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1.
为明确春季调控措施对冬小麦生长发育和籽粒产量的影响,以冬小麦品种石新828为材料进行田间试验,4个处理分别为:起身期追全部氮肥(除基肥外,下同)并叶面喷多效唑(N1);起身期追2/3氮肥并喷多效唑+拔节期追1/3氮肥(N2);起身期追1/3氮肥+拔节期追2/3氮肥(N3);拔节期追全部氮肥(N4)。生育期间测定群体和个体生育特性,成熟期调查产量性状。结果表明,N1和N2处理小麦拔节期的总茎数、叶面积指数(LAI)和干物质积累量均显著高于N4和N3处理。孕穗期N4和N3处理小麦的总茎数、LAI和干物质积累量显著高于N1和N2处理。开花到成熟期各处理的总茎数、LAI和干物质积累量差异均不显著。孕穗期前,不同处理的株高差异不显著,孕穗期后,N4处理的株高最高,且显著高于N1处理。各处理基部节间直径和中上部节间长的差异不显著,N4处理基部第一节间长度显著大于其他处理。随追氮时期前移或前期施氮量增多,不孕小穗数减少,结实小穗和穗粒数增加,N1比N4处理不孕小穗数显著减少,结实小穗和穗粒数显著增多。N1处理小麦成熟期的千粒重最高,且显著高于N4处理。N1处理的籽粒产量最高,且显著高于N3和N4处理。起身期追氮配合多效唑调控,可以获得比拔节期追氮更高的穗粒数和千粒重,从而获得更高的产量。  相似文献   

2.
Four field experiments comparing 24 durum wheat varieties grown at different periods during the 20th century in Italy and Spain were carried out to assess the changes caused by breeding activities on the number of grains per main spike and its determinants: number of spikelets per spike, number of grains per spikelet, fertile flowering and grain setting. Increases of 0.14 grains spike−1 year−1 (0.43% year−1 in relative terms) and 0.08 grains spike−1 year−1 (0.22% year−1) were observed in Italian and Spanish varieties, respectively. The overall change in the number of grains per spike in Italian germplasm (29.5%) was due to increases in both, the number of spikelets per spike (7.5%) and the number of grains per spikelet (20.3%), while in Spanish varieties the increase in the number of grains per spike (19.5%) was only attributed to the improvement of the number of grains per spikelet. The increase in the number of fertile florets per spike (about 12%) was similar in both countries, but while it explained more than 70% of the changes in the number of grains per spike in Spanish varieties, grain setting was responsible for most of the improvement in the number of grains per spike in the Italian germplasm. The percentage of florets setting grains was 68 and 64% in modern Italian and Spanish varieties, respectively. Most of the changes in the number of grains per spikelet were found in the upper part of the spike on Italian varieties, whilst they were more evenly distributed in the Spanish ones. The main achievement derived from the introduction of the Rht-B1 dwarfing gene was an increase in the number of grains per spikelet, but it did not have any effect on the number of spikelets on the main spike. The lack of genetic associations between grain setting and both the number of spikelets per spike and the number of fertile florets per spike suggests that future yield gains may be obtained through increases in the three components independently.  相似文献   

3.
《Plant Production Science》2013,16(2):189-198
Abstract

Grain number per spike of wheat is lower in early sowing than in the conventional standard cultivation in Yamaguchi, Prefecture, Japan. Components of the grain number per spike in five cultivars were analyzed with respect to temperature during the spike development period throughout three growing seasons 2001/2002, 2002/2003 and 2003/2004 to find the cause of the problem of early sowing cultivation. The plants sown in early-October and late-November were called the early sown group and the standard group, respectively, in the following. Three of the five cultivars, Hokushin, Akitakko and Nanbukomugi, showed a strong winter habit, which requires very cold temperatures for spike differentiation. The other two cultivars, Iwainodaichi and Airakomugi, had a moderate winter habit. Grain number per spike and grain yield were decreased by early-sowing (compare with the standard group) in almost all cultivars throughout the three growing seasons. The three cultivars which had a strong winter habit had fewer spikelets per spike in the early-sown group than in the standard group. The other two cultivars which had a moderate winter habit had fewer grains per spikelet in the early-sown group. The higher the temperature during the spikelet formation phase, which is from flag leaf initiation to terminal spikelet initiation, the higher the number of spikelets per spike in the standard group. The spikelet number per spike in the early-sown group increased with the increase in productive tillers under fertile conditions. Such conditions also increased the grain number per spike.  相似文献   

