USE OF TRUE POTATO SEED FOR BETTER YIELDS

Potato seed being bulk commodity faces quality, availability, transportation and storage problems in Pakistan. True potato seed (TPS) being low-cost planting material can reduce production, storage and transport cost also with limited disease transmission. Nine TPS hybrid families were compared with variety Diamant during two autumn and spring seasons at National Agricultural Research Centre, Islamabad in nursery and field. Nursery management trials; substrate, hilling, planting time and geometry for maximum tuber production were also compared for maximum benefit.\ud \ud Amongst the TPS hybrid families, the performance of MF-1xTPS-67, TPS-7xTPS-67, MF-1 x TPS-13 and MF-11 xTPS-67 was better in autumn seasons than spring seasons by producing >500 and >300 tubers m-2 respectively in nursery evaluation. These families were also superior for plant vigor, plant height, leaves per plant, leaf area index, plant dry weight, crop growth rate, tuber yield m-2 and average tuber weight.\ud \ud Amongst the PTS hybrid families, the performance of MF-1 x TPS-67, TPS-7 x TPS-67, MF-1 x TPS-13 and MF-11 x TPS-67 was better in autumn season than spring seasons by producing >500 and >300 tubers m-2 respectively in nursery evaluation. These families were also superior for plant vigor, plant height, leaves per plant, leaf area index, plant dry weight, crop growth rate, tuber yield m-2 and average tuber weight.\ud \ud The same TPS families confirmed to be better than other families and standard variety Diamant under field conditions for two autumns. These TPS families were found significantly better for plant height, leaves per plant, number of stems m-2, leaf area, leaf area index, plant dry weight, crop growth rate and number of large (>55mm) and medium size (35 to 55mm) tubers m-2 resulting in higher yield. The yields of these four families were significantly higher (25.23, 24.75, 25.62 and 23.84 t/ha respectively) than other families, The percentage of marketable yield was higher in TPS families than that of control veriety Diamant.\ud \ud Seed being the most expensive input in potato cultivation, was significantly (2-3 times) less required in all the TPS families thus reducing cost of production and increasing net benefit. Cost benefit ratio was higher in TPS families thus reducing cost of production and increasing net benefit. Cost benefit ratio was higher in TPS families and net income from high yielding TPS families was three times higher than variety Diamant.\ud \ud Different substrate and hilling after germination increased the tuber number and average tuber weight. The substrate composed of soil, sand and farmyard manure in 1:1:1 ratio produced significantly higher tuber number and tuber yield per unit area as compared to loam soil and mixture of soil and FYM. Hilling also the average tuber weight and 12cm hilling in three installments, 4cm each, gave significantly better results.\ud \ud Planting time and planting geometry affected number of tubers significantly. October planting produced maximum tubers m-2 than September planting. Maximum average tuber weight was higher in September planting. Planting geometry of 25x4cm was the best fro seedling tuber production in nursery beds.\ud \ud Regarding planting materials; seedling tubers and seed tubers produced higher number and weight of tubers and better yield while transplanted seedlings produced very small tubers and gave the lowest yield. The transplanting during autumn season was not successful that may be due to short growing period and early frost incidence during the month of December. Number of tubers per plant was higher in seedling tubers and seed tubers of TPS families as compared to seed tubers of Diamant variety. Seed tubers of TPS families produced higher percentage of medium of large size tuber than that of Diamant variety. The economic benefit was significantly higher from TPS families in seedling tubers and seed tubers over Diamnat (seed tubers) and transplanting of TPS seedlings.\ud \ud The use of seedling tubers for commercial potato production brings the maximum net profit and highest cost benefit ratio making it the most liked planting materials and showed better potential for adoption of TPS technology for potato production in Pakistan. The dissemination of this technology at mass scale is needed to harvest the benefits