Rice cropping is an intensive enterprise. To be sustainable and to use water efficiently, rice
requires adequate plant-essential nutrients. Nutrient supply has an impact on both grain yield
and grain quality.
In this project we have developed a nutrient balance model which summarises the impact of
rice cropping on soil nutrients. The main concerns highlighted from this model are that, on
average, all soil nutrients, except sulphur and calcium are being depleted. This work should
alert rice growers to the potential for yield losses due to nutrient depletion. A plant nutrient
diagnostic protocol is still required for Australian rice varieties.
A protocol has been developed to induce the yield-reducing disorder known as straighthead.
This will facilitate the design of studies aimed at understanding the cause of this problem.
The current theory being tested is that micronutrient deficiencies, e.g., copper or zinc, cause
the problem. Further testing is required to confirm the findings made up to now.
This project has also demonstrated for the first time, that grain Fe and Zn can be increased in
rice grains by as much as 44 and 26% respectively following applications of these elements in
foliar fertilizers. During this study we also demonstrated the value of non-contaminating
grain processing equipment for use in the study of micro-nutrients in rice.
Variation in germplasm is seen as an asset to the breeding program. A literature review of
world data from non-cultivated species of the genus Oryza has been assembled and will be a
valuable source of information for plant breeders and other scientists seeking specific traits.
During this study we also developed a new taxonomic key to aid the correct identification of
the 4 Oryza species which are found in Australia.
Rice accumulates phosphorus (P) to about 0.35% by weight in brown grains. As 85% of
Australia’s rice is exported we sought germplasm to reduce this loss. Samples we obtained
from a long-term study in Japan clearly demonstrated the impact of P-deficiency on grain
yield and grain quality (low P, K and Mg concentrations). Preliminary studies were made at
Yanco of the mutant rice known as lpa-1. The key feature of lpa-1 is that it deposits more
phosphorus into inorganic P but less into organic or phytate P in the grain. We suggest that
the line lpa-1 should be incorporated into high yielding Australian rices to produce a rice
which could provide a better nutrient intake for humans and monogastric animals.
Linkages have been established with the Yezin Agricultural University in Myanmar and the
rice program of the Central Agricultural Research Institute. These linkages have the potential
to boost our understanding of the nutrient requirements of rice under long-term cultivation
and also provide access to cold-tolerant germplasm from regions with higher altitudes.
This report represents the end of research supported by the Rice CRC . Project 2302 has
enabled us to better understand the importance of nutrients to sustainable rice production but,
at the same time, has left many promising lines of research worth further study.