施钾对不同基因型棉花光合特性及产量和品质的影响

在田间条件下,研究了施钾对抗虫杂交棉中棉所38、抗虫棉新棉33B、常规棉中棉所12光合特性和产量及品质的影响。结果表明,与不施钾相比,不同基因型棉花施氯化钾225.kg/hm2,棉花叶面积指数(LAI),叶绿素荧光动力学参数PSⅡ最大光化学量子效率(Fv/Fm)、PSⅡ潜在光化学活性(Fv/Fo)、PSⅡ实际光化学效率(ФPSⅡ),叶片净光合速率(Pn)、气孔导度(Gs),棉花干物重及分配到生殖器官的比例,棉花总成铃数、铃重和衣分均有不同程度提高;中棉所38、新棉33B和中棉所12皮棉产量分别增加13.60%、10.66%和4.21%;棉纤维2.5%跨距长度、比强度、马克隆值和纤维整齐度等品质也得到改善。中棉所38和新棉33B比中棉所12施钾的效果更好,生产上应优先给抗虫杂交棉和抗虫棉品种施用钾肥。     

适宜施氮量提高棉花氮磷钾养分积累和皮棉产量

  【目的】  棉花是喜磷喜钾作物,适宜的施氮量不仅可以保证棉花的营养生长,还会促进磷、钾的吸收。为此我们研究了中熟和中早熟棉花品种的适宜施氮量。  【方法】  田间试验于2019—2020年在河南安阳开展。试验采用裂区设计,主区设7个施氮量:0、60、120、180、240、300、360 kg/hm2,依次记为N0、N60、N120、N180、N240、N300、N360;副区为黄河流域两个主栽棉花品种冀棉228 (中熟)和鲁棉研28号(中早熟)。在棉花采收期,测定了棉花地上部生物量、产量及氮、磷、钾含量,计算氮、磷、钾累积量和皮棉生产效率。  【结果】  与N0相比,中熟品种冀棉228地上部生物量在施氮0～240 kg/hm2范围内,随施氮量的增加显著增加,施氮量超过240 kg/hm2后生物量不再显著增加;而中早熟品种鲁棉研28号地上部生物量在施氮量超过180 kg/hm2后,就不再显著增加。施氮显著增加了冀棉228和鲁棉研28号地上部的氮、磷、钾累积量,冀棉228分别增加了37.5%、23.5%、29.2%,鲁棉研28号分别增加了47.2%、34.0%、35.5%。鲁棉研28号提高的幅度大于冀棉228。棉花氮、磷、钾积累量的增加65.9%～82.4%是由于地上部生物量的增加,17.6%～34.1%是由于地上部氮、磷、钾含量的增加。冀棉228的单株成铃数和鲁棉研28号的单铃重均随着施氮量的增加呈先增加后降低的趋势,通过线性加平台模拟得到的两个品种的最高产量施氮量分别为180和188 kg/hm2,对应的皮棉产量分别为1661和1538 kg/hm2。氮、磷、钾皮棉生产效率均随施氮量增加而显著降低。磷素、钾素皮棉生产效率与氮素皮棉生产效率呈正相关。产量收获指数与氮、磷、钾的累积量显著负相关,而与氮、磷、钾收获指数间呈显著正相关,可作为肥料利用效率的间接选择指标。  【结论】  适宜的施氮量可有效提高棉花地上部生物量和氮、磷、钾含量,二者的增加共同提高了棉铃和地上部的氮磷钾累积量,生物量增加对提高氮磷钾积累量的贡献率为65.9%～82.4%,氮、磷、钾含量增加的贡献率为17.6%～34.1%。氮素皮棉生产效率与磷素、钾素的皮棉生产效率呈正相关。综上,氮素吸收可促进棉花对磷、钾素的吸收,本试验条件下,冀棉228和鲁棉研28号皮棉产量和氮磷钾吸收利用率均较高的施氮量分别为180和188 kg/hm2。     

