Studies on the effect of Plant spacing and Different Doses Nitrogen on Growth and Yield of Chilli (Capsicum annum L.) under the Open Field Conditions in Kabul, Afghanistan

The investigation into the impact of nitrogen doses and spacing on the growth and yield-related parameters of chili was conducted during the Spring season of 2022 at the Experimental Farm of the Department of Horticulture Science, Kabul University. The study explored the effects of varying nitrogen doses (0 kg/ha, 100 kg/ha, 140 kg/ha, and 180 kg/ha) and different spacings (40cm × 45cm, 50cm × 45cm, and 60cm × 45cm) on key parameters including days to fifty percent flowering, number of primary branches, plant height, plant spread, fruit dimensions, average fruit weight, fruit yield per plant, fruit yield per plot, and days to maturity. In general, an increase in nitrogen dose was associated with higher values for the number of primary branches, days to 50% flowering, plant height, number of fruits per plant, fruit yield per plant, fruit yield per plot, plant spread, and days to fruit maturity. However, nitrogen doses did not significantly influence fruit traits such as length, width, and average weight. Meanwhile, different spacing had a notable impact on the number of primary branches, plant height, number of fruits per plant, fruit yield per plant, fruit yield per plot, plant spread, and days to maturity. Wider plant spacing correlated with increased primary branches, fruits per plant, fruit yield per plant and per plot, and greater plant spread. Conversely, reduced plant spacing resulted in increased plant height. The interaction between spacing and nitrogen doses significantly affected only the number of branches, with non-significant interaction effects observed for all other yield and yield-related parameters. Increased nitrogen application, particularly at a rate of 180 kg N per hectare, led to improved chili fruit yield. Similarly, wider plant spacing, specifically at 60 cm × 45 cm, demonstrated the highest increase in chili yield.