Relationship between the change of starch and sucrose contents in flag leaf and the grain dry matter accumulation during heading and grain filling in hybrid rice
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With the hybrid rice Weiyou 64 and W6154s×Teqing, the relationship between the changes of starch and sucrose levels in flag leaf and the dry matter accumulation of grains was studied. Sucrose content in flag leaf of the two combinations increased rapidly from 5 to 15 days after heading, which significantly paralleled with the increase of the dry matter accumulation and sucrose content in the grains of the upper part of panicle during the same period. Starch content in flag leaf decreased significantly from 5 to 10 days after heading. Most of the upper grains in panicles ceased to accumulate dry matter and reach plumpness after 20 days of heading. These results suggested that during the filling of upper grains in the combinations the relationship between the sink and the source was balanced and coordinated well. The dry matter of most of the lower grains in panicles was still accumulated slowly after 20 days of heading, and the average weight of lower grains was significantly less than that of the upper grains after ripening. Sucrose level in flag leaf declined fast, while starch level changed less after 20 days of heading, which suggested that the capacity for synthesizing and....Keywords:
Panicle
Flag (linear algebra)
Sink (geography)
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The effects of nitrogen supply (1N, 2N) at heading on the pattern of accumulation of dry matter and nitrogen in the caryopses at different positions on panicle were investigated to clarify the positional differences of caryopsis growth. The photosynthetic activities and the nitrogen contents of leaf blades were also taken into account. Caryopsis position on panicle was selected as shown in Fig. 1. Results are summarized as follows; 1. The superior caryopsis (I) at the upper position on panicle, in the control, accumulated the dry matter and nitrogen rapidly and in a short duration at the first half of ripening period. On the other hand, the inferior caryopsis (VI) at lower position on panicle accumulated these materials slowly and over a long duration at the second half of ripening period. 2. Nitrogen supply at heading increased markedly the rate of accumulation of dry matter and nitrogen in all caryopses, but had little influences on the duration of the accumulation and on the time of the rapid accumulation in ripening period, as compared with the control. 3. Nitrogen content of all caryopses at maturity was clearly increased as the quantlty of nitrogcn supplied increased. Grain weight also increased but not so much as the nitrogen content. The ratios of increase of both grain weight and nitrogen content by the nitrogen supply were very remarkable in the inferior caryopsis (VI) which was ill-ripened ln the control. 4. The increase of grain weight and grain nitrogen content by the nitrogen supply at heading was caused by the rise of accumulating rate of these materials in caryopsis throughout the ripening period. 5. Nitrogen supply at heading maintained the photosynthetic activities and the nitrogen contents of leaf blades at relatively high level during ripening period. Nitrogen contents of leaf blades in each plot began to decrease abruptly at 10 days after heading and reached the lowest level at 25 days after heading relatively. 6. It was suggested that the occurrence of the early increased rate of accumulation of translocated substantes might be need for the improvement of ripening of inferior caryopsis and the factors controlling the accumulation rate of inferior caryopsis might involve not only the supplylng ability of source organs but also the function of inferior caryopsis for sink organ.
