Investigation of the usability of some beneficial bacteria and seaweed in watermelon (CXitrullus lanatus (Thumb.) Mansf.) seedling production

In plant production, cultivating healthy and high-quality seedlings represents a fundamental step towards achieving high yield and quality goals. This study explores the effects of applying PGPR (Arthrobacter sp, Azospirillum lipoferum, Bacillus subtilis) species and seaweed extracts both individually and in combination on the growth and development of watermelon plants (Citrullus lanatus (Thunb.) Mansf.). For the research, seeds of the Crimson Sweet variety of watermelon were germinated in a medium composed of peat and perlite. Once the first cotyledon leaves emerged, the seedlings were irrigated with pure water. Applications began weekly after the cotyledon leaves had fully grown, continuing until the seedlings reached planting maturity. In the trial, key parameters such as stem length, stem thickness, number of leaves, internode length, and root length were taken into consideration for plant growth measurements. Additionally, the fresh and dry weights of leaves and roots, as well as the weight of the plant's green parts, were meticulously recorded. The study also included analysis of color distribution within the plant tissues, examining L, a, b*, C, and hue values. The results obtained showed that the best values in seedling growth and weight parameters and the highest efficiency in terms of plant development were provided by AZL+DY (Azospirillum lipoferum+ Seaweed) and ArtB+DY (Arthobacter sp + Seaweed) combinations. The highest values in terms of chlorophyll (SPAD) amount were measured in BCS+DY (Bacillus subtilis+Seaweed) and combination (ArtB+BCS+AZL+DY) applications. In terms of color measurements, ArtB (Arthobacter sp) applications and its various combinations had notable positive effects. In conclusion, it has been proven that combining PGPR with seaweed extract supports the growth and development of watermelon seedlings while providing significant benefits for agricultural sustainability. Such practices hold great potential for enhancing efficiency in plant production by encouraging the cultivation of healthy and quality seedlings. It is thought that the combined use of these biostimulants may be an effective strategy, especially in organic seedling production.