring 100 days before final harvest; (3) stalk biomass rather than stalk sucrose concentration was the major determinant of stalk sucrose accumulation; (4) maximum stalk sucrose concentration was stable across cultivars and crop classes at a value of 0.48 g g⁻¹ stalk dry weight; (5) commercial yield expressed as the fresh millable stalk yield plateaued up to 230 days before final harvest and well before the attainment of maximum stalk biomass and sucrose yield due to increases in dry matter content during growth; (6) maximum stalk sucrose concentration on a fresh weight basis was obtained at a later crop age and was more variable across crops than maximum stalk sucrose concentration on a dry weight basis. The study highlighted the major influence that stalk dry matter content has on the relationship between sucrose yield and commercial yield, and that biological interpretation of crop response to climatic and management factors is difficult based on commonly available fresh weight measures of productivity. Optimising economic return from commercial sugarcane production requires further understanding on the factors controlling the dynamics of stalk dry matter content.     

吉育86在新疆超高产的干物质积累与产量性状分析

本研究以引进并在新疆连续获得超高产的大豆品种吉育86为研究对象，以当地具有高产潜力的新大豆23号为对照，通过对两个品种的生育期、农艺性状、干物质积累、叶面积指数、净同化量、叶生产力以及产量构成因子进行比较，旨在分析吉育86在新疆超高产表现中的干物质积累与产量构成性状，以期为建立吉育86在新疆超高产表现及高产品种选育提供理论依据。结果表明：（1）初花期后，吉育86根系生物量逐渐高于新大豆23号；整个生育期，吉育86花荚生物量相对较高；完熟期，吉育86荚果干物质量较新大豆23号显著高16.7%。（2）两个品种的叶面积指数、净同化量均在鼓粒期达到峰值，此时新大豆23号叶面积指数较吉育86高80%；鼓粒期后，吉育86净同化量和叶生产力显著（P<0.05）高于新大豆23号。（3）吉育86株高与节数合理，分枝较少，株型相对紧凑，群体优势较为明显。（4）吉育86的单粒重、百粒重、收获株数显著（P<0.05）高于新大豆23号。综上所述，吉育86株型结构合理，群体优势明显，叶面积指数适宜，光合产物利用率较高，有利于营养器官干物质积累量向籽粒转移，充分发挥其高产潜力，获得超高产。     

水稻育秧基质理化性状对秧苗品质的影响

以木薯渣、甘蔗滤泥、稻田土为原料配成不同水稻育秧基质,以‘桂育9号’为供试品种,探究不同水稻育秧基质理化性状对秧苗品质的影响。结果表明:除不定根数、单位面积秧苗数外,秧苗各性状皆与基质的理化性状存在显著或极显著相关性。基质容重的减小和孔隙度的增大使得秧苗株高、叶面积、单位体积基质生产秧苗鲜重显著增大,而根系盘结力显著减小;基质p H中性左右对秧苗品质无显著影响。在2.7 m S范围内,基质电导率增大对株高、叶面积、单位体积基质生产秧苗鲜重有显著促进作用;碱解氮、速效磷、速效钾、有机质对秧苗株高、SPAD值、叶面积和单位体积基质生产秧苗鲜重有显著促进作用,其中速效磷还对秧苗茎基宽、叶龄、地上部干重、发根能力有显著或极显著促进作用,而与根系盘结力则呈极显著的负相关。     

Growth Responses of Drought Resistant Rice Cultivars to Soil Compaction under Irrigated and Succeeding Non-irrigated Conditions during the Vegetative Stage

Abstract

We investigated whether drought resistant rice cultivars exhibit higher dry-matter production under wet and dry compacted soil conditions in the vegetative stage and determined the dominant factors governing resistance to soil compaction. Three rice cultivars, a drought-sensitive Nipponbare, and drought-resistant Senshou and Dular, were grown in pots at four soil bulk densities (SBD) ranging from 1300 to 1600 dry soil kg m^?3. Root and shoot dry matter productions was slightly smaller in Nipponbare over the 29 days after sowing under irrigated conditions than in the other cultivars at all SBDs. Senshou and Dular also maintained a higher dry matter production, both in relative and absolute values, than Nipponbare under the condition of withheld irrigation from days 29 — 39 after sowing. The higher stomatal conductance and leaf water potential of these two cultivars were supported by a larger root system which was mostly accompanied by lower top-root ratios in the irrigated and compacted soils. The higher plant growth rate under the non-irrigated condition might have been a result of both the higher water absorption rate and water use efficiency, which in turn were supported by the larger root biomass. We conclude that the ability of rice to rapidly develop a root system in the early vegetative phase under compacted soils facilitates plant production under subsequent soil desiccated conditions.     