4.
《Plant Production Science》2013,16(3):198-202
Summary

A rice husk restricts the grain development physically. We examined the correlation of the total husk volume on a panicle, a parameter of yield capacity, with the nitrogen concentration (per dry weight) and the dry weight of the above-ground part of the plant, using single-stem-trained japonica rice (cv. Nipponbare) plants. The growth of rice plants was regulated by shading at two levels and nitrogen application at three levels from about 40 days before the heading (about 10 days before the panicle initiation). The number of spikelets per dry weight of the above-ground part of the plant at the end of the spikelet differentiation stage was linearly correlated with the nitrogen concentration at that time. The ratio of the spikelet dry weight at heading to the dry weight of the above-ground part of the plant at the end of the spikelet differentiation stage increased as the nitrogen concentration increased at a low nitrogen concentration, but the increase of the ratio slowed down at a nitrogen concentration of 2%. Decrease in dry weight of the spikelet resulted in a decrease of lemma size. Therefore, the ratio of the total husk volume on a panicle to the plant dry weight at the end of spikelet differentiation stage also increased as the nitrogen concentration increased at a low nitrogen concentration, but the increase stopped at a nitrogen concentration of 2% in contrast to the ratio of the spikelet number to the dry weight of the plant. These results suggest that, to increase the total husk volume on a panicle by nitrogen application, dry-matter production must be increased by the nitrogen application.  相似文献   

5.
Sink strength plays an important role in grain filling of cereals but how it is related to the pre-anthesis non-structural carbohydrate (NSC) reserves is not clear. This study investigated if and how an increase in NSC reserves could enhance sink strength, and consequently improve grain filling of later-flowering inferior spikelets (in contrast to the earlier flowering superior spikelets) for rice varieties with large panicles. Two “super” rice varieties (the recently bred high-yielding rice) and two New Plant Type (NPT, named in IRRI for the extra-large panicle) rice lines were compared with two elite inbred varieties under field-grown conditions. Three nitrogen (N) treatments, applied at the stages of panicle initiation, spikelet differentiation or both, were adopted with no N application during the mid-season as control. Both super rice and NPT rice showed a greater yield capacity as a result of a larger panicle than the elite inbred rice. However, a lower percentage of filled grains limited the realization of higher yield potential in super rice and especially in NPT rice, due to their lower grain filling rate and the smaller grain weight of their inferior spikelets. The low grain filling rate and small grain weight of inferior spikelets are mainly attributed to a poor sink strength as a result of small sink size (small number of endosperm cells) and low sink activity, e.g. low activities of sucrose synthase (SuSase) and adenosine diphosphoglucose pyrophosphorylase (AGPase). The amounts of NSC in the stem and NSC per spikelet at the heading time are significantly and positively correlated with sink strength (number of endosperm cells and activities of SuSase and AGPase), grain filling rate, and grain weight of inferior spikelets. Nitrogen application at the spikelet differentiation stage significantly increased, whereas N application at the panicle initiation or at both panicle initiation and spikelet differentiation stages, significantly reduced, NSC per spikelet at the heading time, sink strength, grain filling rate, and grain weight of inferior spikelets in super rice. The results suggest that pre-anthesis NSC reserves in the stem are closely associated with the sink strength during grain filling of rice, and N application at the spikelet differentiation stage would be a good practice to increase pre-anthesis NSC reserves, and consequently to enhance sink strength for rice varieties with large panicles, such as super rice varieties.  相似文献   

