Headwaters initiate material export to downstream environments. A nested headwater study examined the flux of dissolved constituents and water from a perennial stream and four ephemeral/intermittent streams in the Upper Gulf Coastal Plain of Mississippi. Water was collected during storm and baseflow conditions. Multiple linear regression was used to model constituent concentration and calculate flux. Event was the major source of water discharged from the ephemeral and intermittent streams however, baseflow was the major source for water discharged by the perennial stream during events. The perennial stream had an area weighted average yields of 10.1, 0.01, 1.03, 0.65 kg/ha/yr of DON (dissolved organic nitrogen), NO3 --N, NH4 +-N and PO4 -3, respectively while large variabilities existed between the ephemeral and intermittent streams. These findings highlight the importance of headwaters in protecting the low order drainage basins as a key to water quality within perennial streams.

Maize (Zeae mays L.) is a second important crop in the country and it is first staple food in high land region. The national average yield is 2.2 t/ha. About 80% maize areas falls in this region. An introduced fungus Gray Leaf Spot (GLS) caused by Cercospora zeae-maydis has caused yield loss an average of 75%. Genetic resistance has been effective control strategy to manage this disease. The main objectives of this work were to develop, evaluate and identify high yielding cultivars tolerant to GLS. Three sets of trials were conducted in Nepal and Korea. GLS evaluation trial-I consisted of 73 genotypes, GLS evaluation trial-II composed of 38 genotypes and mid altitude hybrid evaluation trial-III consisted of 12 genotypes. Exotic, semi exotic and local germplasm of different origins were used. Among these tested genotypes, tolerant genotypes were Thai 717S31-21-3×[TZMi407 × TZMi211-11- 2-1-1-B-B-B-B-B (5.2t/ha), Pioneer12 × MASynVAR-5 F2 (5.0 t/ha) and MA SynVAR-5 F2 × Thai 919 S3 4-5-4 (4.7t/ha) with GLS mean score 2.7, 1.5 and 1 respectively in trial-I. In trial-II, superior genotypes were KYM33 × TZi3 (7.6t/ha), KYM33 × TZi18 (7.5 t/ha) and KYM33 × P45 (7.4 t/ha) with GLS scores 1.4, 2.4 and 2.5 respectively. Similarly in trial-III, high yielding genotypes were MASynVAR-5 (11.0t/ha), and TZMi407×87036- 9-1-1-1-B-B-B/TZMi102×90113-5-3-2-2-B-B-B-B (9.8t/ha). These hybrids and their parents will use to introgress resistant genes to breed better tolerant maize cultivars for Nepal.

A field study was conducted to develop an economically suitable combination of organic and inorganic fertilizers for sugarcane cultivation in sandy acidic soil of a commercial sugarcane farm under Old Himalayan Piedmont Plain of Bangladesh. Results revealed that the treatment T4 which received 75~% of Recommended fertilizers (N 120, P 35, K 100, S 25, Zn 2 kg ha-1 ) + 10 Mg ha-1 Rice mill ash + Mg ha-1 press mud significantly produced higher sugarcane yield (72.34 Mg ha-1 ) among all the treatments except T5 having 100~% of Recommended fertilizers + 10 Mg ha-1 Rice mill ash + 10 Mg ha-1 press mud, which was identical. T4 also gave the highest net economic benefit at Bangladesh Taka 15,920.47 per hectare from the added nutrient management. Thus, the integrated use with organic and inorganic fertilizer is highly essential for sustainable production of sugarcane in commercial farm of the region in Bangladesh, where it has been grown year after year.

Field experiment was conducted during 1993-94 season to determine the pattern of nutrient uptake and productivity of maize/sweet potato intercropping system. Four levels of nitrogen (0, 50, 100 and 150kg N ha-1 ) and four levels of potassium (0, 40, 80 and 120kg K2 O ha-1 ) formed treatment variables. Plants were sampled periodically to determine dry matter and tissue concentrations of N and K in the individual plant components of intercropped maize and sweet potato. Nitrogen and potassium fertilizer did not interact significantly to nutrient uptake by any plant parts of intercropped maize and sweet potato. But application of N fertilizer independently enhanced N uptake in all the plant parts of maize and sweet potato. The uptake of N in leaf, leaf sheath, stem, husk, and cob of maize increased upto 90 days after planting (DAP) but grain continued to accumulate N till its maturity. Sweet potato exhibited a wide variation in N uptake pattern. Sweet potato leaf shared the maximum uptake of N at 50 DAP which rapidly increased at 70 DAP and then declined. Declination of N uptake by petiole and stem were observed after 120 DAP whereas N uptake by tuber increased slowly upto 90 DAP and then rapidly till harvest. Rate of applied K had very little effect on the uptake patterns in different components of intercropped maize. Pattern of K uptake by leaf, petiole and stem of sweet potato showed almost similar trend to N uptake. But uptake of K by tuber increased almost linearly with the K application. Pattern of N and K uptake by grain and tuber paralleled the grain yield of maize and sweet potato respectively. Intercropped productivity of maize and sweet potato found to be better by the application of 100kg N and 120 kg K2 O ha-1