Irrigation water salinity influences at various growth stages of Capsicum annuum

Availability of fresh surface water for irrigation is declining in southern New Mexico, and saline groundwater is increasingly used for irrigation. This study evaluates the effects of irrigation using saline water on the chile pepper plants. The chile pepper (Capsicum annuum L.) cultivars selected include, AZ 1904, NuMex Joe E. Parker, NuMex Sandia Select, LB 25, and 3441. Salt tolerance of these five cultivars was studied at various growth stages including germination, emergence, vegetative growth, flowering and fruiting stages in a greenhouse set up. The five saline treatments included for germination were tap water of EC 0.6 (control), well water of EC 3 and 6, and RO concentrate of EC 8 and 10 dS/m. During plant emergence and growth, natural water ECs for irrigation were 0.6 (control), 3, 5 and 8 dS/m. Increasing irrigation water salinity increased mean germination time but did not affect the final germination percentage. Increasing irrigation water salinity increased mean emergence time but the final percentage emergence was affected significantly only after EC ≥3 dS/m. Plant growth was significantly affected after several weeks of continuous exposure to saline water application (EC ≥3 dS/m). Increasing salinity decreased days to flowering, photosynthesis, stomatal conductance, relative fresh shoot and fruit weights, and water use efficiency. Results show that the selected chile pepper cultivars can be irrigated up to an irrigation water salinity level of ≤3 ds/m. Among all the cultivars, 3441 was found to be the most tolerant to salinity. Environmentally sound reuse of RO concentrate will encourage desalination in water scarce areas and greenhouse chile cultivation.