The research was carried out at the Central Potato Research Institute (CPRI), Modipuram, Meerut Campus and India between 2012 and 2013 (Experiment work period 2013-2016 and written work period 2016-17). Potato virus-free certified micro plants were collected from (CPRI) Modipuram, Meerut. Two varieties, kufri Bahar and kufri Surya, were chosen for tissue culture studies in the lab (Fig 1a, 1b and 1c).
(Meenakshi, 2020). Harvested microtubers were washed with sterile distilled water and remove the adhering constituents and dipped for 10 minutes in a dilute fungicide solution (Bavistin, 0.2 per cent), dried on filter paper and preserved in petri dishes in the light at 20°C for 2 days (Fig 1d and 1e). Petri dishes were wrapped in parafilm and refrigerated at 4°C for 4 months in dark. After three months, the microtubers were removed from the refrigerator and brought to room temperature for 12 days. Microtubers were sprouted within 12 days and planted directly into the seedbeds at a spacing of 10 x 30 cm during the first week of November 2012 and 2013 in net house where Plot size was 1.5 m x 2 m = 3 m
2/treatment. In this experiment used Split Plot Design with five replications and three treatments. The net house soil was sandy loam texture, organic carbon (0.47 per cent), rich in available phosphorus (51.2 kg/ha) and medium in available potassium (160.4 kg/ha) and had neutral pH. (7.5). The planting depth was 4 cm and planting geometry was 30 cm (row to row)/*10 cm (plant to plant). The, fertilizers applied consisted of 100 kg N, 53 kg P
2O
5 and 67 kg K
2O per hectare, as calcium ammonium nitrate, diammonium phosphate and muriate of potash respectively. Full doses of P and K were applied just before transplantation of
in vitro microtubers while N was split in three equal applications. A light irrigation was given with the help of a shower just after transplanting of
in vitro microtubes. Two times irrigations were given daily with the help of a shower for a week and after that need based irrigation was given. Manual weeding was done(Fig 2a and 2b). Haulms of the crop were pulled at 90 days after transplanting while harvesting carried out manually after 15 days (Fig 2c and 2d). Five plants were tagged from each treatment and the growth parameters were measured. Plant emergence was recorded in the net house on alternate days beginning with the first plant’s emergence after 7 days of planting. The yield parameters (Fig 2e and 3a) were recorded in the net plot at harvesting minitubers. For potato shape index five tubers per sample were drawn from each treatment in five replications (Fig 3b). Each tuber was measured for maximum length, width and thickness representing three different planes. The maximum value, across a particular plane was taken and PSI formula
(Singh et al., 2004). The obtained poll data were statistically analysed using a completely randomised design and the software IRRISTAT
(IRRI, 1999). After harvesting, minitubers were transferred in cold storage at 4°C and relative humidity conditions for 190 days.
In the next season the experimental field was ploughed with a tractor-drawn disc plough for burying the Dhaincha crop a month before planting for preparatory tillage. For pre-sowing irrigation, the field was prepared with two cross disc harrowing and two cross tiller operations to achieve the desired tilth. The field was cross-planked to keep the soil moist. The layout was created by hand.The experiment was designed as a split plot with five replications.
Before planting, the amounts of nitrogen, phosphorus and potash were applied. In all plots, phosphorus (Diammonium phosphate 18% N, 46% P
2O
5) and potassium (Muriate of potash 60% K
2O) were applied at a uniform rate of 80 kg P
2O
5 and 100 kg K
2O ha
-1. The remaining half doses (90 kg per ha of N) were applied as urea, which was broadcasted in-furrow at the time of earthing up after 25 days of planting. Gross plot size was 5.85 m x 2m = 11.7 m
2 and the ridges were prepared at 65 cm intervals using a tractor-drawn ridger and tubers were manually planted 20 cm apart at a depth of 10.0 cm. After 15 days of planting, experimental plots were gap filled. Manual weeding was used to control weeds by desiccating weeds and improving aeration in the ridges, which was then earthed up. For water management, the crop was lightly irrigated every 8 days after planting and the irrigation was turned off 10 days before tuber harvesting. For the control of whiteflies and insects imidacloprid, ostheon, trizophos and thimethoxam were spread at the different intervals as per requirement. Phorate @ 25 kg a.i ha
-1 was applied in the soil at the time of earthing up. For the control of late blight metabolix, metalaxyl and cymoxanil were spread at different intervals as per requirement. Harvesting was done manually in the morning hours (Fig 3c and 3d). The tubers were left in the field for 2.5 hours to allow the soil to dry and be removed. The required observations were recorded in the same manner as in the net house. The pooled data were statistically analysed using a split-plot design and the IRRISTAT software
(IRRI, 1999).