Production and evaluation of new microbic strains on zucchini (Cucurbita pepo L.) plants and control of Powdery mildew and Cladosporiosis
Authors: Domenico Prisa  , Giordano Menci  
Published: July 2024

Research objective: The main objective of this article is to report the results obtained from the use of new microbial strains on vegetable plants. In particular, the article will deal with two important topics: i) the study of the effect of microorganisms on the biomass of vegetable plants; ii) the possible control of mortality due to diseases such as powdery mildew and Cladosporiosis. The information reported in this research work can support the design of cropping systems in which agricultural sustainability is fundamental due to the presence of microorganisms with biostimulating activity and as a possible alternative to synthetic plant protection products. Materials and Methods: The plants were grown in pots under controlled conditions; 30 seedlings per thesis, divided into 3 replications of 10 plants each, were planted in early February 2024. The plants used in the trial were Cucurbita pepo L.. The six experimental groups in cultivation were: i) group without microorganisms, irrigated with water and previously fertilised substrate; ii) group with Paecilomyces lilacinus, irrigated with water and previously fertilised substrate, (4.5 x 106 spores/ml), 5ml of product sprayed per kg of substrate; iii) group with Azospirillum sp., irrigated with water and previously fertilised substrate, (4 x 108 spores/g), 1g of mixed product per kg of substrate; iv) group with Glomus sp., irrigated with water and previously fertilised substrate, (3 x 109 spores/g), 1g of mixed product per kg of substrate; v) group with Trichoderma viride, irrigated with water and previously fertilised substrate, (3.6 x 108 spores/ml), 5ml of product sprayed per kg of substrate; vi) group with mix Bacillus subtilis, Pseudomonas sp. and Trichoderma viride, irrigated with water and previously fertilised substrate, (2.3 x 108 spores/ml) 5 ml of product sprayed per kg of substrate. On 5 June 2024, plant height, number of leaves, total leaf area per plant (mm2), primary root length (mm), biomass of the aerial and root system, number and weight of fruits, flowers number and the number of plants dead from powdery mildew and cladosporiosis attacks were recorded. Results and Discussion: The experiment showed that the use of of different types of probiotic and plant defence microorganisms can indeed significantly improve the vegetative and root growth of Cucurbita pepo L.. All treatments showed a significant improvement over the untreated control for the agronomic parameters analysed. The Bacillus subtilis, Pseudomonas sp. and Trichoderma viride treatment with a mix of microorganisms was significantly the best in terms of increasing vegetative and root biomass. Improvements were also found in plant height, number of leaves, leaf area and root length. In addition, significant effects were found on the number of flowers and fruits as well as fruit weight. The trial also revealed the significant effect of the products on the control of powdery mildew and Cladosporiosis, in which case the product PL (Paecilomyces lilacinus) was the best on the two diseases. Conclusions: Experiments have shown that the use of microorganisms can significantly improve the growth, vegetative and root biomass of Cucurbita pepo L.. The treatment also offers increased resistance to mortality that can occur in nursery cultivation. A variety of horticultural and ornamental species have already been tested with microorganisms in previous trials, which highlight other interesting and innovative aspects of the use of microorganisms. Due to the importance of using microbial inoculums in plants, the new agricultural experiments are extremely important as they may allow the development of new products for organic and sustainable farming systems and lead to better results.