Yield, Protein, and Remobilization of Water Soluble Carbohydrate and Nitrogen of Three Spring Wheat Cultivars as Influenced by Nitrogen Input

Plant breeders have attempted to use extended green leaf duration (EGLD) traits for spring wheat (Triticum aestivum L.) yield improvement in Montana. The objective of this study was to investigate the yield, protein, harvest index (HI), remobilization of water-soluble carbohydrate (WSCRM) and nitrogen (NRM), N uptake, nitrogen harvest index (NHI) and nitrogen recovery in grains (NRG) of two spring wheat cultivars with EGLD (Vida and Reeder) and one without the traits (Outlook) as influenced by N input rates at dryland and irrigated environments. Vida, selected from a cross between Reeder and Scholar, exhibited a greater grain yield but lower protein content compared with Reeder and Outlook; this yield advantage likely resulted from higher HI, as well as greater postanthesis biomass (PABM) accumulation of Vida under irrigation. The yield advantage was greater at the irrigated site (23%) than at dryland (7-12%). The average contribution of WSCRM to grain yield (WSCCGY) was 8 and 12%, and NRM to grain N (NRCGN) was 67 and 60% at the dryland and irrigated site, respectively. No evidence showed Reeder and Vida had a greater WSCCGY or NRCGN than Outlook. The WSCRM and NRM were influenced by N input rates. Lower grain protein contents in Vida than in Reeder and Outlook was attributed to higher N contents in the straw and greater biomass yields of Vida even though Vida took up more N from soil. High N application rates reduced the NHI and NRG for all cultivars at both dryland and irrigated environments.