Salt sensitivity of corn at various growth stages

Abstract

This study was conducted to determine the relative salt tolerance of corn (Zea mays L.) at different growth stages from germination to maturity when grown in organic soil. Another objective was to determine how rapidly and to what extent the salinity of the irrigation water can be increased during the growing season without decreasing the yield of corn. Germination tests on 16 cultivars showed that corn is relatively tolerant during germination. All but 2 cultivars germinated satisfactorily at soil water salinities, ECsw up to 10 dS/m (1 dS/m=1 mmho/cm). In separate greenhouse experiments, emergence of nine corn cultivars grown in an organic muck soil was delayed by increasing soil salinity but the final emergence percentage 6 days after planting was unaffected by ECsw up to 9.3 dS/m. Seedling growth was much more sensitive to salinity than seed germination. The threshold ECsw for dry matter yields at 21 days was below 1.0 dS/m for most cultivars. Salinities above this threshold of 1 dS/m decreased seedling growth 4.9% per unit increase in ECsw. The salt tolerance thresholds for ear and grain yields were much higher than for seedling growth, while yield decrements per unit increase in EC, above this threshold were greater. Fresh ear yields of Bonanza, a sweet corn cultivar, decreased 7.7% per unit increase in ECsw above a threshold of 5.8 dS/m. Dry grain yields decreased 10.1% per unit increase above 5.5 dS/m. Increasing the salinity of the irrigation water to 9 dS/m at the tasseling and/or grain filling stages did not significantly decrease yields below those obtained where irrigation water salinities were kept constant.