Hybrid Rice Liangyoupeijiu Research Articles

Influence of cultivation techniques on dry matter partitioning, nitrogen distribution pattern and yield of super hybrid rice Liangyoupeijiu

Liangyoupeijiu was grown under different crop cultivation techniques viz: conventional tillage and transplanting (CTTP), no tillage and transplanting (NTTP), conventional tillage and direct seeding (CTDS) and no- tillage and direct seeding (NTDS) during 2011 and 2012. Results showed that, CTTP had higher leaf dry weight than NTTP. Maximum leaf dry weight reduced in direct seeded than transplanted rice. Shoot dry weight reduced by 6% both in transplanted and direct seeded rice from heading to 12 days after heading (DAH) in both the years. No tillage and transplanting had higher export percentage of dry matter and transport percentage of dry matter among the cultivation techniques in both the years. At heading, leaf nitrogen concentration (%) and nitrogen uptake (g m-2) were higher in transplanted than direct seeded rice and significantly higher nitrogen uptake was observed under conventional tillage and transplanting in both the years. The physiological nitrogen use efficiency was higher in no-tillage than conventional tillage in both the years. Total nitrogen (kg ha-1) uptake was higher in conventional tillage than no tillage either in transplanted or in direct seeded rice and was higher under conventional tillage and transplanting among the cultivation techniques in both the years. Grain yield was closely associated with uptake of total nitrogen at heading. Although, direct seeded rice had more than 23% higher panicle number than transplanted rice but conventional tillage and transplanting produced higher grain yield due to higher uptake of nitrogen by grain at maturity and bigger sink size. Bangladesh Rice J. 26 (2): 51-62, 2022

Physiological characterization and thylakoid ultrastructure analysis in super high-yield hybrid rice leaves under drought stress

Rice serves for more than a third of the world's population. However, drought stress (DS) affects its growth and yield. In order to understand plant drought adaptability, we explored the physiological and thylakoid ultrastructural alteration in super high-yield hybrid rice Liangyoupeijiu (LYPJ) under DS. Results showed that DS altered the thylakoid ultrastructure; twisted and fractured stroma thylakoids and more starch granules in chloroplast of LYPJ were present. Also, DS lowered chlorophyll and carotenoid contents in LYPJ after 7 d. DS reduced the proportion of unsaturated fatty acids in thylakoid membranes and increased the content of linoleic and abscisic acids (ABA) and osmotic substances such as calcium and potassium in LYPJ. Based on these results, we concluded that although DS severely affected normal growth, plants employed various strategies, such as changing their membrane lipid fluidity, increasing endogenous ABA and osmotic substance contents and stabilizing the grana thylakoids, in order to adapt to drought stress.

Grain-filling pattern of super hybrid rice Liangyoupeijiu under direct seeding and transplanting condition

To evaluate the grain-filling pattern, Chinese first super hybrid rice, Liangyoupeijiu was grown under tillage and establishment methods at a spacing of 20 cm × 20 cm with one seedling hill-1 and at a seeding rate of 22.5 kg ha-1 in Changsha, Hunan Province, China in 2012. Our results showed that, superior grain weight in TP had always higher than DS up to 24 DAH but at 36 DAH, grain weight had similar in both TP and DS. Middle grain weight was higher in TP than DS up to 18DAH but it was higher in DS than TP at 24 – 36 DAH and at 36 DAH, grain weight of DS had significantly higher than TP. Inferior grain weight was higher in TP than DS up to 12 DAH but it was higher in DS than TP at 24 -36 DAH and at 36 DAH, grain weight of DS had significantly higher than TP. Grain-filling rate of superior grain had higher in TP than DS up to 18 DAH but it was higher in DS than TP at 30 DAH. In middle grain, it was higher in TP at 6DAH but in DS, it was higher at 30 DAH. In inferior grain, it was higher in TP at 36 DAH but in DS, it was higher at 30 DAH. The heavier grain was found in TP only in superior grain but DS had heavier grain both in middle and inferior grain. Grain-filling rate of superior grain was higher in TP than DS and it was similar in both TP and DS in middle grain. But in inferior grain, it was significantly higher in DS than TP. Transplanting method produced slightly higher grain yield due to higher sink size (more number of spikelet’s caused by longer panicle and more number of spikelet per cm of panicle) but it was statistically similar with DS. DOI: http://dx.doi.org/10.3329/ijarit.v4i1.20972 Int. J. Agril. Res. Innov. & Tech. 4 (1): 11-15, June, 2014

