Milk-ripe Stage Research Articles

Leaf water relations characteristics of differently potassium fertilized and watered field grown barley plants

Seasonal leaf water relations characteristics were studied in fully irrigated spring barley (Hordeum distichum L. cv. Gunnar) fertilized at low (50 kg K ha−1) or high (200 kg K ha−1) levels of potassium applied as KCl. The investigation was undertaken from about 14 days before anthesis until the milk ripe stage in leaves of different position and age. Additionally, the effects of severe water stress on leaf water relations were studied in the middle of the grain filling period in spring barley (cv. Alis). The leaf water relations characteristics were determined by the pressure volume (PV) technique.

Fluctuation of Ethylene Production in Excised Panicles and Flag Leaf Blades during Grain Ripening in Rice(Oryza sativa L.).

Ethylene production and its fluctuation in panicles and flag leaf blades in the rice plant (Oryza sativa L.) during the grain ripening stage were examined. The effect of plant growth regulators (growth retardants and brassinosteroids) on fluctuating ethylene production in rice panicles were also investigated. The results are summarized as follows: (1) Ethylene production was readily determined by excising and incubating 2 to 3 panicles and flag leaf blades of rice for 24 h in a test tube stoppered with a serum cap. Under these conditions, ethylene production in ripening panicles increased significantly when exposed to light (about 30 μE·m-2·sec-1) as compared to conditions of darkness. However, light exposure reduced ethylene production below the levels achieved in darkness in flag leaf blades in contrast to the results with panicles. (2) Light-stimulated ethylene production in the panicle fluctuated during grain ripening, reaching its maximum rate of production at the milk-ripe stage. Lower rates were observed before and after the milk-ripe stage. (3) A high rate of ethylene production was maintained in the flag leaf blade until the milk-ripe stage, followed by a rapid decrease in subsequent stages. (4) In greenhouse experiments, the application of plant growth retardants (paclobutrazol and GRH-624) and brassinosteroids (brassinolide and epibrassinolide) several days prior to heading resulted in increased panicle fresh weight with concomitant increases in ethylene production as compared to control at the milk-ripe stage. The data suggest that light-dependent ethylene production in rice panicles is related to the different maturation stages following anthesis and fertilization in the rice plant.

Changes in cell-wall composition and degradability of sorghum during growth and maturation

Samples of sorghum (Sorghum bicolor Moench × Sorghum sudanense Stapf, cv ‘P 988’) were harvested at five growth stages. Quantitative methylation and acetalation–methylation methods were used to examine changes during growth of cell-wall polysaccharides, their association with phenolic compounds and the effects of changes on rumen degradability. Cellulose degradability, as measured by a nylon-bag method, decreased from 82·5% at the youngest stage to 36·5% at the milk-ripe stage, at a greater rate of change than degradability of dry matter. Among the monosaccharides contributing to cell-wall polysaccharides, the degradabilities of arabinose and uronic acid residues were consistently higher than those of xylose and glucose, the main components of structural carbohydrates. Recovery of parent neutral sugars from cell wall polysaccharides, calculated as the sum of partially methylated alditols, was in good agreement with the values obtained by direct estimation of individual sugars as their alditol acetate derivatives. Total non-starch polysaccharide content increased from 31·1% to 45·1% between the first two growth states, with little change evident thereafter. The relative proportion of individual to total sugars remained consistent throughout growth. The values for arabinose, xylose and glucose residues accounted for 4·9%, 27·9% and 63·0% of total neutral sugars, respectively. The pattern of glycosidic linkages detected could be mainly ascribed to the presence of (1–4)-β-D-glucans (cellulose), arabinoxylan, (1–3)(1–4)-β-D-glucans, (1–4)-β-D-galactan, (1–3)(1–6)-β-D-galactan, rhamnogalacturonan and, possibly, xyloglucan. The cellulose content of the five sorghums was, in order of growth, 14·3%, 21·8%. 22·3%, 21·2% and 22·0% of dry matter. The ratio of the mixed-linked g1ucan:cellulose decreased during growth. Arabinoxylan, the predominant hemicellulosic polysaccharide, was estimated to comprise about 33% of total neutral sugars consistently for all sorghum samples. Arabinose, found largely as terminal residues in the cell walls, carried various amounts of alkali-labile substituents, particularly at position 0–5, depending on the growth stage of sorghum. The extent of 0–5 substitution was closely correlated with both the lignin content (total phenolics minus phenolic acids, r = 0·903) and with cellulose degradability (r = 0·915).

