Kochia scoparia emergence from saline soil under various water regimes.

Abstract

Kochia scoparia (L.) Schrad. invades disturbed soils and serves as a pioneer species on saline rangelands and sodic mine spoils. The percent germination of kochia seeds declined with increasing salinity, averaging -3.3%/dS/m between 12 and 30 dS/m. The emergence and early survival of kochia seeded into 2 media whose respective saturated-paste extracts averaged 1 and 18 dS/m in electrical conductivity (ECe) were investigated in a greenhouse under simulated rainfall regimes. Water was applied according to 3 average rates: 0.6 mm/day (low); 1.2 mm/day (medium); 2.5 mm/day (high). These rates were administered in 2 phases. Phase I (14 days) involved low and medium on the nonsaline seedbeds, and medium and high on the saline seedbeds. Phase II (42 days) followed sequentially on only the saline soil in Phase-I:II combinations of high-high, high-medium, medium-medium, and medium-high. Kochia seedlings did not emerge under the low rate. Seedlings did emerge from the nonsaline seedbeds when watered at the medium rate, but failed to emerge from the saline seedbeds treated only at this rate. Seedlings emerged from the saline soil under all regimes that included the high rainfall rate. About 30 plants successfully emerged from every 100 seeds sown in the seedbeds where ECe decreased to 15.7 dS/m or less. Despite the severely saline seedbed, kochia emerged within 3 days at a rate of 8 plants/day under the Phase I high regime because the water apparently diluted saline seedbed-solutions sufficiently for germination to occur. Phase II of the medium-high regime stimulated a similar response but only after 13 days under the wetter rate. Kochia's germination and emergence favor its addition to seed mixtures designed to establish forages in saline soils.