Assessing the Effect of Different Water Table Depths on Water Use, Yield and Water Productivity of the Okra Crop
Authors: Gul N., Babar M.M., Sarki A., Shaikh I.A., Mangrio M.A.
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An experimental study was carried out on a Lysimeter with the aim of partially meeting WRs (Water Requirements) of the Okra crop through SWT (Shallow Water Table) while maintaining the SWT at various levels below the ground surface. Under the study, CWR (Crop Water Requirement), yield, water productivity, salt accrual and contribution of SWTs towards meeting the CWR are assessed. The study was designed in accordance with the principles of CRD (Complete Randomized Design) with three treatments and four replications. The treatments; viz. T1, T2, and T3 consisted of maintaining the WTDs (Water Table Depths) at 45, 60 and 75 cm, respectively, below the ground surface. The crop was irrigated with a good quality water having ECw = 0.50 dS m-1 and pH = 7.3. The results of the study showed that the crop consumed the maximum amount of water under T1 treatment, followed by T2 and then by T3 treatment. Accordingly, the contribution of SWTs towards the CWR is 94.8, 93.2 and 42.9% of the total CWR under the T1, T2, and T3 treatments, respectively. Maximum yield is attained under T3 treatment, followed by T2 treatment and then by T1 treatment. Likewise, maximum water productivity is achieved under T3 treatment, followed by T2 treatment and then by T1 treatment. The dry bulk density (ρd) of the soil, under T1 and T2 treatments, increased slightly; however, it remained unchanged under the T3 treatment. The ECse (Electrical Conductivity) of the soil increased, whereas, the pH value of the soil decreased under all the treatments. Statistically, significant difference (p < 0.05) is observed in CWR, yield, water productivity, contribution of SWT towards crop water use, plant height and weight of the Okra pod; whereas, the difference in ρd, ECse, pH and length of the pod is observed as not significant (p > 0.05) under the three treatments. Accordingly, to make profitable use of SWTs, improve WUE and productivity, and maintain soil fertility, the depth of SWT be controlled at 75 cm for growing of the Okra crop. Adapting to this guideline will help in availing the maximum contribution of SWTs towards meeting the CWR and achieve the larger aim of water conservation.