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 cos t; consequently, more practical and reliable methods need to be develo ped. We evaluated the reliability of salinity crop production function s obtained with a triple line source (TLS) sprinkler system, the repro ducibility of the results from different years and site locations with in the TLS, and the minimum plot size per cultivar that allows for con sistent results. Ninety-six percent of the 154 EC(aw) (electrical cond uctivity of the applied water)-grain yield response functions obtained from 6 yr of field experiments with the TLS had significant correlati on 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%) va lues 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 TL S plot indicate that the response functions were independent of locati on within the TLS. The EC50 and SE values of eight barley cultivars gr own 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 6 0-m TLS system, elemental two-row 1.2-m-long plots, and 10 saline trea tments, 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.