|| Home || SEARCH|| Contact || Free Research Publications  ||  Eshop || Privacy Statement ||

Download full report (200k - HINT: right click and save the file to your hard disk before opening)

Increasing Cold Tolerance in Rice
by selecting for high polyamine and gibberellic acid content

by Assoc. Prof. Naidu Bodapati, Prof. Shu Fukai and Rob Williams

Report Prepared

September 2002

RIRDC Publication No 05/197 RIRDC Project No UQ-91A

Executive Summary
Low temperature at rice sowing time contributes to poor crop establishment and this accounts to about $30 million loss annually. Once in 3-4 years rice crop suffers from cold damage at pollen development stage leading to panicle sterility. This sterility accounts for up to $120 million loss in some years. This project aimed at providing some practical or agronomic ways to minimise the cold stress damage in the short to medium term by using osmoprotectants and/or gibberellic acid (GA), a phytohormone. Long term benefits are expected from plant breeding by the application of physiological mechanisms that control the cold tolerance.

We have demonstrated that seedling vigour at low temperature can be enhanced by 34% by treating seed with low concentrations of GA. Rice plants naturally accumulate spermine, an osmoprotectant, to overcome environmental stresses. We have shown that soaking seed with spermine solution significantly increased seedling vigour. Longer availability of spermine to the growing seedling by split application was proven to be more beneficial than only one application. However, GA was required to be applied only once in the seed soak solution and split application was not beneficial. We have also found that seedlings of cold tolerant genotypes actually accumulated higher amounts of spermine naturally compared to the susceptible ones, suggesting enhancing spermine and/or GA content by breeding can lead to cold tolerant rice cultivars.

Foliar application of osmoprotectants resulted in the disappearance of 3 protein bands, this indicating the down-regulation of some genes.

Low pollen viability due to cold stress leads to sterility and reduced yields. However, foliar application of commercially available osmoprotectant, glycinebetaine resulted in doubling the number of pollen grains compared to control plants. Field trials with foliar application of glycinebetaine at Yanco during 2000/2001 season resulted in 11% yield increase. This result was obtained although cold stress was not significant and better results or yield advantage should be possible during cold years.

Cost of GA for seed treatment or glycinebetaine for foliar application would be about $1/ha and hence this would be very practical to use at farm level. However, our current work is being focussed on the possibility of incorporating these mechanisms into new rice cultivars to obtain cold tolerance.

 


Site map Contact us Feedback Links Disclaimer Privacy Statement

Last updated: February 2006    Copyright RIRDC
http://www.rirdc.gov.au/reports/RIC/05-197sum.html