Basil as Secondary Crop in Cascade Hydroponics: Exploring Salinity Tolerance Limits in Terms of Growth, Amino Acid Profile, and Nutrient Composition

Abstract

In a cascade hydroponic system, the used nutrient solution drained from a primary crop is directed to a secondary crop, enhancing resource-use efficiency while minimizing waste. Nevertheless, the inevitably increased EC of the drainage solution requires salinity-tolerant crops. The present study explored the salinity-tolerance thresholds of basil to evaluate its potential use as a secondary crop in a cascade system. Two distinct but complemented approaches were used; the first experiment examined basil response to increased levels of salinity (5, 10 and 15 dS m−1, compared with 2 dS m−1 of control) to identify the limits, and the second experiment employed a cascade system with cucumber as a primary crop to monitor basil responses to the drainage solution of 3.2 dS m−1. Growth, ascorbate content, nutrient concentration, and total amino acid concentration and profile were determined in both experiments. Various aspects of basil growth and biochemical performance collectively indicated the 5 dS m−1 salinity level as the upper limit/threshold of tolerance to stress. Higher salinity levels considerably suppressed fresh weight production, though the total concentration of amino acids showed a sevenfold increase under 15 dS m−1 and 4.5-fold under 5 and 10 dS m−1 compared to the control. The performance of basil in the cascade system was subject to a compromise between a reduction of fresh produce and an increase of total amino acids and ascorbate content. This outcome indicated that basil performed well under the conditions and the system employed in the present study, and might be a good candidate for use as a secondary crop in cascade-hydroponics systems.

Optimising Soilless Culture Systems and Alternative Growing Media to Current Used Materials

“…Avdouli et al [11] investigated the performance of basil in a soilless culture cascade system. In such as system, the used nutrient solution drained from a primary crop is directed to a secondary crop, enhancing resource-use efficiency while minimising waste.…”

Salinização secundária no semiárido e seus impactos no solo, na agricultura e cultivo das plantas – uma revisão

“…Os autores reportaram que houve uma redução das massas de matéria fresca e seca da parte aérea das plantas com o aumento da salinidade, de 7,86 e 6,76% por acréscimo unitário na condutividade elétrica da água e que a taxa de crescimento e altura das plantas não foram influenciadas de forma significativa pela salinidade, não gerando sintomas que inviabilizasse o cultivo do manjericão. Avdouli et al (2021) examinaram, em duas abordagens, os limites de tolerância de salinidade do manjericão, num sistema hidropônico em cascata. Os resultados confirmam que os vários fatores do crescimento e desempenho bioquímico avaliados no manjericão apresentaram o nível de salinidade de 5 dS m -1 como o limite superior de tolerância ao estresse, justificando no presente estudo que o manjericão pode ser uma boa opção para uso como cultura secundária em sistemas hidropônicos em cascata.…”

Effect of NaCl or Macronutrient-Imposed Salinity on Basil Crop Yield and Water Use Efficiency

“…The total DM of both leaves and stems in the current research significantly decreased with G-NS8 treatment (from 25.7 and 21.8 g m −2 to 11.1 and 7.1 g m −2 , respectively) and G-SS8 treatment (from 25.3 and 22.4 g m −2 to 5.1 and 3.9 g m −2 , respectively). Moreover, in a recent study Avdouli et al, (2021) [30] explored the salinity tolerance of basil when irrigated either through enriched nutrient solutions to achieve salinity levels of 5, 10, and 15 dS m −1 , or through the runoff drained from a cucumber crop in a cascade cropping system, with the EC of the drainage solution reaching up to 3.2 dS m −1 . The results obtained from that study showed a significant reduction in height, leaf area, and fresh and dry matter of the plants in both experimental setups when EC values exceeded the threshold of 5 dS m −1 .…”