Super High Yield Research Articles

Plant-type Characteristics in Populations with Different Yield of Yongyou 12

Using indica-japonica super rice Yongyou 12, we compared the plant-type characteristics among three types of populations(high yield: 10.5–12.0 t ha–1; higher yield: 12.0–13.5 t ha–1; super-high yield: 13.5 t ha–1). The main results indicated that in super-high yield population, the mean values of panicle length, total grains per spike, number of the primary and secondary rachises were 21.56, 356.34, 20.46, and 73.98, respectively, being higher than those in the high and higher yield populations. However, the seed-setting rate in the primary and secondary rachises showed slight reduction. Super-high yield population had longer length, larger width and higher rolling rate, smaller leaf basic angle and dropping angle, more green leaves after heading for the top-most three leaves in comparison with the other two populations. Compared with the other two populations, super-high yield population had higher plant height, longer length of top three internodes, higher ratio of sum of panicle and neck internode to plant height 39.84% and ratio of neck internode to stalk length 37.75%. The decreased length of basal three internodes, increased culm diameter, culm wall thickness and dry weight of culm and sheath made higher anti-broken strength and lower lodging index in super-high yield population.

水稻超高产育种的研究

水稻是世界上最重要的粮食作物之一，是世界近一半人口主要的粮食作物，是我国60％以上人口的主食，我国稻米消费量占全部粮食消费量的40%左右。目前，我国水稻需求约在1850~1900亿kg左右，产需缺口仍在100~150亿kg左右。进一步提高水稻单产是解决世界粮食安全问题的关键。本文概述了超级稻的由来、国内外研究动态和趋势、水稻超高产育种的分子生物学基础，并对水稻超高产育种的未来提出展望。Rice is the most important food crop in the world and feeds over half of the global population. It is the staple food for more than 60% of the population and the rice consumption accounts for 40% of the all food consumption in China. At present, the demand of rice is 185~190 billion kilograms of China and the countless gap is still in 10~15 billion kilograms. The key to solve the problem of the world food security is increasing the rice yield. This article summarizes the origin, domestic and foreign research dynamic and trend of super rice and the molecular basis of super high yield breeding research, and proposes the outlook for the future of rice breeding programs.

Effects of cultivation patterns on winter wheat root growth parameters and grain yield

Grain yields of winter wheat are greatly affected by different cultivation patterns through regulating root growth and development. In this study, we established four cultivation patterns, i.e. farmers’ traditional cultivation pattern (T1), optimized T1 cultivation pattern (T2), super high yield cultivation pattern (T3) and optimized T3 cultivation pattern (T4). The variations of wheat root growth parameters were analyzed in two growth years (2008–2009 and 2009–2010). The results indicated that there were significant differences in yield factors among four patterns. Temporal variations of total root dry weight (TRDW), total root length (TRL) and average root diameter (ARD) in four patterns exhibited a single peak curve. The maximum of TRDW and TRL in T1 appeared at the heading stage, whereas those in T2, T3 and T4 were postponed to anthesis. The peak appearance time (te) and the maximum growth rate (tm) of TRDW and TRL in T2, T3 and T4 were retarded. The maximum values (wmax), average growth rate (c¯) and maximum growth rage (cm) of TRDW, TRL and ARD in T2, T3 and T4 were significantly higher than those in T1. In comparison with T1, the mean values of RDWD and RLD in T2 in upper soil layers (0–20cm) reduced remarkably. Similarly, the mean values of RDWD and RLD in T4 were also markedly lower than those in T3. In the middle and lower soil layers (40–100cm), however, the mean values of RDWD and RLD in T2 were significantly higher than those in T1, and these parameters in T4 had also significant difference with T3. In the 20–100cm soil layers, the gray correlation coefficients among grain yield, RDWD, RLD and ARD in T2 were higher than T1. Above 60cm soil layers, these coefficients in T3 were higher than in T4. In deep soil layers (60–100cm), however, these coefficients in T3 were lower in T4. These results suggested that optimized cultivation patterns may enhance wheat grain yield by changing the root distribution among soil layers, prolonging the root growth duration, increasing root growth rate and enhancing the absorption ability to water and nutrition in deep soil layers.

