Meta-Analysis of Evolution Trend from 1950s to 2000s in the Relationship between Crop Yield and Plant Density in Maize

Abstract

The relationship between crop yield and plant density in maize is essential for improving cropping system because of the fact that maize compensates for low plant density is less than other cereals such as wheat. To determine the evolution trend of yield-density relationships from maize plant density experiments reported in China, and to provide potential approaches to improve maize yield, based on requirements for meta-analysis, we collected the historical data of maize plant density experiments from the 1950s to 2000s in China containing values more than 1500 pairs of plant densities and their crop yield. Evolution trends of maximum crop yield, optimal plant density and yield per plant within six decades were examined after all eligible data sets were subject to fitting parabola model and further to statistical analyses such as histogram, correlation, and path. Crop yields in the 1970s and 1980s were considerably higher than those in the 1950s and 1960s. Crop yield steadily increased in recent three decades and reached the maximum of 10.5 t ha-1 . Annual yield increment was 150 kg ha-1 after 1960s. Optimum plant densities for different decades varied from 4.5 to 6.8 plant m-2 , showing (1950s and 1960s) (1970s and 1980s) 1990s 2000s. Yield per plant for different decades varied from 0.08 to 0.17 kg and in the order: 1950s (1960s and 1970s) 1980s, then gradually increased after 1980s, with a greet increase in 2000s. Crop yield loss due to departures from the optimal plant density appeared an increased trend in recent three decades. On the basis of increasing plant density, promoting yield per plant throughout breeding and cultivation approaches may lead to a higher level of maize production.