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Quantifying historical changes in maize leaf angle and factors affecting it can enhance our understanding of canopy architecture and light capture, and hence crop productivity. Our objectives were to (1) quantify leaf angle genetic gain per canopy position in Bayer's legacy maize (Zea mays L.) hybrids; (2) dissect the contribution of breeding from plant density on historical changes in leaf angle; and (3) synthesize our findings with literature to determine leaf angle changes over a century of breeding. We measured leaf angle in 78 maize hybrids released between 1980 and 2020 across eight environments in the US Corn Belt. We found that new hybrids had on average 6° more erect leaves than old hybrids. The leaf angle genetic gain (toward more erect leaves) was on average 0.08% year−1 for the middle canopy leaves and eightfold larger for the flag leaf. Our results revealed a synergistic effect with similar contributions of maize breeding and plant density on historical leaf angle changes in the middle canopy. However, changes in the bottom and top canopy leaves were due to breeding. Our results, combined with literature, revealed consistent trends toward more vertical leaves over a century of maize breeding, but the leaf angle genetic gain is slowing down in the last decades. This suggests that leaf angle may have reached near‐optimum levels and that multiple ways to maintain the grain yield genetic gain have been functioning in maize breeding. Our study provides prospects to inform breeders and crop modelers to better understand maize leaf architecture and crop yields. Core Ideas: Leaf angle genetic gain is not consistent across canopy positions.Breeding and plant density have similarly contributed to leaf angle changes in the middle canopy.Leaf angle changes in the bottom and top canopy were mainly attributed to breeding.Vertical leaves at the top and horizontal leaves at the bottom were beneficial for yields of modern hybrids.Maize leaf angle genetic gain is slowing down compared to earlier years (1930–1980). [ABSTRACT FROM AUTHOR]

Solar radiation levels (SRL) in suboptimal or super-optimal levels modify biomass accumulation. Moreover, sample size might modify the precision of growth estimators; however, little is known about the joint effects of these factors on the precision of growth estimators in nonlinear models. The aim of this study was to determine whether SRL and sample size could change the precision of the growth models. To this, three SRL (100, 70 and 50% of available solar radiation) were established in escarole (Cichorium endivia L. var. latifolia). In each SRL, the Schumacher's nonlinear model was fitted in 100 sample sizes to investigate if the increase in sample size and reduction of SRL could reduce the errors of estimates. Reduced SRL (70 and 50%) improved the precision of the model. The sufficient sample size for estimating growth parameters with lesser error increased when SLR was higher; however, 264 plants were sufficient to estimate growth parameters with best fits to this crop. We proved the increase in sample size jointly with the attenuation of solar radiation are effective methods to providing growth estimates with a lesser error. The method for estimating the sufficient sample size proposed here might be extended for several studies where nonlinear models are used to obtain growth estimates. By using these simple methods, both researchers and farmers might have a competitive advantage in planning their experiments or cropping systems, mainly in sites or seasons where light-sensitive crops need to be cultivated. [ABSTRACT FROM AUTHOR]