Irrigation water quality and mulching effects on tuber yield and soil properties in potato (Solarium tuberosum L.) under semi-arid conditions of Indian Punjab

A field experiment was conducted for 5 years from 2009 to 2015 at Punjab Agricultural University Regional Research Station, Bathinda, Punjab, India to observe the effect of irrigation water quality on tuber yield, soil characteristics and water productivity of potato under mulched conditions in light textured soil under semi arid climate of Indian Punjab. The experiment was conducted in split plot design with three mulch treatments viz. no mulch (M-0), rice straw mulch @ 6 t ha(-1) (M-s) and polyethylene mulch, black 50 mu m (M-p) in main plots and three irrigation water qualities viz. canal water alone (CW), poor quality saline-sodic ground water alone (GW) and cyclic use of CW and GW (CW-GW) in sub plots. The experimental soil was alkaline in reaction, low in organic carbon, medium in available phosphorus and high in available potassium. The electrical conductivity (EC) and residual sodium carbonate (RSC) of canal water and ground water was 0.45 dS m(-1), -0.6 mmol(c) L-1; and 2.2 dS m(-1), 6.44 mmol(c) L-1, respectively. The results revealed that under unmulched conditions (M-0), CW and CW-GW gave significantly higher tuber yield than GW. Mulching, in general, resulted in significantly higher marketable tuber yield than in non mulched conditions. The tuber yield was statistically at par with M-s and M-p, irrespective of the irrigation water quality. Similar trends were observed in case of yield attributing parameters viz. plant height, number of haulms per plant and number of marketable tubers per plant. The water use efficiency was higher under M-s and M-p than under M-0. The highest water use efficiency was recorded in M-s under CW irrigation. Among the quality parameters, dry matter and total sugars increased with application of saline-sodic GW as compared to CW-GW and CW irrigation due to higher abiotic stress due to salts.