Dataset on the effects of plant density and micronutrient fertilization on sunflower growth and photosynthetically active radiation under semi-arid conditions of South Africa
Description
This dataset was generated from a field experiment conducted to evaluate the effects of plant density and micronutrient fertilization on sunflower (Helianthus annuus L.) growth and canopy photosynthetically active radiation (PAR) under semi-arid conditions in the North West Province of South Africa. The experiment was carried out during two consecutive growing seasons (2022/23 and 2023/24) at the North-West University Experimental Farm (Molelwane) and the Department of Agriculture Experimental Farm at Taung. The experiment was arranged as a 5 × 3 factorial in a split-plot design with four replications. The main plot factor consisted of three plant densities of 37,037, 55,556, and 74,074 plants ha⁻¹, established using a constant row spacing of 75 cm and within-row spacings of 30 cm, 20 cm, and 15 cm, respectively. The subplot factor comprised five micronutrient treatments: iron (Fe), zinc (Zn), manganese (Mn), a combined Fe + Zn + Mn treatment, and an untreated control. Nitrogen was supplied as limestone ammonium nitrate (LAN), while phosphorus was applied as single superphosphate. Macronutrient application rates were determined from pre-plant soil analysis and applied by band placement at planting, whereas micronutrients were applied before the flowering stage. Before planting, soil samples were collected from depths of 0–15 cm and 15–30 cm at each site and analysed for pH, nitrate nitrogen, ammonium nitrogen, available phosphorus, exchangeable potassium, iron, zinc, manganese, organic carbon, and particle size distribution. Daily meteorological data, including rainfall, maximum temperature, and minimum temperature, were obtained from the South African Weather Service throughout the study period. The dataset includes measurements of sunflower plant height, stem diameter, number of leaves per plant, leaf area, leaf area index (LAI), and photosynthetically active radiation (PAR) above and below the crop canopy. PAR and LAI measurements were obtained using an AccuPAR LP-80 ceptometer, while other growth parameters were measured using standard agronomic procedures. The dataset also contains soil physicochemical properties, fertilizer application rates, weather records, analysis of variance (ANOVA) outputs, least significant difference (LSD) mean comparisons, and Pearson correlation analysis among the measured variables. These datasets provide a comprehensive resource for understanding the combined influence of plant density, micronutrient nutrition, and environmental conditions on sunflower growth and canopy light interception under semi-arid conditions. The data can be used by researchers, agronomists, crop modellers, extension specialists, and policymakers for comparative studies, meta-analyses, precision agriculture applications, and the development of sustainable sunflower production strategies in water-limited environments. Keywords:Leaf area index, Iron, Zinc, Manganese, Semi-arid.
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This dataset was generated from a field experiment conducted to evaluate the effects of plant density and micronutrient fertilization on sunflower (Helianthus annuus L.) growth and canopy photosynthetically active radiation (PAR) under semi-arid conditions in the North West Province of South Africa. The experiment was carried out during two consecutive growing seasons (2022/23 and 2023/24) at North-West University Experimental Farm at Molelwane and the Department of Agriculture Experimental Farm at Taung. The experiment was arranged as a 5 × 3 factorial in a split-plot design with four replications. The main plot factor consisted of three plant densities of 37,037, 55,556, and 74,074 plants ha⁻¹, established using a constant row spacing of 75 cm and within-row spacings of 30 cm, 20 cm, and 15 cm, respectively. The subplot factor comprised five micronutrient treatments: iron (Fe), zinc (Zn), manganese (Mn), a combined Fe + Zn + Mn treatment, and an untreated control. Nitrogen was supplied as limestone ammonium nitrate (LAN), while phosphorus was applied as single superphosphate. Macronutrient application rates were determined from pre-plant soil analysis and applied by band placement at planting, whereas micronutrients were applied before the flowering stage. Before planting, soil samples were collected from depths of 0–15 cm and 15–30 cm at each site and analysed for pH, nitrate nitrogen, ammonium nitrogen, available phosphorus, exchangeable potassium, iron, zinc, manganese, organic carbon, and particle size distribution. Daily meteorological data, including rainfall, maximum temperature, and minimum temperature, were obtained from the South African Weather Service throughout the study period. The dataset includes measurements of sunflower plant height, stem diameter, number of leaves per plant, leaf area, leaf area index (LAI), and photosynthetically active radiation (PAR) above and below the crop canopy. PAR and LAI measurements were obtained using an AccuPAR LP-80 ceptometer, while other growth parameters were measured using standard agronomic procedures. The dataset also contains soil physicochemical properties, fertilizer application rates, weather records, analysis of variance (ANOVA) outputs, least significant difference (LSD) mean comparisons, and Pearson correlation analysis among the measured variables. These datasets provide a comprehensive resource for understanding the combined influence of plant density, micronutrient nutrition, and environmental conditions on sunflower growth and canopy light interception under semi-arid conditions. The data can be used by researchers, agronomists, crop modellers, extension specialists, and policymakers for comparative studies, meta-analyses, precision agriculture applications, and the development of sustainable sunflower production strategies in water-limited environments.