不同基因型抗虫棉氮磷钾养分吸收与分配特征

【目的】探讨不同抗虫棉品种植株干物质与氮、磷、钾养分积累分配特点,为制定棉花高产栽培管理措施提供依据。【方法】在大田条件下,选用三个抗虫棉品种(冀棉169、鲁棉研21号和岱字棉99B)为研究对象,比较研究了三个品种的干物质积累与氮磷钾吸收特性。【结果】冀棉169产量最高,两年分别比鲁棉研21号提高了27.9%和25.5%,分别比岱字棉99B提高了65.9%和41.1%。三个品种单铃子棉重的变化趋势与产量一致,而单株结铃数和衣分则不同。冀棉169棉株各器官干物质和氮磷钾积累量均较高,尤其在生育中后期,营养器官保持最高的氮磷钾养分积累量,促使其干物质积累量显著高于其他两个品种,为棉铃发育提供了充足的物质基础,铃叶比较大,因此结铃最多,单铃子棉重最大,皮棉产量最高,使得养分利用效率也最高。鲁棉研21号棉株各器官干物质和氮磷钾积累量均最低,主要是由于营养器官氮磷钾养分快速积累期结束最早,加之向棉铃分配比例最高,从而限制了营养器官的生长发育,影响生育中后期棉铃的发育,使之不仅结铃数最少,单铃子棉重较小,产量也较低。岱字棉99B棉株各器官干物质和氮磷钾积累量虽最高,但其快速积累期出现在盛花期以后,棉株贪青,结铃数虽较多,但单铃子棉重最小,使之产量最低,养分利用效率也最低。【结论】不同年代抗虫棉品种产量提高的主要原因是单铃子棉重的增加,其次是单株结铃数的提高。单铃子棉重和单株结铃数的增加主要归因于棉株总生物量和向生殖器官转运量的协同提高,特别是生育中后期保持高的同化物和生殖器官运转比例;而生物量的增加依赖于养分积累量和利用效率的提高。     

氮肥基追比对南疆杂交棉氮素吸收、生物量及产量的影响

探索不同氮肥基追比水平下杂交棉的氮素吸收、干物质积累及产量的变化规律,为南疆杂交棉高产高效栽培技术提供理论依据。以兆丰1号和鲁棉研30号为试验材料,设3个氮肥基追比处理(N1,基肥∶追肥=0∶10;N2,基肥∶追肥=2∶8;N3,基肥∶追肥=4∶6),研究了氮肥基追比对杂交棉氮素吸收、干物质积累及产量的影响。结果显示,随着氮肥追肥比例的减少,植株生物量和氮素吸收量先升后降。其中N1处理不利于棉株干物质积累和氮素的吸收,显著降低了累积速率,使棉花生育期提前、衰老加快;N2处理提高了干物质快速积累速率,延长了快速积累持续时间,增加了开花后生物量积累、氮素吸收量以及花后同化物与氮素向生殖器官中的转运;N3处理由于追肥比例较少,开花后干物质与氮素的积累量以及花铃期干物质与养分向生殖器官中的分配比例减少。本试验条件下,两个杂交棉品种的基肥∶追肥=2∶8处理的棉花干物质及氮素累积最为协调,并能同步增加单株结铃数和铃重,进而实现增产。     

