When phosphorus is deficient, the crops grow slowly, are short and thin, erect, have few branches, and the leaves are small and easy to fall off; the color is ordinary, dark green or gray green, and the leaf margins and petioles often appear purplish red; the root system is stunted, maturity is delayed, and the yield and quality are reduced. Symptoms of phosphorus deficiency generally start from the old leaves at the base of the stem and gradually develop upwards. Symptoms of phosphorus deficiency in major crops are as follows:
1. Wheat: The plant is thin and small, with few tillers, the leaves are dark green and slightly purple, and the leaf sheaths are particularly purple. Symptoms develop from leaf tip to base, from old leaves to young leaves, and poor cold resistance.
2. Maize: From the seedlings, the leaf tip develops along the leaf edge to the leaf sheath, which is dark green with purple red, and gradually expands to the entire leaf. The symptoms turn from the lower leaves to the upper leaves, and the base to the whole plant is purple. Severe phosphorus deficiency The leaves withered and turned brown from the leaf tip, the silking was delayed, the ears were not fully developed, bent and deformed, and the ears and grains were poor.
3. Potato: The plant is thin and small. In severe cases, the top stops growing, the leaves, petioles and leaflet edges are somewhat shrunken, the lower leaves are rolled up, the leaf edges are scorched, the old leaves fall off early, and the tubers sometimes have some rusty brown spots.
4. Rice: The plant is thin and small, with no or few tillers, erect, narrow, dark green leaves. In severe cases, the rice clusters are tightly bundled, the leaves curl up longitudinally, and there are reddish-brown spots, and the growth period is prolonged.
5. Soybean: The plant is thin and small, the leaves are dark green, the leaves are narrow and pointed, upright, brown spots appear on the leaves after flowering, and the seeds are small. In severe phosphorus deficiency, the stems and leaves turn dark red.
6. Peanut: The old leaves are dark green to blue-green, and later turn yellow and fall off, and the base of the stem is red.
7. Cotton: The plant is short and old, the leaves are dark gray, the stems are thin, and the base is red. There are few fruit branches, small leaves, purplish red on leaf margins and petioles, poor root development, delayed maturity, easy fall off of buds, and reduced yield and quality.
8. Rapeseed: The plant is thin and small, leaves emerge late, the upper leaves are dark green, and the base leaves are purple or dark purple. Sometimes purple spots or plaques appear on the edges of the leaves, which are vulnerable to freezing damage. Branches small, delayed flowering and maturation.
9. Tobacco: The whole plant is clustered, the leaves are narrow, dark, upright, the old leaves have necrotic spots, and turn brown after drying. Tobacco leaves are dull in color after roasting.
10. Tomato: Purple red appears on the back of early leaves, some small spots first appear between the veins, and then spread to the whole leaf, and the veins and petioles finally turn purple. The stem is slender, rich in fiber, and the leaves are small, and the leaves appear in the later stage, and the fruiting is delayed.
11. Cucumber: The plant dwarfs. In severe cases, the young leaves are small and stiff, and dark green. Large water-soaked spots appear on the cotyledons and old leaves, and spread to the young leaves. The spots gradually turn brown and dry, and the leaves wither and fall off. .
12. Onion: Phosphorus deficiency usually occurs in the late growth period. Generally, the growth is slow, and the tips of old leaves dry up and die. Sometimes the leaves show green-yellow and brown mottling.
13. Apple: small leaves, dark green to purple with bronze, few branches, few leaves, small fruit.
14. Peach: The leaves are dark green to bronze, or develop into purple; the older leaves are narrower and curled near the edge of the leaves; the leaves are deciduous in the early stage, and the leaves are sparse.