Changes in cellular and water soluble sugar contents during grain filling period in three parts of main culm of spring wheats.

Changes in culm contents, cell wall constituents, net cellular matter and water soluble sugar content (WSC) were determined from anthesis to maturity in three parts of the main culm, peduncle, second and lower internodes, for three spring wheat varieties, tall Haruhikari, semi-dwarf Haruyutaka and tall late Selpek. After anthesis cell wall constituent and net cellular matter increased in peduncle and the second internode, associated with the elongation, but a little in the lower internodes, of which elongation has almost ceased at anthesis (Fig. 2). Contrary to this, WSC as a storage material increased in each part until milk ripening, decreasing to almost zero at maturity, presumably due to translocation to the ear. WSC has been rapidly accumulated before anthesis in the lower internode, but started to store at about anthesis in peduncle and the second internode, and attained the maximum at about a week before milk ripening in the lower internodes, just at the milk ripe stage in the second internode and several days after milk ripening in peduncle. For all varieties the percent WSC was higher in the second internode and the amount of WSC in the lower internodes was more than in peduncle and the second internode at milk ripe stage, suggesting that the second and lower internodes were main storage organs. In addition the percent and amount of WSC were larger for semi-dwarf Haruyutaka than for tall Haruhikari and Selpek.

Difference in single leaf photosynthesis between old and new rice varieties II. A physiological basis for the difference in stomatal conductance between varieties.

Using many rice varieties differing in the year of registration, the physiological basis for higher stomatal conductance in new varieties at the ripening stage was examined. (1) At the heading stage, no varietal difference was observed in the rate of bleeding from the section of stem after sunset; whereas at the milk ripe stage, a marked varietal difference was found in the rate. Namely, the newer the variety was, the higher was the rate. (2) At the milk ripe stage, a positive and fairly close correlation existed between the bleeding rate and stomatal conductance (gs) in most cases. This fact suggests that, in new varieties, the higher ability to supply water actively to leaves, based on the higher physiological activity of roots, resulted in the larger gs. (3) No difference was found in aerenchyma resistance (the resistance to air flow through aerenchyma extending from leaves to roots in the plant body) before heading. After heading, however, the trend that the newer varieties had the lower aerenchyma resistance appeared and became more and more marked with time. From this, it was suggested that, in new varieties, the better development of the aerenchyma enabled the plant to supply root tissues with oxygen from the aerial part better, which maintained higher physiological activity of roots at the ripening stage.

Effect of continuous ethephon application on culm length, sugar content and yield in spring wheats.

Three varieties of spring wheat, tall Haruhikari, semi-dwarf Haruyutaka and tall late Selpek, were grown in a 5 cm equidistant square pattern (400 plants/m2) and the 100 ppm of ethephon was applied four and six times at four days interval during the period from double ridge stage to flag leaf emergence (DR treatment) and from flag leaf emergence to anthesis (CE treatment), respectively. The ethephone treatments did not influence the phenological events (Table 1), but inhibited culm elongation (Fig. 1), especially the lower internodes in DR treatment and the upper internodes in CE treatment (Table 2). The effect of shortening in culm length was more in CE treatment and in tall varieties than in DR treatment and in semi-dwarf variety. The water soluble sugar content in culm changed higher in CE treatment (Fig. 2), indicating a highly negative correlation with culm length at milk-ripe stage regardless of the treatments and varieties (Fig. 3). The grain yield in DR treatment was higher in all varieties than those in controls, though not significant, mainly due to the increase in number of ears and grain number per ear (Table 4).

