Chlorophyll Concentration and Morphological Diversity in Corn Lines at Different Vegetative Stages

Abstract

The objective of this study was to assess the chlorophyll content of corn lines at different vegetative stages and the diversity between them. The study was conducted in the experimental field of the Roque Institute of Technology (ITR) located in Roque, Celaya, Guanajuato, Mexico. We used 32 corn lines from CIMMYT and four lines from the breeding program of the ITR. The evaluation was conducted in the spring-summer cycle of 2014 at two planting dates. We used a completely randomized block design with three replications. The experimental unit consisted of two rows of five linear meters with a distance of 0.75 meters between rows. Chlorophyll was measured at six different stages: V6, VT, R3, R4, R5 and MF. The agronomic variables recorded were: PH, CH, LAC, LBC, FF, MF, PM, CC, CL, DC, RC, KR and GY. The results of the analysis of variance showed significant differences between lines, dates and their interaction. On average, 18 lines were found with chlorophyll concentrations above 51 SPAD units in the two environments. This indicated that these materials had a high potential for field performance. Using cluster analysis UPGMA method, we identified seven groups for chlorophyll and eight groups for agronomic characteristics for a breeding program. The groups were associated to the homogeneous characteristics of each variable. *Corresponding author. M. M. Elos et al.1068

Nitrogen Fertilizer Management for Maize Production under Tropical Climate

“…However, it is possible to predict relative yield with a certain level of accuracy. At the phenological stage R1, Sunderman et al (1997) and Elos et al (2016) found CI averages of 57.9 and 50.3, respectively, which is consistent with the values reported in the present finding (between 43 and 56) (Fig. 2).…”

“…Although there is a great variation in the response of different maize hybrids due to their nutritional demand, which varies not only from hybrid to hybrid but also in different stages and different edaphoclimatic conditions, the CI and leaf N concentrations found in the present work were consistent with previous studies. Other authors, using different hybrids in several climatic conditions, reported a critical CI ranging from 50 to 57 (Sunderman et al, 1997, Elos et al, 2016) and a critical leaf N level from 27 to 35 g N kg -1 (Cantarella et al, 1996). Both critical levels for these variables were found in the present study in the range of values considered ideal for grain yield, and, since they were measured at the R1 stage, they might represent a useful tool with which to predict yield at earlier stages of growth.…”

“…As N forms part of the chlorophyll molecule, the increase in leaf N concentration directly influenced the CI readings (Elos et al, 2016). This may also be related to grain yield, and the determination of the CI in the leaf has been suggested to predict the demand for N fertilization in maize topdressing (Piekkielek and Fox, 1992;Varvel et al, 1997;Masuka et al, 2012).…”