Yield and tillering response of super hybrid rice Liangyoupeijiu to tillage and establishment methods

Tillering is an important agronomic trait for rice grain production. To evaluate yield and tillering response, Liangyoupeijiu (super hybrid rice) was grown in Hunan, China during 2011–2012 under different methods of tillage (conventional and no-tillage system) and crop establishment methods (transplanting at a spacing of 20cm×20cm with one seedling per hill and direct seeding at a seeding rate of 22.5kgha−1). Our results revealed that, at maximum tillering (Max.) and at maturity (MA) stages, direct seeding (DS) resulted in 22% more tillers than transplanting (TP) irrespective of tillage system. Tiller mortality reached a peak between panicle initiation (PI) and booting (BT) stages, and was 16% higher under conventional tillage (CT) than under no-tillage (NT). Transplanting required 29% more time for the completion of tillering and less for DS. Tillering rate was 43% higher in DS than TP under either CT or NT. There was a positive correlation between panicle number per m2 and maximum tiller number per m2, but not panicle-bearing tiller rate. The panicle bearing tiller rate was higher under DS than TP and higher under NT than CT. Tiller dry weight gradually increased up to heading (HD) stage, and was 14% higher under TP than DS. Leaf area (cm2tiller−1) gradually increased from Max. to HD stage and then decreased by 34% in conventional tillage transplanting (CTTP) and 45% in no-tillage transplanting (NTTP) from 12DAH–24DAH (days after heading), but was similar (35%) under DS under either CT or NT. Grain yield was higher under CTTP owing to the larger sink size (heavier panicle, more spikelets in per cm length of panicle) than under DS.

Changes of Photosynthetic Membrane Function and Protein Complexes in Flag Leaves of Liangyoupeijiu during Leaf Senescence

The purpose of this study was to explore the content variation of thylakoid membrane protein complexes and its relationship with light absorption,transformation and transfer in flag leaves of high-yield hybrid rice Liangyoupeijiu during senescence.A rice cultivar,Liangyoupeijiu was grown in the field.Through chlorophyll a fluorescence transient,physiological and biochemical techniques,we studied the function of photosynthetic membrane.The content changes of thylakoid membrane protein complexes were also investigated by Blue-native polyacrylamide gel-electrophoresis(BN-PAGE).The results showed that chlorophyll content,photosynthesis and thylakoid membrane protein content of flag leaves rose and peaked at heading stage,then began to decline.It still maintained a high level at flowering and filling stages,and the significant decline appeared untill the stage of milky and wax ripeness.The stability of protein complexes(i.e.inverse degradation rate)during leaf senescence showed an order of LHCII PSIIcore PSIcore ATPase Cyt b6/f LHCI.Protein complexes and electron transport activity of PSI declined later but more quickly than those of PSII.The decreased chlorophyll a/b ratio could be explained by the relative enrichment of light-harvesting antenna to reaction center with leaf senescence.The stable LHCII kept the high level of absorbing energy in the late of flag leaf growth,which may play an important role in adjusting the energy distribution and dissipation during leaf senescence.

The effects of enhanced UV-B radiation on photosynthetic and biochemical activities in super-high-yield hybrid rice Liangyoupeijiu at the reproductive stage