Root Activity Distribution in Milk Ripe Stage of Paddy Rice Plant Cultivated by Plow and Rotary Tillage

Root Activity Distribution in Milk Ripe Stage of Paddy Rice Plant Cultivated by Plow and Rotary Tillage

Growth phases of spring wheat in terms of dry matter partitioning and its relation with some characteristics of varieties.

前報において春播コムギ2品種の乾物分配率を検討したところ, 春播コムギの生長は止葉分化期, 止葉出葉期, 開花期および乳熟期を転換点として5つの生育相に区分されることが明らかとなった. 本研究では, 生育特性の異なる3品種(長稈ハルヒカリ, 半倭性ハルユタカ, 長稈, 晩生 Selpek)を用いてこの結果を確認するとともに, 各生育相における葉身, 穂, 子実の乾物分配率(Y)を出芽後日数(X)に対する回帰で示し(第3図), 回帰式の係数および定数を用いてこれら3品種の特性を検討した(第2表). 生育相I(出芽期～止葉分化期)および生育相II(止葉分化期～止葉展開期)における葉身への分配率はYl1=b1X+c1およびYl2=-b2X+c2の一次式で示されたが, 長稈品種のSelpekは係数b2の値が小さいことから, 生育相IIの期間が長く, この間の稈への分配が大きいことが示唆された. また, 生育相III(止葉出葉期～開花期)では, 穂(子実を除く)への分配率はYe=-a3(X-b3)2+c3で示されたが, 曲線の膨らみを示す係数a3の値は品種間に差がみられず, 穂の伸長する期間の長さは3品種とも同様であった. しかし, 曲線の頂点の高さを示す定数c3の値はハルユタカで高く, 大きなシンク容量を形成したことが示唆された. 一方, 生育相IV(開花期～乳熟期)においては, 子実への分配率はYg=b4X-c4で示され, 同じ長稈品種でもハルヒカリは分配速度を示す係数b4の値が小さく, 開花期前後の稈の伸長による稈への分配が大きかったことが示唆された.

Differences in productivity between short- and long-culm varieties and their relationships with cell wall and cellular components of culm in spring wheat.

Grain yield, total dry weight and harvest index of twelve and twenty-three wheat varieties, including short-and long-culm types, were measured in 1985 and 1986. In 1986, the percentages of cell wall and cellular components in the culm were also measured by the detergent method. Long-culm varieties had higher total dry weight, but lower harvest index than short-culm varieties in both years. The grain yields of long-culm varieties were, however, higher in 1985 (dry conditions), but lower in 1986 (wet conditions) than those of short-culm varieties. Grain yield was correlated positively with total dry weight in 1985, but with harvest index in 1986. The weight of cell wall constituents in the culm attained a maximum-just after anthesis and maintained a near maximum value until maturity in almost all varieties. The culm dry weight and the weight and percentage of cell wall constituents measured at the milk-ripe stage were larger in long-culm varieties than in short-culm ones, and correlated positively with total dry weight at maturity. On the other hand, the weight of cellular contents increased until the milk ripe stage and then decreased, suggesting that reserve materials stored in the culm may be translocated to the grain after the milk ripe stage. The percentage of cellular contents was about 10% higher in short-culm varieties than in long-culm ones at the milk ripe stage.

Factors affecting the ripening process of different rice cultivars.

