Author
 |
MARCHETTI, MARCO |
|
Submitted to: Rice Production
Publication Type: Experiment Station Publication Acceptance Date: 6/1/1996 Publication Date: N/A Citation: N/A Interpretive Summary: Technical Abstract: The causes of panicle blight (PB) are not known but there is strong evidence that it is not an infectious disease such as blast or sheath blight. It is believed to be one of several manifestations of heat-related plant stress. PB is characterized by near-simultaneous floral abortion shortly after heading (7-10 days); that is, pollination is successful but forming grains quit growing, desiccate and often become colonized by secondary fungi. Shortly after heading (3-7 days) panicles take on a dull cast, the glumes appearing less turgid. During the following weeks the glumes turn various shades of tan and some are colonized by secondary fungi It has been observed that the abscission layer, a zone of specialized cells at the base of each grain, degrades prematurely, effectively interrupting the flow of water and sugars to developing kernels and the floral parts above the zone. This could explain the desiccation of glumes and abortion of developing kernels. Abscission is a normal process but it usually is completed nearer to grain maturity. It facilitates separation of ripe grain from panicles. PB has been associated with overcast days and high temperature, especially night temperatures with lows of 75F and above. There are varietal differences in susceptibility to PB. The more susceptible varieties include Maybelle, Cypress, Jackson, and Katy. |