基于同异性分析的不同类型棉花品种纤维品质特征与分类评价

为精确分析中国棉花纤维品质的区域特征、分布规律及综合性评价,以2005-2014年国家棉花品种区域试验531个参试品种纤维品质数据为材料,运用作物育种同异性分析理论对杂交棉和常规棉品种的纤维品质进行综合评价。结果表明：1）常规棉品种纤维品质符合审定标准Ⅰ型、Ⅱ型和Ⅲ型的品种数分别占参试常规棉品种数的1.58%、28.42%和14.74%,杂交棉纤维品质符合审定标准Ⅰ型、Ⅱ型和Ⅲ型的品种分别占参试杂交棉品种数的0.59%、19.94%和10.56%。黄河流域常规棉品种、杂交棉品种纤维品质综合同一度分别为0.869 3和0.888 8,长江流域杂交棉纤维品质综合同一度为0.864 3,西北内陆棉区常规棉纤维品质综合同一度为0.890 5。2）不同棉区常规棉与杂交棉纤维品质性状比较表明,西北内陆棉区常规棉品种纤维品质性状优于黄河流域杂交棉;而黄河流域杂交棉又优于黄河流域常规棉和长江流域杂交棉,黄河流域常规棉与长江流域杂交棉纤维品质性状差异不显著。可见,黄河流域棉区适宜种植推广中长绒、高比强和高马克隆值的常规棉品种;长江流域棉区适宜种植中长绒、高比强度和高马克隆值的杂交棉品种;西北内陆棉区适合种植长强细的优质常规棉品种,可作为棉纺工业纺中高支纱的优质棉生产基地。本研究对优化我国优质棉区域布局和种植结构调整有重要参考价值。     

~(60)Co-γ射线对不同陆地棉品种辐照效应和耐旱突变体筛选

为研究~(60)Co-γ射线对不同棉花品种的辐照效应,并筛选耐旱突变体,本试验利用~(60)Co-γ射线对棉花品种鲁棉532、K638和K836的种子进行辐照(250 Gy)处理。结果表明,~(60)Co-γ射线辐照处理显著降低了鲁棉532、K638和K836种子的发芽率、发芽势和出苗率,与未经辐照处理(CK)相比,K836发芽率、发芽势和出苗率分别下降了38.9%、45.9%和48.5%,降幅最大,且~(60)Co-γ射线辐照处理显著降低了K836棉苗叶片的光合速率、叶绿素含量、棉苗生长和籽棉产量,但对鲁棉532和K638影响不显著;在经辐射诱变K836的M1群体中发现了大量生长发育异常的棉株,但在鲁棉532和K638的辐射M1群体中极少有发育异常突变体,说明250 Gy是诱变K836的适宜剂量,而鲁棉532和K638的适宜剂量应提高。将经辐射诱变的中熟品种K836的M2和M3种子分别播种于临清旱棚内和敦煌大田,共筛选出了3个耐旱突变体(DT-1、DT-2和DT-3)。本研究结果为利用~(60)Co-γ射线诱变选育耐旱棉花品种奠定了一定的理论基础。     

转基因抗虫棉对棉花纤维品质的影响

以一组不同抗虫类型的陆地棉(Gossypium hirsutum L．)抗虫品种和一组常规棉(G．hirsutum L．)品种作为亲本，按照不完全双列杂交(NCⅡ)试验设计配制杂交组合，将亲本材料和F。代杂交种子按照随机区组设计方法，同时在网室和试验田进行棉花抗红铃虫(Pectinophora gossypiella Saunders)鉴定和棉花抗虫性对棉花纤维品质的影响试验。结果表明，具有外源抗虫基因的抗虫棉材料对红铃虫具有很强的抗性，抗虫棉的纤维品质较好，大多数抗虫棉品种达到了育种目标要求。相关分析结果表明，棉花种子虫害率与马克隆值成显著负相关；与衣指成显著正相关；与2．5％跨距长度、整齐度、比强度、伸长率和子指等指标相关性较低。利用外源抗虫基因转化的棉花新品种，用其作为亲本采用杂交育种法可以培育出优质的抗虫棉花新品种，而且提高棉花品种的抗虫性并不影响棉花纤维品质。     

