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Articles by D.E. Leihner
Total Records ( 2 ) for D.E. Leihner
  B.C. Roy , D.E. Leihner , T.H. Hilger and N. Steinmueller
  The experiments were carried out from 1996 to 1998 at the Bangladesh Rice Research Institute in Gazipur. Four rice varieties-Nsail and BRRI dhan31 (BR31) in the wet season (WS) and HB6 and BRRI dhan29 (BR29) in the dry season (DS) were tested. Nsail and HB6 were local, whereas BR31 and BR29 were modern varieties. Four N rates- 0, 50, 100 and 150 kg N ha-1were given. The rates of 50, 100 and 150 kg N ha-1 were given in three application schedules-two, three and four splits. The pattern of leaf area index (LAI) and crop growth rate (CGR) differed among the varieties. LAI and CGR of DS varieties were very low during early growth stages compared to WS varieties. LAI increased gradually and reached its peak around PI stage in Nsail, whereas for the other varieties, peaks were around heading stage. HB6 always showed a lower LAI than the other varieties. The yield-LAI relationship showed that the optimum LAI of the modern variety for achieving the highest yield ranged from 4 to 5, whereas the optimum range of the traditional DS variety was between 3 and 3.5. The LAI of the lodging-prone variety Nsail was above optimum throughout the growing season and the relationship between LAI and yield was negative. Nitrogen rate had a profound effect on leaf area development. Two-split treated plots of BR31 and 3-split treated plots of HB6 and BR29 showed the highest LAI around PI and heading stages in most of the cases. In Nsail, the CGR peaked before PI stage, whereas for BR31 and HB6 the peaks were reached around heading stage and declined thereafter. For the modern DS variety, an almost steady growth rate was observed. In most cases, the 3-split treated plots of BR29 showed higher CGR at PI and heading stages compared to the other split arrangements. Higher CGR after heading for the modern DS variety BR29 compared to other varieties may have led to a higher grain yield in BR29.
  B.C. Roy , D.E. Leihner , T.H. Hilger and N. Steinmueller
  Nitrogen accumulation, uptake and use efficiency of wet and dry season varieties were determined from field experiments conducted in 1996 to 1998 at the Bangladesh Rice Research Institute (BRRI) in Gazipur, Bangladesh. Four rice varieties were tested, Nsail and BR31 were planted in the wet season (WS) and HB6 and BR29 were planted in the dry season (DS). Nsail and HB6 are local, whereas BR31 and BR29 are modern varieties. The experiments were laid out in a two-factorial randomized complete block design with four replications. The two factors were nitrogen rate and its application schedule. Four N rates-0, 50, 100 and 150 kg N ha-1 were given. The rates of 50, 100 and 150 kg N ha-1 were given in three application schedules-two, three and four splits. Transplanting was done on the first week of August and first week of January for the WS and DS, respectively. Nitrogen uptake differed greatly among the varieties and nitrogen rates. The increase of total N uptake with N rate was almost linear for the modern varieties, whereas the traditional varieties showed a quadratic relationship between total N uptake and N level. Effect of N split application on N uptake was small, but the difference among the split applications were more pronounced when higher amont of N was applied. Genotypic difference in grain and straw N concentration of all the varieties was observed and increased with each increment of N fertilizer. Averaged across treatments and years, the highest grain N concentration was observed in BR31 and the lowest in BR29. The straw N concentration at different N rates were more pronounced in the wet season varieties, especially Nsail, which had the lowest straw N concentration when no N was applied but showed highest straw N concentration when 150 kg N ha-1 was applied. The agronomic fertilizer efficiency and the apparent N recovery percentage varied greatly among the varieties and decreased with higher N rates. The agronomic efficiency of the DS varieties was higher compared to the WS varieties. Across the years, the N recovery percentage of the tested varieties at different N rates and application schedules ranged from 20 to 40% for Nsail, 24 to 43% for BR31, 29 to 40% for HB6 and 35 to 51% for BR29.
 
 
 
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