Interaction of irrigation and nitrogen fertilization on yield and input use efficiency of sesame cultivars

The effect of irrigation regimes and nitrogen (N) rates and their interactions on sesame (Sesamum indicum L.) yield is not completely evaluated; hence, the current study was conducted to investigate effects of these factors on sesame yield, N fertilizer use efficiency (NFUE), irrigation water use efficiency (IWUE), and seed oil content. The experiment was carried out in a semiarid region of Iran during 2016 and 2017 growing seasons outlined in a randomized complete-block design with a split factorial arrangement of treatments with three replicates. The main plots were allocated to the deficit and full irrigation regimes. Factorial combination of three N levels (0, 60, and 120 kg N ha(-1)) and three sesame cultivars (Oltan, Dashtestan, and Naz) were assigned to the subplots. When averaged over the years and cultivars, the results showed that the enhancement of applied N (0-120 kg N ha(-1)) increased sesame seed yield by 81% with full irrigation and by 51% with deficit irrigation. Maximum IWUE was found in Oltan treated with 120 kg N ha(-1) under full irrigation (0.26 kg m(-3)), while the minimum value was found in Naz treated with 0 kg N ha(-1) under deficit irrigation (0.05 kg m(-3)). The mean comparisons of NFUE showed that in the 60 kg N ha(-1) treatment, each kilogram of applied N led to the production of 13.8 and 4.5 kg seed ha(-1) with full and deficit irrigation, respectively. In contrast, in the 120 kg N ha(-1) treatment, each kilogram of applied N resulted in the production of 7.6 and 2.1 kg seed ha(-1) in the full and deficit irrigation regimes, respectively. In general, the optimal rates of N depended on the sesame cultivar and varied for different regimes of irrigation. Managing N fertilizer levels to meet sesame demands based on the amount of water applied and the type of cultivar not only prevented a negative environmental effect, but also increased yield and conserved agricultural inputs for sesame grown in arid and semiarid regions.

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