International Journal of Plant & Soil Science

The experiment was conducted at Research Farm of the Department of Vegetable Science, CCS Haryana Agricultural University, Hisar during winter season of 2020-21. The treatments comprising of three planting dates (25^th September, 10^th October and 25^th October) and four levels of nitrogen (0, 75, 100 and 125% of RDN) were laid out in a randomized block design (factorial) with three replications.

Potato tuber quality parameters like dry matter of tubers and haulms, reducing, non-reducing and total sugar were recorded maximum under 10^th October planting, whereas, ascorbic acid and specific gravity of tubers were found non-significant. While, among the different nitrogen levels, 125% of RDN application recorded significantly maximum values for reducing, non-reducing and total sugar, while ascorbic acid, dry matter content of tuber as well haulms increased with increase in nitrogen levels upto 100% of RDN. Specific gravity of tubers was found maximum where no nitrogen was applied.

The highest values for nitrogen, phosphorus and potassium uptake in haulms and tubers were registered with 10^th October planting, whereas, nitrogen uptake in haulms, phosphorus uptake of tubers also found at par with 25^th October planting. Among the nitrogen levels, maximum NPK uptake in haulms and tubers were recorded with 125% of RDN application, whereas, phosphorus and potassium uptake by haulms was increased significantly with increasing nitrogen levels upto 100% of RDN application. The leftover NPK in soil after harvest was noted maximum with earlier planting (25^th September), while among the different nitrogen levels, leftover nitrogen in soil was increased with increasing levels of nitrogen upto 100% of RDN, while, phosphorus and potassium availability was recorded in reverse trends.