Effect of superabsorbent polymer and plant bio-regulators on growth, yield and water productivity of Indian mustard (Brassica juncea L.) under different soil moisture regimes

Abstract

A field experiment was conducted during 2018-19 to evaluate the field efficacy of superabsorbent polymer (SAP: Pusa hydrogel) and plant bio-regulators (PBR’s) on growth, yield attributes, yields and water productivity of Indian mustard (Brassica juncea L.). Different PBR’s like salicylic acid (SA, 100 ppm), thiourea (TU, 0.1%) and potassium nitrate (PN, 1.5%) along with SAP (2.5 kg/ha) were compared with control under moisture stress and normal moisture regimes in a factorial randomized complete block design with three replications. Crop under normal moisture regimes obviously resulted the maximum values of growth, development and yield parameters than the moisture stress regime. The combined application of SAP+PBR’s, especially SAP+SA followed by SAP+TU further improved these growth and yield parameters under both the moisture regimes, but greater response was observed under moisture stress regime. The negative effect of moisture stress on growth and yield parameters led to significant decrease in seed, stover and biological yields by on an average 11.3, 6.7 and 8.0 %, respectively over the normal moisture regime. Further, seed yield penalty due to moisture stress was recorded the maximum under the control (17.7-20.4 %) followed by SAP (14.9 %) and least under the SAP+PBR’s applied treatments (4.2-6.4 %). This signifies the beneficial role of SAP and PBRs in mitigating the moisture stress and reducing the yield losses under deficit moisture conditions. Among different moisture stress mitigation options, the highest seed yield (2.63 t/ha) and biological yield (9.47 t/ha) were recorded with SAP+SA which was remained on par with SAP+TU and SAP+PN but significantly higher by 8.7-24.6 % and 4.8-17.6 %, respectively over the rest of the treatments. The water productivity was recorded significantly higher (~ 9.6 %) under moisture stress than the normal moisture regime. Further, SAP+SA resulted the maximum water productivity under both moisture stress (1.83 kg/m3 ) and normal moisture (1.56 kg/m3 ) regimes, which was also found to improve water productivity significantly by 15.8-41.9 % over the SAP and control treatments under moisture stress regime while by 17.2 % over the control under normal moisture regime. Thus, the use of PBR’s along with SAP can be recommended to maximize the yield and water productivity levels of Indian mustard, in addition to save the irrigation water under rainfed/limited water availability conditions.