Slogan of berm

(1) According to the stem data "Exploring the relationship between the ratio of free water to bound water and tidal flooding time in Spartina alterniflora", it is known that the flooding time is the independent variable of this experiment.

(2) Spartina alterniflora is a kind of herbaceous salt marsh plant in the beach, and the seawater in its actual living environment should be used in the experiment. The water intake is the original growth place of Spartina alterniflora.

(3) The smaller the ratio of free water to bound water, the weaker the metabolic activity of plants and the stronger the stress resistance. Combined with coordinate curve A, the stress resistance is the strongest when it is flooded for 3h/d, and the metabolic activity is the strongest when it is flooded for 0 h/d. 。

(4) Due to the long-term flooding of plants, the energy of anaerobic respiration of root cells is too little, and the metabolic product alcohol poisons cells, resulting in poor plant growth.

So the answer is:

(1) submergence time

(2) Spartina alterniflora sampling (Spartina alterniflora initially grows)

(3)0 ? three

(4) Lack of energy supply and alcoholism caused by anaerobic respiration.