Based on total water use, monthly rainfall of a growing season (December to March) and soil available water, water balance was prepared for onion in the 1992-93 rabi season at the Shallow Red-Brown Terrace soil area of Bangladesh. This prepared water balance revealed that initial coil water storage was only equivalent to the water requirement of onion for December and that onion was deficit in water from January to March. The importance of soil management in increasing initial water storage in order to improve water balance was demonstrated and alternative management practices for the area were suggested.

1. The experiment was carried out to determine which factor played the dominant role in determining the nutritional status of aphids: a) trichomes as a physical defense or b) plant nitrogen content together with leaf moisture. ‘The influence of trichomes on ladybird beetles was also studied.

2, Terminal and young leaves had the highest trichome density, nitrogen content and leaf moisture, and the lowest infestation of aphids and visiting ladybird beetles.

3. Trichome density, nitrogen content and leaf moisture decreased with increased leaf age, but the total number of aphids and ladybird beetles in corresponding leaf categories were found to increase with leaf age.

4, The individual relationship between trichome density, nitrogen content and leaf moisture compared with that of aphid population was found to be negative,

5. The number of total and well-developed embryos was higher in aphids developed on terminal and young leaves with higher nitrogen content and leaf moisture.

6. Leaf age and nutritional status did not affect the size of the largest aphid embryo.

7. The percentage of alatoid nymphs was higher in mature leaves compared with other leaf categories.

The experiment was carried out at the Bangabandhu Sheikh Mujibur Rahman Agricultural University in order to evaluate root growth of sweet potato intercropped with maize at different application levels of nitrogen and potassium fertilizer. Sweet potato at 100% population density was intercropped with maize at 50% population density at four nitrogen fertilizer levels (0, 50, 100, 150 kg N ha^-1) and four potassium levels (0, 40, 80, 120 kg K₂O ha^-1). Nitrogen and potassium fertilizers were applied in combination in order to observe their individual and combined effect on intercropped sweat potato root growth. Nitrogen and potassium fertilizers did not interact significantly with intercropped sweet potato root growth, yet increased N levels independently increased thickened root number but not tuberization index, tuber diameter or tuber fresh weight. However 100 kg N ha^-1 had the best indices of intercropped sweet potato root growth parameters. Potassium had no effect on tuber initiation although it had a great effect on intercropped sweet potato tuberization index, tuber diameter and tuber fresh weight, Sweet potato without intercropping had the highest tuber diameter and tuber fresh weight. However 100 kg N ha^-1 and 120 Kg K₂O ha^-1 produced the highest number of tuberous roots and a higher tuberization index. ‘These growth parameters narrowed the difference in root growth between sole and intercropped sweet potato.

This study investigates some characteristics of soil surface temperature calculated form a multiple soil layer model (MSLM). Assuming a diurnal forcing in the model temporal variations in surface temperature are analyzed. The amplitude of temperature variation is smaller compared with theoretically-derived amplitude. The MSLM potentially underestimates absolute values of surface temperature. It is suggested that the thickness of the top soil layer of the model be set at 0.1 - 1 mm in order to obtain realistic temperatures.

Performance of onion under different reduced light levels was evaluated at the Bangabandhu Sheikh Mujibur Rahman Agricultural University research farm during winter season, 1998-99. The light levels were 100, 75, 50, and 25% PAR (Photosynthetically Active Radiation). The reduced light treatments were imposed using mosquito nets immediately after the establishment of onion seedlings and were maintained up to final harvest. Except plant height, all the studied parameters of onion were decreased with the decrease of light levels. Plant height was increased with the increase of light levels where the tallest plant (61.87 cm) was observed under minimum light level, i.e. 25% PAR which was similar to 50% PAR level. The smallest plant (44.29 cm) was observed under full light (100% PAR). Number of leaves per plant and bulb diameter manifested an almost similar response where the highest values of both parameters were observed under full light level and did not vary significantly up to 50% light reduction. Further, significantly the lowest values were observed under 75% reduction of light i.e., minimum light treatment. Both fresh and dry yields of onion obtained under full sunlight were the highest (21.17 and 3.53 t/ha) but these yields were statistically equal to the yield obtained under 25% PAR reduction for fresh yield, and under 50% PAR reduction for dry yield, Compared with fresh and dry yields under full sunlight, the yield reduction under 25; 50; and 75% light reduction levels was 15 and 13; 28 and 20; and 42 and 41%, respectively.

SDS-PAGE patterns of outer membrane proteins of Ralstonia solanacearum were compared with those of R. picketti, Erwinia carotovora subsp. carotovora, E. carotovora subsp. atroseptica, Burkholderia gladioli pv. gladioli and B. caryophylli. These species were discriminated easily on the basis of the dominant bands. For intraspecific grouping of R. solanacearum, outer membrane proteins for twenty-three strains isolated from Brazil were extracted by LiCl and analyzed by SDS-PAGE. All strains had protein bands of ca, 30 and 42 kDa. The strains showed various polypeptide patterns associating with the both original hosts and biovar. Major differences among Brazilian strains were detected when comparison was conducted basing on bands of 27, 29, 38 and ranging from 58 to 190 kDa. Biovars 3 and 2 from tomato were discriminated clearly from the other strains by absence of a 58 kDa band. In potato strains, biovar 1 was different from biovar 2 by the presence of 110 kDa band. On the whole, strains of the same biovar isolated from the same host exhibited uniform pattern. The SDS-PAGE profiles of membrane proteins will be useful as a benchmark for an intraspecific grouping of R. solanacearum.

For monitoring behavior of wilt bacteria Ralstonia solanacearum strains (biovars 1, 2, 3) in root systems of various plants, multi-antibiotics-resistant strains were induced and used as inoculants, By tracing of the wilt bacteria, marked results were obtained. The population changed dynamically depending upon plant species tested. Distinct decrease of the wilt bacteria was observed in root systems of lettuce, rice, onion, welsh onion, maize, cucumber and soybean, The population of each biovar varied obviously during the plant cultivation for 60 days. Biovar 2, generally was less frequently present except for the cases of zucchini and cowpea. Though biovars are the groups based on the utilization of carbohydrates, correlation with plant species in affinity was partly indicated in present studies.

The recent geological studies have showed the composite origin of Sulawesi Island. To see the faunal difference between the eastern and western parts of Sulawesi, a survey team consisting of 10 Japanese and 3 Indonesian researchers visited the island during the period from 7 to 24 October, 1999 and collected insects from various habitats of S and SE Sulawesi. The major target organisms were plant galls and the gall makers, ants, planthoppers, leafhoppers, treehoppers, aphids, butterflies, beetles, parasitic Hymenoptera and so on. The report describes an outline of the survey and summaries of tentative results.