Effects of plant architecture and drought stress level on lucerne forage quality

Breeding for enhanced quality in lucerne (Medicago sativa) frequently involves selection for higher leaf‐to‐stem ratio, multifoliolate leaves or short‐internode stems. Three populations selected for such alternative morphologies and a reference cultivar were evaluated for forage yield, leaf‐to‐stem ratio and protein and fibre concentrations in leaves, stems and whole plants. Four managed environments were obtained by combining two stress levels (moderate or nil) with two sowing times. The population selected for high leaf‐to‐stem ratio, as well as the short‐internode population, had highest leaf‐to‐stem ratio (1.27) across six harvests in two non‐stress environments. The latter population had higher stem protein (12.9%) and lower stem neutral‐detergent fibre (NDF) concentration (58.7%) than other populations. The multifoliolate population had intermediate quality, showing low expression of the multifoliolate trait (14.0% across four environments), particularly under stress (10.5%). The autumn‐sown, fully irrigated environment had, on average, highest dry‐matter yield (4.19 t ha^?1) and lowest leaf‐to‐stem ratio (0.74). Drought‐stressed environments had lower plant NDF (?12.3% on average) and leaf protein (?9.7%), and higher stem protein (+8.6%) than fully irrigated environments. The results suggested that environmental effects might have greater impact on quality than genetic effects, even for a population set including material selected for quality‐driven morphology.     

马铃薯抗旱品种的筛选与评价(一)

本文对24个马铃著品种(系)在旱作栽培条件下进行了评价,产量表现最高的为晋薯1号、乌盟851、坝薯10号和紫花白。块茎产量与茎叶覆盖度、根系拉力、茎叶干鲜重、根干鲜重、根数之间呈直线正相关,与出苗天数、块茎形成天数则呈直线负相关。根系拉力与根数、株高、茎叶干鲜重、根干鲜重呈直线正相关;与出苗天数和形成块茎天数呈负相关。结果表明,高根系拉力产生高块茎产量。因此,根系拉力可作为鉴定植株生长早期耐旱性的一个参数。     

马铃薯主要生理性状和产量性状相关性的研究

以大西洋、滇薯6号、PB04和PB08 4个加工型马铃薯品种(系)为供试材料,进行不同品种块茎形成期主要生理性状和收获时产量特性的比较及部分性状间的相关性研究。结果表明:在马铃薯的块茎形成期大西洋的光合速率最强,根系活力较强,抗逆性较强,其农艺性状和块茎产量特征均表现较好。相关分析结果显示,马铃薯的块茎数量、块茎产量、干物质含量和块茎淀粉含量与光合速率呈正相关,生物产量、块茎数量、块茎产量、干物质含量和块茎淀粉含量与叶片电导率呈负相关,而生物产量与根系活力呈正相关。     

Identification of cassava (Manihot esculenta Crantz) genotypes with early storage root bulking

Early bulking (EB) cassava varieties shorten the growth period from planting to harvesting. Cassava is preferred by farmers to many other crops because of its high-yielding potential and ability to survive a 4- to 6-month dry season. However, the crop in some cases is only able to remain alive during the dry season without further starch accumulation. This and some other factors, such as pest destruction during dry season and inability to use the same land for cultivation of other crops such as vegetables, therefore necessitate the development of EB cassava genotypes. The objective of this study was therefore to identify EB cassava genotypes using the difference in fresh storage root yield (FSRY) at different plant ages. Thirty-four cassava genotypes were evaluated at Umudike and Otobi in Nigeria in two seasons at two plant ages of 7 and 12 months after planting (MAP) for FSRY. The data generated were used to classify the cassava genotypes as EB or late bulking (LB). Cassava genotypes with less than 100% increase in FSRY at 12 MAP over the yield at 7 MAP were regarded as EB, whereas those with more than 100% increase were regarded as LB genotypes. This basis was used considering the fact that root thickening in cassava commences at about 2 MAP; hence, the root yield at 7 and 12 MAP represents accumulation of assimilates for 5 and 10 months, respectively. About 65%, 62%, and 79% of the genotypes were classified as EB genotypes at Otobi, Umudike, and across the two locations, respectively.     

株行距和施肥量对木薯产量及生长的影响

采用裂区试验设计方法,研究株行距和施肥量对华南5号木薯产量和生长的影响.结果表明:在本试验株行距和施肥量条件下,施肥量对木薯产量和生长的影响比株行距大.密植(0.6～0.8 m)有利于提高淀粉产量、鲜薯产量和鲜薯淀粉含量,以0.8m株行距最佳,而疏植(1.2～1.4m)有利于提高单株薯数、单株鲜薯重、单株鲜茎叶重、收获指数和茎径.施肥有利于提高淀粉产量、鲜薯产量、单株鲜薯重、单株鲜茎叶重、茎径、株高和单株薯数,但降低鲜薯淀粉含量和收获指数.丰产栽培技术要兼顾单位面积株数、单株鲜薯重和鲜薯淀粉含量.建议在土壤肥力差和少施肥时,用0.6 m株行距;土壤肥力中等且较高施肥时.采用0.8 m株行距;土壤肥力中上且优越水肥管理,采用1.0 m株行距.     