Glass-forming ability, fragility parameter, and mechanical properties of Co–Ir–Ta–B amorphous alloys

The effect of partial substitution of Co by Ir in Co57−x IrxTa8B35 (at.%, x = 0, 5, 10, and 15) alloys on glass-forming ability (GFA), fragility parameter m, and mechanical properties was investigated. It was found that the glass-forming ability reflected by critical diameter for glass formation is in good agreement with the width of supercooled region (ΔTx). The Co47Ir10Ta8B35 BMG exhibits the best GFA yielding the formation of an amorphous rod with a diameter of 5 mm, along with the largest ΔTx value of 64 K. The Ir-bearing Co47Ir10Ta8B35 BMG presents a lower fragility parameter m than Co57Ta8B35 BMG, which indicates better thermal stability and GFA. In addition, the Co47Ir10Ta8B35 BMG shows super-high yield strength of ∼5200 MPa and ultimate compressive strength of ∼5600 MPa as well as significant plasticity of ∼1.2%. The combination of good GFA, large ΔTx and excellent mechanical properties for the new Co–Ir–Ta–B BMG is significant for scientific research and industrial application.

Effect of nutrient application on dry matter accumulation and translocation of early rice

Plot experiments were set up with rice cultivar Xiangzaoxian45 in Yiyang and Xiangyin to investigate the effects of different nutrient application on dry matter accumulation and distribution in early rice.Six treatments were used in each experiment including T1(fertilization application without nitrogen),T2(conventional fertilization application used by farmers),T3(fertilization application for high yield and high efficiency),T4(fertilization application for super high yield),T5(fertilization application for super high yield and high efficiency A) and T6(fertilization application for super high yield and high efficiency B).The results showed that dry matter accumulation after heading stage in Yiyang and Xiangyin with T3 increased by 43.55% and 18.85%,respectively and the corresponding yield of early rice increased by 4.20% and 4.80%,respectively,compared to T2 under the condition of saving 20% nitrogen fertilizer.In the experiment conducted in Yiyang,dry matter accumulation after heading stage and yield of early rice with T5 increased by 80.85% and 16.60% respectively,with T6 increased by 94.00% and 18.75%,respectively,compared to those with T2;and in Xiangyin,dry matter accumulation after heading stage and yield of early rice with T5 increased by 23.64% and 10.10%,respectively,with T6 increased by 22.91% and 6.75% respectively,compared to those with T2.There was an extremely significant correlation between yield and dry matter accumulation after heading stage at different soil fertility levels.Therefore it is an important way to increase the accumulation of dry matter after heading stage for improving the yield of early rice.

Distribution, Yield Structure, and Key Cultural Techniques of Maize Super- high Yield Plots in Recent Years

Maize high-yield potential and small-area super-high yield researches were conducted in different areas in 2006-2010.The geographical distribution,yield components,and key cultivation techniques of 159 maize super-high yield plots with yield higher than 15 000 kg ha 1 were analyzed.Most high-yield plots were distributed in high latitude(40°-43°N) and high elevation regions(1000-1500 m) with abundant sunlight and high temperature in daytime and low temperature during night.These condi-tions were primary factors for super-high yield of maize.The cultivars with super-high yields had the average yield of 16 692 kg ha 1 with 88 950 ears ha 1,541 kernels per ear,1000-kernel weight of 360.0 g,and ear weight of 191.8 g.According to the result of path analysis,the ear and kernel numbers were significantly correlated with kernel yield.The key techniques for maize high-yielding cultivation included selection of cultivars with tolerance to high density,reasonable dense planting,abundant sup-plies of water and fertilizer,proper filed management,and film mulching.

