Marginal analysis of water productivity function of tomato crop grown under different irrigation regimes and mulch managements

Abstract

► Wider frequency irrigation (with 30 mm depth) is most beneficial for tomato crop. ► Difference between SET , against maximum WUE and yield, narrowed down under mulches. ► Black polyethylene mulch can be a good option under water scarce situation. During the winter season (November–March) of 2003–2004 and 2004–2005 a field study was carried out at the Research Farm of the University (Latitude 22°58′N, Longitude 88°31′E and altitude 9.75 m amsl), Gayeshpur, India. Aim of the study was to evaluate the sole and interactive effect of irrigation frequencies and mulches on performance and water productivity functions of tomato crop. The experiment was composed of three irrigation frequencies {rainfed (RF); CPE 50 and CPE 25 where irrigation was given at 50 and 25 mm of cumulative pan evaporation (CPE)}, kept in the main plots. The subplots consisted of four mulch managements {no mulch (NM), rice straw mulch (RSM), white polyethylene mulch (WPM) and black polyethylene mulch (BPM)}. Fruit yield under CPE 25 was 39.4 Mg ha −1 ; it reduced by 7 and 30% respectively under CPE 50 and RF condition. Different mulches increased fruit yield by 23–57% over non-mulch condition. Irrespective of mulching, water use efficiency (WUE), net evapotranspiration use efficiency (WUE ET ) and irrigation use efficiency (WUE I ) were found to be the highest (22 kg m −3 , 71 kg m −3 and 22 kg m −3 respectively) under moderately wet (CPE 50 ) soil environment. Among different mulches, BPM recorded the highest WUE (25 kg m −3 ), WUE ET (73 kg m −3 ) and WUE I (26 kg m −3 ) values. Critical values of seasonal evapotranspiration (SET) against maximum WUE and maximum yield were computed through marginal analysis of water productivity function. It was observed that the difference between these critical values was narrowed down under bio or polyethylene mulches compared to the bare situation.