RESPONSE OF SAFFLOWER TO SALINE SOILS AND IRRIGATION

Elias S. Bassil and Stephen R. Kaffka

 Abstract

Salt tolerant crops can be grown with saline water from tile drains and shallow wells as a practical strategy to manage salts and sustain agricultural production in the San Joaquin Valley of California.  Safflower was grown using a salinity gradient in previously salinized plots that varied in ECe from 1.8 to 7.2 dS m^-1 (0 to 2.7 m depth) and irrigated with either high quality (ECi < 1 dS m^-1) or saline (ECi 6.7 dS m^-1) water.  Safflower tolerated greater levels of salinity than previously reported.  Plants in less saline plots recovered more water (515 mm ± 18 SE) and at a greater depth (below 1.5 m) than in more salinized plots (435 mm ± 9 SE).  Differences in pre-dawn and mid-day plant water potential, between plants in high and low salt plots, were significant at several dates.  Leaf area index was reduced by 1 unit over this salinity range.  Plant populations were not affected, however plant height was reduced by 32 cm at higher salinity.  Seed, oil yield and oil quality were not affected by increasing ECe, but oil percent and 1,000-seed weight increased slightly.  Plants adjusted to increasing salt stress in saline soils and water by increasing harvest index.  Harvest index increased due to a reduction in the stem to total biomass ratio.  Bud weight per m² was less affected by salinity.  Low temperatures and higher than average relative humidity in spring likely moderated the effects of salinity.

Key words:  Safflower, saline irrigation, water use, seed yield, oil quality, harvest index