Culture medium volume and plant training method affect some traits of greenhouse eggplant in soilless culture

Today, soilless culture systems in greenhouses are of paramount importance. The culture medium is one of the most crucial sections in soilless culture. Coir alone or combined with perlite in different ratios is considered as an important media composite. Since the cost of coir is high, this research aimed to study the effect of the culture medium volume and the plant training method on some traits of greenhouse eggplant (Solanum melongena ‘Belen’). The experiment was carried out in a completely randomized design (n=3). The first factor was culture medium volume at three levels (pots with 7 L, pots with 5 L and pots with 3.5 L) and the second factor was the plant training method at two levels (two stems and three stems). The culture medium consisted of 50% coir and 50% perlite (by vol.). The highest plant height, fresh weight of aerial parts and dry weight of aerial parts, root fresh and dry weight, number of leaves per plant, leaf area, mean fruit number per plant and mean fruit weight were obtained in plants cultured in pots with 7 L and two stems, although the difference was not significant (P>0.05) compared with plants cultured in pots with 3.5 L and two stems. The greatest total yield (1,809 g plant^‑1) and water use efficiency (15.73 kg m^‑3) belonged to plants cultured in pots with 7 L, which did not differ significantly (P>0.05) from plants cultivated in pots with 3.5 L (1,492 g plant^‑1 and 12.98 kg m^‑3, respectively). Based on the results, it can be concluded that planting in pots with 3.5 L culture medium and two stems is recommended for greenhouse eggplant ‘Belen’. Effective pore space, bulk density, pH, and EC of culture medium were 85%, 0.12 g cm^‑3, 7.2 and 2.1 dS m^‑1, respectively.