Effect of canal and desalinated water irrigation with varying levels of fertigation on fruit yield and nitrogen uptake of tomato under polyhouse conditions

A study was conducted at PAU Regional Research Station, Bathinda during 2017–18 to investigate the effect of quality of irrigation water and fertigation levels on the growth, yield, N content and uptake in tomato (Solanum Lycopersicum L.) under polyhouse conditions. The treatments included two irrigation water qualities viz. canal water (CW) and desalinated water (DSW) and three fertigation levels viz. 100%(F1), 80%(F2) and 60%(F3) of recommended NPK. Both the water qualities CW and DSW produced statistically similar dry matter production and total fruit yield of tomato. Increasing fertigation level from 60% of recommended NPK dose (F3) to 100% (F1) significantly increased the total dry matter and fruit yield of tomato at successive growth stages (120 days after transplanting (DAT), 150 DAT, 180 DAT and at maturity). The N content of different partitioned plant parts viz. leaves, stem and roots decreased with each successive growth stage, irrespective of water quality and fertigation levels. Water quality had no significant effect on the N content and uptake of leaves, stem and roots at successive growth stages. The fertigation level (F1) recorded significantly higher content and accumulation of N in leaves, stem and roots compared to F2 and F3 at all growth stages. The absorption of N by tomato leaves increased with increasing plant age up to 150 DAT whereas the total N accumulation tended to decline at 180 DAT and maturity at all the fertigation rates in both the water qualities. Unlike tomato leaves, the total N assimilation in stem and roots continued to increase at successive stages of tomato growth up to maturity. The N content in fruits produced with both water qualities was also statistically similar but the fertigation levels had a significant effect on the N content of fruits at 7th picking and final harvest. Fertigation had a significant effect on soil available nitrogen content of soil. It is concluded that desalinated water proved to be as good a source to that of canal water for production of tomato with 100% recommended NPK fertigation levels under protected cultivation.