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.

Commercial cultivation of the haitai (Laminaria japonica Aresch.) in North China has had a rapid development in recent years. To date, however, the production activities are limited to the cities of Dairen, Chefoo and Tsingtao and take place only in bays and harbours where sea water is exceptionally fertile because of continual sewage disposal into these places. Extension of haitai cultivation to other places in North China has not met with success because of the relatively low fertility of the sea water. We have succeeded in devising a method of applying fertilizer to the growing Laminaria by putting fertilizer solution in earthenware bottles and placing them inside bamboo baskets on which the Laminaria was growing. Because of its porous nature, the earthenware gradually released soluble NaNO3 or NH4NO3 to the fronds of haitai in its immediate vicinity and the Laminaria was able to grow in a single growing season to commercial quality inspite of the low fertility of the sea water. By means of this unique method of fertilizer application, it is now possible to extense haitai cultivation to places originally not fitted for commercial planting of this much-demanded seaweed. The earthenware method of fertilizer application has an important drawback, namely the increase of cost of production because of additional expenses in the containers, the fertilizer and the human labor involved. It would be much better economically if naturally fertile bays might be found and utilized for haitai cultivation. In the East China Sea region along the Chekiang and North Fukien coasts, seawater is very fertile as evidenced by their rich algal growths, and especially the luxuriant growths of the sea mustard (Undaria pinnatifida) and Ecklonia kurome. In Tsingtao, both the Undaria and the Laminaria grow only in fertile places where they compete with each other. It is therefore not unreasonable to infer that as far as the fertility of the water is concerned, the Chekiang and North Fukien coasts, especially in places such as the East Saddle island and its vicinity where the sea mustard grows luxuriantly, should be suitable to the growth of Laminaria japonica. However the Laminaria is a seaweed of the colder seas and the highest summer water temperature is generally not more than 20 ℃ in the principal places of its production. Its transplantation to Dairen and then to Tsingtao where tile summer water temperature may reach 28 ℃ or higher has already shortened its growth period to about 9 months in a year. Its transplantation further south down to the Chekiang and North Fukien coasts where summer temperature at its highest is over 30 ℃ will naturally introduce many more difficulties, especially in further shortening the growth period and in keeping the fronds over the hot summer. Summering Laminaria in places like Tsingtao has been a great difficulty, and despite special means taken, such as lowering the fronds to 6–10 meters below the sea surface, losses of the “seed fronds” (for spore production in the autumn) have been very great. It would therefore be practically impossible to summer Laminaria in the East China Sea region where in about half of the year, the surface sea temperature is higher than 20℃ and where the highest summer water temperature would be at least 2–3 degrees higher than that at Tsingtao. With the introduction of the method of cultivating Laminaria sporelings in the summer at artificial low temperature (summer sporelings cultivation method), summering Laminaria is no more a serious problem to the haitai growers. The present problem is rather the relative length of its growth period in the new region, since the Laminaria must have a minimum growth period in order to achieve sufficient length and weight to be of commercial value in a single growth season. It is evident, therefore, that before attempt is to be made to introduce the Laminaria to the East China Sea region, we must have a precise knowledge of the effect of temperature on the growth and development of Laminaria japonica. It is thus the aim of the present experiment to study the growth of the Laminaria in nature under different temperatures, to find out the temperatures favorable and optimum for its growth. A simple experiment on the development of the Laminaria was also conducted to find out if it would be able to develop sporangia if continually cultivated at temperatures of and above 10 ℃.