Comparative analysis of maize (Zea mays) crop performance: natural variation, incremental improvements and economic impacts

Abstract

Summary Grain yield from maize hybrids continues to improve through advances in breeding and biotechnology. Despite genetic improvements to hybrid maize, grain yield from distinct maize hybrids is expected to vary across growing locations due to numerous environmental factors. In this study, we examine across‐location variation in grain yield among maize hybrids in three case studies. The three case studies examine hybrid improvement through breeding, introduction of an insect protection trait or introduction of a transcription factor trait associated with increased yield. In all cases, grain yield from each hybrid population had a Gaussian distribution. Across‐location distributions of grain yield from each hybrid partially overlapped. The hybrid with a higher mean grain yield typically outperformed its comparator at most, but not all, of the growing locations (a ‘win rate’). These results suggest that a broad set of environmental factors similarly impacts grain yields from both conventional‐ and biotechnology‐derived maize hybrids and that grain yields among two or more hybrids should be compared with consideration given to both mean yield performance and the frequency of locations at which each hybrid ‘wins’ against its comparators. From an economic standpoint, growers recognize the value of genetically improved maize hybrids that outperform comparators in the majority of locations. Grower adoption of improved maize hybrids drives increases in average U.S. maize grain yields and contributes significant value to the economy.

Planting Arrangement, Population Density and Fertilizer Application Rate for White Maize (<i>Zea mays</i> L.) Production in Bandarban Valley

“…Both the hybrids produced identical number of kernel rows per ear (Table 2) but planting arrangement affected the number of kernel rows per ear significantly. Planting in wide rows or in twin-rows resulted in identical but significantly lower number of kernel rows per ear compared with narrow rows at 50 cm, which agrees with Abuzar et al [14] who observed progressive decrease in kernel rows per ear with increasing plant density from 60,000 to 140,000 plants per ha suggesting that compared with other traits in modern hybrids the resistance of kernel rows per ear to plant competition might be less [12].…”

“…Improvement of agronomic management practices also contributed greatly to increasing grain yields [11]. However, the yield performance differs remarkably across hybrids depending on environmental conditions [12] and agronomic management. Among the agronomic factors influencing the grain yield of maize, plant population density is the most important one [13,14].…”

ARGOS8 variants generated by CRISPR‐Cas9 improve maize grain yield under field drought stress conditions

“…With increasing knowledge on plant response to drought stress and molecular understanding of gene networks underlying the physiological processes that impact drought tolerance, monogenic drought tolerance in maize has become possible by a transgenic approach. Indeed, there are multiple examples of the validation of the efficacy of transgenes in elite hybrids under field conditions (Castiglioni et al, 2008;Guo et al, 2014;Habben et al, 2014;Leibman et al, 2014;Nuccio et al, 2015;Shi et al, 2015). With the advent of CRISPR-Cas enabled advanced technology, a new technique is now available to provide new sources of genetic variation for plant breeding.…”

Genetic gains in grain yield, morphological traits and yield stability of middle-late maize hybrids released in Serbia between 1978 and 2011

“…Grain yield stability can be defined as the ability of the hybrid to produce grain despite the environmental factor variations that can occur in different localities and different years (Leibman et al 2014). Apart from the grain yield, yield stability is one of the most significant traits for genetic potential increase through time (Tollenaar and Lee 2002).…”