Manganese efficiency in relation to differential production and allocation of carbohydrates between source and sink organs of diverse wheat genotypes

Mineral nutrition of plants affects the metabolism of carbohydrates between source and sink organs in plants during grain filling. Minimal information exists on source–sink dynamics of carbohydrate and manganese (Mn) flow through wheat plants over their reproductive development. The present investigation unravels the relationship between Mn efficiency of a genotype and production and partitioning of carbohydrates during grain filling period. A whole-plant dry matter accumulation and carbohydrate production study, under different Mn supplies, was conducted to characterize dry matter, Mn and carbohydrate accumulation in source (leaves and tillers) and sink (spike with grains) of wheat plants. The Mn-efficient genotype PBW 550 had higher dry matter accumulation and Mn uptake than inefficient genotype, PDW 314 under both Mn supplies. The concentration of total soluble sugars (TSS) at maturity was higher in source of PDW 314 than PBW 550 and the decline of TSS from anthesis to maturity was least in source and sink of PDW 314. When Mn was supplied, the concentration of starch increased in sink of PBW 550 but not in PDW 314. During grain filling period, the highest increase in starch concentration was in the sink of PBW 550. The deficiency of Mn differentially hampers the production of dry matter and carbohydrates in Mn-efficient and -inefficient genotypes. The differential carbohydrate dynamics between source and sink in plants of diverse wheat genotypes under different Mn supplies may be one of the physiological mechanisms governing Mn efficiency.