Boron is essential for germination of pollen grains and growth of pollen tubes and for seed and cell wall formation. It also forms sugar/borate complexes associated wit surgar translocation and is important in protein formation. Boron Deficiency generally stunts plant growth, the growing point and younger leaves first. This indicates boron is not readily translocated in the plant. Boron deficiencies include reduced flowering, thickened, curled, chlorotic leaves; and soft or necrotic spots in fruits and tubers.

Sulfur can enter plant leaves from the air as sulfur dioxide gas. Sulfur is a part of every living cell and is a constituent of two of the 20 amino acids which form proteins. Plants deficient in sulfur show a pale green coloring of the younger leaves, although the entire plant can be pale green and stunted in severe cases. Leaves tend to shrivel as the deficiency progresses. Sulfur, like nitrogen, is a constituent of proteins, so deficiency symptoms are similar to those of nitrogen. Nitrogen deficiency symptoms are more severe on older leaves, however, because nitrogen is a mobile plant nutrient it moves to new growth. 

Magnesium is the central atom in the chlorophyll molecule, so it is actively involved in photosynthesis. Magnesium and nitrogen are the only soil nutrients that are constituents of chlorophyll. Much of the magnesium in plants is found in the chlorophyll. Magnesium deficiency symptoms first appear on lower (older) leaves, generally, because magnesium is translocated within the plant. They show a yellowish, bronze, or reddish color, while leaf veins remain green.

Iron is a catalyst to chlorophyll formation. It acts as an oxygen carrier in the nodules of legume roots, and also helps form certain respiratory enzyme systems. Iron deficiency shows up as a pale green leaf color (chlorosis), with sharp distinction between green veins and yellow interveinal tissues. Because iron is not translocated within the plant, deficiency symptoms first appear on the younger leaves at the top of the plant. Severe deficiency may turn the plant yellow to bleached white and can result in the death of plant limbs. 

Zinc is one of the first micronutrients recognized as being essential for plants and one of the most common limiting yields. Although it is required in small amounts, high yields are impossible without it. Zinc aids synthesis of plant growth substances and enzyme systems. IT is necessary for production of chlorophyll and carbohydrates. Zinc is not translocated iwthin the plant, so symptoms first appear on the younger leaves and other plant parts.