Effects of Zeolite and Deficit Irrigation on Sweet Pepper Growth

The use of zeolites in agriculture as a soil conditioner is becoming an important field of research in crop growth. To study the effect of synthetic zeolites and deficit irrigation on sweet pepper (Capsicum annuum L.) cultivation, an experiment was conducted in a controlled environment. In particular, sweet peppers were cultivated in a glasshouse using polypropylene pots filled with sandy loam soil, to which 2% zeolite was added. The zeolite employed in the experiments was obtained using coal fly ash as a raw material. The experiment consisted of two main treatments: (a) soil with a zeolite at 2% (Z) and (b) soil without a zeolite as a control (C). Three subplot treatments consisted of (1) full irrigation at 100% of the available water content (AWC) (100); (2) deficit irrigation at 70% of the AWC (70); and (3) deficit irrigation at 50% of the AWC (50). Sweet pepper cultivation started on 24 April 2023 and lasted until 23 June 2023; during the trial, the environmental data, such as the soil humidity, air temperature, and relative humidity, and some crop parameters, such as the plant height, leaf number, and the SPAD index, were monitored. At the end of the trial, the fresh and dry plant weights, the dry matter content, and the leaf water potential were measured. The results showed that, for the plant fresh weight and dry matter content, no significant differences were observed in the treatments and their interactions, whereas, for the other parameters, the statistical analysis showed significant differences. The study suggests that the soil's structural benefits, resulting from zeolite application, are not followed by an equal positive effect in terms of sweet pepper growth under deficit irrigation conditions.