Salt tolerance of corn in the Sacramento-San Joaquin Delta of California

Summary

A three year field experiment was conducted to establish the salt tolerance of corn in the Sacramento-San Joaquin Delta of California. The study was essential because of the grave consequences of allowing the surface waters in the Delta to become excessively saline and the absence of salt tolerance information on organic soils. The relative yield (Y _r) of corn grain was found to be related to soil salinity (the average electrical conductivity of soil water in the root zone during the growing season, $\overline {EC}$ _sw ) by Y _r=100−14 ($\overline {EC}$ _sw−3.7) when $\overline {EC}$ _sw ≧3.7. Below an $\overline {EC}$ _sw of 3.7 dS/m, grain yield was equivalent statistically to nonsaline conditions. As $\overline {EC}$ _sw . exceeded the threshold value of 3.7 dS/m, Y _r was reduced at the rate of 14%/(dS/m). Excess salinity reduced yield by reducing both kernel mass and, to a lesser extent, plant density. An almost identical relationship was found between $\overline {EC}$ _sw , and total shoot growth on a relative basis. Thus, to prevent loss in corn yield, the salinity of the applied water and management practices (including irrigation timing, irrigation amount, and leaching) must prevent $\overline {EC}$ _sw from exceeding 3.7 dS/m, on the average, during the growing season.