Panicle
Caryopsis
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Starch produced and accumulated in the straw particularly in leaf sheath and culm by the heading time is translocated into the growing dars after heading. Thus at 20∼25 days after heading starch content in the straw decreases to almost trace. In the following period starch accumulates again in the straw vainly. It is caused by the excessive production of starch by photosynthesis beyond the sufficient amount of starch required to grain development. In the control plots, amount of starch accumulated in the straw by the heading time and that accumulated again at the later stage of ripening vary with the different condition of nitrogen supply, indicating the balance between the number of spikelets and the quantity of starch produced, ie, the balance between the number of vessels and the quantity of substance to be delivered into them. Thus, in the plot B, starch production is less in relative proportion to the greatest number of spikelets formed due to high nitrogen level, and consequently the reaccumulation of starch is the least. On the contrary in plot C, being supplied with nitrogen top-dressing at the heading time, starch production is excessive in proportion to the number of spikelets and starch is stored in the straw vainly, because nitrogen supplied at the heading time has no effect in increasing the number of spikelets but is very effective in promoting photosynthetic production during the period after heading (fig. 2 and 3). The balance mentioned above determines the seed-setting percentage as well as the weight of grains (fig. 4). In the shaded plot, starch contained in the straw before heading is exhausted more rapidly than that of control plots and no further accumulation takes place. Translocation of carbohydrates from the straw to the ears is recognized not inhibited by the shading treatment. The seed-setting rate and weight of grains in the shaded plots are lower than these of the control plots. The difference in the seed-setting rate and weight of grains is caused mainly by the difference in these characters of spikelets located on the secondary rachis-branches, ie, the spikelets on the secondary rachis-branches, excluding spikelets at the top of the branches, are very changeable in these characters and are very influential in determining these characters as a whole ear (fig. 5). Content of nitrogen, phosphorus and potassium in the plant as well as the total amount per hill of these nutrients are determined with the control plot and the shaded plot in plot A. It is shown that the shading treatment inhibits remarkably not only the absorption of phosphorus but also the teanslocation of this element from the straw to the ears, whereas there is no such a change with nitrogen and potassium (fig. 7 and 8).
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We have been considering that nitrogen dressing at the heading stage of rice plant is rather unfavorable for the ripening. From the results of our experiments, however, it was made clear that it is possible to increase the fertility or grain weight by supplying the top-dressing of nitrogen to the rice plant which was very low in contents of nitrogen at heading stage. Furthermore higher yield was obtained by the top-dressing of nitrogen at the early period of flower primordia differentiating stage than that the heading stage. This is due to the increase of spikelets per panicle, even though the fertility and grain weight were decreased. High yielding rice plants-more than 900∼975 kg. per hectare in brown rice-showed higher fertility compared with that of the rice plants which were cultivated with the usual method. The cause of the high fertility has been considered as follows : Nitrogen content of high yielding rice plants was lower than that of ones cultivated with usual methed before heading. After heading, however, higher accumulation of nitrogen than the control was observed. Much starch was produced and stored in the straw, especially in leaf sheath and culm, in the heading stage of high yielding rice, compared with the control. After heading starch translocated rapidly into ears. Until about 20 days after heading, starch contents in the straw once decreased, but in the following period, they increased again.
Panicle
Rice plant
Hectare
Primordium
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The study with 25 two-line hybrid rice strains showed that their water retaining capacity was different with their combinations. On the whole, the water content in leaf and stem-sheath decreased during heading-grain filling stage, while that in panicle increased first and then decreased, with a peak at 7th day after heading. Stem-sheath was the main organ for water retaining. The correlation of panicle yield with both leaf and stem-sheath water content was positive at the 1st day after heading but became negative later, and that with whole stem-plant water content was positive after heading. The chlorophyll content of the two-line hybrids increased first and then decreased, with a peak at the 7th day after heading. Comparing with normal rice (male parent), the chlorophyll content of most two-line hybrids was lower, and the decreasing rate was faster than that of normal rice after heading. For two-line hybrid rice breeding, it should preferentially consider to select those hybrids which have a clearer dominance of plant water retaining capacity and a higher chlorophyll content at earlier and middle heading-grain filling stage, and an obvious dry matter transportation from leaf and stem-sheath at later heading-grain filling stage. For two-line hybrid rice planting, it should not only pay attention to the supply of water and nutrients, especially nitrogen at earlier and middle heading-grain filling stage, but also control nitrogen and water in time to prevent leaf green clinging and to promote dry matter transportation from leaf and stem-sheath to grain at later heading-grain filling stage.
