Response of canola plant (brassica napus l. )‎ to reducing nitrogen fertilizer rates by adding humic substance

الملخص EN

Two field experiments were carried out at Itay El-Baroud Agricultural Research Station Farm – El Behira Governorate- Egypt during two successive winter seasons of 2016 /2017 and 2017/2018 to investigate the possibility of reducing nitrogen fertilizer rates by adding humic substance (Actosol^®) and their effects on growth, yield, yield components and some chemical properties of Serow 4 canola variety plants.

The studied treatments consisted of seven different doses of recommended nitrogen (30 kg N / fed) with or without Actosol (6 liters / fed) as follows: 50 % nitrogen without Actosol (50 % N-Act.

), 75 % nitrogen without Actosol (75 % N-Act.

), 100 % nitrogen without Actosol (100 % N-Act.

), zero nitrogen with Actosol (0 % N+Act.

), 50 % nitrogen with Actosol (50 % N+Act.

), 75 % nitrogen with Actosol (75 % N+Act.

), and 100 % nitrogen with Actosol (100 % N+Act.

).

The experimental design was randomized complete block with three replicates.

Results showed that decreasing nitrogen rates with or without humic substance (Actosol) linearly decreased plant height, number of branches and fruits/plant, 1000-seed weight, seed yield/plant, seed yield/fed and seed oil yield/fed, while it had increased, but non-significantly, seed oil content.

However, application of Actosol increased all characters, except seed oil content where it had no significant effect on that trait at all studied nitrogen rates.

Treatment of (75 % N+Act.

) was better than (100 % N-Act.

) for most studied characters.

Therefore, nitrogen fertilization rate can be reduced by about 25% of the recommended by adding the recommended dose of Actosol (6 liters / fed).