1. Introduction Water is an essential resource affecting growth, development and yield of crops. Potato is very sensitive to water availability as potatoes have shallow root system. pre-sowing irrigation is advantageous for uniform germination. Total water requirement of crop at seedling stage varies between 350-550mm depending upon soil type, climate and crop duration. Lack or excess of soil moisture affects tuber yield and quality.

2. Irrigation Methods Water requirement of a TPS nursery can be fulfilled by various methods including, 1.Sprinkler irrigation, 2.Trickle/Drip Irrigation and 3.Furrow Irrigation

3. Sprinkler Irrigation: Sprinkler irrigation system provides irrigation water like rain fall. Sprinkler irrigation system has characters such as, 1.It saves around 30-35% water than flood irrigation system. 2.It can be used to improve the microclimate of the nursery. 3.Irrigates a large area uniformly and at a time. 4.Minimizes soil erosion and prevents damage to soil structure. 5.The initial cost of establishment is high.

4. Drip Irrigation: Drip irrigation system is system of irrigation where water is supplied directly into the root zone of the plant. Drip Irrigation system has following characters: 1.It saves around 50% water than flood irrigation system. 2.Fertilizers can be applied to seedlings along with water. 3.Minimizes soil erosion but may causes soil salinity. 4.Evaporation losses are minimum but initial cost is high.

5. Furrow Irrigation System Drip Irrigation System

6. Furrow Irrigation System is a traditional system of applying water to the nursery. True potato seeds are sown on ridges and furrows prepared before sowing. This system of irrigation has characters such as, 1.Wastage of precious irrigation water. 2.Water logging conditions may occur in heavy soils. 3.Not suitable for TPS nursery. 4.There are chances of soil erosion and soil salinity problems. Furrow Irrigation System:

7. Quality of Irrigation Water Availability of good quality water is a very important input in nursery business. Potential sources of water include lakes, ponds, streams, wells and municipal water supplies. Potato is very susceptible to salinity of soil or water. Sprinkler irrigation with salt containing water may cause water burn damage to foliage. Most of the anions are phytotoxic and cations like Na+ damages soil structure.

8. Favorable Water Quality Parameters

9. Potato is a sensitive crop therefore, following criteria may be considered while finalizing the irrigation water source: 1.Minimum Level of contaminants and debris in water. 2.Water Storage facility in most demanding period (June-August). 3.Duration of the water availability from irrigation sources. 4.Environmental and legal limitations for using the water source. 5.Quality and quantity of the irrigation water. Selection of Irrigation Source

10. Water Quality Parameters for Different Sources Note: SS: suspended solids, DO: dissolved oxygen, EC: electrical conductivity, TN: Total Nitrogen, TP: Total Phosphorous, BOD: Biological Oxygen Demand, COD: Chemical Oxygen Demand