VALIDATION OF SALINITY CROP PRODUCTION-FUNCTIONS OBTAINED WITH THE TRIPLE LINE SOURCE SPRINKLER SYSTEM

Traditional methods of screening crops under field conditions for salt tolerance produce low selection efficiencies at a relatively high cost; consequently, more practical and reliable methods need to be developed. We evaluated the reliability of salinity crop production functions obtained with a triple line source (TLS) sprinkler system, the reproducibility of the results from different years and site locations within the TLS, and the minimum plot size per cultivar that allows for consistent results. Ninety-six percent of the 154 EC(aw) (electrical conductivity of the applied water)-grain yield response functions obtained from 6 yr of field experiments with the TLS had significant correlation coefficients (P < 0.05), and 77% of the standard errors (SE) of the estimated EC50 (EC of the applied water that reduces yield by 50%) values were < 2.0 dS m-1. The EC50 and SE values of four barley (Hordeum vulgare L.) cultivars sown at the center and at the far end of the TLS plot indicate that the response functions were independent of location within the TLS. The EC50 and SE values of eight barley cultivars grown in different years indicate nonsignificant differences (P > 0.05) in 79% of the 29 comparisons performed. The EC50 values of four barley cultivars grown in hill plots and in two-row, three-row, and six-row plots did not differ statistically (P > 0.05). With a typical 30- by 60-m TLS system, elemental two-row 1.2-m-long plots, and 10 saline treatments, 120 salinity crop production functions can be developed. Hence, this system is a reliable and practical field method for developing salinity-crop production functions and screening for salt tolerance.