We investigated the light reactions, CO2 assimilation, but also the chloroplast ultrastructure in the upper three functional leaves (flag, 2nd, and 3rd leaves) of the Chinese super-high-yield hybrid rice (Oryza sativa L.) Liangyoupeijiu (LYPJ) with ultraviolet-B (UV-B) treatment during reproductive development. Photosynthetic parameters showed that the upper 3 functional leaves of LYPJ entered into senescence approximately 15 days after flag leaf emergence (DAE). Leaves in UV-B treatment exhibited greater efficiency in absorbing and utilizing light energy of photosystem II (PSII), characterized by higher chlorophyll (Chl) content and the whole chain electron transport rate (ETR). However, UV-B radiation reduced activities of Ca2+-ATPase and photophosphorylation. The significantly decreased activity of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) was greatly associated with the decline in photosynthetic efficiency. The net photosynthetic rate (P N) and stomatal conductance (g s) suffered strong reductions before 25 DAE, and afterwards showed no significant difference between control and treatment. UV-B treatment delayed chloroplasts development of flag leaves. Chloroplast membranes later swelled and disintegrated, and more stromal thylakoids were parallel to each other and were arranged in neat rows, which might be responsible for better performance of the primary light reaction. It is likely that accumulation of starch and an increase in the number of lipid droplet and translucent plastoglobuli were results of an inhibition of carbohydrate transport. Our results suggest that long-term exposure to enhanced UV-B radiation was unlikely to have detrimental effects on the absorption flux of photons and the transport of electrons, but it resulted in the decrease of photophosphorylation and Rubisco activation of LYPJ. The extent of the damage to the chloroplast ultrastructure was consistent with the degree of the inhibition of photosynthesis.

Head rice yield of “super” hybrid rice Liangyoupeijiu grown under different nitrogen rates

“Super” hybrid rice varieties have been widely grown in farmers’ fields since the late 1990s in China due to their high yield potential. The objective of this study was to compare head rice yield and related grain quality traits between a “super” hybrid variety, Liangyoupeijiu (LYPJ), and an ordinary hybrid variety, Shanyou 63 (SY63), across a wide range of nitrogen (N) rates. The two hybrid varieties were grown under field conditions with seven and six N treatments in 2004 and 2005, respectively, in Hubei province, China. Grain yield, head rice yield, head rice percentage, chalky rice rate and other grain quality traits were measured in the two years. Although the difference in grain yield was small between the two varieties, the average head rice yield across N treatments for LYPJ was 34% and 24% higher than that for SY63 in 2004 and 2005, respectively. Head rice percentage was significantly affected by N rates, but LYPJ maintained higher head rice percentage than SY63 across a wide range of N rates. The higher head rice percentage of LYPJ was associated with its lower chalky rice rate compared with SY63. LYPJ had higher amylose content, greater gel consistency, and lower protein content than SY63, suggesting a better palatability of cooked rice for LYPJ than for SY63.

Characteristics of the Mesophyllous Cells in the Sheaths of Rice ( Oryza sativa L.)

The photosynthesis of rice sheath plays a significant role to furnish rice yield, and it is accounted for 10 to 20% of the final yield. But, limited studies have been done to address this phenomenon and to characterize the mesophyllous cells of rice sheath and how it may attribute to the rice yield. In this paper, super hybrid rice Liangyoupeijiu, its parents Wumang 9311 and Peiai 64S, and hybrid rice Shanyou 63 were studied as the experimental materials, and the characteristics of the mesophyllous cells of rice sheaths were examined by microscopic and super-microscopic observation as well as chlorophyll absorption spectrums. The results showed that rice sheath was rich in the intact mesophyllous cells full of chloroplasts, grana and thylakoids, which were much the same as those of rice blade. The absorption spectrum curves of the Chi. a and b of the sheaths were similar to those of the blades. The stomatal density in the outer epidermises of the sheaths was comparable to those in the up- and down-epidermises of the blades. The significant tests proved that the amount of chloroplast per mesophyllous cell of the sheaths was almost the same as those of the blades, and the mesophyllous cells in the sheaths were also rich in chlorophylls. The chlorophyll content of rice sheath reached about 50% of the chlorophyll content of rice blade, and the P n of the sheath/the blade ranged from 13.60 to 34.57%. Therefore, rice sheath was also full of the intact photosynthetic apparatus similar to those in rice blade, and had capabilities of photosynthesis. The statistical analysis revealed that the physiological senescence of the photosynthetic apparatus in both the sheath and the blade of Liangyoupeijiu was significantly slower than those of the other varieties at the late stages. The profuse grain-filling stage was an inflexion point of the physiological senescence of the chloroplasts and the chlorophylls of both the blades and the sheaths.