In order to make clear the factors affecting the ripening, four cultivars (Nanching 11, Suweon 258, Akenohoshi and Yamabiko) were examined on ordinary paddy field. The former three cultivars produced about 40, 000 grains/m2 and cv. Yamabiko did 27, 000/m2 at 3.5-5 of maximum leaf area index each. Yields of brown rice were ranging 5-6 tons/ha on all cultivars. The percentage of fully ripened grains in each cultivar, which expressed by the ratio of weight of 1, 000-whole-grains to weight of 1, 000-winnowed grains, was obtained as follows, 93% in cv. Yamabiko, 80% in cv. Nanching 11, 77% in cv. Suweon 258 and 73% in cv. Akenohoshi. The weight of 1, 000-raw-grains at 15 days after heading showed a high positive correlation to 1, 000-whole-grains of harvest time in all cultivars (r=0.978). It seemed that the final weight of 1, 000-whole-grains was strongly affected by a volume of young kernel at the milk-ripe stage. The weight of raw-grain, showing kernel's volume, highly correlated to the sucrose content per grain at 5 days after heading in each cultivars (r=0.981). As a result of multiple regression analysis, both factors the leaf area per grain and the rachis-weight per grain, could be expronated the sucrose content per grain at 5 days after heading, i.e., standard partial regression coefficients were shown 0.786 in the former and 0.431 in the latter (R=0.936), respectively. It is concluded that the highest value of ripening of cv. Yamabiko owed to its highest amount of the leaf area per grain among the four cultivars.

Studies on Morphogenesis in Rice Plant : X. Ultrastructure of the dorsal vascular bundle in the ovary and a transport mechanism.

The dorsal vascular bundle of the rice ovary in milk-ripe stage has been observed with an electron microscope. The sieve elements are accompanied by few companion cells with small number of plasmodesmata (Fig. 1). Conducting networks composed of abundant cndoplasmic reticulum and plasmodesmata are ramified like a cobwebs through the bundle parenchyma cells and nucellar projection (Figs. 2, 3, 4 and 5). The parenchyma cells between phloem and xylem are controlled in low osmotic and low turgor pressure (Fig. 2), and some parenchyma cells adjacent to the vessels have many mitochondria (Fig. 4), but no transfer cell has been observed in the ovary. The cell walls of the nucellar projection commence to be thickened and lignified at about 7 days after flowering (Figs. 5 and 7). It may be possibly supposed that, the phloem current flows out directry to free space from the sieve elements, and the greater part of water is absorbed and drained out by the vessels, and the assimilates are absorbed by the bundle parenchyma cells and are transported to the endosperm through the networks composed of endoplasmic reticulum and plasmodesmata (Fig. 8).

On Superficial Root Formation in Rice Plants

As designated previously, shoots of rice plants consist of "shoot units", each with an apical leaf basal bud and upper and lower roots zones. And roots of upper shoot units concentrate near the soil surface and produce a net with many branched roots. These are usually called superficial roots. Up to the present, it has been believed that after such superficial root formation during the period from the young panicle formation stage to the heading, rice plants complete the formation of the root system. But as the result of an investigation of the superficial root formation by the authors, it is found that the superficial root formation continues until the full-ripe stage of rice plants. As it is well known, the developmental process of rice plants from the young panicle formation stage to the full-ripe stage is divided into the following stages: the differentiating stage of rachis branch, the spikelet differentiation stage, the reduction division stage, the pollen formation stage, the heading stage, the flowering stage (the fertilization stage), the milk-ripe stage, the dough-ripe stage, the yellow-ripe stage and the full-ripe stage. In the rice cultivar "Mubo-aikoku" grown in wagner pots, it has been clarified that the superficial root system according to progress of such stages is formed as follows : Elongation of primary roots initiated from the ninth shoot unit comes to a stop at the spikelet differentiation stage (Fig. 1). Thick secondary lateral roots and thick tertiary roots appear in the same shoot unit during the period from the spikelet differentiation stage to the flowering stage (Fig. 6 and 7). And fourth, fifth and sixth lateral roots emerge in the milk-ripe stage to elongate until the dough-ripe stage (Fig. 6 and 7). Primary roots initiated in the tenth shoot appear in the spikelet differentiation stage and the elongation ceases at the flowering stage (Fig. 1). Elongation of secondary lateral roots takes place in the milk-ripe stage and tertiary lateral roots begin to emerge at the pollen formation stage. Fourth lateral roots appear in the milk-ripe stage and cease to elongate in the yellow-ripe stage. fifth and Sixth lateral roots emerge in the tenth shoot unit at the yellow-ripe stage and elongate the full-ripe stage (Fig. 6 and 7). In the, eleventh shoot unit, growth of primary roots in length ceases in the dough-ripe stage (Fig. 1 and 3). And secondary lateral roots start to emerge in the reduction division stage. Tertiary lateral roots appear in the flowering stage and fourth lateral roots emerge in the dough-ripe stage. These continue to elongate until the full-ripe stage (Fig. 6 and 7). As to upper primary roots of the twelfth shoot unit, these roots become visible in the reduction division stage and elongate to the dough-ripe stage (Fig. 1). Secondary lateral roots appearing i1] the reduction division stage continue to grow until the full-ripe stage and tertiary lateral roots emerge in the full-heading stage, stopping elonga-tion in the yellow-ripe stage (Fig. 1 and 7). Fourth lateral roots come into sight in the yellow-ripe stage and continue to elongate until the full-ripe stage (Fig. 6 and 7). The superficial roots of all of upper shoot units, in general, show such features as : (1) the period of elongation of thick secondary roots are longer than that of thin secondary roots (Fig. 6), (2) tertiary lateral roots are found in lower primary roots of upper shoot units and fourth, fifth and sixth lateral roots are found in upper primary roots of upper shoot units (Fig. 5 and 6), (3) in tertiary, fourth, fifth and sixth lateral roots of upper primary roots of upper shoot units, two kinds of branched roots are respectively formed, one being thicker in diameter than the other (Fig. [the rest omitted]

