Soil salinization means that the soil salt content is too high (more than 0.3%), which makes crops low-yield or unable to grow. There are two conditions for the formation of saline-alkali soil: first, the climate is dry and the groundwater level is high (above the critical water level); The other is low-lying, with no drainage outlet. Groundwater contains a certain amount of salt. For example, its water surface is close to the ground and the area is relatively dry. After the water rising to the surface evaporates due to capillary action, salt is left: over time, the salt content of soil gradually increases, forming saline-alkali soil; If it is a depression and there is no drainage outlet, the water in the depression will evaporate, leaving salt and forming saline-alkali land.

Distribution: Salinized land in China is mainly distributed in North China Plain, Northeast Plain, Northwest Inland Area and Coastal Area.

Adverse effects:

1, soil hardening, fertility decline.

2. It is unfavorable for crops to absorb nutrients and hinder crop growth.

Prevention and control:

Measures to control saline-alkali land include water conservancy improvement measures (irrigation, drainage, silting, rice planting, seepage prevention, etc.). ); Agricultural improvement measures (leveling land, improving farming, applying exotic soil, fertilizing, sowing, crop rotation, interplanting, etc.). ); Biological improvement measures (planting salt-tolerant plants and pasture, green manure, afforestation, etc.). ); And chemical improvement measures (using gypsum, phosphogypsum, calcium sulfite and other improving substances. ). Four aspects. Because each measure has a certain scope of application and conditions, it must be treated comprehensively according to local conditions.

Saline-alkali land is expected to become an oasis. Scientists in China have successfully cloned a salt-tolerant gene.

Scientists in China have successfully cloned a key salt-tolerant gene from a halophyte and introduced it into many plants. This discovery is expected to turn saline-alkali land, which accounts for about a quarter of the total land area of the earth, into an "oasis".

The research team led by Professor Zhao Yanxiu and Professor Zhang Hui of Shandong Normal University started this research from 1999, and recently discovered this gene after sequencing the gene of Suaeda salsa 1755. The expert group of the high-tech development plan of the Ministry of Science and Technology accepted this research result. The State Patent Office announced this achievement in the 28th patent announcement of Volume 18 this year.

The full name of this gene is "the full-length cDNA of Na+/h++ antiporter (SsNHX 1)". A protein determined by this gene can make Suaeda salsa form an "ionic compartmentalization" mechanism to detoxify sodium ions in cells.

According to reports, Suaeda salsa is a common Chenopodiaceae plant on saline-alkali land in China. It can tolerate 3% salinity and grow in seawater. It can grow to 1 m high on saline-alkali land and 30 cm on the beach. The researchers of the research group transferred this gene into Arabidopsis thaliana and made a comparative experiment: Arabidopsis thaliana can complete its life history under the condition of 1/2 seawater irrigation; Under the condition of pot culture, 15 days without watering can still grow and bear fruit after rehydration. While all the control strains died. Among all known published materials, the transgenic plants they cultivated have the strongest salt tolerance.

At present, this achievement has been applied to cultivate transgenic plant seedlings suitable for saline-alkali soil growth. The reporter saw in the laboratory of the School of Biology of Shandong Normal University that the newly cultivated salt-tolerant transgenic plants include tomato, soybean, rice and fast-growing poplar, which grow well in thousands of media. The staff said that it won't be long before the transplant can be implemented.

Saline-alkali land is a widely distributed soil type on the earth's land, accounting for about 25% of the total land area. In China alone, the area of saline-alkali land exceeds 33 million hectares. More than 6,000 hectares of saline-alkali land are added every year in the Yellow River Delta of Shandong Province. As a result, a lot of land was abandoned. Experts believe that this discovery has a very broad application prospect for China, a populous country with decreasing arable land resources, and can well combine economic benefits, environmental protection and sustainable development.