Abstract
The final leaf number is an important morphological characteristic of maize (Zea mays L.) and is therefore an important input parameter in some maize crop models. In this study, field experiments were conducted from 2013 to 2016 at 23 sites across China, which were located between latitudes of 26°30′ and 46°45′ N, focusing on five modern maize cultivars, in order to determine the amplitude of variation in mean leaf numbers between each cultivar, identify differences between the mean leaf numbers of cultivars under different climatic conditions, and clarify the effects of the differences in final leaf numbers on aboveground dry matter (DM) and grain yield. The results showed that the mean final leaf numbers increased in the order of XY335 < NH101 < ZD909 < ZD958 < DH11 among the five cultivars, with the wide distribution ranges of final leaf numbers being 17.0–23.3 (DH11), 16.7–22.3 (ZD958), 16.7–22.0 (ZD909), 16.7–22.3 (NH101), and 17.0–22.0 (XY335) across all locations. In addition, leaf numbers above and below the primary ear showed the same trends with the mean final leaf numbers for the same cultivars. Many climatic factors were found to significantly affect the final leaf numbers across four maize-growing regions in China, and the result of stepwise regression indicated that the influences of photoperiod and temperature, in particular, were greater than other climatic factors for these cultivars. Finally, there were found to be significant and positive relationships between the final leaf number and (1) the maximum leaf area index (LAImax), (2) DM at both silking and physiological maturity, and (3) grain yield for the same cultivars across all locations. The results of this study are of great importance for guiding future trans-regional maize cultivation and further model calibration.
Highlights
Maize is one of the most important foods and feed crops in the world [1,2], and is widely cultivated throughout the world from tropical to temperate climatic zones within latitudes of approximately 45◦S to 50◦ N and at elevations from 0 to over 3800 m above sea level [3,4]
The highest coefficients of variation were obtained for ZD958 and NH101, with values of 7.1 and 6.5%, respectively, while values of 6.1, 6.0, and 6.0% were obtained for DH11, ZD909, and XY335, respectively (Table 2)
These results suggest that the final leaf numbers for ZD958 and NH101 were more sensitive to environmental variation than those of the other three cultivars
Summary
Maize is one of the most important foods and feed crops in the world [1,2], and is widely cultivated throughout the world from tropical to temperate climatic zones within latitudes of approximately 45◦S to 50◦ N and at elevations from 0 to over 3800 m above sea level [3,4]. Several morphological characteristics of maize (i.e., final leaf number, plant height, ear height, and leaf area) which reflect plant growth and development vary in different environmental conditions, even for the same cultivar [9]. Many previous studies found that photoperiod and temperature may affect the final leaf numbers of maize [7,12,13]. Many of these studies showed the final leaf number increased with an increasing photoperiod [14,15,16]. When different maize cultivars were compared for a wide range of photoperiods, the response of final leaf numbers was not very consistent [17]. Regarding the response of final leaf number to temperature, some previous studies demonstrated an overall increase in final leaf number with increasing mean temperature [13,18]
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