Studies on the Development of Endosperm in Rice : 11. Development of starch granules in endosperm tissue.

Increase in size of the starch granules began to precede from the central portion of endosperm tissue and reached the maximum size (39μ in major diameter) by the 15th day after anthesis falling on around 10 days after begining date of the granule formation. According as a portion of the endosperm tissue was on the more outside, the begining date of the granule formation was delayed more, and the increase in size of the starch granules proceeded at a slower pace. Accordingly, starch granules found in the exterior cell layers were always smaller in size than those found in the interior ones. And the starch granules in the outermost cell layer facing the aleuron layer were delayed most. Their final size was as small as 6μ in major diameter on about the 35th day after anthesis, i.e., on around 25 days after begining of starch granule formation. Average size of the whole starch granules showed increase at the most remarkably rapid pace during the period from 10th to 18th day after anthesis, and continued to show an increase until the 35th day to the extent of 23×19μ, thus completing the increase in size. It was generally found that there was little or no significant difference in size of the starch granules contained in each cell. And that it seemed that there was no any appreciably great difference in the number of starch granules in each cell, irrespective of remarkably great differences in size of cells. Size of starch granules of the sample variety "Yoneshiro" (japonica) was generally larger than that of starch granules of such sample varieties as "T136" and "Mushakudanti" (indica). We inferred the following types of routes of translocation of the material substances composing of starch granules into the endosperm tissue. At the very early stage, direct translocation of substances into endosperm from surrounding nucellus (route a) might be fairly noticeable, besides the supply of substances from the vascular bundle on the outside of dorsal side (conducting strand). In and after milk-ripe stage, route (a) had no longer been noticed. Instead, the route (b) translocation "conducting strand→nucellar epidermis→surface cell layer of endosperm (aleuron layer)→starch cell layers" seemed to have probably played the important role in translocation. In and after dough-ripe stage, it seemed that translocation route has come to be increasingly confined to the route (c) translocation "conducting strand→nucellar projection→dorsal side of endosperm". In spite of the fact that the pathway of starch materials in the endorperm cell was becoming increasingly narrower due to the growing size in starch granules after dough-ripe stage, a considerably large amount of materials have been translocated through the endosperm tissue. From this fact, it is suggested that the starch materials have been translocated not only by the simple physical stream in the cell, but also with a help from a certain "carrier" which pocesses enzymatic or chemical activities.

