Use of Municipal Solid Waste Compost as Growing Medium Component for Melon Seedlings Production

The impacts of municipal solid waste compost (MSWC) in different contents were evaluated in melon (Citrulus melo L.) seed germination and seedling production in nurseries study. Extracts (10-0 up to 10-6 dilutions) of MSWC evaluated for seed priming/germination in Petri dishes. The MSWC extracts at 10-1?10-6 enhanced (up to 20%) seedling germination as well as shoot and root radicle length. However, pure extracts (at 10-0) delayed the seed germination for 3 days which was less than 25%. Under nursery conditions, six media [(% v/v): peat: MSWC (100:0) as control; peat:MSWC (85:15); peat: MSWC (70:30); peat:MSWC (55:45); peat:MSWC (40:60) and peat:MSWC (0:100)] were prepared from commercial peat and MSWC. Seedling growth/development parameters were assessed. Seed emergence enhanced when low MSWC content (< 30%) used while increased MSWC content (>60%) reduced (up to 80%) emergence and delayed up to 6 days the emergence time. Under nursery conditions, addition of MSWC (especially in content greater than 30%) reduced leaf numbers produced, seedling fresh weight (and dry matter content), chlorophyll a and total carotenoids content. Increased MSWC content into the substrate affected negatively the seedling height and leaf internal CO2 concentration. Stem diameter, leaf fluorescence and chlorophyll b content accelerated when 15-45% MSWC content used into the substrate. No significant differences observed in leaf stomatal conductance in plants grown in different MSWC contents. No visual phytotoxicity obtained macroscopically. Thus, low content (up to 30%) of MSWC may act as an alternative substitute of peat in melon seedling production.