Shoichi Yoshida

Chemical Forms, Mobility and Deposition of Silicon in Rice Plant

Abstract The study of chemical forms and physiological mobility of elements found in plants is always essential to establishing the roles of elements in plant life. Such information in combination with the results of growth experiments will lead to more. reliable conclusions on the physiological functions of elements.

Zinc deficiency of the rice plant in calcareous soils

Abstract Until very recently zinc deficiency of the rice plant had not been shown to occur in the field. Y. L. NENE (1) was the first to show that a foliar application of zinc sulfate corrects a disorder of the rice plant long known as Khaira disease in North-Central India.

HISTOCHEMISTRY OF SILICON IN RICE PLANT : III. The Presence of Cuticle-Silica Double Layer in the Epidermal Tissue

As seen in the previous paper1) the use of HF-etching method has added much information to the mode of silicon deposition in rice tissues. The results obtained cover a wide range from root to husk. However, the importance of silicon deposition in epidermis in relation to the resistance of plants to diseases or insect pests makes it desirable to continue further studies of the mode of silicon deposition in outer region of epidermis. The study of microstructure of epidermis in connection with silicon deposition will provide valuable information to the mechanism of resistance rice plant to blast disease, because penetration of the rice leaf by piricularia oryzae is ordinarily through the cuticle rather than via the stomata. It will be of importance also to the study of a possible role of silicon in water economy of rice plant as already suggested by the present authors.

HISTOCHEMISTRY OF SILICON IN RICE PLANT : II. Localization of Silicon within Rice Tissues.

Abstract As seen in the previous paper1) the use of HF-etching method has added much information to the mode of silicon deposition in rice tissues. The results obtained cover a wide range from root to husk. However, the importance of silicon deposition in epidermis in relation to the resistance of plants to diseases or insect pests makes it desirable to continue further studies of the mode of silicon deposition in outer region of epidermis. The study of microstructure of epidermis in connection with silicon deposition will provide valuable information to the mechanism of resistance rice plant to blast disease, because penetration of the rice leaf by piricularia oryzae is ordinarily through the cuticle rather than via the stomata. It will be of importance also to the study of a possible role of silicon in water economy of rice plant as already suggested by the present authors.

Role of siucon in rice nutrition

Abstract In spite of tremendous efforts by many plant physiologists, it still remains unsolved whether or not silicon is essential to higher plants. It is, however, generally accepted that some plant species markedly respond to silicon under some conditions and accordingly silicon is often described as a beneficial element.

The accumulation process of carbohydrate in rice varieties in relation to their response to nitrogen in the tropics

Abstract Because the edible portion of the rice grain consists mainly of starch, the study of its metabolism is highly important.

Photosynthesis, crop growth, and respiration of a tall and short rice varieties

Abstract The crop growth rate (CGR) of IRS and Peta increased as leaf area index (LAI) increased up to certain values. Beyond these values, the CGR was almost constant. The plateau value of CGR was greater for IRS than for Peta. The respiration of the crop for both varieties did not increase linearly but asymptotically with increase in LAI. The gross photosynthesis was estimated from (CGRx0.9)+respiration. The gross photosynthesis of both varieties increased with increasing LAI up to about 6, then showed little further increase. The maximum gross photosynthesis of IRS was greater than that of Peta. The respiration of both varieties was approximately 40 percent of gross photosynthesis over a wide range of values for LAI and leaf area ratio. The similar relationship was also found for 6 varieties of different plant type. These data suggest that the balance between photosynthesis and respiration is relatively stable over a broad range of photosynthetic rates for all varieties tested. Thus, it is unlikely tha...

Effect of water stress on grain filling in rice

Water stress, by affecting the rate of grain filling, decreased yield per panicle of rice by 29–40% in the small-seeded variety IR747(L) and by 19–32% in the large-seeded variety PP6R-13-12-3. It had little effect on the duration of grain filling. High nitrogen level increased culm+sheath and leaf blade weights substantially in both varieties, but decreased starch concentrations (determined for IR747(L) only) at flowering in the culm+sheath significantly. Relatively more starch remained in the culm+sheath of the water-stressed plants at maturity. The balance sheet suggested that plants grown at a low nitrogen level were more dependent on “reserve starch” and that the percentage of reserve starch that went to the panicle was higher in the stressed plants than in the unstressed plants. High nitrogen level increased the nitrogen concentration in the culm+sheath at flowering by about 80%. At harvest, the concentration decreased substantially irrespective of nitrogen levels and varieties. Relatively more nitro...

HISTOCHEMISTRY OF SILICON IN RICE PLANT : I. A New Method for Determining the Localization of Silicon within Plant Tissues

While the essentiality of silicon to the growth of higher plants, in a strict sense, has remained questionable, beneficial effects of the element on the growth of rice plant have been repeatedly confirmed by Japanese workers1),2),3),4) to date. Recently, Japanese soil scientists have focused their efforts on the improvement of Akiochi, a well-known physiological disease of paddy rice, and have found that the application of silicate slags is one of the most effective practices. Systematic studies conducted by OTA et al. 5) OBATA) and revealed that silicon is the main factor responsible, for the beneficial effects of silicate slags on the improvement of Akiochi.

Grain-filling characteristics of rice varieties (Oryza sativa L.) differing in grain size under controlled environmental conditions

Eleven rice varieties differing in grain size were grown under controlled environmental conditions during the grain-filling period. The grain weight of upper grains in a panicle was examined at successive stages of growth during the grain-filling period. The effect of temperature on the rate and the duration of the period of grain-filling was determined using Khao Lo, a large-grain variety, and Bom Dia, a small-grain variety. Both the grain-filling rate and duration of the period of grain-filling differed among rice varieties and were positively and significantly correlated with the grain size. The duration of the grain-filling period from flowering to the time when almost maximum grain weight was attained ranged from 12 days at 32/24°C in Bom Dia to 36 days at 20/12°C in Khao Lo. The grain-filling rate was low in small-grain varieties, and generally increased with increasing grain size. By lowering the temperature, the grain-filling rate decreased, the duration of the grain-filling period increased but t...