|Henry, Christopher - University Of Arkansas|
|Gaspar, Jason - University Of Arkansas|
Submitted to: Rice Technical Working Group Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 12/23/2015
Publication Date: 7/2/2016
Citation: Henry, C.G., McClung, A.M., Gaspar, J.P. 2016. Evaluating rice cultivars using subsurface drip irrigation (SDI). Proc. 36th Rice Technical Working Group Meeting, Galveston, TX, p. 137, March 1-4, 2016. CDROM.
Technical Abstract: Nearly 2.6 million acres of rice in the USA are produced using a flooded paddy system. However due to depletion of ground water, climate patterns that have resulted in reduced precipitation, and increasing competition with urban areas for water resources, the future of rice production in parts of the USA is in jeopardy. Little research has been conducted in the USA to develop rice varieties that have the yield potential for production under reduced water use scenarios. The goal of this research is to identify cultivars that possess water stress tolerance. Fifteen rice cultivars representing nine conventional long grains, two conventional medium grains, and four indica cultivars were evaluated using a subsurface micro-irrigation system over two years at Stuttgart, AR. Each plot was represented by two drill seeded rows ( 1.7 sq. m) and the subsurface drip pressure compensated line was buried 20 cm on 60 cm intervals (emitter spacing of 20 cm). This resulted in one line per two rows of plants. The plots were fully irrigated until the plants reached the 4-5 leaf stage and then the irrigation treatment levels were applied. The irrigation treatments were arranged in four zones with cultivars randomized within three blocks for each treatment. An Acclima™ controller and sensor array were used to maintain four soil moisture levels at set-points consistent with just above the wilting point and just above the field capacity for a Dewitt silt loam soil (30%, 24%, 20%, and 14% volumetric soil water content). Additionally, weekly readings using a Dynamax soil moisture probe were used to monitor the soil moisture of each individual plot. The four irrigation treatments were separated by a non-irrigated border consisting of four rows. In both years final plant height, grain yield per plant (average of 3-4 plants), and days to harvest were measured while data on days to heading, disease incidence, and water stress symptoms were determined for each plot in only one year. Actual soil moisture treatments, averaged from each plot from respective treatments, were 33.5%, 30.8%, 25.4%, 20.0% in 2014. In 2015, dryer conditions persisted resulting in actual average treatment levels of 24.9%, 21.5%, 17.9%, and 13.5%. A range of panicle symptoms were observed in response to increasing water stress including blanking, sterility, delayed tillering, and panicles which did not emerge. Plot soil moisture was used as a covariate in the analysis of variance. Varieties were significantly different for plant yield, with Teqing, Francis and Rondo having the highest yield independent of irrigation treatment levels. We evaluated the percent reduction in yield to determine which varieties best maintained yield potential due to limited available water. This was done by dividing each of the three deficit irrigation level plot yields by the fully irrigated treatment average yield for each cultivar. The cultivars that had the highest yield from this analysis were PI312777, Rondo, and Saber. These varieties may maintain better yield stability than the other cultivars when exposed to limited water conditions. There was no cultivar by irrigation treatment interaction found. Such results may be useful in understanding cultivar response to limited water conditions.