J Integr Plant Biol. ›› 1957, Vol. 6 ›› Issue (2): -.

• Research Articles •    

A Preliminary Investigation on Salt Tolerance of Rice Plant

Ting Tsing, and Fang.Yi-hsiung   

Abstract: The present study was carried out with a local variety of rice plant called “Lao Lai Ching”. Six plants were cultivated in each pot containing 25 kg of garden soil weighed on air-dried basis. Experimental pots were grouped according to the following successive growth stages: early tillering, late tillering, shooting, heading-flowering and milky-ripening stages. At each of these stages, salt water, amounted to 4600—5000 ml. was added at once to the experimental pots. The concentrations of NaC1 tested were 0.0 (control) 0.25, 0.50, 0.75, 1.0 and 1.5%. Eight pots were used for each salt concentration, comprising a total of 48 pots within a group. In the case of the two last growth stages, an additional higher concentration (2.0% NaCl) has been tested. Tap water was supplimented daily to the same fixed level. Both the growth and productive characters of experimental and control rice plants were recorded after harvest, but the chloride contents in their leaves, stems, etc. were determined with samples taken one month before the harvest. The results obtained can be summarized as follows: (1) After adding salt water, the chloride content of pot water decreased gradually. The rate of disappearence was much slower in those pots in which the plants were in early and late tillering stages than those in shooting, heading-flowering or milky-ripening stages. This is understandable since the growth vigour of the plants in the first two stages will certainly limit their total absorptive capacity. (2) Rice plants of different growth stage manifest different degree of salt tolerance. Those in early and late tillering stages as well as in shooting stage were found to be more sensitive to salt, while those in heading-flowering and in milky-ripening stages displayed a greater resistance. (3) Under the conditions of our experiments, treatment of rice plants in early and late tillering and in shooting stages with 0.25% NaCl solution did not decrease the yield; while a similar treatment with concentration over 0.50% did affect the grain yield, particulary at the higher concentrations. Furthermore, it should be noted that treatment at the early tillering stage with 1.5% salt water led invariably to death of the treated plants. On the other hand, salt concentration as high as 1.0% did not change grain yield when it was applied to rice plants at heading-flowering and milky-ripening stages. For these latter stages, a significant drop in grain yield was only observed in those groups treated with 2% NaC1 solution. (4) Treatment if rice plants in shooting stage with salt water induced the formation of abnormal spikelets and non-productive shoots, particularly at higher concentrations. However, no influence on heading and flowering was observed when rice plants in heading-flowering stage were so treated. (5) Analysis of chloride contents of different parts of rice plant points out to the following order of decreasing chloride concentration: stem, leaf sheath, leaf blade, root and grain. In general, treatment of rice plants in early and late tillering and in shooting stages with salt water up to a concentration of 1.0% did not affect the chloride content. However, a gradual increase in tissue chloride content has been observed when the treatment was made at heading-flowering or at milkyripening stage. Such an increase was very marked in those plants treated with 1.5% and 2.0% NaCl solutions. The above difference might possibly be accounted for by the fact that salt treatment at early and late tillering and at shooting stages resulted in a greater accumulation of salt in the old and later dying-away leaves which were not included in our samples for chloride determination.

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