6.
Water and nitrogen (N) availability are the main factors influencing crop growth globally. Poorly distributed or insufficient water for crop growth requirements decreases yields in drought-prone areas such as those with a Mediterranean type environment. Cereal grain yield is a complex trait of interrelated components: plants per unit land area, spikes per plant, spikelets per spike, grains per spikelet, and single grain weight (SGW). The effect of water limitation and timing on development of yield components was studied in detail at the spike level in spring wheat (Triticum aestivum L.) cultivar Amaretto. An experiment with three watering treatments (control watering, CONT; drought prior to pollination, DR1 and terminal drought, DR2) was arranged in a large greenhouse (20 m × 30 m), with the use of standard field-trial machinery. Automated blackout curtains were used to control day length, which was set to correspond to that at 40°N. With watering treatments, two N application rates (60 and 120 kg N ha−1) were used to investigate the N effect and potential watering × N interaction on yield formation and realisation. The water deficit effect exceeded the effect of N on fertile floret and grain number and SGW. DR1 strongly reduced the number of fertile florets and grains, whereas terminal drought reduced the number of grains per spike. Resuming the watering at pollination markedly enhanced photosynthesis, and hence grain filling capacity, resulting in the highest SGW in DR1. Enhancement in availability of key resources was associated with reduced rate of fertile floret and grain abortion, which resulted in higher grain to fertile floret ratio in DR1. Spikelets in the mid-section of the spike dominated yield formation in all treatments. In DR1 this was especially emphasised as 53% of the grain yield was produced in spikelets 4–6, whereas in DR2 and CONT this was 45 and 41%, respectively. Grains in proximal position in the spikelets produced about 80% of the spike grain yield, the proportion being slightly higher in stressed plants and plants receiving 60 kg N. No marked N × water deficit treatment interaction occurred for any of the measured parameters.  相似文献   

7.
施氮量对小麦穗花发育及穗粒数的影响   总被引：2，自引：0，他引：2  
为了解小麦穗发育与氮素营养的关系,通过田间试验,设置90、180、270kg·hm-2三个施氮量水平(分别用N1、N2和N3表示),选用半冬性小麦品种豫麦49和弱春性品种太空6号为材料,研究了施氮量对小麦主茎幼穗长度、第九小穗小花发育进程、每穗总小穗数、不孕小穗数、小穗结实率、产量及其构成的影响。结果表明,随着时间的推移,小麦主茎幼穗长度对施氮量响应逐渐明显,豫麦49和太空6号分别表现为N3N2N1和N2N3N1。豫麦49第九小穗第4~6朵小花发育进程对施氮量响应差异显著,且分化程度随施氮水平的提高而增加;太空6号第3~6朵小花进程对施氮量响应差异显著,其中第3朵小花在发育进程前期N2处理快于N1、N3处理,中期和后期N2、N3处理快于N1处理,第4~6朵小花分化程度则一直表现为N2N3N1。不同施氮处理间总小穗数、不孕小穗数、小穗结实率、产量、穗粒数等指标差异亦显著,且品种之间对施氮反应存在差异,其中豫麦49的总小穗数、小穗结实率、产量、穗粒数呈N3N2N1,而太空6号呈N2N3N1;豫麦49小穗结实率呈N3N2N1,而太空6号呈N2N3N1。由此可见,施氮量对小麦产量的影响与其对小穗中部小花发育、每穗总小穗数、不孕小穗数和单穗结实率的影响相一致。  相似文献   

8.
The critical period for yield determination in barley (Hordeum vulgare L.) is situated in the pre-heading phases. During the latest part of the critical period one of the most important yield components (i.e. the number of grains per spike) is set in two- and six-rowed barley. In wheat, much is known about the role of the spike in assimilate acquisition for the establishment of grains per spike, but not in barley. This paper evaluates how biomass partitioning between vegetative and reproductive organs impacts floret development and primordia survival in response to radiation during different periods in the crop cycle, in barley lines. Field experiments were carried out using two- and six-rowed near isogenic barley lines differing only in spike type. Shading treatments were applied at different periods during the crop cycle (from 60 to 15 days before and after heading) reducing the intercepted radiation (ca. 70%). Dynamics of floret primordia initiation and mortality and of floret development for different spikelet positions along the spike were measured, and biomass partitioning between vegetative and reproductive structures was calculated.