Effect of Ordered Transplanting and Optimized Broadcasting on Super High Yield and Photosynthetic Productivity and Exploration of Rice Super High Yield Model

Rice seedling broadcasting is a technique of light and simple cultivation method in China and the stable super high yield from using the method relies on the ordered plantation of rice.Three planting methods including ordered transplanting(OT),optimized broadcasting(OB) and cast transplanting(CT) using dry-raising seedlings in plastic plates were compared with mechanical transplanting(MT) to investigate the photosynthetic productivity and matter accumulation characteristics during the formation of super high yield in respect of seedling establishment,tillering,LAI,grain-leaf ratio,photosynthetic potential,matter production,accumulation and translocation in late stages.Using methods of ordered transplanting and optimized broadcasting rice seedlings had the better population quality with earlier seedling establishment at the beginning,and their LAI,leaf area duration,grain-leaf ratio,matter production,accumulation in each growing stage,and net photosynthetic rate and matter translocation in later growing stages were all significantly or very significantly superior to those of cast transplanting.Moreover,in late growing stages,they showed comparatively better population light transmittance and ventilation,slower senescence,and higher matter production and lodging resistance as well.The transplanting hill number for of 3-and 2-hole closely gathered plates were 30–60 percent less than that for single-hole ones,which improved transplanting speed.Although 3-hole seedlings had earlier seedling establishment in early growing stage,2-hole seedlings kept higher matter production and lodging resistance in middle and late growing stages.Eventually,two hole seedings had higher yield than 3-hole seedlings and 1-hole seedlings.With their higher population starting point,earlier seedling establishment,proper matter accumulation in early growing stage as well as higher matter production,accumulation and translocation ability in later growing stages,ordered transplanting and optimized broadcasting methods were capable of leading to the stable super high yielding cultivation of super rice.Two-hole plate transplanting seedlings showed better matter production and obvious growth superiority during the whole growth stage,and 3-hole one also showed growth superiority in some aspects,which could lead us to the conclusion that 2-and 3-hole plate seedlings ordered transplanting are new-typed cultivation patterns of super high yielding in super rice.

Effects of Nitrogen Application on Accumulation and Distribution of Nitrogen， Phosphorus， and Potassium of Summer Maize under Super-high Yield Conditions

Establishing a high quality population is an important prerequisite to achieve high grain yield.Nitrogen(N) application is one of the most important practices in maize(Zea mays L.) production and plays a critical role in regulating population quality.To explore the effects of N application on accumulation and distribution of N,phosphorus(P),and potassium(K) of summer maize under the conditions of super-high yield(≥13 500 kg ha-1),we planted two maize cultivars(Suyu 20 and Xundan 20),wtih different N application levels across three years,and the highest grain yield reached to14 753 kg ha-1.The results showed that in the growth process,N,P,K accumulation increased gradually in the plants and grains of Suyu 20 and Xundan 20,and showed a curvilinear change in leaves,stems and sheatheswith a peak value at trumpeting stage and anthesis stage,respectively.The increasing of N accumulation and transfer rate in leaves at filling stage promoted the N and P accumulation of grain at mature stage,leading to super-high yield groups.In Suyu 20,yield,grain production per kg N,N agronomy efficiency,N utilization efficiency,N,P,K content in leaves,stems and sheathes were the highest at 450 kg ha-1which were 14 753 kg ha-1,44.0 kg,19.24%,38.63%,335.4 kg ha-1,178.2 kg ha-1,230.7 kg ha-1,respectively.But N,P,K accumulation and yield decreased when N application level was too high or too low.According to the regression equations between N application rate and yield of two varieties,for Xundan 20 the optimal N amount was 457.0 kg ha-1,the range of optimum N was 418.5 495.4 kg ha-1,418.3 495.7 kg ha-1 for super-high yield groups;and for Xundan 20,the optimal N was 452.7 kg ha-1,the range of optimum N was 410.8 494.6 kg ha-1

