Desalinated and Brackish Water Conjunctive use in Irrigation Strengthening Adaptation and Resilience in Water-Scarce Regions Santiago Island - Cape Verde

Abstract

The scarcity of water resources remains a global challenge. Finding alternatives to increase water availability is an imperative for adaptation and resilience in Cabo Verde. The research developed consisted in evaluating the use of desalinated, blended1 and brackish water in a light textured soil and its impacts on the productivity of tomato (Solanum lycopersicum), sweet potato (Ipomoea batatas) and zucchini (Cucurbita pepo) crops. The yield of tomato crop, irrigated with blended water (T2 with 2.5 dS/m), was 23.38 ton/ha; followed by irrigation with blended water (T3 with 3.5 dS/m) with a yield of 16.56 ton/ha, and irrigation with brackish water (T4 with 5.75 dS/m) whose yield was16.93 ton/ha. The lowest yield recorded (4.8 ton/ha) was with the treatment T1, irrigation with desalinated water. Regarding fruit quality, no significant variations were observed in tomato quality parameters, however, the variety Savana F1 is sensitive to apical rot. The average weight of the fruits differed according to the treatments: T1 (33.3g), T2 (39.7 g), T3 (32.4 g) and T4 (26.9 g). In terms of yield decrease (Qy) the following values were recorded: T1 (Qy =79.5%), T3 (Qy =29.2%) and T4 (Qy =27.6%) compared to the best treatment, T2 (23.38 ton/ha). The zucchini crop despite being moderately sensitive to salinity, did not adapt to the environmental conditions of the trial. The yield of sweet potato crop, irrigated with T1, was 14.6 ton/ha, followed by T2 with 11.08 ton/ha and T3 with 9.15 ton/ha. The lowest value verified (5.87 ton/ha) was with T4, brackish water. Regarding tubers quality, no significant variations were observed, but the average weight was better with the T1 treatment (199.4 g) followed by T2 (181.5g) and T3 (141.4g) and lastly T4 (126.3g). In terms of Qy, T2 (Qy =24.1%), T3 (Qy =37.3%) and T4 (Qy =60%) were the best compared to T1 (14.6 ton/ha). The results show that irrigation with blended water (desalinated and brackish) in adequate doses is a solution for increasing water availability and strengthening the resilience of agricultural systems in Cabo Verde (SID).