杂交棉与常规棉干物质积累和氮磷钾吸收分配及产量比较

利用田间试验,研究了杂交棉豫杂35和常规棉中棉41在施N 225、P2O 5 90、K2O 135 kg/hm2条件下的干物质积累和氮磷钾吸收分配及产量形成特点。结果表明,杂交棉和常规棉的干物质及氮磷钾的阶段积累量变化趋势基本相同;而杂交棉的干物质和氮磷钾在各时期的积累量和日积累强度均明显高于常规棉。随着生长发育进程杂交棉后期干物质和氮磷钾的阶段积累比例比常规棉的高,表明杂交棉在后期有较强的生长和积累的优势。所以,加强杂交棉的后期管理能更好的发挥其增产潜力。杂交棉和常规棉的干物质和氮磷钾在各器官的分配,均表现随生长发育转向生殖器官的比例不断提高,但杂交棉略高于常规棉。在本试验条件下,杂交棉皮棉产量1778.23 kg/hm2,一生吸收 N、P2O5、K2O总量分别为 242.92、82.12、247.76 kg/hm2,N∶P2O5∶K2O=1∶0.34∶1.02;常规棉皮棉产量1377.21 kg/hm2,一生吸收 N、P2O5、K2O总量分别为195.42、65.64、194.09 kg/hm2,N∶P2O5∶K2O=1∶0.34∶0.99。     

施氮量对长江流域滨海盐土棉花氮素吸收利用的影响

【目的】长江流域下游棉区棉花种植逐渐向沿海地区集中,但该地区棉花生产中氮肥运筹不合理问题突出,本研究旨在揭示长江流域滨海盐土棉花氮素吸收利用对施氮量的响应特征,以期为该区棉花的合理氮肥运筹提供理论依据。【方法】2010年和2012年在江苏省大丰市稻麦原种场(33.2°N,120.5°E)滨海盐土棉田,以湘杂棉8号棉花品种为材料,设置施氮(N)量0、150、300、375、450、600 kg/hm2试验,研究了长江流域下游滨海盐土条件下,施氮量对棉花产量、不同空间部位生物量和氮素累积分配特征以及氮素利用的影响。【结果】随施氮量的增加,棉花皮棉产量和氮肥表观利用率均呈先升高后降低的趋势,并在301 374 kg/hm2施氮量范围内,皮棉产量和氮素表观利用率达到最高,氮肥农学利用率、氮肥偏生产力和氮素生产效率则随施氮量的增加呈降低趋势。施氮量通过调控棉花不同果枝部位氮含量和氮累积量的动态特征影响氮素和生物量的累积转运,进而影响棉花产量。适宜施氮量(301 374 kg/hm2)下,棉株各部位氮素含量和氮素累积动态特征参数比较协调,有利于光合产物向生殖器官的转运,进而提高产量;过量施氮增加了棉株各部位氮素含量,棉株下部氮素累积速率加快,氮素快速累积期持续时间延长,棉株中部氮素快速累积期持续时间延长,棉株中下部的光合产物以及氮素向生殖器官的分配减少,吐絮期氮素的吸收比例和累积量增大,产量降低;施氮不足则降低了棉株各部位氮含量,加快了各部位氮素含量的降低,减少了氮素累积量,降低了棉株生物量和皮棉产量。【结论】在长江流域滨海盐土地区,棉花生产的推荐施氮量为301 374 kg/hm2,该施氮量下棉花产量和氮肥表观利用率相对较高。超过该适宜施氮量,棉花产量降低归因于棉株中下部光合产物和氮素向生殖器官的转运受到抑制,并且增加了生育后期氮素的吸收比例和累积量,棉花贪青晚熟。低于该施氮量则由于氮素供应不足,氮累积量和生物量减少,导致产量降低。     

播期对短季棉品种产量及养分利用效率的影响

以4个短季棉品种(中棉所50、鲁棉研35、邯686、豫早棉9110)为材料,研究了早播(4月25日播种,密度设置为52 500株/hm2)与正常播期(5月15日播种,密度设置为75 000株/hm2)条件下的子棉产量、皮棉产量及养分利用效率,结果表明:早播对短季棉品种的生育期无显著影响,早播条件下,短季棉品种的子棉产量、皮棉产量、衣分均高于正常播期,生物量、每100 kg皮棉产量氮、磷、钾吸收量低于正常播期,氮、磷、钾养分利用效率高于正常播期。本试验条件下,早播提高了短季棉品种氮、磷、钾养分利用效率,从而提高了子棉、皮棉产量。     

