Water use efficiency of green gram (Vigna radiata L.) impacted by paddy straw mulch and irrigation regimes in north-western India

Abstract

A multilocation field experiment was conducted at Students’ Research Farm, Department of Agronomy, Punjab Agricultural University (PAU), Ludhiana and PAU, Regional Research Station (RRS), Bathinda, during summer 2019. The experiment was conducted in RCBD with 15 treatment combinations with 3 replications. The treatments comprised of 3 mulch levels i.e., M0, M6, and M12 i.e., no mulch, 6 and 12 t ha−1, respectively, and 5 irrigation schedules i.e., I10, I20, I30, and I40 with 10%, 20%, 30% and 40% depletion of available soil water (ASW), respectively, and IR (PAU recommendation as 4 irrigations). The growth parameters (plant height, dry matter accumulation and leaf area index), yield attributing characters namely pods per plant, number of seeds per pod and thousand-grain weight, seed and straw yield were significantly higher in M12 than M6 and no mulch (M0). The growth parameters, yield attributes, seed and straw yield were significantly higher for I10 due to increased irrigation frequency (5–6 irrigations). Both M0I10 (seven irrigations without mulch) and M6I30 (3 irrigations with straw mulch (6 t ha−1)) treatments observed comparable seed yield (1.06 t ha−1). Therefore, the substantial increase in seed yield with lower crop water use with the usage of straw mulch saves a considerable amount of water. Subsequently, the use of 6 t ha−1 of straw mulch with 3 irrigations (30% depletion from available soil water) facilitated a higher seed yield. The crop water use (CWU) was highest for M0 as due to bare soil, resulted in more evapotranspiration. The bio-physical productivity (BPWP) and water use efficiency was found to be maximum for mulch treatments. The I10 reported maximum CWU, whereas, Bio-physical water productivity (BPWP) were higher for I40 treatment where only one irrigation was given in this treatment. The WUE was maximum in I30 treatment at Ludhiana and in I20 at Bathinda location.