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

Abstract

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).