This study was carried out at Plant Production Department, Faculty of Agriculture (Saba Basha), Alexandria University, Egypt, during 2018 and 2019 seasons to determine the relation of irrigation intervals to yield and yield components of some Egyptian cotton varieties. The yield trial was conducted at Sakha Agricultural Research Station, Agricultural Research Center, Egypt. Three interval irrigations were used every 14, 22 and 30 days. Three Egyptian cotton varieties i.e. Giza 86, Giza 92 and Giza 94 were chosen for this study.
Results showed that the highest mean performance values recorded by A1 (irrigation every 14 days) for boll weight, number of boll per plant, seed cotton yield/plant, seed cotton yield/feddan, lint cotton yield/plant, lint cotton yield/feddan, lint cotton percentage and seed index in both seasons. On the other hand, the lowest mean values were given by A3 (irrigated every 30 days) for all studied traits. Likewise, the highest mean values recorded by cotton variety (Giza 94) for all studied traits under the irrigation frequencies compared with cotton varieties Giza 92 and Giza 86 at 2018 and 2019.
The results also cleared that the less effect for water stress condition was recorded by Giza 94 cotton variety and the highest effect for water stress on yield and yield component was given by Giza 92 cotton variety. From the aforementioned results, Giza 94 can be planted in the regions with limited water resources and use it as a parent to produce new combinations that are more tolerant to drought stress.