The most common characteristics of potassium deficiency in vegetables are: yellowing starts from the tips and edges of the old leaves in the lower part of the plant, extending inward along the mesophyll, then the leaf edges become brown and scorched, and the leaves become shriveled and scorched. There are brown spots. The disease develops from the lower leaves to the upper leaves. Potassium deficiency in common vegetables is now described as follows: Cabbage and cauliflower: These two vegetables have large and thick leaves, a long growth period, large growth in the above ground, high demand for potassium, and high consumption of potassium in the soil. Large, so symptoms of potassium deficiency are most likely to occur. When potassium is deficient in the seedling stage, the edges of the lower leaves turn yellow or develop yellow-white spots, and plant growth deteriorates significantly. Entering the bulbing stage or the curd development stage, due to the accelerated leaf development and rapid increase in growth, potassium absorption increases sharply. According to reports, the amount of potassium absorbed by autumn cabbage during the bulbing stage can account for about 90% of the total growth period. Therefore, it is also the most vulnerable period for potassium deficiency, which often manifests as scorching of the edges of the outer leaves, yellowing between the veins, and early shedding. Potassium-deficient cabbage leaves have fewer inner leaves, are not tightly packed, and are small and loose. In severe cases, the inner leaves cannot be packed. Cauliflower bulbs are stunted, small, not firm, with poor color and poor quality. The symptoms of potassium deficiency in the above two vegetables are particularly obvious in vegetable fields with relatively light texture and high nitrogen application.

Chinese cabbage, green vegetables: Potassium deficiency is also common in leafy vegetables such as Chinese cabbage and green vegetables. Symptoms are mainly concentrated in the necrotic shape of the leaf edges, which may be related to the high water content, softness of the leaves, rapid progression of lesions, and rapid water loss and necrosis at the edges. Potassium deficiency in Chinese cabbage initially causes yellow-white spots to appear on the edges of the lower leaves, which quickly expand and join into dead spots, and the leaf edges become dry and curled. This is especially likely to occur during the balling stage, causing difficulty or loose balling, and seriously affecting yield and quality. decline. Long-stemmed cabbage used for pickling in autumn and winter often suffers from potassium deficiency due to its long growth period. At the beginning, gray-white spots of varying sizes appear on the leaf edges, which can easily lead to fungal infection and stains. In severe cases, the leaf margins become necrotic and curled, and the edible rate is significantly reduced. Potassium deficiency in pakchoi with a short growth period is relatively rare. Potassium deficiency occasionally occurs in vegetables. The symptoms are mainly manifested in yellowing patches on the lower leaf margins, which then develop into dehydration-like necrosis of the leaf margins, and the leaves roll downward. The growth vigor of the plant deteriorates significantly, and the old leaves wilt and fall off early.

Beans: Bean crops have a unique nutritional characteristic, that is, they require a large amount of potassium, but their ability to absorb potassium is relatively weak, so they are prone to potassium deficiency. Vegetable soybeans will occur whether they are cultivated in spring or autumn. The symptoms are that the edges of the lower leaves (not necessarily the lowest leaves) turn green, yellow and white, but the browning usually does not occur quickly and can last for some time. Hangzhou Vegetable Farmers It is called "gold edge". It occurs frequently during the plum rain season, so it is also called "Mei Yu plague". Entering the flowering and pod stage, the edges of the lower old leaves are scorched, the leaf surface is wrinkled and uneven, and the color deepens and often becomes bronze; the pods are sparse, the pods are many, the seeds are not full, and the yield and quality are significantly reduced. Potassium deficiency in broad beans first manifests as brown spots between the veins of the lower leaves, mostly concentrated on the leaf edges, and then develops into browning and death of the leaf edges. The disease develops from lower leaves to upper leaves, and in severe cases, the entire plant appears wilted. There are few flowers and pods, the pods are underdeveloped, and most of them are deformed fruits with large heads and thin tails. Broad bean red spot disease is easily confused with potassium deficiency, so attention should be paid to the difference. Red spot disease has small reddish-brown spots on the entire leaf, which can occur on the front or back of the leaf and in different leaf positions; the stems and petioles also have lesions that are easy to connect into stripes, which are different from potassium deficiency. When kidney beans (green beans) are deficient in potassium, the leaves will turn yellow evenly from bottom to top, but the veins will still remain green. Leaves with severe symptoms may also develop necrotic brown patches.

In addition, legumes such as cowpeas, lentils, and peas often suffer from potassium deficiency. Especially when too much nitrogen is used, the leaves become dark, the lower leaf edges turn yellow and brown, the leaves shrink, and flowering and pod formation occur. Few, lack of vitality.

Cucumber: Potassium deficiency often occurs during the flowering and fruiting stage. The symptoms are that the tips and edges of the lower old leaves turn yellow first, and then gradually expand to the interveinal mesophyll. In severe cases, the leaves will scorch, curl and fall off prematurely, and the plant will wilt. Fruit development is hindered, often with deformed fruits such as a large head, a thin pedicle, and a mallet shape, and the quality of the product is reduced.

Tomato: Yellow-brown spots appear on the lower leaves. Symptoms begin at and near the leaf tips. The leaves are gray-green in color, less shiny, the leaflets are burned, and the leaf edges are curled. Old leaves fall off easily. The fruit develops slowly, has uneven maturity, uneven coloring, slow color change near the fruit base, and mottled green in between, which is called "green back disease". Plants are wilted and susceptible to gray mold infection.

Watermelon: Generally, the leaf edges and leaf tips at the lower nodes become yellow and accompanied by brown spots, which then develop and expand. The entire leaf edge becomes brown and necrotic, and the leaves curl inward. It is easy to occur under long-term rainy and early sunny conditions.

Fruit development is hindered, fruit setting is difficult, sugar content is reduced, and quality declines.

Allium vegetables: Once onions, scallions, four-season spring onions and other vegetables are deficient in potassium, their stems and leaves will become weak, and the tips of the tubular leaves will become yellow and shriveled, often drooping and falling apart. The edible rate and commerciality of shallots are poor. The bulbs of onions are underdeveloped, and the bulbs are small and unable to be substantial, which affects the quality.