Yield Component Differences between Direct-Seeded and Transplanted Super Hybrid Rice

Super hybrid rice Liangyoupeijiu was grown by transplanting (TP) at a spacing of 20 cm×20 cm with one seedling per hill and by direct-seeding (DS) at a seeding rate of 22.5 kg ha-1 (about 120 seeds m-2) in Changsha, Hunan Province, China in 2004 – 2010. Grain yield and yield components were measured each year, and some physiological factors were determined in 2009. There was no significant difference in mean grain yield across years between DS and TP. DS produced more panicles per m2 but less spikelets per panicle than TP. The differences in number of spikelets per m2, spikelet filling percentage and grain weight between DS and TP were not significant. A large number of panicles per m2 in DS was derived from the increased number of tillers per m2 rather than increased rate of panicle-bearing tillers, and the number of tillers per m2 was mainly determined by the number of hills per m2 because the number of tillers per hill was small in DS plants. Tillering rate, tillering duration as well as carbohydrate and nitrogen metabolism were critical to the reduced number of tillers per hill in DS. In DS plants with fewer spikelets per panicle, the numbers of primary branches and secondary branches per panicle, spikelets per primary and secondary branches, and also panicle length and spikelets per unit panicle length were smaller. These differences were attributed to the smaller source leaf size as well as lower root activity and the nutritional status at panicle initiation.

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.

Microcalorimetric Investigation on Effects of LaIII on Metabolic Activity of Mitochondria Isolated from Hybrid Rice

Rare earth elements (REEs) have beneficial influence on plant growth and are widely used in agriculture practice, but little is known about the behavior of the REEs in mitochondria of plant cell. Thermogenic metabolic curves were determined by the ampoule method at 303 K using a TAM air isothermal microcalorimeter in mitochondria isolated from hybrid rice Liangyoupeijiu (Oryza sativa L.), and the effect of La(III) on its mitochondrial metabolism was investigated. From the obtained heat flux curves, the crucial parameters including as activity recovery rate constant (k) and maximum heat power (P(max)) were determined. Application of La(3+) in concentrations ranging from 0 to 120 microg/ml significantly increased k and P(max) values with the high point reaching 346 and 222% of the control, respectively. Concentrations from 140-150 microg/ml had the opposite effect. These results were consistent with previous reports on the effects of REEs on plant growth. It was concluded that the La-induced change of mitochondrial metabolic activity is a possible mechanism by which La(III) ions influences hybrid rice growth.

Responses of superhigh-yield hybrid rice Liangyoupeijiu to enhancement of ultraviolet-B radiation

Effects of 111 days enhanced UV-B radiation on leaf pigments, grain quality, photosynthesis and growth were determined in Chinese superhigh-yield hybrid rice ( Oryza sativa L.) Liangyoupeijiu (Peiai 64S × 9311). The chlorophyll concentrations of leaves under enhanced UV-B radiation were slightly reduced in the tillering stage, but recovered to levels equal to or above those of control in the later growth stages. Leaves treated with enhanced UV-B radiation for 99 days exhibited higher absorbance in the UV region than controls. Amylose concentration of UV-B treatment was significantly increased by 4.1%. Crude fat concentration, crude protein concentration and vitamin B 1 showed no significant difference between control and treatment. The light-saturated photosynthetic activity of UV-B treated leaves normalized on fresh weight or chlorophyll concentration was, respectively, 45.2 and 35.3% higher than controls. Both indoor and field experiments indicated that UV-B treated leaves were more tolerant to photoinhibition, and its D o values tended to be higher than controls during the strong light period of midday. The D1 protein turnover played more important role in UV-B treated leaves against strong irradiance than in control leaves. Little difference was observed in the maximal PSII quantum efficiency of UV-B treated and control leaves during the process of leaf senescence. UV-B radiation reduced diseased grains per panicle and led to a higher seed setting rate. It may have a direct harmful effect on pathogens or reduced susceptibility of UV-B exposed plants to pathogens. Our results suggest that long-term exposure to enhanced UV-B radiation is unlikely to have detrimental effects on the photosynthetic capability of Liangyoupeijiu, and tends to inhibit its growth and biomass.