Tests with Some Insecticides against the Paddy Borer, Schoenobius incertulas , in Taiwan 1

Tests made all the second paddy crop in Taipei in 1960 to study the initial and residual effects of parathion, Sumithion ( O,O -dimethyl- O -(3 methyl-4 nitrophenyl) thioposphate), dimethoate and endrin against primarily the newly hatched larvae of the paddy borer, Schoenobius incertulas Wlk., indicated that control by the residues or the plant metabolites of these compounds was better with higher concentrations or dosages, and appeared to vary considerably with the stage of growth of the plants. At the maximum tillering stage, excellent control was obtained with parathion for about 12 days, with Sumithion for about 7 days, but dimethoate lost its persistent effect rapidly 1.5 to .5 days after treatment. Endrin gave poor residual effect in one test at the maximum tillering stage but at the heading stage it gave as good results as parathion, and was better than Sumithion. Re-sidual effect of these chemicals at the heading stage of paddy plants was, on the whole, poorer than at the maximum tillering stage. At the maximum tillering stage, Sumithion and parathion gave better control initially than dimethoate or endrin. When the plans were thoroughly wet with the sprays, no significant difference in initial kill was obtained with a 0.02% or a 0.04% concentration with either parathion or Sumithion. At the heading stage dimethoate at a 0.06% concentration appeared to be better than parathion or Sumithion at a 0.04% concentration. At the milk-ripe stage dimethoate gave the best initial control followed by parathion and Sumithion. In these tests endrin was found to penetrate deeply into the leaf sheath and killed 30% to 57% of the young larvae feeding within.

Analysis of Developmental Factors Determing Yield and Yield Prediction in Lowland Rice.

I. Effects of temperatures and light intensities. In 1955 and 1956, rice plants were subjected to 20 conditions differently controlled by temperatures and light intensities in different 10-day periods in growth, and the compound effects of temperature and light intensity on the ripening of rice grains were examined. 1) Under compound conditions of high temperatures and reduced light intensities, most unfavourable effects on ripening were brought about, and the effects of reduced light intensities were the more intesitive under the higher temperatures, especially on the milk-ripe stage. (cf. Figs. 1 and 2.) 2) It was considered to be worthy of attention that a high constant temperature (31-32°C) as well as a low temperature (21-20°C) in reduction division stage seemed to reduce the percentage of fertilized grains to a considerable extent. 3) An optimum temperature for ripening on the ripening stage seemed to be 22°C, approximately, when the temperatures were kept constant during the day and the night, and higher temperatures than 25°C showed unfavourable effects on ripening of rice grains. And it was made clear from the following experiment that high temperatures in nighttime are much more harmful on ripening of rice grains than those in daytime. II. Effects of the range of daily temperature. In 1956, rice plants were subjected to different ranges of daily temperature in different 10-day periods of their growth, to examine the effects of temperature ranges on the ripening of rice grains. 1) Marked effects on ripening were found in the periods from reduction division stage to yellow-ripe stage, and, in most cases, favourable effects were brought about by the ranges of 10°C or 15°C, but the optimum ranges for ripening varied with day temperatures and growth stages. 2) An important fact was found that there exists an optimum night temperature for ripening on each stage of growth independently of day temperaures, as seen in Fig.3. It was considered worthy of notice that optimum night temperatures on the ripening stages seem to be considerably low. 3) On the other hand, an optimum day temperature for ripening on each growh stage could hardly be seen, except for reduction devision stage. (An optimum day temperature on reduction devision stage seemed to be about 31°C.)

Physiological Studies on the Mechanism of Ripening in Rice plant.