Pre-heading shading reduced fertile florets per spike (P < 0.001). In the immediate pre-heading treatment, distal floret primordia could not reach a fertile floret stage due to a low rate of floral development.

The amount of assimilates partitioned to the spike at heading affected the number of fertile florets per spike in both barley types. However, when spike biomass at heading was corrected by nitrogen concentration, the fitness of the relationship did not improve in relation to the first one. In relative terms, radiation restrictions during the immediate pre-heading phase increased the amount of biomass partitioned to the growing spike.  相似文献   


9.
为了明确种植密度对冬小麦结实特性和产量的影响，于2020-2021年以大穗型品种衡观35和多穗型品种济麦22为试验材料，设置4个种植密度水平，分别为每公顷基本苗180万（D180）、300万（D300）、420万（D420）和540万（D540）株，比较分析了不同种植密度下冬小麦小花结实、籽粒空间分布特征和产量的差异。结果表明，随着种植密度的降低，衡观35主茎穗上部和I分蘖穗下部、济麦22主茎和I分蘖穗中上部小穗位的结实粒数呈增加的趋势。降低种植密度促进了两个品种穗中部小穗位弱势小花、上部和下部小穗位强势小花的结实。衡观35主茎穗中上部和I分蘖穗中部小穗位的结实粒数均高于济麦22。开花期穗干重与可孕小花数呈显著正相关。低种植密度处理下开花期穗干重的增加为其获得较高的穗粒数奠定了良好的物质基础。种植密度对千粒重影响不显著，但显著降低了衡观35的穗数。由于产量构成三要素的协调作用，两个品种均在D300处理下获得了最高产量，但与其余种植密度处理间差异均不显著。综合来看，在保证穗数的前提下，适当降低种植密度会促进冬小麦主茎和分蘖穗结实，进而增加穗粒数和产量，可节约生产成本，有利于冬小麦绿色高产高效生产。  相似文献   

10.
Abstract

The number of grains per spikelet and the number of spikelets per spike are important factors that influence grain yield in wheat. Three wheat genotypes in four foreign groups (OA, OC, OH and OJ) differing in spike type and Japanese cultivars (cvs) were grown under various combinations of seeding densities and fertilization levels. In all groups, the spikelet number per spike and the spike length at maturity were highest at low seeding densities and high levels of fertilization. The OA group (Nepal) and Haruyutaka (Japanese cv) gave a weak response in spikelet number per spike, while the OJ group (Xinjiang Uygur, China) gave a weak response in spike length. The OC group (except for T6), the OH group (Tibet) and Japanese cvs (except for Haruyutaka) responded to treatments in both spikelet number per spike and spike length. The T6 genotype in the OC group (Nepal) gave a weak response in both spikelet number per spike and spike length. Although the OA group had the longest spikes and the OJ group had the shortest spikes, there was no difference in the duration of spike elongation between the OA group and the OJ group. Spike length appeared to be determined mainly by the rate of spike elongation and was not restricted by the dry weight of the spike during the growth phase of the spike.  相似文献   

11.
不同密度下玉米穗茎生长与雌穗分化的关系   总被引：8，自引：3，他引：5  
以3个玉米杂交种为试验材料,在不同种植密度下研究玉米植株穗分化过程中雌幼穗和茎秆的生长动态与每穗小花数的关系。结果表明:穗分化与茎秆等各器官具有同伸关系。雌穗分化前期,幼穗生长缓慢,茎秆开始加速生长;性器官形成期幼穗生长加速,穗重、茎重与每穗小花分化数呈正相关,穗重增长率与茎重增长率之比也与每穗小花分化数呈正相关,且都随密度增大而减少。  相似文献   

