Breeding of some cucumber hybrids according to some water stress criteria under plastic houses conditions

The study was conducted at the College of Agriculture - University of Anbar during three agricultural seasons, the autumn of 2021 and the spring and autumn of 2022, with the aim of producing F1 hybrids of cucumbers for greenhouses that are resistant to drought stress. Four Gynoecious lines were used, which were planted in the autumn season 2021, and 12 reciprocal and reverse hybrids were produced by full Diallel-crosses, and then planted in the spring season 2022 for the purpose of performance evaluation. Three hybrids were selected that were superior in characteristics of growth and yield with the best parents and a certified hybrid for comparison (Kanz) planted in the autumn season 2022 in an experiment carried out within the design of split plots with two factors according to the randomized complete block design (RCBD) and with three replications. The first factor included 6 genotypes and the second factor included two levels of moisture depletion at 25% and 50% of the available water calculated on the weight method, and the results were as follows. The results of evaluating the performance of the produced combinations showed the superiority of three hybrids, 4×1, 4×3, and 1×4, as they recorded distinct yields of 4.97, 4.38, and 4.20 kg plant-1 respectively. The same hybrids recorded a significant positive hybrid vigor of 34.84%, 18.91% and 14.03%, respectively. The same hybrids were introduced into the third season experiment with the two best parents, 4 and 1, and it appeared that the 4×1 hybrid excelled in plant yield, amounting to 4.06 kg plant-1, and recorded the best values in all studied stress tolerance criteria, as it reached 4.06 and 4.05 in MP and GMP criteria respectively, and in SSI, YR and TOL criteria, it recorded values of 0.70, 0.10 and 0.42, respectively, and in STI, HM, YI, and DI criteria, values of 1.22, 4.05, 1.22, and 0.94, respectively while the parent P1 recorded the lowest values in stress tolerance criteria. From study concluded that the differences in the chemical responses and the amount of production of cucumber, due to the genetic variation of the genotypes under study. Three locally produced hybrids achieved superiority in yield during high moisture depletion. We recommend preserving parents 1 and 4 due to their distinctiveness and using them to produce distinctive hybrids.