Ameliorating cotton yield response index to nitrogen via variety selection and intercropping as ecofriendly tactics

ATIONALIZING nitrogen (N) use via lowering its application rate is a crucial tactic for reducing the environmental issues. However, low N supply could limit sustainable production of cotton. This research tested the response of cotton varieties (Giza 95, Giza 96 and Giza 97), grown solely or accompanied with cowpea (©) plant, to different N levels (0, 30, 45 and 60 kg N fed-1). All tested traits substantially responded to variety, and N level and their interaction. Giza 96 was the excelsior variety for producing the highest seed and lint yields surpassing Giza 95 by 14.11 and 9.66%, and Giza 97 by 1.98 and 1.85%, respectively. As expected, cotton plants experienced declined growth due to lowering N rate. While, raising N rates up to 45 kg fed-1, where fertilizing with 45 kg N fed-1+© treatment resulted in significant improvements in cotton yields, reaching increases of 1.62 times in seed yield and 1.74 times in lint yield compared to no N application. It should be noted that under N rates lower than 45 kg N fed-1+© treatment, Giza 97 was the potent variety for out yielding the highest seed and lint yields. According to estimation of yield response index, there is no any variety of the tested cotton varieties was belonging to efficient and responsive to N application. Therefore, it could be concluded that application of N at a rate of 45 is sufficient to fulfill the N requirement of cotton plants intercropped with cowpea.