Characteristics of Water Use and Dry Matter Accumulation and Distribution inDifferent High-yielding Wheat Cultivars under Supplemental Irrigation Basedon Soil Moisture

Water shortage is a serious problem threatening sustainable agricultural development in the North China Plain, where winter wheat(Triticum aestivum L.) is the largest water-consuming crop. The objective of this study was to guide wheat production in this area by selecting high water efficient cultivar and improving irrigation regime. In a two-year field experiment from autumn of 2007 to summer of 2009, irrigation quantum was controlled based on testing soil moisture(SM) in 0–140 cm depth,which was designed in low(SM of 65% at jointing and 55%–60% at anthesis stage), medium(SM of 75% at jointing and65%–70% at anthesis stage), and high(SM of 75% at jointing and 75% at anthesis stage) levels. Water use efficiency(WUE), dry matter accumulation and distribution in wheat plant, and grain yield were tested and compared among 14 commercial cultivars.Based on grain yield and WUE, the 14 cultivars were clustered into three groups, namely, super-high yield and high WUE group(I), super-high yield and medium WUE group(II), and high yield and low WUE group(III). One representative cultivar was selected from each group to compare the amount and proportion of water consumption during sowing–jointing, jointing–anthesis,and anthesis–maturity periods. Shannong 15 from group I had significantly lower water consumption from sowing to jointing than Jimai 22 from group II and Yannong 21 from group III, and significantly higher water consumption from jointing to anthesis.However, water consumption amount and proportion had no significant differences among the three cultivars from anthesis to maturity. Under medium SM condition, soil water consumption in Shannong 15 was significantly higher than that in Jimai 22 and Yannong 21, but such advantage in Shannong 15 disappeared under high SM condition. Under medium and high SM conditions,translocation amount and ratio of dry matter accumulated before anthesis and its contribution to grain were significantly higher in Shannong 15 than in Jimai 22 and Yannong 21. Among the three cultivars, harvest index was the highest in Shannong 15, the medium in Jimai 22, and the lowest in Yannong 21.

Post-Anthesis Photosynthetic Assimilation and the Changes of Carbon and Nitrogen in Different Varieties of Spring Maize

Dry matters production after anthesis is very important for maize yield.To further clear its role in super high yield con-dition(high density with ample water and fertilizer supply),we compared yield components in three cultivated varieties,including Denghai661(DH661),Zhongdan 909(ZD909) and 970.According to the theory of yield performance,the post-anthesis yield performance parameters were analyzed.The changes of net photosynthetic rate,the contents of chlorophyll,soluble sugar,starch,total C and N were measured in the ear leaf.The results showed that there were significant differences in the yield among three varieties.Varieties with higher yield(DH661 and ZD909) had higher kernel weight per ear,while DH661 had more grains per ear(466.7) and ZD909 had higher 1000-kernel weight(392.7 g).The post-anthesis dry matter production and its partitive ratios in grains were both higher in the two varieties with higher yield.Yield performance analysis showed that the mean leaf area index(mLAI) and leaf area duration(LAD) were significantly and positively correlated with post-anthesis dry matter production and yield.The chlorophyll,total carbon and total nitrogen content decreased slowly and C/N ratio increased slowly in the two varieties with higher yield.The net photosynthetic rate(Pn) was relatively higher in the ear leaves in the whole grain filling stage.The photosynthate not only supplied to kernels but also stored as starch in leaves at the early phase of grain filling.Only when Pn de-clined at late phase of grain filling the accumulated starch began to degrade for the kernel filling.These results indicated that the balance between carbon and nitrogen metabolism,and slowing down the photosynthate decrease in ear leaf are responsible for maintaining higher mLAI and LAD,resulting in higher yield.

