|Bauer, Armand - USDA-ARS COLLABORATOR|
Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 24, 1997
Publication Date: N/A
Interpretive Summary: Since air temperature strongly affects spike components in spring seeded cereals, the large variations in daily temperature or delays in planting dates, common to spring barley growing regions, make it important to understand temperature effects on spike and whole plant development for management and modeling purposes. Bowman (two-rowed) and Azure (six-rowed) )were grown in controlled environment chambers and at constant temperatures of 18 and 26C or at either 18 and 26C for 4, 8, and 12 days after emergence and then transferred to the other temperature. Spike development coincided more with plant Haun stage than accumulated growing degree-days (GDD) whereas the GDD needed to produce a leaf responded oppositely. Spikelets per spike generally decreased as temperature during the spikelet development phase increased. The growing degree-days to produce a leaf was positively related to air temperature, which suggests that warm temperatures actually slow barley leaf development. Since barley is most sensitive to stress factors during the spikelet formation phase, knowledge of the growth stage when spikelets form is important in managing for high yield potential. The results of this study suggest that mechanisms controlling yield potential and plant development in spring barley are affected by temperature prior to and during the spike development stages.
Technical Abstract: Spikelets are a major component of grain yield in spring barley (Hordeum vulgare L.). Since air temperature strongly affects spike components, the large variations in daily temperature or delays in planting dates, make it important to understand temperature effects on spike and plant development for management and modeling purposes. The objectives of this study were to odetermine effects of changing temperature regimes on the phyllochron, apex development, and spike components in spring barley. Bowman (two-rowed) and Azure (six-rowed) were grown at temperatures of 18 and 26C or at either 18 and 26C for 4, 8, and 12 d after emergence and then transferred to the other temperature. Phyllochron was greater for control plants at 26C than at 18C and for plants grown first at 18C then at 26C compared to those grown at 26C then at 18C. Apex double ridge stage occurred between 8 and 12 d after seedling emergence. Spikelets, kernels, and heads per plant were generally lower for plants grown first at 18C then at 26C compared to plants grown at 26C then at 18C. These data suggest that temperature during spikelet development has the greatest effect on spike components. Spike development coincided more with plant Haun than accumulated growing degree-days whereas the phyllochron responded oppositely. Knowing when the apex forms spikelets is necessary for interpreting plant responses for making management decisions and model development.