When the crop is deficient in phosphorus, it grows slowly, is short and thin, is erect, has few branches, and leaves small and easy to fall off; the color is generally dark green or gray-green, the leaf margin and petiole often appear purple-red; the root system is poorly developed, the maturity is delayed, and the yield and quality are reduced. The symptoms of phosphorus deficiency generally start from the old leaves of the stem base and gradually develop upward. The symptoms of phosphorus deficiency in major crops are as follows.
● Wheat: The plant is small and thin, with less tillering, dark green leaves with a slight purple color, and purple on the leaf sheath is particularly obvious. The symptoms develop from the tip to the base, from the old leaves to the young leaves, and the cold resistance is poor.
● corn: from the seedlings, in the leaf tip part along the leaf edge to the leaf sheath development, dark green with purple-red, gradually expanding to the entire leaf, the symptoms from the lower leaves to the upper leaves, the base to the whole plant purple, severe phosphorus deficiency From the tip of the leaf, the withering is brown, the silking is delayed, the development of the ear is incomplete, the bending is deformed, and the ear is poorly formed.
● Potato: The plant is small and small. When it is severe, the top stops growing. The leaves, petioles and leaflets are somewhat shrunk. The lower leaves are rolled up, the leaves are burnt, the old leaves fall off in advance, and the tubers sometimes produce some rust brown spots.
● Rice: The plants are small and small, no sparse or less tillering, the leaves are erect, narrow and dark, and the color is dark green. In severe cases, the rice groves are tight, the leaves are longitudinally constricted, have reddish-brown spots, and the growth period is prolonged.
● Soybeans: The plants are small and thin, the leaves are dark green, the leaves are narrow and pointed, and they stand upright. After flowering, the leaves show brown spots and the seeds are small. When the phosphorus is severely deficient, the stems and leaves become dark red.
● Peanut: The old leaves are dark green to blue-green, and then turn yellow and fall off, and the base of the stem is red.
● Cotton: the plant is short, old, with dark leaves, thin stems and red base. There are few fruit branches, small leaves, leaf margins and petioles often appear purple-red, root system is poorly developed, maturity is delayed, buds are easy to fall off, and yield and quality are reduced.
● Rapeseed: the plant is small, the leaves are late, the upper leaves are dark green, the base leaves are purple-red or dark purple, and sometimes purple spots or plaques appear on the edges of the leaves, which are susceptible to freezing damage. Branches are small, delaying flowering and maturity.
● Tobacco: The whole plant is clustered, the leaves are narrow, the color is dark, the erect, the old leaves have necrotic spots, and become brown after drying. The smoked leaves are dark and dull.
● Tomato: The early leaves showed purple-red on the back, some small spots appeared in the veins, and then spread to the whole leaf, and the veins and petioles finally turned purple. The stem is slender, rich in fiber, the leaves are small, and the coils appear in the later stage, and the fruiting is delayed.
● Cucumber: The plant is dwarfed. When it is severe, the young leaves are small and stiff, and they are dark green. The cotyledons and old leaves have large water-stained spots, which spread to the young leaves. The plaques gradually turn brown and dry, and the leaves are wilted and shed.
● Onion: Phosphorus deficiency is mostly manifested in the late growth stage. Generally, the growth is slow, the tip of the old leaf is dry and dead, and sometimes the leaves show greenish yellow and brownish spots.
● Apple: The leaves are small, with bronze dark green to purple, less hair branches, few leaves, and small fruit.
● Peach: The leaves turn dark green to bronze, or develop into purple; one is narrower than the old leaves, and the outer leaves are curled outward; the early leaves are scarce.