Improving Estimates of Individual Leaf Area of Sunflower

Simple, accurate, and nondestructive methods of determining leaf area of plants are important for many experimental comparisons, Determining individual leaf area (LA) of sunflower (Helianthus annuus L.) can involve measuring leaf length (L) and breadth (B). The objectives of this held study were to compare published and new models to determine the most precise model to predict the area of individual leaves of sunflower plants and to test the applicability of these models between sowing times, with three genotypes differing in maturity and stature; and at different times during crop growth. The best model, which included both the L and B factors (LA = at. + dL + eLB + c), accommodated changing leaf shape during crop development. The relationship between leaf dimensions and LA was significantly improved when sowing time and the times of leaf sampling were included in the relationship; however, no significant differences were found among genotypes. The relative increase in precision with more complex models was considered. Both length and breadth measurements were needed to attain precision for all leaf sizes, and given the availability of computer-based statistical packages, the use of relatively complex models in the assessment of individual leaf areas would appear to be a practical option