Submitted to: ASAE Annual International Meeting
Publication Type: Proceedings
Publication Acceptance Date: June 1, 2003
Publication Date: July 27, 2003
Citation: WAGGONER, A.E., OSBORN, G.S., PINSON, S.R. USING A MOISTURE TRANSPORT MODEL FOR IDENITFYING THE GENES EXPRESSING FIELD FISSURE RESISTANCE IN RICE SEED. ASAE ANNUAL INTERNATIONAL MEETING. PAPER NO. 036193, 20 PP. 2003.
Field rice fissuring is an important factor to consider for geneticists developing new varieties of rice. Field fissuring occurs mainly as the result of readsorption of ambient moisture by the endosperm resulting in differential swelling causing internal stress. The source of the moisture is typically rain or high humidity in the field as the crop matures. The fissures cause breakage during milling resulting in reduce whole kernel yield. Weather cannot be controlled and the most likely control point for reducing field fissuring is at the genetic level. The objective of this project was to develop a tool for the geneticist to be able to rapidly identify if a line is resistant to field fissuring and determine the component of the seed mainly responsible for conveying resistance so the search for the responsible genes can be focused. This work examined 4 representative varieties of rice with known field fissure resistance: Cypress (high), Lemont (medium), LaGrue (medium), and Teqing (low). Tests were conducted to determine moisture adsorption and desorption rates for white, brown and paddy rice. Equilibrium moisture properties were also measured. A three dimensional finite difference model was written to account for moisture transfer within seed at all three states. Diffusivity values were determined for seed components. These values were used in the model to determine the magnitude and location of moisture gradient within the endosperm to compare varieties under ambient drying and rewetting conditions. The magnitude of the gradients directly corresponded with field observation of field fissuring. The source of fissure resistance was not the same for each variety as hull and bran layer moisture resistance was important, but high endosperm diffusivity also appeared to play an important role. The combination of all moisture transfer properties also appeared to convey resistance.