Abstract
Experiments to find out appropriate technology for the production of TPS seedling tubers and their utilization under Bangladesh conditions were conducted at TCRC, BARI, Gazipur and BAU, Mymensingh during 1998-99 to 2000-2001 seasons. The area of studies covered increasing the germination of TPS and production and utilization of seedling tubers in relation to different abiotic factors. Eight months old TPS gave significantly better germination than 20 months old TPS either water soaked or sun treated both under petridish and nursery bed conditions. GA3 treated seeds always gave higher germination (94-98%) than water soaked or sun treated seeds, and showed 46-49% higher germination over the control. TPS either soaked in water for 120 hrs or sun treated for 18 hrs gave 60-65% and 52-60% germination respectively, which was 10-16% higher over the control. The germination of TPS was in the range of 97-98% under 80-100% soil moisture level and at 15-20°C temperature regime. Decrease of soil moisture or temperature reduced the percentage of germination. Maximum yield of tubers and economic return were obtained when the seeds were sown on Nov.1 (4.69 kg/m2) or Nov.15 (4.98 kg/m2) and haulms were cut at 95 (4.09 kg/m2) or 110 (4.48 kg/m2) days after sowing (DAS). Among three spacings studied, the highest yield (5.66 kg/m2) and economic return (BCR 2.81) were obtained from the closest spacing of 25cm x 4 cm. For seedling tuber production in raised bed, thinning of seedling did not appear to be required if sowing of TPS was done carefully with 2-3 seeds /hill at a spacing of 25cm x 4cm. Earthing-up 3 times (30, 45 and 60 DAS) or 2 times (35 and 55 DAS) in the raised bed produced identical yield of seedling tubers, while the latter gave higher economic return (BCR 2.69). The fertilizer dose of 175-115-210 kg of N, P2O5 and K20/ha applied as basal and two top- dresses of N and K20 at 35 and 55 DAS gave higher yield of seedling tubers (6.21 kg/m2) than basal and one top-dress of N and K20 (5.59 kg/m2). The highest economic yield of potato was obtained either by planting <5g size seedling tubers at 60cm x 5 cm spacing or planting three <1g size seedling tubers in one hole or two 1-<5g size seedling tubers in one hole at 60cm x 10 cm spacing. Whole and cut pieces of seedling tubers of same weight produced statistically similar economic yield of both seed and total tubers.