Characteristics of Super-high Yield Population in Yongyou Series of Hybrid Rice

A field experiment was conducted using the representative indica-japonica hybrid rice Yongyou 11, Yongyou 12,Yongyou 13, Yongyou 15, and Yongyou 17 to compare between super-high and high yield populations formed by the regulation of cultivation measures. The results showed that the spikelets of the super-high yield population was higher than that of high yield population, with difference very significant, but the seed-setting rate and 1000-grain weight of the super-high yield population were lower than those of high yield population. The average spikelets per panicle was significantly higher than that of high yield population, meanwhile the number of the primary and secondary branches and total grains were higher than those of high yield population, showing a significant or very significant difference. The dry matter accumulation of the super-high yield population was a little lower than that of the high yield population at the jointing stage, but higher at heading and maturity stages. From the critical leaf-age for productive tillers to jointing stage, the super-high yield population had a steady growth with less ineffective tillers and lower peak number of tillers after jointing stage, the super-high yield population had a steady decline in number of tillers and had higher productive tillers rate, leaf area index, photosynthetic potential and dry matter accumulation, compared with the high yield population. The super-high yield population had higher culm diameter and culm wall thickness in the basal first, second and third internodes, as well as higher bender moment and anti-broken strength, and lower lodging index than the high yield population.

Enhancement of plastic deformation in FeCoNbB bulk metallic glass with superhigh strength

The effect of B on the glass-forming ability of FeCoNbB alloys was investigated. Bulk metallic glasses with critical diameters up to 3 mm and superhigh yield strength of 4860 MPa were synthesized in (Fe0.5Co0.5)71−xNb6B23+x (x = 0, 2, 3, 4 and 5) alloy system. Besides, Cu was added to the Fe33.5Co33.5Nb6B27 alloy with the aim at enhancing mechanical properties, and it was found that proper amount of Cu addition could effectively improve the compressive plasticity from 1.4% to 3.7% without obvious strength decreasing. The enhancement of plasticity is ascribed to the formation of clusters in Cu-contained FeCoNbB bulk metallic glasses.

Yield Potential of High-Yield Rice Varieties in the Tohoku Region of Japan

To achieve a super high brown rice yield exceeding 10 t ha -1 in the Tohoku region (relatively cold), a two-year field experiment was conducted. The yield components, morphological traits and dry matter production among the Japonica type high-yield variety “Fukuhibiki,” indica type high-yield variety “Takanari,” large grain type high-yield variety “Bekoaoba” and two conventional Japonica type varieties were compared. Although the traits relating to high yield varied greatly, the three high-yield varieties all showed a large sink size, heavy rice yield at 30 days after heading (30 DAH) and a high harvest index. The effects of nitrogen application and planting density on the morphological traits, dry matter production and yield in the large grain type variety Bekoaoba were investigated. Although high nitrogen application (HN) increased the brown rice yield from 8 to 9.5 t ha -1 , regulation of the timing of topdressing and/or planting density under HN could not increase the brown rice yield beyond 10 t ha -1 . Strategies to achieve a super high-yield rice in the Tohoku region were discussed.

Analysis on yield components of elite maize variety Xundan 20 with super high yield potential

Xundan 20 was released by Hebi Academy of Agricultural Sciences in 2003. The stability, adaptation and yield components of Xundan 20 were analyzed using data from Huanghuaihai national tests in 2001 and 2002 and from high yield trials from 2005 to 2010. The results showed that variety Xundan 20 yielded most and increased significantly than Nongda 108 (Control, CK) in Huanghuaihai national tests in 2001 and 2002. The yield potential of variety Xundan 20 was so high that it created a series of new record in China. The yield of variety Xundan 20 of 15971.7 kg/ha created the highest record of summer maize in China in 2007, with the yield components of 77835 plant/ha, 205.2 g/ear, 596.16 grains/ear and 350 g per 1000-grain. The variation coefficient of variety Xundan 20 was small and its yield was stable. It is based on excellent comprehensive resistance of variety Xundan 20 to main disasters in Huanghuaihai region such as diseases, pests and lodging. Key words: Maize, Xundan 20, stability, wide adaptability, yield components, super high-yield.