GENOTYPIC VARIATIONS IN POTASSIUM UPTAKE AND UTILIZATION IN COTTON

Genotypic differences in potassium (K) uptake and utilization were compared for eight cotton cultivars in growth chamber and field experiments. Four of the cultivars (‘SGK3’, ‘SCRC18’, ‘SCRC21’ and ‘SCRC22’) typically produce lower dry mass and the other four (‘Nannong8’, ‘Xiangza2’, ‘Xinluzao12’ and ‘Xiangza3’) produce greater dry mass in K-deficient solution (0.02 mM). The mean dry weight of seedlings (five-leaf stage) of cultivars with greater biomass was 155% higher than that of cultivars with lower biomass yield under K deficiency. However, all the genotypes had similar dry matter yields in K-sufficient solution (2.5 mM). Thus, the four cultivars with superior biomass yield under low K medium may be described as K efficient cultivars while the inferior cultivars may be described as K inefficient. Although seeds of the studied cultivars originated from different research institutes or seed companies, there were little differences in seed K content among them, irrespective of their K efficiency. Consequently, there were no significant differences in K accumulation in seedlings (4 d after germination in a K-free sand medium) just before transferring to nutrient solutions. However, the K efficient genotypes, on average, accumulated twice as much K at 21 d after transferring to K-deficient solution (0.02 mM). A much larger root system as well as a slightly higher uptake rate (K uptake per unit of root dry weight) may have contributed to the higher net K uptake by the K efficient cultivars. In addition, the K efficiency ratio (dry mass produced per unit of K accumulated) and K utilization efficiency (dry mass produced per unit of K concentration) of the K efficient cultivars exceeded those of the K inefficient genotypes by 29% and 234%, respectively, under K deficiency. On average, the K efficient cultivars produced 59% more potential economic yield (dry weight of all reproductive organs) under field conditions even with available soil K at obviously deficient level (60 mg kg^?1). We noted especially that the four K inefficient cultivars studied were all transgenic insect-resistant cotton, suggesting that the introduction of foreign genes (Bt and CpTI) may affect the K use efficiency of cotton.     

DIVERSITY AND IMPLICATIONS OF SOYBEAN STEM NITROGEN CONCENTRATION

Soybean [Glycine max (L.) Merr.] shoot nitrogen (N) traits are important for seed production and may hold potential for improving seed yield and quality. Field experiments were established to survey shoot N traits in i) plant introductions, ii) a recombinant inbred line (RIL) population, and iii) modern cultivars. A wide range of N concentrations was observed at beginning seed fill for leaves, petioles, and stems and at maturity for stems. Significant genotypic variations in stem N traits were found in modern cultivars and the RIL population. Molecular marker analysis identified multiple loci associated with stem N concentration. Significant relationships between various tissue N traits and seed yield and quality were also observed. These results illustrate the importance of N dynamics in vegetative tissues for soybean yield and seed composition. The observed variation in N traits indicates that selecting for vegetative N traits could potentially increase yield and improve seed quality.     

Identification of a maize (Zea mays L.) inbred line adapted to low‐P conditions via analyses of phosphorus utilization,root acidification,and calcium influx

