Effect of Growing Substrates on Vegetative Characteristics of Peperomia magnoliifolia in an Interior Green Wall

Choosing an efficient and light weight growth media is one of the most important issues in the implementation of interior green walls. In recent years, the use of soilless culture in the world, including Iran, has been developing. In this regard and considering the use of agricultural organic biodegradable waste in culture media can play an important role in achieving a sustainable environment in addition to its economic advantages. Therefore, this study aimed to compare common media with agricultural organic waste (novel/composition) on growth characteristics of Peperomia plant.

The effect of five different growing substrates ratios (60:40 v/v%) were as follows: 1) peat moss + perlite; 2) compost composition (rice husk compost + tea waste + leaf soil+ rice hull) + perlite, 3) leaf soil compost + perlite, 4) rice hull compost + perlite, 5) tea waste compost + perlite, was conducted in form of a completely randomized design with t replications for Peperomia. In this study, growth traits such as leaf number, shoot count, shoot and root fresh and dry weights; physical properties of media, such as bulk and particle density, water holding capacity, and chemical indices including organic matter percentage, pH and porosity of the substrate, phosphorus, nitrogen, potassium, organic carbon percentage and cation exchange capacity and C/N ratio were measured.

The physicochemical analysis of the substrates combined showed that the composition of tea waste and perlite had superiority over the other media in terms of nitrogen content, water holding capacity, organic matter and organic carbon percentage as well as cation exchange capacity (Table 1). In addition, the lower bulk density in waste tea and perlite (0.15 g/cm-3) compared to the other studied media, can be an ideal indicator for application in the interior green walls (Table 1). Results of analysis of variance showed that different growing substrates have a significant effect (P ≤ 0.01) on the growth characteristics of Peperomia ornamental plant (Table 2). So that, Peperomia grown on compost composition (rice hull compost+tea residues+leaf compost) showed superiority in all measured traits in comparison with other media (Table 3). One of the important indicators for evaluating the advantage of substrates is the shoots dry weight (Golestani et al., 2020). In this study, plants grown on compost composition (rice hull compost+tea residues+leaf compost) had higher shoot dry weight and leaf number, which could be due to higher percentage of nutrients (N, P and K) in this media (Table 3). In contrast, the plants grown in the media of rice husk compost + perlite had the lowest growth characteristic compared to other treatments (Table 3). The decrease in growth parameters in this substrate can be attributed to the low percentage of nutrients, water holding capacity and cation exchange capacity. The results presented here are in agreement with the results of Padasht Dehkaei and Gholami (2009) on Dracaena marginata Ait. and Beaucarnea recurvate and the results of Mahbob Khomami and Dehkaei (2010) on Ficus benjamina plant cv. Starlight.

According to the results of this study, compost composition (rice hull compost+tea residues+leaf compost) due to its proper nutritional characteristics, low substrate weight and cost as well as abundance of these substrate in North regions of Iran, can be a good substitute for common peat moss for interior green walls and sustainable green space development.