Progress on genetics of rice grain shape trait and its related gene mapping and cloning

Increase of crop production is the primary goal of crop breeding. Rice grain shape is a quantitative trait that is directly related to yield traits and has a close relationship with quality traits. The evaluation of grain shape is mainly grain length, grain width, grain thickness, length/width, and length/thickness. In recent years, the quantitative genetic research on rice grain shape has made a significant progress and a number of important genes associated with rice grain shape have been cloned. This paper reviews the classic genetic analysis on rice grain traits, QTL mapping, grain shape gene cloning and functional analysis, and their application in rice breeding for super high yield.

Effects of Nitrogen Application and Planting Density on Morphological Traits, Dry Matter Production and Yield of Large Grain Type Rice Variety Bekoaoba and Strategies for Super High-Yielding Rice in the Tohoku Region of Japan

To achieve super high yield of more than 10 t ha-1 in the Tohoku region (colder area of Japan), we conducted a two-year field experiment using a large grain type high-yielding rice variety Bekoaoba. Although high nitrogen application (HN) increased the top dry weight at the full heading stage only slightly, it increased the sink size (single grain weight x the number of spikelets per area), leaf area index and nitrogen content at the full heading stage and accordingly the dry matter production during the ripening period. As a result, the gross hulled rice yield was higher under HN than under standard nitrogen application (SN). Under HN, early topdressing increased not only the number of differentiated spikelets but also the number of degenerated spikelets. As a result, the sink size and gross hulled rice yield of the plants were not changed by the early topdressing. Under HN, the higher planting density increased the number of panicles per area but decreased the number of spikelets per panicle. As a result, the sink size and gross hulled rice yield were not changed with the planting density. In conclusion, HN produced the gross hulled rice yield of more than 9 t ha-1. However, the gross hulled rice yield could not be increased more than 10 t ha-1 by regulation of the timing of topdressing and /or the planting density. We discussed the strategies for super high-yielding rice in the Tohoku region.

Clustered QTL for source leaf size and yield traits in rice (Oryza sativa L.)

Improvement of plant type plays an important role in super-high yield breeding in rice (Oryza sativa L.). In the present study, a set of backcross recombinant inbred lines derived from a cross of 9311 and Zhenshan97, both elite indica hybrid parents, were developed to identify quantitative trait loci (QTL) for flag leaf size, panicle and yield traits. Forty-seven QTL for 14 traits were detected in common in the two environmental trials, of which nine genomic regions contained clustered QTL affecting plant type traits and yield traits. Four co-localized QTL on chromosomes 1, 6, 7 and 8 involving QTL for flag leaf size (flag leaf length, width and area) contained the QTL for yield traits such as panicle weight (PW) and secondary branch number (SBN), and in all cases alleles from 9311 increased source leaf size and were associated with increased sink size and yield (SBN and PW). Using a subset of overlapping substitution lines for the QTL region on chromosome 1, the QTL were validated and narrowed into a 990 kbp interval (RM3746–RM10435) with pleiotropic effects on flag leaf size, PW, SBN and spikelet number per panicle. These QTL clusters with large effects on source leaf size and yield-related traits provide good targets for marker-assisted breeding for plant type improvement and high-yield potential in rice.

