Effect of Radiation Levels and Plant Population on Growth and Yield of Wheat (Triticum aestivum L.)

Abstract

A field experiment was conducted at the Professor Purnendu Gain Field Laboratory, Agrotechnology Discipline, Khulna University, Khulna, during the period from November 2018 to March 2019 to study the effect of radiation levels and plant population on the growth and yield of wheat (Triticum aestivum L.).The study included four radiation levels, viz., S₁ = full sunlight, S₂ = 75% light (25% reduction of light), S₃ = 55% light (45% reduction of light), and S₄ = 25% light (75% reduction of light), and three plant population densities, viz., P₁ = 160 plants m⁻², P₂ = 200 plants m⁻², and P₃ = 230 plants m⁻². The two-factor experiment was laid out in a Randomized Complete Block Design (RCBD) with three replications. The results showed that both radiation levels and plant population exerted significant influence on most of the plant characters studied. The highest grain yield (3.82 t ha⁻¹), highest number of grains per spike (50.27), highest 1000-grain weight (51.88 g), and maximum straw yield (4.81 t ha⁻¹) were found in the S₁ treatment. In most cases, the S₂ treatment had almost similar effects on the plant characters as the S₁ treatment. The lowest grain yield (1.88 t ha⁻¹), minimum number of grains per spike (36.04), lowest 1000-grain weight (42.81 g), and minimum straw yield (2.85 t ha⁻¹) were found in the S₄ treatment. At harvest, the tallest plants were observed in the S₃ treatment (93.76 cm).The present study revealed that 230 plants m⁻² produced the highest grain yield (3.15 t ha⁻¹), which did not differ significantly from 200 plants m⁻² (2.96 t ha⁻¹). The highest 1000-grain weight (49.03 g) was obtained from 160 plants m⁻². However, 160 plants m⁻² resulted in the lowest grain yield (2.73 t ha⁻¹), while comparatively lower grain numbers per spike were produced from 230 plants m⁻². The plants grown under full sunlight with 230 plants m⁻² showed the best performance and produced the highest grain yield (3.94 t ha⁻¹). The highest number of grains per spike (52.40) and 1000-grain weight (53.53 g) were observed in the P₂S₁ treatment, where 200 plants m⁻² were grown under full sunlight. Poor performance was shown by plants grown under 25% of available light at all plant densities, resulting in the lowest grain yield. The lowest number of grains per spike (34.93) and the lowest 1000-grain weight (39.11 g) were obtained from the P₃S₄ treatment. The lowest grain yield was obtained from the P₁S₄ treatment, where 160 plants m⁻² were grown under 25% of full ambient light.