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This experiment was conducted from variety Norin 8, in 1956 as a part of "Studies on Analysis of the Mechanism of the Ripening of Rice Plant" under controlled light intensity and nitrogen supply before and after the heading time. The main result obtained from this experiment are as follows : 1) Judging from the changes of carbohydrates amoung each organs (leaf-blade, leaf-sheath, culm) as shown figure 1, found out the carbohydrates having important connection to the production of grain, depends upon the sugars and starch, main storing part of ones restricted in leaf-sheath and in culm. Inhibiting effect of the photosynthesis to the rice plant come to decreasing of starch-content (%) more speedy than the sugars does. 2) Relation between the change of the carbohydrates (total sugar+starch) in leaf-sheath and in culm and the ripening under natural conditions shown figure 2. In case of much N-fertilizer applied under natural condition, showing sudden decrease of carbohydrates at about 5 days before heading, course of this decreasing seems to be the consumption of carbohydrates to the elongation of upper-nodes of culms and of ears. 3) By inhibiting the intensity of the photosynthesis at 16-7 days before heading, showing the decrease of the accumulated carbohydrates affecting the accumulation of the ones at begining of the ripening. In one case, when the ripening process completed in eary period, resulting the lighter kernel weight per 1000 on account of uncomplete development of the floret along the ear and. decreased number of spikelets per ear. By the results of decreased power of accumulation, reaccumulation of the carbohydrates in the culm remain maximum among the plots (as illustrated in Fig. 2-2). 4) Shading of the plants during the period of 6-15 deys after heading resulting the covering of the lowering of the photosynthesis, much amount of the accumulated carbohydrates translocated to the ear at early stages, conditioning the poorly developed kernels and increased the uncompletely developed grains (Fig. 2-3). 5) Prohibiting the intensity of the photosynthesis during the 16-25 days after heading translocation of the carbohydrates to the ear almost accomplished, development of the grains delayed transitionary affectionated the increasing effects of poorly developed grains and lighter kernel weight per 1000 (Fig. 2-4). 6) Shading of the sunlight at the later period of the kernel growth, 26-35 days after heading no influences of the treatment to, the kernel-development was seen (Fig. 2-5). 7) Accumulating power of carbohydrates to the culms at the later stage of the ripening having the positive relation between the photosynthsesis power of rice-plant and accumulating ability of the carbohydrates to the ear, from the results, special attentions will be paid to the ratio hull-rice vs. straw weight. 8) Judging from these results obtained, the authors estimate the fitness of the accumulating power of carbohydrates to the seed-production about 28-29% both in much fertilizer and in less one under natural conditions.
Elongation
Rice plant
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The dry matter accumulations of grain, enzyme activities, chlorophyll contents and grain quality traits of different panicle-type cultivars planted in four N-fertilizer levels were examined. The results showed as follows: The grain dry matter accumulations for different panicle type cultivars were not the same, for erect-panicle japonica cultivars, GR_0 and the rate of grain filling were low during early grain filling period because of the large number of grains per panicle and the high density of grain, but the rate of grain filling was higher during late grain-filling period, the difference of the grain filling between the upper and low part in one panicle was obviously found, which might be the important factors that made the appearance quality poor. The activities of starch phosphorylase and Q enzyme in the grains were different in the cultivars with three type panicles and in the grains from different sites of the panicle, the differences above were concerned with grain filling speed during early and late grain filling period, grain enzyme activity differences in different sites of the panicle were found in the cultivars with poor appearance quality. Chlorophyll contents of flag leaves during heading and maturing stages were correlated with quality characters. The gel consistency had the tendency to be more rigid and the protein content increased with the increase of chlorophyll content in the flag leaves.
Panicle
Japonica rice
Grain Quality
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In this experiment,eight rice cultivars were applied for leaf-cutting treatment at the anthesis.The results indicated that leaf-cutting could lower the percentage of ripened grains and grain weight,especially influence greatly the grains with late flowering,and reduce the yield.The order of the effect that leaves contributed to curved panicle rice's grain filling is as follows:the flagthe second leave from the topother leaves,while to semi-erect panicle rice flag is the largest.Cutting leaves could significantly increase not-ripened grains percentage.There were little differences among effect of leaves to yield with different panicle type rice.The effect to yield of flag with curved panicle was much more than that of semi-erect panicle.
