Investigating the Replacement of Peat Moss and Coco Peat Substrate with other Economical Substrates in Cultivation of Physalis peruviana Seedling

Growth medium is an important and effective factor in the seedling production process. An appropriate growing medium should be available, relatively low cost and lightweight, resulting in higher use efficiently and better economical transportation. A healthy and strong seedling is necessary for better growth and development of mature plants in the field condition. According to reports, several factors including internal parameters and environmental agents have significant effects on seed germination and seedling growth. Light (intensity and quality), air humidity and substrate characteristics are considered as the most important environmental factors effective on seedling growth and development. Investigating the seed germination indices and seedling growth parameters under influence of type of substrate is crucial to produce seedlings with low cost and high quality. Physalis peruviana is an exotic fruit belonging to the Solanaceae family. The fruit is an enriched source of vitamins (C and A), iron, phosphorus and fiber. The fruit or its derivatives are used to produce certain products such as jellies, jams, juices and ice cream. The purpose of the current study was to investigate the possibility of replacement of common and high cost substrate components such as peat moss and coco peat with some other local and economical materials to produce low cost seedlings of Physalis peruviana with appropriate quality.           

The current study was conducted based on completely randomized design with four replications in Mashhad city, Iran. The treatments included A (control): coco peat 60 % + peat moss 30 % + perlite 10 %, B: palm peat 60 % + peat moss 30 % + sand 10 %, C: palm peat 60 % + compost 30 % + sand 10 % and D: palm peat 60 % + vermicompost 30 % + sand 10 %. Physalis seeds was sown in the seedling tray. The number of germinated seeds was recorded every day to calculate germination indices including germination percentage and speed. Germination percentage was calculated by dividing the number of germinated seeds by the total number of sown seeds. At the end of 60th day, the fresh weight of stem and root was measured by digital scale (accuracy 0.001 g). The height of the aerial part and root length were measured with ruler. Leaf chlorophyll index was measured with chlorophyll meter (Model SPAD 502 Plus Chlorophyll Meter). Collar diameter and leaf area were measured by caliper (0.01 mm precision) and leaf area meter (Li-3100 cor), respectively.

The effect of substrate components on all measured traits such as seed germination percentage and speed, leaf number, leaf area, fresh and dry weight of stem and root, collar diameter, chlorophyll index, height of stem and root, electrolyte leakage and leaf relative water content was statistically significant at 5 % probability level. The results showed that the highest root fresh weight was related to seedlings grown on C substrate (2.3600 g) with no significant difference with D (2.2450 g) and B (2.2125 g) substrates. The highest value of fresh and dry weight of stem was related to control treatment (3.50 g and 0.350 g, respectively). Also, seedlings grown on C substrate had highest root dry weight (0.1525 g). The highest collar diameter was related to treatment D (3.0125 mm). The effect of studied treatments on leaf chlorophyll index was significant and the highest value (30.75 %) was recorded in seedlings grown on D substrate which was significantly higher than the control. The highest seed germination percentage was recorded in control (96.68 %) with no significant difference with substrates D (95.89 %) and B (93.61 %). Seeds sown in substrate C showed the lowest germination rate (82.68 %).  The highest and lowest germination speed were recorded in substrate D (14.43 %) and substrate C (13.15 %), respectively. Based on recorded data, the highest electrolyte leakage was for seedlings grown on control substrate (28.985 %). The results showed that substrates B (9.50 cm2) and D (9.25 cm2) had the highest value of leaf area. According to studies conducted in different crops, the kind of substrate components could be effective on morphological, physiological and biochemical characteristics of plant. Generally, seed sowing in substrates with more water storage capacity, porosity and nutrients amount, and better texture and structure lead to better growth and development of root, subsequently resulting in stronger seedlings with higher qualitative characteristics.

The results of the current study indicated that the seedlings of Peruviana grown on alternative substrates had appropriate growth and proper characteristics (especially treatment D). Due to the easy availability of these compounds in the country, it seems that tested substrates could be used as a low-cost and favorable alternative for imported and expensive control substrate in P. Peruviana cultivation.