Phosphorus (P) fertilizers are essential for achieving high crop productivity, but declining soil P reserves and cost of fertilizers suggest that improving crop varieties for improved use efficiency of P be important for sustainability. To explore the possibility of selecting crops suitable for low P conditions, two maize (Zea mays L.) inbred lines, i.e., W22 and W23 were compared for growth, root morphology, and electrophysiological parameters, under hydroponic conditions with either insoluble P source (LP) or soluble P source (HP) in a factorial completely randomized design. Relative shoot biomass of W23 was significantly (38%) greater than that of W22 with LP, while relative root biomass of the two inbred lines did not differ. With LP, the P stress factor was the lowest (25%) and P dissolution in hydroponic solution was the greatest for W23. Root electrophysiological analysis revealed that W23 had 89% greater H⁺ efflux and 225% greater Ca²⁺ influx than W22 with LP. The distant elongation zone (DEZ) of W23 root was significantly longer and more shoot‐ward than W22 with LP. Thus, W23, having significantly greater relative shoot biomass, lower P stress factor, greater P dissolution, greater H⁺ efflux and Ca²⁺ influx, longer and more shoot‐ward DEZ, was better adapted to low‐P condition compared to W22. In the future, the W23 inbred line can be used for developing low‐P stress resistant varieties to utilize native insoluble soil P efficiently or to produce commercially acceptable yields using lower rates of soluble P fertilizers.     

Effect of genetic improvement of grain yield and nitrogen efficiency of mid‐season indica rice cultivars

Genetic improvement (GI) of mid‐season indica rice (Oryza sativa L.) in China has been experienced four typical plant types during the past several decades, i.e., early tall cultivars (ET), dwarf cultivars (DC), semi‐dwarf cultivars (SDC) and super rice cultivars (SR). However, little is known about the changes in fertilizer nitrogen (N) efficiency and their relationships with grain yield during the GI. With 12 representative mid‐season indica cultivars of the four types during GI, the effects of GI on grain yield and nitrogen efficiency were investigated. The results show that GI significantly increased grain yield and agronomic efficiency (AE) of N fertilizer but had no significant effect on recovery efficiency (RE) of N fertilizer. The low percentage of filled grains in modern SR limited its yield potential and the further increase in AE. GI decreased the N uptake from heading to maturity, leading to lower RE in modern rice cultivars. The rapid decline of the activities of root oxidation and nitrate reductase in SR during grain filling might be the physiological reasons for the lower percentage of filled grains and lower N uptake from heading to maturity.     

Effect of Recent Genetic Improvement on Some Analytical Parameters of Tomato Fruit Quality

Abstract

Poor flavor in tomato fruit is a serious consumer concern. It could be said that tomato flavor has declined as variety selection and tomato production has placed emphasis on yield, fruit size, firmness, disease resistance, and processing performance and not on aspects of organoleptic fruit quality. Consumers frequently associate recent varieties with a lack of flavor, although such an association has not been proven. We have reviewed the scarce available literature on the influence of recent genetic improvement on quality attributes of tomato. As a case study, we have analyzed several parameters related to fruit quality in some traditional Spanish cultivars and commercial F1 hybrids of tomato. Organic acids and sugars were determined by high performance liquid chromatography (HPLC). Sodium (Na), potassium (P), and phosphorus (K) were analyzed by atomic absorption spectroscopy. Levels of respiration and ethylene production were measured, and fruit firmness was determined using a texture analyzer. All determinations were performed at two maturity stages, representing two frequent consumption stages. Differences between traditional cultivars and hybrids were found for respiration rates, ethylene production, P and K fruit contents. We also found important differences between “old” and “modern” cultivars for their organic acids profile. All cultivars showed similar levels of malic and succinic acids, but the modern hybrids showed a ～75% higher content of citric acid. This could be due to the F1 hybrids carrying chromosomal segments recently introgressed from wild Lycopersicon species. The influence of recent genetic improvement on quality attributes of tomato fruit is discussed.     

