Phosphorus Efficiency of Wheat (Triticum aestivum) Genotypes Inoculated with Mycorrhizal Fungi under Calcareous Soil Conditions

This
research aimed to study P efficiency of six wheat genotypes (Triticum aestivum) inoculated with mycorrhizal fungi under three levels of P under calcareous soil conditions and to quantify the contribution of root growth
and hyphae length in P uptake. Plants were grown in pots with three levels of P
supply in soil P0
(without P fertilizer), P1 (50% of recommended P
fertilizer, 75 mg P/kg soil), and P2 (100%
of recommended P fertilizer, 150 mg P/kg soil). Half of the pots were
treated with mixed mycorrhizal
species (Glomus intraradices and Glomus macrocarpium) in with six replicates in randomized complete
block design. The wheat genotypes were harvested 85
days after planting. The results showed that the response of shoot dry weight
of wheat genotypes without mycorrhizae to increase of P supply was vigorous
except genotype V6. In contrast, all
the wheat genotypes inoculated with mycorrhizal fungi were less. All wheat
genotypes with mycorrhizal inoculation
except V4 with and without mycorrhizal and V6 without mycorrhizal attained more than 80% of its maximum shoot
yield already at the lower level available. So
all wheat genotypes with mycorrhizal inoculation were considered to be P efficient except V4 and
all genotypes without mycorrhizal were regarded as P inefficient except V6. The wheat genotype V6 had extensive roots growth in
limited P supply (P0) and the shorter roots observed in wheat genotype V4. The
wheat genotype V6 had long hyphae length as
compared to other wheat genotypes
whereas the shorter hyphae length
observed in wheat genotype V4. The adaptation of wheat genotypes to low level
of soil P is closely related to better improved root system and the increase in the mycorrhizal hyphae length may be two
of the main possible mechanisms of P efficiency in wheat. At low and high P level, the genotype V6 was given the highest values with and without
mycorrhizal inoculation followed by V3 and V2, whereas
genotype V4 was given the lowest
values of the shoot P uptake followed by V5. In contrast, the results of this study
suggested that root growth system and mycorrhizal hyphae length would be  suitable parameters for selecting P efficient
wheat genotypes especially under limited P supply.