Effects of different nitrogen management models on agronomic characters and nitrogen fertilizer utilization efficiency of early rice

Using on Luliangyou996 as provided material, choosing middling fertility field for experiment, setting up 5 treatment levels, which are: fertilizer model without N, farmers-familiar fertilizer model(150 kg/hm2,according to N), the optimal-nutrient management model(120 kg/hm2), super-high-yield and high-efficient model(150 kg/hm2), super- high-yield model(180 kg/hm2), various forms of nitrogen nutrition on agronomic characters and nitrogen use efficiency on early rice were studied. The results showed that: super high yield and high efficient model could promote root growth, increase chlorophyll content of leaves, enhance the formation and accumulation of photosynthetic products, enhance the nutrient absorptivity of rice, compared to the farmers familiar fertilizer models which are treated at the same nitrogen fertilization level, its yield increased 5.61%, nitrogen use efficiency increased by 9.06 percentage points, relativly increased 34.49%. It showed that super high yield and high efficient model can improve the yield of rice,can be expected to effectively improve the nitrogen utilization, reduce nitrogen losses, decrease the pollution caused by fertilizer application.

Photosynthetic Characteristics of a Super High Yield Cultivar of Winter Wheat During Late Growth Period

The mechanism of high yield of winter wheat in the field at late growth period was investigated by measuring the photosynthetic characteristics of photosystem II (PSII) and xanthophylls cycle, which could provide physiological reference for breeding. Weimai 8 (W8), a super high yield cultivar, and Lumai 14 (L14), a control cultivar were object. The photosynthetic rate (Pn), parameters of chlorophyll fluorescence and chlorophyll content were measured. The Pn, maximum photochemical efficiency of PSII (Fv/Fm), quantum yield of PSII electron transport (ΦPSII), efficiency of excitation energy capture by open PSII reaction centers (Fv′/Fm′), and photochemical quenching coefficient (qP) were higher in Weimai 8 compared to that in Lumai 14, a commercial high yield cultivar. Furthermore, Weimai 8 showed a lower nonphotochemical quenching coefficient and a lower de-epoxidized ratio of the xanthophyll cycle pigments than of Lumai 14 at late growth period. At mature stage, chlorophyll content of different leaves decreased both in Weimai 8 and Lumai 14. Chlorophyll content in flag, second and third leaf from the top of plant decreased more in Lumai 14 than in Weimai 8. These results suggested that Weimai 8 had more antenna pigments to absorb light energy, and had higher photosynthetic capability and photochemical efficiency of PSII. The yield of Weimai 8 was also higher than that of Lumai 14.

Changes in chloroplast ultrastructure, fatty acid components of thylakoid membrane and chlorophyll a fluorescence transient in flag leaves of a super-high-yield hybrid rice and its parents during the reproductive stage

In plants, it is well established that chloroplast is one of the early targgeted organelles to breakdown during leaves senescing. Here we applied a newly developed super-high-yield hybrid rice ( Oryza sativa) LiangYouPeiJiu (LYPJ) and its parents lines to investigate changes in ultrastructure of chloroplasts, fatty acid composition of thylakoid membrane lipids and chlorophyll (Chl) a fluorescence transient in natural senescing leaves. We found that at full expansion of flag leaves in three lines, chloroplasts often showed oblong shapes with a typical membrane system of stroma and grana thylakoids, whereas their shapes had been changed from oblong to spherical during senescence. Our data showed that the initiation of senescence displayed accumulation of starch and an increase in the number and size of plastoglobuli with the damaged thylakoid membranes; subsequently, swollen thylakoid membranes in stroma and in grana with a significant increase in MDA content, and disorganization of thylakoid membrane system with significant changes in fatty acid composition of thylakoid membrane lipids were developed. Compared with its parents, the newly developed hybrid rice LYPJ had the highest capacity of carbohydrate transport from leaves (sources) to ears (sink), marked with the lowest accumulation of starch grains in the leaf chloroplasts, and the slowest senescing rate of chloroplast in overall leaf senescence process. Chl a fluorescence transients of three kinds of flag leaves were analyzed by so-called JIP-test. The results of analysis suggest that these findings inculding a high inherited activity of antioxidant enzymes and high photosynthetate transport to pretect chloroplast structure in the hybrid rice LYPJ have close relations to its super-high yield.