不同氮效率玉米品种亲本自交系花粒期氮素转运特性

【目的】为明确不同氮效率玉米品种亲本自交系花粒期氮转运与代谢特性,从溯源的角度探析不同氮效率玉米品种亲本自交系花粒期的氮素吸收、转运与利用特性。【方法】以氮高效型玉米品种‘鲁单818’的亲本自交系 (母本Qx508,父本Qxh0121) 和氮低效型玉米品种‘鲁单981’亲本自交系 (母本Q319,父本Lx9801) 为供试材料,盆栽条件下研究不同氮素供应水平 (N 0 g/盆、7.1 g/盆和14.2 g/盆,记作N0、N1和N2) 对4个不同氮效率玉米亲本自交系花粒期干物质积累、氮素积累、氮素分配与利用效率以及叶片氮代谢关键酶硝酸还原酶活性、可溶性蛋白含量变化的影响,并探讨分析不同氮效率玉米品种氮素利用的生理机制与遗传特性。【结果】吐丝后各自交系干物质由营养器官向生殖器官转移,表现为茎叶干物重显著降低,穗和粒的干物重显著增加,且Qxh0121和Q319的干物质重均显著高于其另一亲本。从吐丝到成熟,茎鞘和叶的氮含量均呈降低的趋势,穗和粒的氮含量显著增加,且Qxh0121和Q319自交系叶片、茎鞘、籽粒氮含量均显著高于其另一亲本自交系。花后氮吸收量均表现为Qxh0121显著高于Qx508,Q319显著高于Lx9801。且在低氮 (N1) 和高氮 (N2) 处理下,Qxh0121氮转运效率较Qx508分别高29.2%和14.3%,花后氮转运对籽粒贡献率较Qx508分别高74.0%和17.4%。Q319氮转运效率较Lx9801分别高43.4%和24.7%,花后氮转运对籽粒贡献率较Lx9801分别高75.3%和39.6%。Qxh0121和Q319的产量和氮肥利用效率也高于对应的自交系。在N1和N2水平下,Qxh0121的产量比Qx508分别高43.3%和42.5%,Q319的产量比Lx9801分别高20.2%和10.5%。吐丝至成熟期叶片硝酸还原酶 (NR) 活性和可溶性蛋白含量的变化均呈单峰曲线,高峰期在吐丝后10 d左右。Qxh0121和Q319的NR活性和可溶性蛋白含量在各时期均高于其另一亲本,表现出较强的氮素吸收和同化能力。【结论】氮高效型玉米品种‘鲁单818’表现为父本高效,氮低效型玉米品种‘鲁单981’表现为母本高效。因此,未来育种应充分挖掘‘鲁单818’的父本Qxh0121及‘鲁单981’的母本Q319的氮高效潜力,提高其花前氮的转移效率以及花后氮向籽粒的分配能力,是其对应杂交种进一步实现高产并增加籽粒氮浓度、减少秸秆氮素残留的关键。     

我国北方37个高产春玉米品种干物质生产及氮素利用特性

选育氮高效品种是实现玉米高产高效生产的根本途径。为探明我国北方目前主推高产春玉米的物质生产及氮素利用特性,本研究选择该区域高产品种37个,采用盆栽试验,依粒重和氮素子粒生产效率划分其类型,分为高产高效（I）、高产中效（Ⅱ）、中产中效（Ⅲ）及低产低效（Ⅳ）4种类型。其中,中产中效型品种最多,为56.8%;高产高效型品种最少,仅为8.1%;高产中效型和低产低效型品种分别为13.5%和21.6%。4个类型品种干物质生产及氮素利用效率开花前差异不显著,开花后是产生差异的关键时期;成熟期I型品种干物质和氮向子粒的分配比例较高,而Ⅳ型品种向根和茎秆的分配比例较高。同时,I型品种的氮转移量、氮转移效率和贡献率显著高于其他3类型品种。经相关和通径分析,氮素干物质生产效率、粒重及氮含量与氮素子粒生产效率显著相关。所以,较高的粒重和较低的植株氮含量是高产氮高效品种的基本特征。     

Variation in seed longevity of rice cultivars belonging to different isozyme groups

