Radiation-use efficiency (g MJ t) was estimated in the pre-flowering period from the slope of the linear regression of cumulative PAR interception on AGDM from the sequential samplings at GS31, GS39, and GS61.
The linear increase in grain yield with year of release was due to counteracting curvilinear (quadratic function) increases in harvest AGDM (P < 0.
The present results suggested that the greater harvest AGDM observed with modern cultivars released since about the mid-1980s was associated with more dry matter accumulation in the preanthesis phase.
This was consistent with a tendency for an increase in AGDM at GS61 with breeding, which in turn appeared to be associated with greater accumulation of stem-and-leaf-sheath DM.
Yield progress from 1972 to 1995 occurred due to increases in both harvest AGDM and HI.
1RS translocation has been associated with improved harvest AGDM in previous studies (Carver and Rayburn, 1994; Villareal et al.
Yet in the four stay-green hybrids (A35/RQL36, AQL39/RQL12, AQL41/ RQL12, A35/RQL12; closed symbols), AGDM was only 13% less under TD compared with ND.
Grain yield under ND was highly correlated with AGDM (r = 0.
Relative rate of leaf senescence was not correlated with yield, AGDM or harvest index (Table 1) because the onset of rapid senescence occurred too late in the grain-filling period to greatly affect yield (Fig.
Under TD, the relative rate of leaf senescence was correlated with AGDM (r = [-0.
Abbreviations: AGDM, aboveground dry mass; CGR, crop growth Re-rate; DAE, days after emergence; GLAM, green leaf area at maturity; ND, no water deficit treatment; PFD, postflowering water deficit treatment; TD, terminal water deficit.
, aboveground dry mass; CGR, crop growth rate; DAE, days after emergence; GLAM, green leaf area at maturity; ND, no water deficit treatment; PFD, postflowering water deficit treatment; TD, terminal water deficit.