12.
【目的】探究水氮管理措施对不同氮效率水稻根系构型、氮素吸收利用和产量形成的影响,以及根系性状特征与氮素吸收利用和产量关系。【方法】试验采用三因素裂裂区设计,主区为2个不同氮效率水稻品种德香4103(氮高效型)和宜香3724(氮低效型),裂区设置"常规灌溉"和"控制性交替灌溉"2种水分管理方式,裂裂区为SPAD指导施肥、优化施肥以及农民习惯施肥3种施氮模式,运用岭回归分析方法探究根系构型与氮素吸收利用和产量的关系。【结果】水稻抽穗期根系性状、产量、每穗粒数、千粒重及总颖花量均存在显著的基因型差异。氮高效品种德香4103每穗粒数多,群体库容量大,产量较氮低效品种宜香3724高0.24%~11.31%;控制性交替灌溉有利于水稻千粒重的增长,常规灌溉则对水稻有效穗数、每穗粒数及群体颖花量提高更为有利;SPAD指导施肥和优化施肥处理能够提高水稻有效穗数和每穗粒数,扩大群体颖花量以保证其对农民习惯施肥的产量优势;由于水氮互作效应的存在,控制性交替灌溉下施氮处理与空白处理水稻千粒重的差距比常规灌溉的大幅降低,使得控制性交替灌溉下施用氮肥的增产效果更佳。德香4103的氮肥生理利用率较宜香3724平均高8.69%,常规灌溉下水稻氮积累量较高,控制性交替灌溉下氮肥回收率、农学利用率、生理利用率均较优;与农民习惯施肥处理相比,SPAD指导施肥与优化施肥模式更有利于水稻氮素吸收利用效率的提高。拔节期、抽穗期和成熟期水稻根系构型与产量岭回归方程的决定系数范围为0.4198~0.9028,其中,抽穗期根系性状与产量关系最为密切,氮高效和氮低效品种的决定系数均超过0.9。在拔节期,水稻细分枝根长对产量影响最大;在抽穗期,氮高效和氮低效品种存在差异,前者是粗分枝根长,后者是细分枝根表面积对产量影响最大;在成熟期,不定根长与产量关系最为密切。水稻抽穗期根系构型对氮积累量变化的解释程度较高,岭回归方程决定系数均接近0.7。就水氮管理措施而言,氮高效和氮低效水稻均应采用常规灌溉配套SPAD指导施肥或控制性交替灌溉结合优化施肥来实现产量的提高。【结论】水稻抽穗期根系构型与产量、氮积累量关系密切,采用合理的水氮管理措施能够实现水稻产量和氮素吸收利用效率的同步提高。  相似文献   

13.
冬、春性小麦品种早播（9月30日）、适播（10月30日）的总小花数、可孕小花数及结实粒数均极显著高于晚播（3月2日）。晚播对春性品种小花分化发育与结实的不利影响小于冬性品种。穗粒数的多少与可孕小花数及其结实率密切相关,而与总小花数及其结实率无明显联系;同时大穗多粒基因型也以较高的可孕小花结实率为生理基础。孕穗期小花数均与叶面积、叶片重、叶鞘重和总干物重呈显著或极显著正相关,而与茎高的相关不显著。此外,冬、春性品种的结实粒数均与成熟期茎叶重、总单茎重、结实小穗数、穗长和穗粒重之间呈极显著正相关,表明良好、协调的营养生长与生殖生长的关系是改善小花发育质量、提高穗粒数的根本保证。  相似文献   

14.
为探究C、N供给时期和供给水平对小麦籽粒建成及蛋白质含量的影响,以冬小麦品种济麦22为材料,采用离体穗培养的方法,设置了三个蔗糖浓度(C1:20 g·L-1;C2:40 g·L-1;C3:80 g·L-1)和四个硝酸铵水平(N1:0.57g·L-1;N2:1.14g·L-1;N3:2.28 g·L-1;N4:4.56g...  相似文献   