The storage potential of seeds harvested at different stages of maturity was studied in ten cultivars of Oryza sativa, representing six known isozyme groups, and in two cultivars of O. glaberrima. Mass maturity (the end of the seed-filling period) was attained between 14.2 and 20.2 days after anthesis (DAA). A comparison of the estimates of p ₅₀ (time in storage for viability to decline to 50%) of seeds harvested at 21, 28 and 35 DAA and stored at 35°C with 15% moisture content showed that maximum longevity was attained between 28 and 35 DAA in most cultivars. Cultivars belonging to isozyme group II survived longer than other cultivars with estimates of p ₅₀ nearly doubled. On the other hand, the floating rices of Group IV had shorter longevity. Within group VI, the upland cultivar survived longer than the lowland cultivar. Both O. glaberrima cultivars survived reasonably well, showing that African rice cultivars also differ in longevity.     

Modern wheat cultivars have greater root nitrogen uptake efficiency than old cultivars

The availability of nitrogen (N) contained in crop residues for a following crop may vary with cultivar, depending on root traits and the interaction between roots and soil. We used a pot experiment to investigate the effects of six spring wheat (Triticum aestivum L.) cultivars (three old varieties introduced before mid last century and three modern varieties) and N fertilization on the ability of wheat to acquire N from maize (Zea mays L.) straw added to soil. Wheat was grown in a soil where ¹⁵N‐labeled maize straw had been incorporated with or without N fertilization. Higher grain yield in three modern and one old cultivar was ascribed to preferred allocation of photosynthate to aboveground plant parts and from vegetative organs to grains. Root biomass, root length density and root surface area were all smaller in modern than in old cultivars at both anthesis and maturity. Root mean diameter was generally similar between modern and old cultivars at anthesis but was greater in modern than in old cultivars at maturity. There were cultivar differences in N uptake from incorporated maize straw and the other N sources (soil and fertilizer). However, these differences were not related to variation in the measured root parameters among the six cultivars. At anthesis, total N uptake efficiencies by roots (total N uptake per root weight or root length) were greater in modern than in old cultivars within each fertilization level. At maturity, averaged over fertilization levels, the total N uptake efficiencies by roots were 292?336 mg N g^?1 roots or 3.2?4.0 mg N m^?1 roots for three modern cultivars, in contrast to 132?213 mg N g^?1 roots or 0.93?1.6 mg N m^?1 roots for three old cultivars. Fertilization enhanced the utilization of N from maize straw by all cultivars, but root N uptake efficiencies were less affected. We concluded that modern spring wheat cultivars had higher root N uptake efficiency than old cultivars.     

转BADH基因大豆对盐碱土壤氮素转化的影响

以转甜菜碱醛脱氢酶(betaine aldehyde dehydrogenase)基因(BADH)大豆、非转基因亲本‘黑农35’、野生大豆、当地栽培种‘抗线王’、耐盐碱性较差品种‘合丰50’等5种大豆品种为材料,在典型盐碱土封闭种植,于大豆苗期、花荚期、鼓粒期和成熟期取根际土,采用经典方法测定氮素转化过程相关的细菌数量、生化功能及速效氮含量等指标的动态变化,为揭示转BADH基因大豆对土壤氮素转化的影响机制提供理论支持。结果表明:与非转基因亲本相比,转BADH基因大豆对苗期和花荚期根际土壤固氮菌数量有促进作用,但抑制苗期和花荚期根际土壤氨化细菌数量,对硝化细菌数量无显著性影响;显著促进成熟期大豆根际土壤固氮作用强度,对大豆苗期、花荚期和鼓粒期根际土壤氨化作用强度有显著抑制作用,显著促进各生育时期硝化作用强度;转BADH基因大豆苗期和花荚期根际土壤铵态氮含量显著降低,对鼓粒期根际土壤铵态氮含量无显著性影响,成熟期根际土壤铵态氮含量显著增高,大豆苗期、鼓粒期和成熟期根际土壤硝态氮含量显著升高,花荚期根际硝态氮含量显著降低。研究结果说明,转BADH基因大豆通过调节苗期、花期根际土壤氮素转化功能菌数量和生化过程强度进而影响氮素转化。