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Adverse effects of waterlogging on germination and survival of wheat, barley and rice seed

Anchalee Chuvativat and T. L. Setter

Tropical Crops Research Group, School of Agriculture
University of Western Australia, Nedlands, W.A. 6009

Seeds of many plants cannot germinate in stagnant water (1) or waterlogged soil, while rice is usually unaffected by these conditions. Experiments were conducted to determine whether differences in germination of seeds during waterlogging were due to adverse effects via (i) infection from soil microorganisms or (ii) chemical changes in soils such as reductions in gas diffusion.

Methods

Seeds were sown in field capacity or waterlogged soil collected from a waterlogging prone site at Waroona, W.A. Waterlogging was imposed with water 5 cm above the soil surface. Seeds were germinated without infection from soil microorganisms during waterlogging by either (i) using sterilized soil (sterilized 15 min at 100 kPa) or (ii) by placing seeds in dialysis tubing which was embedded in the surface of non sterile soil. The dialysis tubing (32 mm flat width) contained 10 mL of 1 mol m-3 CaSO4 such that the tubing with seeds formed a layer 3-5 mm thick. By using dialysis tubing the seed could be exposed to changes in soil nutrients and gas concentrations which occurred as a result of waterlogging, while preventing the seeds from coming in contact with the soil microorganisms. Survival was measured as the percent of seeds which produced a coleoptile and radicle at 25 C in a Petri dish.

Results and discussion

There was no germination of wheat and barley seeds in soil during four days of waterlogging because all seeds died (see Table and Figure). In contrast, wheat seeds in sterilized soil or in dialysis bags in non.sterilized soil had 30.40% germination during waterlogging. Rice was more tolerant to waterlogging than wheat and barley and no seeds died during 4 day treatments. Survival of wheat and barley seeds decreased proportionally during 1-4 d of waterlogging in non.sterilized soil (Fig.). Results with sterile soil and dialysis tubing indicate that infection of seed by soil microorganisms was responsible for 40% of the reduction in germination of wheat during waterlogging; the remainding was presumably due to chemical changes in the soil such as gas diffusion limitations and/or to microorganisms associated with the seed.

Table. Percent germination (and survival) of Figure. Percent survival of wheat, seeds at different conditions of waterlogging barley and rice seeds during 4 d of (W/L) or low 02 treatment for 4 d. Data are waterlogging. expressed as % of germination (or survival) in (a) field capacity soil or (b) aerated solution culture.

Measurement of 02 adjacent to waterlogged seeds in soil showed that at 4 d the soil solutions were in equilibrium with 1-10 kPa 02. Treatment of seeds in solution culture with 10 kPa 02 did not have large adverse effects on germination or survival relative to waterlogged soil (Table). Changes in other soil gases (2) will be discussed in relation to the above results.

1. Morinaga, T. (1926). Am. J. Bot. 13: 126-140.

2. Setter, T. L. and Bywaters, T. (1989). Proc. 5 th Aust. Agron. Conf., Perth.

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