Biostimulant Effect and Biochemical Response in Lettuce Seedlings Treated with A Scenedesmus quadricauda Extract

Abstract

The use of natural biostimulants is becoming an attractive option in order to reduce the use of fertilizer and increase the yield of crops. In particular, algal extracts are suitable candidates as they positively affect plant physiology. Among crops, lettuce often requires the use of biostimulants to improve both the quality and quantity of production. The aim of this work is to investigate the potential use of a Scenedesmus quadricauda extract as a biostimulant in order to obtain sustainable cultivation and a reduction in the cost of chemical fertilizers in lettuce cultivation. Therefore, the effect of S. quadricauda extract on lettuce seedlings was explored by evaluating the physiological parameters, chlorophyll, carotenoid, and total protein contents as well as several plant enzymatic activities involved in primary and secondary metabolisms. The experiment was performed by growing plants on inert substrate (pumice) with a 16-h photoperiod, by carrying out two consecutive radical treatments, one week apart, using a concentration of the extract corresponding to 1 mg Corg L−1. Lettuce plants were sampled at 1, 4, and 7 days from the first treatment and 7 days from the second treatment. The results showed that the S. quadricauda extract positively affected the growth of lettuce seedlings, mainly acting at the shoot level, determining an increase in dry matter, chlorophylls, carotenoids, proteins, and influencing the activities of several enzymes involved in the primary metabolism.

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

“…The experiments were carried out using pumice as an inert substrate in transparent containers (40 × 20 × 10 cm) as reported in Puglisi et al [14]. The substrate was wetted with 1 L of Hoagland solution: [25].…”

“…Experimental trials were composed of five replications for treatment and control, and each replicate was made of 10 seedlings. The seedlings were then grown for 21 days (from the first treatment) in a growth chamber at 25 ± 2 • C, with a 16 h photoperiod, being irrigated every day with 100 mL distilled water according to the experimental condition described in Puglisi et al [14].…”

“…showed to positively affect the fresh weight, total antioxidant capacity, and total carotenoids content in lettuce cultivated for spring and summer crop [16]. More recently, an extract from Scenedesmus quadricauda showed a biostimulant effect on lettuce seedlings, increasing their growth at shoot level, and by influencing the activities of several enzymes involved in the primary and secondary plant metabolisms [14].…”

“…Among these natural biostimulants, microalgae and their extracts showed to be good candidates, since it was shown that they may increase plant growth as well as improve the germination process, aiming to attain sustainable and environmentally friendly agricultural systems [7][8][9][10][11][12][13][14][15].…”

Effect of Microalgal Extracts from Chlorella vulgaris and Scenedesmus quadricauda on Germination of Beta vulgaris Seeds

“…Recently, Barone et al [ 19 ] have shown that extracts from microalgae Chlorella vulgaris or Scenedesmus quadricauda may act as biostimulant in the early stages of sugar beet cultivation, when added after 5 days to the Hoagland growth solution, by improving root and plant growth and modulating gene expression related to the nutrient acquisition in sugar beet. Moreover, these extracts were successfully applied at the root level in the cultivation substrates, showing to exert a biostimulant effect on tomato and lettuce seedlings [ 20 , 21 ].…”