1. Lecture 3 Plant nutrition 3.4b

2. Problem with nutrient solutions is maintaining the availability of iron due to precipitation of iron out of the solution. Add chelators that form complexes with cations (Fe, Ca) in which cation is held by ionic forces rather than covalent bonds. Chelated ions remain physically available for the plant. The Role of Chelators in nutrient solution DTPA chelated to an Fe3+ ion that binds through N atoms and three ionized O atoms; Resulting ring structure clamps the Fe

3. Mineral deficiencies disrupt plant metabolism and function Inadequate supply of an essential element results in nutritional disorder manifested by characteristic deficiency symptoms Group 1: Deficiencies in mineral nutrients that are part of carbon compounds (N, S) Group 2: Deficiencies in mineral nutrients that are important in energy storage or structural integrity (P, Si, B) Group 3: Deficiencies in mineral nutrients that remain in ionic form (K, Ca, Mg, Cl, Mn, Na) Group 4: Deficiencies in mineral nutrients that are involved in redox reactions (Fe, Zn, Cu, Ni, Mo) For more examples on nutrient deficiencies, please visit http://3e.plantphys.net/article.php?ch=t&id=289

4. Nitrogen deficiency Symptoms - stunted - older leaves or whole plants yellowish green - sometimes all leaves become light green and chlorotic at the tip - leaves die under severe N stress - all leaves are narrow, short, erect, and lemonyellowish green except for young leaves, which are greener - entire field may appear yellowish - reduced tillering - reduced grain number

5. Phosphorus deficiency Symptoms - plants are dwarfed or stunted - plants develop very slowly in relation to other plants growing without phosphorus deficiency - some species such as tomato, lettuce, corn and crucifers develop a distinct purpling of the stem, petiole and the undersides of the leaves - under severe deficiency conditions, there is also a tendency for leaves to develop a blue-gray luster - in older leaves under very severe deficiency conditions, a brown netted veining of the leaves may develop - necrotic spots = small spots of dead tissue