Seven different irrigation schedules along with an unirrigated control treatment were tested on the cabbage (Brassica oleracea var. capitata L.) cultivar, Atlas 70 in a silty-clay-loam Plinthic Paleustult of Bangladesh during the 1993-94 growing period. The irrigation schedules were as follows; irrigation of the crop by allowing 60, 45, 30 and 15% depletion of available soil moisture (DASM) and supply of 20 mm irrigation water (IW) at IW: CPE (cumulative pan evaporation) ratios of 0.6, 0.9 and 1.2. Both gross and marketable yields of cabbage recorded in the plots irrigated at 30 and 15% DASM (5 and 8 irrigations) as well as at IW: CPE ratios of 0.9 and 1.2 (5 and 6 irrigations) were identical and significantly higher than those in all the other treatments. Thus the findings clearly indicated that cabbage may be grown with irrigation considering these criteria in order to achieve satisfactory yield in the experimental area. The total water use by cabbage for these 4 highest yielding irrigation schedules ranged from 158.44 to 183.23 mm. Maximum efficiency of irrigation water in terms of marketable yield (602.35 kg/ha/mm) was achieved when irrigation led to 30% DASM.

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Heat-sensitive stages in pod setting of common bean (Phaseolus vulgaris L.) were investigated using heat-tolerant varieties (Haibushi and Ishigaki 2) and a heat-sensitive variety (Kentucky Wonder) in a phytotron with controlled air tem-perature. After subjecting the plants to heat treatment (daily mean air temperature around 33°C) for one day or five days, pod setting ratio of opened flowers was examined. Four sensitive stages were identified in the flower buds of heat-tolerant varieties, Haibushi and Ishigaki 2. Flowers which had already opened and immature pods were not heat-sensitive. One of the four sensitive stages corresponded to 1 day to 2 days before anthesis in the three varieties. Other two sensitive stages corre-sponded to the period of around 9 days before anthesis and the period of around 12 days before anthesis. The period of around 11 days was less sensitive in heat-tolerant varieties. However, in Kentucky Wonder, flower buds were heat-sensitive also during this period. The last sensitive period corresponded to 15 to 25 days before anthesis in the three varieties. When very young flower buds in the stage were exposed to high night temperature for five days, they developed malformed flowers and flower shedding occurred. Heat treatment (e.g. day/night: 34.2°C/33.0°C) applied for one day (24 hours) to flower buds expected to open the next morning reduced drastically the pod setting ratio. To identify more precisely the heat-sensitive stages, an experiment consisting of heat treatment for eight hours (32.5°C from 4: 00 p.m. to 0: 00 a.m. or from 0: 00 a.m. to 8: 00 a.m.) was carried out. However, the treatment did not suppress pod setting, suggesting that high temperature (32.5°C) at the time of pollination, germination of pollen grains and fertilization did not affect directly the processes but that heat stress for a duration longer than 8 hours exerted cumulative injurious effects on reproductive organs.

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A virus isolate from Alstroemeria sp. showing chlorotic mosaic along veins was characterized and identified. The isolate AlMV-Y showed a narrow host range in 4 species of 3 families among 34 species of 12 families, and consisted of filamentous virus particles with 700-800 nm long and 12 nm wide. Scroll and pinwheel type inclusion bodies were also observed in the cytoplasm of mesophyll cells in ultrathin sections. The virus was transmitted by Myzus persicae and Neotoxoptera formosa non-persistently. Molecular weight of viral coat protein subunits was estimated to be 33kD. The isolate was purified and rabbit antisera (As-AlMV-Y) to AlMV-Y were produced. The isolate positively reacted with antisera to alstroemeria mosaic potyvirus produced by Drs. BRUNT and BOUWEN. Based on the results obtained, the virus isolate was identified as alstroemeria mosaic potyvirus (PHILLIPS et at., 1986, INOUYE et at. 1992) . Alstroemeria mosaic potyvirus was easily detected from samples from growers' fields or flower shops by serological methods using As-AlMV-Y. By tissue immunobinding assay and other serological methods, the virus was also detected from root systems.Alstroemeria originated in South America and many varieties were produced from wild species. As there are few studies on virus diseases of alstroemeria and other plants in the same or corresponding families which are mainly observed in tropical and subtropical area, it is suggested that study on virus diseases of these plants is significant for their future gene conservation, breeding of new varieties and production.

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Effects of urbanization on the vegetation structure of the home gardens was investigated in West Java, Indonesia. The study sites were divided into the most, intermediate and the least urbanized sites. The number of ornamental plant species and their relative values were the highest in the most urbanized sites and the lowest in the least urbanized sites. The intermediate urbanized sites had intermediate values. Positive correlation was detected between the area of home gardens and the number of species in both ornamental and non-ornamental plants. For all the sites the number of non-ornamental plant species increased at a higher rate with the increase of the area than was the case for ornamental plant species. In all the study sites the ratio of the number of non-ornamental plant species to the number of ornamental plant species was higher in the back and side yards than front yards. The ratio of the number of ornamental plant species in the plant community layers was high in the lower layer and low in the higher layer. The high ratio of ornamental plant species depended on the large number of species in the lower layer in the most and intermediate urbanized sites, and the lack of the higher layer in the most urbanized sites.

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Ponkan mandarin (Citrus reticulata Blanco) trees were subjected to shading for three weeks at two levels: high (70-75%) and low (55-65%), either at the end of anthesis (stage I), during major fruit drop (stage IIA) or at the onset of fruit expansion (stage IIB) . The objective was to monitor effects on source-leaf non-structural carbohydrate content, photosynthetic rate, fruit set, growth and quality; and thus evaluate fruit developmental responses to source limitations. Early shading (stage I) did not affect the fruit set and quality, whereas shading during the major fruit drop period (stage IIA) reduced the fruit set. Late shading (duringg high fruit growth rate) reduced the fruit size and increased the titratable acidity. Compared to early shading, late shading reduced the content of leaf non-structural carbohydrates and the photosynthetic activity of fruitless shoots significantly. High shading level caused larger reductions in fruit size, quality and weight than low shading although differences were not always significant.

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Mechanism and inheritance of resistance to rice tungro disease in the rice varieties Basmati 370 and IR 50 were studied. Resistance of Basmati 370 was associated with its resistance to rice tungro spherical virus (RTSV) infection, which was controlled by a single recessive gene. Individual selection for its resistance to RTSV infection in the F₂of a cross with a susceptible variety was effective in securing resistance in the F₃. The RTSV resistance showed a genetic relation with heading date and grain width. Resistance of IR 50 was associated with its resistance to the green leafhopper (GLH), which was controlled by a single partially dominant gene. Individual selection for GLH resistance in the F₂of a cross with a susceptible variety was ineffective in securing resistance in the F₃. However, line selection in the F₅was effective in securing resistance to GLH and virus infection in the later generations. Resistance to GLH in IR 50 was not related to heading date, culm length, panicle length, grain shape or resistance to the brown planthopper.

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