Effects of drought on chlorophyll fluorescence in potato (Solanum tuberosum L.). II. Relations between plant growth and measurements of fluorescence

Summary Relations between measurements of the slow kinetics of chlorophyll fluorescence and growth and yield were examined in seven potato genotypes grown either fully irrigated or droughted from the time of plant emergence. Drought reduced total dry matter production and yields and increased tuber dry matter concentration. Drought increased harvest index in cv. Spunta, but decreased it in cv. Pentland Crown. Total dry matter production was correlated with each of constant fluorescence, variable fluorescence and the half life of the decay in variable fluorescence. These correlations were determined largely by the effect of treatment, and did not discriminate effectively between genotypes within a treatment.     

Increased productivity through integrated soil fertility management in cassava–legume intercropping systems in the highlands of Sud-Kivu,DR Congo

Smallholder farmers in sub-Saharan Africa are confronted by low productivity and limited investment capacity in nutrient inputs. Integrated soil fertility management (ISFM) aims at increased productivity through the combined use of improved germplasm, judicious fertilizer application and organic matter management, adapted to the local farming conditions. We hypothesize that the application of these different ISFM components can result in significant increases in productivity and economic benefits of cassava–legume intercropping systems. Participatory demonstration trials were conducted in the highlands of Sud-Kivu, DR Congo with 12 farmer groups during 3 seasons. Treatments included the farmers’ common practice (local common bean and cassava varieties, seed broadcast and manure addition) and sequentially added ISFM components: improved bean and cassava germplasm, modified crop arrangements, compound NPK fertilizer application and alternative legume species (groundnut or soybean). The use of improved germplasm did not result in yield increases without simultaneous implementation of other ISFM components. Modifying the crop arrangement by planting cassava at 2 m between rows and 0.5 m within the row, intercropped with four legume lines, increased bean yields during the first season and permits a second bean intercrop, which can increase total legume production by up to 1 t ha⁻¹ and result in an additional revenue of almost 1000 USD ha⁻¹. Crop arrangement or a second legume intercrop did not affect cassava storage root yields. Fertilizer application increased both legume and cassava yield, and net revenue by 400–700 USD ha⁻¹ with a marginal rate of return of 1.6–2.7. Replacing the common bean intercrop by groundnut increased net revenue by 200–400 USD ha⁻¹ partly because of the higher market value of the grains, but mostly due to a positive effect on cassava storage root yield. Soybean affected cassava yields negatively because of its high biomass production and long maturity period; modifications are needed to integrate a soybean intercrop into the system. The findings demonstrate the large potential of ISFM to increase productivity in cassava–legume systems in the Central-African highlands. Benefits were, however, not observed in all study sites. In poor soils, productivity increases were variable or absent, and soil amendments are required. A better understanding of the conditions under which positive effects occur can enable better targeting and local adaptation of the technologies.     

Long-term effects of mulch,fertilization and tillage on cassava grown in sandy soils in northern Colombia

Cassava (Manihot esculenta Crantz) is often cultivated in sandy soils that are very low in nutrients and organic matter. Under such conditions, yields often decline when the crop is grown successively without fertilizer application. An 8-year on-farm trial was conducted on sandy soils in northern Colombia to study effects of (1) surface mulching with residues of the grass Panicum maximum, (2) moderate applications of N, P and K fertilizer and (3) tillage on crop productivity, root quality and soil properties. Mulch applications significantly increased root and top biomass, increased root dry matter content while reducing its yearly variation, and decreased root HCN, particularly in the absence of fertilizer. Mulch applications also significantly reduced soil temperatures within the top 20 cm and increased soil organic carbon, K, P, Ca and Mg. Without mulch, soil pH decreased over the years. Annual applications of 21 kg ha⁻¹ P resulted in a build-up of soil P, whereas no build-up of soil K was observed with applications of 41 kg K ha⁻¹. The application of N, P and K fertilizer significantly increased root and top biomass and reduced root HCN, especially if no mulch was applied. Where both mulch and fertilizer applications were absent, root yield and top biomass declined over the years. Tillage, except when combined with fertilizer application, had no effect on root yield, top biomass, root dry matter or HCN contents. Neither were effects of tillage observed in any of the studied soil parameters. The trial indicated that, to sustain cassava productivity in poor sandy soils, applications of plant mulch and/or chemical fertilizer are highly desirable.