Occurrence of fungal diseases of lowland rice in the province of Lampung, Indonesia, was surveyed during rainy season, from December, 1979, to January, 1980. It was indicated that the most prevalent air-borne diseases in this district were Cercospora leaf spot and panicle blight. There was no obvious varietal difference in the development of both diseases among rice varieties observed. Cercospora leaf spot occurred first on leaves of seedlings in nursery, decreased after transplanting, and then rapidly increased after the stages of flowering. At the dough-ripe stage, all leaves were heavily infected by the disease. The diseased rice plants growing in fields adjacent to nursery was suggested to be a major source of the primary inoculum. Helminthosporium blight also occurred on seedlings, but it decreased after transplanting and seldom observed at the flowering to harvest stages. Panicle blight appeared on rice hulls as early as after flowering and increased as the age of rice advanced. At harvest, the diseased grains exceeded 30% of mature grains and their weight was reduced to a large extent. Frequency of isolation of fungi from diseased hulls suggested that the causal fungi of the panicle blight in this area are not Sphaerulina or yzina, causal fungus of Cercospora leaf spot, but rather some other fungi belonging to genus Helminthosporium, Curvularia and Fusarium.

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Relationship between the efficiency of solar energy utilization and growth parameters in seven sugarcane varieties were studied at the experimental field of Okinawa Agricultural Experiment Station.
Changes with time of efficiencies of solar energy utilization were drawn as a parabolic-like curve with the maximum value in June and July.
Significant varietal difference in Eu was found only in early and middle periods. It was considered that different values of Eu related more to magnitude of net assimilation rate than to size of leaf area index.
Eu of RK65-37 and RK65-368 was higher than Eu of NCo310 in early and middle periods of growth, but Eu of NCo310 was higher than Eu of other varieties in late period of growth. In selection of varieties with higher Eu exceeding NCo310, in addition to keeping higher LAI, more stress should be placed on selection of varieties with higher NAR.

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[in Japanese]

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From 1976 to 1977, the recovery of fertilizer nitrogen by rice plants was studied using ¹⁵N isotope tracer technique in frame and pot experiments in Java, Indonesia.
The total recovery ratio by the rice plants after three split applications of fertilizer (basal dressing, top dressing 30 days after transplanting, top dressing at panicle formation stage) ranged from 26-63% in the two substations where the soil consists of brown latosol and grumusol, respectively.
Data on the recovery ratio for fertilizer application at each period of growth showed higher values for top dressing at the panicle formation stage. In the experiments aimed at evaluating the effect of the planting density, N recovery ratio was higher in the 20×20 cm and 25×25 cm plots than in the plots with higher planting density.
In the frame test with straw application, there was no clear difference in N recovery ratio between the control and straw treatment, but, in the pot experiments, N recovery ratio decreased with straw application. This difference was ascribed to the difference in the amount of soils used (frame test and pot experiment) and soil temperatures.
No significant difference was observed between N recovery ratios obtained in the experiments in Indonesia and in similar experiments conducted by one of the authors in Japan.

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[in Japanese]

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