High-Throughput Sensing of Aerial Biomass and Above-Ground Nitrogen Uptake in the Vegetative Stage of Well-Watered and Drought Stressed Tropical Maize Hybrids

The measurement of agronomical parameters of maize (Zea mays L.) indicating its biomass and nutritional status provides important information to understand its responses to the environment. The detection of significant differences among maize hybrids would be very useful in plant breeding programs screening for N uptake and drought tolerance. The aim of the study was to assess the efficacy of high-throughput sensing measurements to determine the aerial biomass and N uptake of tropical maize hybrids grown in well-watered (control) and drought stress treatments. Experiments were conducted at the National Corn and Sorghum Research Center in Thailand in the years 2007 through 2009. High-throughput canopy reflectance measurements using spectral indices from the literature and newly developed for this study were performed regularly along with biomass samplings until flowering. The relationship of the spectral indices with each of aerial biomass and N uptake had coefficients of determination of up to 0.8 and were also able to distinguish between drought stress levels. Through most sampling dates and stress levels, varieties were similarly classified in their amount of aerial biomass and N uptake by destructive and non-contacting measurements. Our results support the possibility of incorporating these methods in the development of high-throughput phenotyping techniques that could prove to be potentially useful for future plant breeding.