AN APPROACH OF DEVELOPING PRODUCTION TECHNOLOGY OF DISEASE FREE QUALITY SEED POTATO

Abstract

The experiments were conducted at the research field and post graduate laboratory of Plant Pathology Department, HSTU, Dinajpur, during November 2014 to march 2018 to improve the technique of low-cost disease free potato seed production protocol. Farm saved seed was compared with certified seed, positive selection seed, seed plot technique’s seed and TLS seeds potato in 1st experiment. The different seed planting time of 15th October, 4th November, 24th November and 14th December and different Haulm pulling time at 68, 75, 82 and 89 DAP were evaluated in 2nd experiment. The different size of mother seed tuber like S1 = 15 to 25 mm, S2 = 25 to 35 mm, S3 = 35 to 45 mm and S4 = 45 to 55 mm diameter with different concentration of gibberellic acid (GA3) like G00 = 00 ppm, G20 = 20 ppm. G40 = 40 ppm, G60 = 60 ppm were used to evaluate in 3rd experiment. The four different categories of seed potato viz. Minituber, Breeder seed, Foundation seed and Certified seed were used to advance generation in 4th experiment. In the 5th experiment 35 to 45 mm and 35 to 45 mm seed tuber with the haulm pulling at 75, 82, 89, 96 and 103 days after planting (DAP) were evaluated to adjusting haulm pulling time for GA3 treated seed tuber. The maximum yield (27.72 ton/ha) was recorded from Positive Selection’s Seeds which was similar with Certified and Seeds of SPT. But, the maximum plants (≥ 8 %, 7.33 % and 4.17 %) were infected by PVY, PLRV and PMV respectively in Farmer’s seed. 100% emergence was recorded from all planting time except 15 October. Maximum late blight (LB) infestation (2.90%) and LB severity i.e. PDI (21.81) was recorded in planting time of 24th November during 1st week of January 2017. At 60 DAP, maximum potato virus Y infected plants (2.08%) were identified from 24th November planting time which was followed by 4th November. At haulm pulling time, the highest percentage (9.38%) of PMV affected plants was counted from 24 November. The maximum infected plants (PRLV 3.13%, PMV 4.69% and PVY 2.6 %) were recorded from late haulm pulling (89 or 82 DAP). The maximum potato yield (29.23 ton/ha) and seed potato yield (23.87 ton/ha) were recorded from 24 November with HP 89 DAP and 4 November with 82 DAP, respectively. The highest (23.05) branch number of sprouts /tuber were recorded from S4G40. The maximum percentage of potato mosaic virus and potato leaf roll virus was found at G60. The maximum and minimum percentage of potato leaf roll virus was found in S1 and S4. The height (42.67 ton/ha) yield was recorded from S4G60 which was similar with S3G40. In 1st, 2nd and 3rd generation, the maximum 0.46 %, 1.39 % and 5.56% plants were naturally infected by potato virus Y in certified seeds. The minimum 0%, 0% and 0.46% plants were naturally infected by potato virus Y in minituber. Similar results were recorded for PLRV. The infestation of Rhizoctonia canker, common scab and deformed tuber of potato were also increased with increasing generation. In 1st generation, the highest healthy tuber yield (36.58 ton/ha) was recorded from breeder seed. In 2nd and 3rd generation, the highest healthy tuber (36.39 ton /ha and 32.85 ton/ha) was found from progeny of minituber. But increasing generation decrease the healthy tuber yield except minituber (7.06% increase in 2nd generation). The maximum infected plants ((PMV 3.70%, PVY 2.78 % and PRLV 4.32 %,) were recorded from late haulm pulling (103 DAP). The maximum seed potato yield (29.28 ton/ha) was recorded from 96 DAP haulm killing which was similar with 89 and 103 DAP haulm killing. The highest benefit-cost ratio was observed in of 35 - 45 mm mother seed (40 ppm GA3 treated) with haulm pulling at 96 DAP (2.83). For seed potato production, best planting time is 1st week of November and haulm pulling at 75 to 82 DAP in conventional system. But by using 40 ppm GA3 in mother seed tuber with haulm pulling at 89 DAP is suitable and profitable for seed potato production. Farm saved seed should be avoided and increasing generation of seed potato decrease the yield of seed potato.