15.
《Field Crops Research》1996,48(1):47-55
Phenological development, shoot dry matter production, grain yield and yield components of rice were examined in relation to drought occurring at various stages of growth. Rice was sown three or four times at three-week intervals in the field in each of two years, and performance in three stress trials was compared with that in corresponding irrigation trials, with the aim of quantifying the response of the crop to water stress of 23–34 days' duration developing at different growth stages. When drought occurred during vegetative stages, it had only a small effect on subsequent development and grain yield. The reduction in yield of up to 30% was due to reduced panicle number per unit area in one trial, and reduced number of spikelets per panicle in another. The effect of water stress on yield was most severe when drought occurred during panicle development. Anthesis was delayed, the number of spikelets per panicle was reduced to 60% of the irrigated control and the percentage of filled grains decreased in one crop to zero. This decrease in grain yield to less than 20% of the control was associated with low dry matter production during the drought period as well as during the recovery period following the drought. When drought occurred during grain filling, the percentage of filled grains decreased to 40% and individual grain mass decreased by 20%. The effect of stress was also related to its severity during grain filling. Stress at this stage hastened maturity. The results suggest that variation in yield components due to water availability is related to the variation in dry matter production at particular growth stages. Results of a supplementary shading experiment show that the relationship between spikelet number per panicle or single grain mass and crop growth rate was the same, whether growth rate was varied by availability of soil water or solar radiation. Filled-grain percentage, however, was more sensitive to drought stress than shading when comparison was made at a similar crop growth rate.  相似文献   

16.
基于高产示范方的机插水稻群体特征研究   总被引：10，自引：2，他引：8  
 考查了机插常规粳稻超高产群体产量构成、干物质积累以及氮素积累等群体特征。2008年对江苏武进区邹区（品种为武香粳9号）、漕桥和前黄镇（品种均为武运粳7号）等3个百亩连片超高产示范方,2009年对江苏省如东县(品种为宁粳3号)的百亩连片超高产示范方进行了调查。结果表明,机插稻产量与颖花量的相关达极显著,要达到10.5 t/hm2以上的产量,每1m2颖花量需≥ 45 000;籽粒产量10.5 t/hm2以上高产机插水稻的花后干物质积累占籽粒产量的70%～80%;高产机插稻氮素积累的优势在有效分蘖临界叶龄期前和抽穗后两个阶段。足够的颖花量是机插粳稻高产群体的基本特征;保证后期氮素供应、发挥后期干物质积累优势、促进大穗的形成是提高机插水稻产量的主要技术途径。  相似文献   

17.
《Plant Production Science》2013,16(4):258-263
Abstract

The spike development in three spring wheat genotypes was studied under various cultural conditions. Two genotypes weakly responsive to cultural conditions in spikelet number per spike (T1 from Nepal and Haruyutaka from Japan) and one weakly responsive to cultural conditions in spike length (U6 from Xinjiang Uygur district of China) were grown under three cultural conditions with different seeding density and fertilization levels : 680 seeds m?2 without fertilizer (unfavorable), 340 seeds m?2 with common fertilizer (common) and 170 seeds m?1 with double fertilizer (favorable). The durations of the vegetative phase, spikelet phase and the spike elongation phase were scarcely influenced by these cultural conditions, although the leaf number was influenced. The development of spikelets seemed to be determined by several factors other than those affecting the developmental processes of the spike. In U6, the increase in shoot apex length during the floral initiation period under the favorable condition was accompanied with an increase in double ridge number and spikelet number per spike, but such a relationship was not observed in T1 and Haruyutaka. T1 and Haruyutaka had a higher rate of spikelet formation under the favorable condition than under the unfavorable condition, but U6 showed a rather lower rate of spikelet formation under the favorable condition. Thus, the effects of the cultural conditions on the spikelet number per spike differed with genotype. At the time of terminal spikelet formation, U6 tended to have a longer spike than T1 and Haruyutaka. However, since the rate of spike elongation was higher in T1 and Haruyutaka than in U6, the spike length at anthesis was shorter in U6.  相似文献   

