Hi! This message has been forwarded to you by Andreas Jenny

>Date: Wed, 28 Apr 2004 16:40:48 -0400
>To: andreas@... (Andreas Jenny),
>From: Norman Uphoff <ntu1@...>
>Subject: Submergence Tolerance of Rice Plants
>
>If you have internet access and do a search for -- michael b jackson
>phool c ram -- you will find an article in ANNALS OF BOTANY (2003)
>entitled "Physiological and Molecular Basis of Susceptibility and
>Tolerance of Rice Plants to Complete Submergence." This explains in
>great detail the processes that impair and even kill young plants
>when completely submerged, as can happen with SRI if there is not
>enough water control, e.g., in monsoon environments, but it also
>gives a lot of insight into the mechanisms whereby rice plants are
>set back by continuous flooding.
>
>The first two sentences of the abstract read: "Rice plants are much
>damaged by several days of total submergence. The effect can be a
>serious problem for rice farmers in the rainfed lowlands of Asia,
>and runs contrary to a widespread belief amongst plant biologists
>that rice is highly tolerant to submergence."
>
>The article (p. 234), e.g., describes how submergence leads to
>depletion of plant protein reserves. Of importance for SRI, research
>is cited that showed that attempt to raise the nitrogen levels in
>submerged plants by providing ammonium sulfate were not beneficial
>but instead reduced plant survival (from 79% to 15%). The
>biochemistry of this is discussed in detail.
>
>The authors have identified some genes that confer submergence
>tolerance in rice, which could be of value for both SRI and non-SRI
>production methods. The references may also provide some interesting
>reading for anyone concerned in this area of rice science. It is
>clear that the claim of SRI that 'rice is not an aquatic plant' has
>a solid scientific foundation. What to do about this is of course up
>to use and others.
>Norman