Panicle
Anthesis
Flag (linear algebra)
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イネにおいて不完全米の発生は水ストレスを与える時期によって異なる. 玄米の生長は登熟期間の乾物供給量に規定されることから, 不完全米発生の差異は登熟期間の乾物生産量に左右されると考えられた. そこでこのことを実験的に検討するために水田土壌を詰めた1/5000aポットに水稲 (品種コシヒカリ) を湛水栽培し, 異なる発育段階 (出穂前15日目, 出穂後2日目と12日目) に給水量を前日の蒸発散量の60%に制限する処理を1週間行った. その結果, 登熟期間の乾物生産量は出穂前の水ストレスによって殆ど変わらなかったものの, 出穂後の水ストレスによって大きく低下した. 出穂前の水ストレス条件下では乾物生産量にかかわらず, 個体当り籾数の低下と籾殻の縮小によって個体当り穂重が低下した. これに対して, 出穂後の水ストレス条件下では乾物生産量の低下に伴い個体当り穂重が低下した. これと同時に一稔実籾重が低下し, 比重0.84から1.06までの籾が増加した. 比重0.84から1.06までの籾は, デンプンの蓄積が不十分な不完全米を内包する. 以上より, 水ストレスは幼穂発育初期では個体当り籾数の低下と籾殻の縮小を介して, 出穂後では玄米のデンプン蓄積の不足を介して, 精籾生産を抑制することがわかった.
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Chalky rice (Oryza sativa L.) grains are induced by high temperature during the grain-filling period. Plant nitrogen status also affects the occurrence of basal- and back-white grains (BBWG). The objective of this study was to elucidate the relations between nitrogen availability per spikelet during the grain-filling period (NGF) and each of the percentage of BBWG and grain protein content (GPC). We further compared the effect of the components of NGF determined before heading (NBH) and after heading (NAH) on BBWG and GPC. We grew the rice cultivar 'Koshihikari' in pots in 2012 and 2013, and top-dressed nitrogen at the panicle formation and heading stages, under two (2012) or three (2013) temperature regimes during the grain-filling period. GPC was explained well by NGF, but BBWG was not. BBWG was best explained in a multiple-regression equation by mean air temperature after heading and by NBH and NAH. The partial correlation coefficients for NBH were 1.6 and 3.0 times those for NAH in 2012 and 2013, respectively. On the other hand, in a multiple-regression equation for GPC, the partial correlation coefficients for NBH were 0.91 and 0.71 times those for NAH in 2012 and 2013, respectively. These results suggest that rice grains are most sensitive to plant nitrogen status before heading for BBWG but after heading for GPC, and that there is an optimal timing for nitrogen top-dressing that would maximize the reduction in BBWG per unit increment of GPC.
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To study the effect of soil moisture on growth and dry matter accumulation of rice in cold region,controlling water treatments(CWT) for the two rice varieties(Shangyu 397 and Suijing 3) at-30 to-35 kPa and-60 to-65 kPa of soil water potential were carried out during tillering stage,panicle initiation stage,1-10 days after heading,11-20 days after heading,respectively.When soil water potential(SWP) during tillering stage was kept at-30~-35kPa,the effect on plant height was very little,the culms of the two varieties were decreased apparently,and areas of three leaves from the top in two varieties were reduced differently.While SWP during panicle initiation stage was kept at-30~-35kPa,the height of the two varieties was decreased obviously and its main reason was that the internodes length from the second node to the forth node were decreased significantly,and areas of three leaves from the top in two varieties were reduced,but the culms and panicles per hill of the two varieties were increased significantly.While SWP before heading stage was kept at-30~-35kPa,the stem dry matter weight(SDM),the sheath dry matter weight(SHDM) and the panicle dry matter weight(PDM) of the two varieties during full heading stage were lower than those of CK,and exportation percentage(EP) of dry matter in every organ of two varieties also were reduced and reduced range at-60~-65kPa was greater than that at-30~-35kPa.While SWP during the beginning of heading stage was kept at-30~-35kPa,EP of dry matter in every organ of Shangyu 397 on the numerous tests was lower than that of CK,but Suijing 3 was opposite.The response of growth and development and accumulation of dry matter of different rice varieties is different on the different developing stage under the different treatmens.The effect of soil moisture on growth and dry matter accumulation of rice during tillering stage and panicle initiation stage is more serious than that in other treatments.
Panicle
Plant stem
Dry weight
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