Submitted to: Industrial Crops and Products
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/6/2001
Publication Date: N/A
Interpretive Summary: New crops with high water use efficiencies and increased drought tolerance are being sought for production in arid regions of the western US. Two plant species with excellent potential as alternatives to more traditional crops grown under irrigated conditions are kenaf and canola. There is however little information available on the water requirements for growing kenaf and canola under irrigated conditions. Both canola and five kenaf varieties were irrigated at five different levels with subsurface drip in a 3 year field-plot study. Water applied ranged from a low of 393 to a high of 1441 mm for kenaf and from 138 to 399 mm for canola. For both plant species total yields generally increased with increased water applied. The high water requirement for growing kenaf as an alternative crop may be a deterrent for growers in water deficient areas. In contrast, canola may be more suited for water sensitive areas, especially when grown as a winter crop. Economics, water availability, an product utilization (e.g. forge, phytoremediation) will help growers decide if and when to grow kenaf or canola as alternative crops in central California.
Technical Abstract: Kenaf (Hibiscus cannabinus L.) And canola (Brassica napus L.) may be alternative crops with many uses for irrigated agriculture in central California. There is however little information available on the water requirements for growing both species under irrigated conditions, particularly with regard to increasing their vegetative growth. This 3- year field-plot study was conducted at Fresno, CA during spring (kenaf) and fall (canola). Five varieties of kenaf (7-N, C-531, C-533, Everglades-11 and Tanung-2) and one variety of canola (Westar) were grown with five irrigation treatments imposed on a Hanford sand loam. Plants were irrigated at five different levels [(25, 50, 100, 125, and 150% of approximated crop evapotranspiration (Etc)] with subsurface drip tubing centered 40 cm deep in the beds. The mean amount of water applied (including rainfall) for all three years ranged from 393 to 1441 mm for kenaf and from 138 to 399 mm for canola. In both species, water use efficiency increased as irrigation levels decreased. Vegetative growth (stems and leaves), root growth, and fiber yields were measured. for kenaf, the mean total shoot dry matter (DM) increased as the level of irrigation was increased from 25 - 125% Etc; additional water (150% Etc) had no increased benefit. Among the varieties, C-531 produced the greatest shoot biomass at the 125% Etc treatment. Fiber yield (base:core ratio) of kenaf was not affected by the irrigation treatments. For canola, shoot DM and leaf:stem ratio increased with irrigation treatment up to 125% Etc. Root DM did not differ significantly among the irrigation treatmtents. These results show that both crops produce maximum vegetative yields at 100-125% Etc in central California.