Determination of Optimal Plant Density of Adapted Maize Varieties in the Low and Mid-altitude Ecologies of Tanzania

Abstract

Purpose: The objective of this study is to validate the commonly recommended plant density in the target zone to maximize maize production and productivity. The commonly recommended plant density is 44,444 plants/ha for decades. However, there is no recent study done to validate this practice if it optimizes productivity under current climate and soil fertility variability. A blanket recommendation has been used for decades without validation for optimum productivity that farmer can realize. 
 Methodology: The factorial experiment was used with the total of 18 treatment combinations in a Randomized Complete Block Design (RCBD) with three replications according to Gomez, A and Gomez, K (1983). The open pollinated varieties (OPV) commonly grown by small scale farmers were planted in three different plant densities of 44,444, 53,333 and 66,666 plants per hector with inter and intra row spacings of 0.75mx0.3m, 0.75mx0.25m and 0.75mx0.2m respectively. Field management was done as usual following the recommended agronomic practices.
 Findings: Analysis of variance (ANOVA) was done using GENSTAT (9th edition) statistical programme software and presented in a tabular form. The results indicated no significant difference in all parameters analysed except for 50% anthesis days (AD) and 50% Silking days (SD) both at 0.1% levels. The overall site mean for grain yield was found to be 6.43t/ha, 7.31t/ha and 6.11t/ha for the plant density of 44,444plants/ha, 53,333plants/ha and 66,666plants/ha respectively. Therefore, based on these findings the optimum plant density was found to be 53,333/ha unlike the commonly used plant density of 44,444 plants/ha.
 Unique Contribution to Theory, Practice and Policy: This study contributes to existing experience and practice commonly recommended by extension officers in many parts of the country without performing a site-specific study to determine the optimum spacing for particular environment. This, study also open up an avenue for further research to validate various research technologies. Plant population, in addition to plant height, maturity class, and row spacings, affects the geometry of plant spacing and leaf distribution. All these factors may affect light and CO2 penetration in the canopy, as well as water use rate (Tharp, B and Kells, J, 2001)