Improved methods for predicting individual leaf area and leaf senescence in maize (Zea mays)

Abstract

The ability to predict leaf area and leaf area index is crucial in crop simulation models that predict crop growth and yield. Previous studies have shown existing methods of predicting leaf area to be inadequate when applied to a broad range of cultivars with different numbers of leaves. The objectives of the study were to (i) develop generalised methods of modelling individual and total plant leaf area, and leaf senescence, that do not require constants that are specific to environments and/or genotypes, (ii) re-examine the base, optimum, and maximum temperatures for calculation of thermal time for leaf senescence, and (iii) assess the method of calculation of individual leaf area from leaf length and leaf width in experimental work. Five cultivars of maize differing widely in maturity and adaptation were planted in October 1994 in south-eastern Queensland, and grown under non-limiting conditions of water and plant nutrient supplies. Additional data for maize plants with low total leaf number (12-17) grown at Katumani Research Centre, Kenya, were included to extend the range in the total leaf number per plant. The equation for the modified (slightly skewed) bell curve could be generalised for modelling individual leaf area, as all coefficients in it were related to total leaf number. Use of coefficients for individual genotypes can be avoided, and individual and total plant leaf area can be calculated from total leaf number. A single, logistic equation, relying on maximum plant leaf area and thermal time from emergence, was developed to predict leaf senescence. The base, optimum, and maximum temperatures for calculation of thermal time for leaf senescence were 8, 34, and 40ºC, and apply for the whole crop-cycle when used in modelling of leaf senescence. Thus, the modelling of leaf production and senescence is simplified, improved, and generalised. Consequently, the modelling of leaf area index (LAI) and variables that rely on LAI will be improved. For experimental purposes, we found that the calculation of leaf area from leaf length and leaf width remains appropriate, though the relationship differed slightly from previously published equations.

Does Maintaining Green Leaf Area in Sorghum Improve Yield under Drought? I. Leaf Growth and Senescence

“…Differences in leaf size were related to differences in leaf number per culm, evidenced by the positive relationship between averaged TLN and APL values ( r = 0.70*, n = 81) for the nine hybrids (data not shown). The observed relationship between TLN and APL is due largely to the association between area of the largest leaf and TLN, as reported for sorghum by Carberry et al (1993) This is consistent with findings of Birch et al (1998) in a study of five maize hybrids varying in maturity and adaptation. It is also consistent with the studies at whole plant level of Hammer et al (1993) on sorghum, where maximum TPLA was related to TLN and CNPP.…”

Can Changes in Canopy and/or Root System Architecture Explain Historical Maize Yield Trends in the U.S. Corn Belt?

“…Available data on LAI over the crop cycle were then used to test the capacity of the model to regenerate leaf area responses to density. The bell‐shaped curve for individual leaf area (LA N ) against leaf number ( N ) was defined by the equation (Dwyer and Stewart, 1986; Birch et al, 1998): where LA max is the area of the largest leaf, x o is the position (leaf number) of the largest leaf, and a and b are fitted coefficients.…”

Influence of Drought Stress on Leaf Traits of Different Strawberry (Fragaria ananassaL.) Varieties in Natural Environment

“…Measuring leaf area was done with a ruler and calculated using the following equation (Birch, Hammer, and Rickert 1998;Montgomery 1911): Leaf area (cm 2 ) = leaf length × leaf width × 0.75.…”