Chemical, Physico-chemical, and enzymatic changes that occur in the seed of rice plant as it grows from fertilization to maturity were studied. 1, There is little synthesis of starch up to the 4th day after flowering. A very rapid synthesis of starch takes place between the 7th and the 20th day. Storage of starch reaches to a maximum about at the 30th day. 2, The contents of sugars, including reducing sugars, increase untill around the 15th day after flowering, and decrease rapidly thereafter. 3, A lot of inorganic phosphorus is present in the seed in an earlier period of its development. After about the middle milk-ripe stage, its content in endosperm falls continuously. In the fluoride stage it is practically negligible. On the contrary it increases in the aleuron layer and embryo. The fact that inorganic phosphorus is not accumulated in the storage organ of starch is suitable for the accumulation of starch, because the starch synthesis by phosphorylase is inhibited by the presence of inorganic phosphorus. 4, The optimal pH for synthesis of starch by phosphorylase is 6.5-6.7. The optimal temperature is around 37°C. The amount of phosphorylase in endosperm rapidly increases untill the 18th day after flowering, hereafter it decreases continuously. After about the 30th day its activity is lost almost completely. The period of the highest activity of phosphorylase closely relates to that of the rapid accumulation of starch. 5. The optimal pH of rice-amylase is 4.1. The amount of amylase is very small in the early period of seed development. It increases from about the 10th day after flowering and reaches the maximum value about the 20th day. 6, The pH value of endosperm at the early stage is around 5 or less. However, it rises to more than 6 after the milk-ripe stage. On the contrary the pH value of aleuron layer and embryo is 5 or less. As the favorable pH value for synthesis of starch by phosphorylase is in the range from 6 to 7, it may be said that the pH condition within the endosperm of the milk-ripe stage later is suitatable for synthesis of starch. As a final conclusion, chemical, physico-chemical, and enzymatic conditions of endosperm are favorable for synthesis or accumulation of starch by the action of phosphorylase as far as the present author has examined.

Studies on the sugar concentration of the juice in the stalk of sugar sorghum (Sorghum vulgare PERS. var. saccharatum BOERL).

The following experiments were made at Tokyo University Farm in 1948 and 1949. For the experimentation one variety of Japanese species was used. Sugar concentration of the juice was estimated by the sugar hand-refractometer, and for crushing the stalks the small compressor of vermicelli was used. EXPERIMENT I : (See Fig. I) Change in the Sugar Concentration of the Juice in the Stalks of Sugar Sorghum after the Heading Time. The best time for cutting and crushing the stalks of sugar sorghum has not been clearly known. It has been differently said either to be in the milk-ripe stage, or in the dead-ripe stage, or in the middle of the two. Experiment No. I. was carried out in order to know clearly about the harvesting time. The result follows : The sugar concentration was the highest from the fifth week to the tenth week after the heading, in other words, between the red-ripe stage (which corresponds to the yellow-ripe stage of wheat) and the dead-ripe stage. The concentration was not so high either in earlier or later period than that. In the earlier period the concentration was low, and in the later period there was a change in the quality of the juice. On the other hand, the amount of the deprived juice was almost same from the heading time to the matured time. The percentage of the weight of the deprived juice to that of the raw stalk was 65∼75% on the average. It is rare in the plant world that the amount of the juice does not decrease long time after the plant was decayed. Therefore, in deciding the time for cutting sugar sorghum, it is not necessary for us to be worried about the amount of juice to be obtained. After all, the cutting time is any day between the fifth and tenth week after the heading. EXPERIMENT II : (See Fig. II) The Effect of the Seeding time on the Concentration of Juice. In 1948 the writer found that there was a difference in the concentration of juice according to the heading time. (Of course, all plants were sown at the same time) The concentration of juice was higher in those that headed later than these that headed earlier, but the latter grew better than the former. Accordingly, in 1949 in order to put off the heading time without impairing the growth of the plant, the seeds were sown as late as possible. The writer compared the concentration of juice of those that were sown late to head later with that of those that were sown early to head earlier. He found the concentration of juice in the former was higher than the later, so long as there was no difference between the two in growth and that there was no difference between the two groups of the plants concerning the amount of juice contained in a plant. EXPERIMEMT III : (See Fig. III) The Effect of the Sowing Density upon the Sugar Concentration of Juice. This experiment was done in order to learn the difference of the concentration of juice between the stalks planted thinly and those planted thickly. The sugar concentration was higher in the latter than in the former group. In this experiment again the difference in the amount of juice obtained from a plant was so little that it could be ignored entirely. Nor were these differences between the amount of the Juice obtained from sugar sorghum of the said two groups per one tan (about one-forth acre).