18.
以常规粳稻品种云粳41为试验材料,采用两因素裂区设计,研究不同密度下水稻一次性施用控释肥和分次施用尿素对直播稻产量及其构成因素、群体光合物质生产的影响,并探讨了不同施肥方式对不同密度下直播稻的产量性状和产量之间的相关性。结果表明:(1)不同施肥方式下,密度相同时,分次施肥的处理比控释肥一次性基施的处理和不施肥对照增产,产量随着施氮量的增加而增加,分次施肥处理的产量显著高于控释肥一次性基施的处理;在相同氮肥条件下,直播稻产量随着直播密度的增加而降低,以基本苗2万/667 m~2的处理产量最高,6万/667 m~2的处理产量居中,10万/667 m~2的处理产量最低。(2)在施用控释肥的处理中,密度相同时,增加施氮量能够显著提高直播稻的有效穗数和每穗颖花数;施氮量相同时,单位面积有效穗数随密度的增加而提高,每穗颖花数刚好相反。单位面积颖花量和实际产量之间呈极显著正相关关系。在形成适宜穗数的基础上提高每穗颖花量,从而增加单位面积的颖花量是提高直播稻产量的主要途径。(3)当密度相同时,抽穗至成熟期总干物质积累量、群体生长率、群体叶面积和总颖花数都随着施氮量的增加而提高。本试验中,以精确定量栽培技术为核心的分次施肥A1RPQ4处理的群体结构优于其他处理,群体茎蘖消长动态最为平稳,抽穗期至成熟期的总干物质积累量、颖花/叶比和粒质量/叶比最大,产量最高,达到875.14 kg/667 m~2。  相似文献   

19.
《Plant Production Science》2013,16(3):203-210
Summary

Generally F1 hybrids from crosses between japonica and indica rice show variable degrees of sterility. Previous studies revealed that among the indica rice, the Aus type has sexual affinity with japonica cultivars giving higher fertility in F1 hybrids. Therefore, we made an effort to obtain higher grain yield by producing F1 hybrids between japonica and Aus-type indica. A field experiment was conducted to investigate the heterosis in these F1 hybrids for dry matter accumulation, spikelet fertility, yield and yield attributes, to find cross combinations with higher grain yield, and examined the relationships of grain yield with some agronomic characters. F1 hybrids flowered earlier than their parent cultivars. Heterosis for dry matter accumulation was positive at the panicle initiation stage, at heading and at maturity. The average heterosis for number of panicles, grain and straw yield per plant, number of spikelets per panicle and 1000-grain weight was positive. A few F1 hybrids showed positive heterosis for number of filled grains per panicle, spikelet fertility and harvest index; but the average heterosis for these traits was negative. Among the yield components, a higher number of panicles per plant and higher number of spikelet per panicle contributed to higher grain yield in F1 hybrids. A significant and positive relationship existed between spikelet fertility and grain yield per plant. The higher grain yield was attributed to higher dry matter production rather than higher harvest index in F1 hybrids, although low spikelet fertility limited yield potential in some F1 hybrids.  相似文献   

20.
Under terminal drought conditions, cereal varieties with limited tillering have been suggested to be advantageous, because they have fewer nonproductive tillers, thereby limiting water consumption prior to anthesis. In this study, four field trials were conducted over two growing seasons in southern Spain, under rainfed and irrigated conditions. Twenty-five genotypes were studied to evaluate the contribution of the main stem (MS) and tillers to grain yield and its components. Significant differences were found among genotypes for these contributions under non-stressed environments, but these differences were not significant under water-stress conditions. The contribution of the MS to plant grain yield was higher than that of tillers (68% vs. 32%) and was stable between years in irrigated trials. However, in the rainfed trials, MS contributed differently depending on year-to-year climate variations. Thus, under favorable weather conditions the contribution of MS to grain yield was higher than in the unfavorable year (85% vs. 59%). In irrigated environments, MS and tiller grain yield depended on the number of grains per spike, spikelets per spike, and thousand kernel weight (TKW). Under water-limited conditions, MS yield depended on the number of grains per spike and grains per spikelet, whereas the number of spikelets and TKW had less influence on MS grain yield. Furthermore, under water-stress conditions, high tillering genotypes showed yield levels similar to the genotypes with restricted tillering. Additionally, there was no significant evidence of a positive or negative effect of maximum tiller number on grain yield under rainfed conditions.  相似文献   

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