Effect of biofertilizers, seaweed extract and inorganic fertilizer on growth and yield of lettuce (Lactuca sativa var. longifolia L.)

Abstract

Due to the excessive use of inorganic fertilizers, the structure of the soil is deteriorated, and the product quality is adversely affected. For this reason, the use of environmentally friendly organic fertilizers in production has increased in recent years. A field experiment was conducted in a plastic greenhouse in the Research Center Field at General Directorate of Agriculture, Dohuk Governorate, Northern region of Iraq during autumn season of 2020 to examine the effect of soil application of the biofertilizer (Corabac) with three levels (0, 5 and 10 g L-1) and foliar spraying with the seaweed (algal extract) at three concentrations (0, 4 and 8 g L-1) and the inorganic fertilizer at two concentrations (0 and 1 g L-1 (N:P:K 10:10:10)) compared with control (without treatment) on growth and yield of lettuce crop (Lactuca sativa L.). The obtained data indicated that the application of the three fertilizers and their interactions significantly induced vegetative growth parameters like stem length and leaf number per plant but did not positively affected leaf area (cm2) and chlorophyll content (%). Head weight (kg), yield (kg m-2), and total yield (ton ha-1) were also notably increased due to soil addition of biofertilizer and foliar spraying of the algal extract and inorganic fertilizer as compared to the control. Biofertilizer, seaweed and inorganic fertilization affected the N, P and K content in lettuce leaves. For a sustainable production in greenhouse lettuce, it is possible to obtain higher head weight and therefore higher yield by using seaweed and biofertilizers, which are considered environmentally friendly.