Foliar Spray Application of Chlorella vulgaris Extract: Effect on the Growth of Lettuce Seedlings

Abstract

Lettuce seedlings often require the use of fertilizers for their cultivation management to achieve appropriate yield. However, for eco-sustainable chemical-fertilizers-free agronomy, the implementation of totally organic farming often cannot support lettuce productivity, therefore new natural biostimulants able to increase lettuce yield could be considered of great interest. In this preliminary work, the foliar spray application of a Chlorella vulgaris extract in lettuce seedlings was investigated in order to achieve better yield performance. Its biostimulant effect was evaluated by monitoring the morphobiometric parameters, chlorophylls, carotenoids, total protein contents, and several enzymatic activities involved in primary and secondary metabolisms of the plant. The experimental trials were carried out by growing lettuce seedlings on inert substrate (pumice) with a 16 h photoperiod for 21 days. The treatment consisted of three consecutive applications by foliar spraying using a concentration of the C. vulgaris extract, corresponding to 1 mg Corg L−1, which were performed one week apart. The results showed that the C. vulgaris extract positively influenced the growth of lettuce seedlings, by increasing the fresh and dry weights, chlorophylls, carotenoids, protein content, and ashes at shoot level. From a biochemical point of view, primary and secondary metabolisms of shoots, in particular nitrogen metabolism, were positively influenced. At the root level, the extract increased dry matter, proteins, and ash content.

Foliar Spray or Soil Drench: Microalgae Application Impacts on Soil Microbiology, Morpho-Physiological and Biochemical Responses, Oil and Fatty Acid Profiles of Chia Plants under Alkaline Stress

“…Microalgae have attracted great attention due to their potentially extensive application in agriculture as biofertilizers. Microalgal biofertilizers may be employed in crop production to improve agricultural sustainability [ 21 ].…”

Multipurpose Agricultural Reuse of Microalgae Biomasses Employed for the Treatment of Urban Wastewater

“…La Bella et al [71] studied the effects of the foliar application of a C. vulgaris extract in lettuce plants, monitoring the morphobiometric parameters, chlorophylls, carotenoids, total protein contents, and several enzymatic activities involved in different biosynthetic pathways. The researchers performed three foliar applications of the microalgal extract, using a concentration of 1 mg Corg L −1 , one week apart.…”

Zinc Nutrition Responses to Agronomic and Yield Traits, Kernel Quality, and Pollen Viability in Rice (Oryza sativa L.)

“…Foliar spray of Zn is more effective than root application due to its higher surface area application, allowing nutrients to be more efficiently absorbed (Fageria et al, 2009 ; La Bella et al, 2021 ). It can also be used to satisfy an acute need for macro- and micronutrients.…”