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Genetic diversity in 30 date palm (Phoenix dactylifera L.) cultivars in Iraq representing 24 female and six male cultivars was investigated using 22 microsatellite [simple sequence repeat (SSR)] primers. The tested SSR markers showed a high level of polymorphism. A total of 188 alleles were detected at the 22 loci ranging from three to 21 with an average of 8.54 alleles per locus. The average of heterozygosity for all cultivars was 0.503; genetic distance among cultivars varied from 0.171 to 0.938 indicating diverse relationships. The cultivar Ghanami Akhder was highly divergent from ‘Ghnami Ahmer’, whereas ‘Jamal Al-Dean’ was very closely related to ‘Qitaz’. Unweighted pair group method arithmetic average ordered date palm cultivars into two main clusters. Principal coordinate analysis exhibited the similar clusters of cultivars as in the dendrogram.
Cucumber (Cucumls sativus L.) and cantaloupe (Cucumis melo var. Cantaloupensis L.) seedlings have been subjected to a wide range of rhyzosphere pH. Each plant was grown in one pot in water culture. The results obtained showed a great influence of pH on plant root length, root diameter and number of roots, in addition to the subsequent effect on the vegetative growth. The experiment suggests the importance of rhyzospher pH to produce healthy cucumber and cantaloupe seedlings with the maximum root performance. Obtained date were discussed according to the prevailed microlimatic conditions.
Protocorm-like bodies (PLBs) multiplication is one of the most preferable in vitro methods to increase the number of orchids that produce very few seeds or seeds that are not able to germinate. In the present study the effects of chitosan and thidiazuron (TDZ) combinations on multiplication, differentiation, and genetic stability of Phalaenopsis gigantea PLBs were investigated using different media. Initial PLBs were cultured in solid New Dogashima (ND) medium and Vacin and Went (VW) medium supplemented with different concentrations of chitosan (0, 5, 10, 15, 20, and 25 mg·L–1) and TDZ (0, 0.1, and 0.5 mg·L–1). The highest mean number of PLBs (353 PLBs) was observed in ND medium with 10 mg·L–1 chitosan and 0.1 mg·L–1 TDZ combination after 20 weeks of culture. Some PLBs differentiated into mature PLBs with a profusion of leaves on the apical region, and tiny plantlets started to develop after 10 weeks of culture. The highest mean number of shoots was observed in VW supplemented with 10 mg·L–1 chitosan and 0.5 mg·L–1 TDZ (16 shoots). Intersimple sequence repeat (ISSR) markers were used to determine the genetic fidelity among mother plant and PLBs obtained from each subculture stage of solid ND medium supplemented with 10 mg·L–1 chitosan and 0.1 mg·L–1 TDZ (the optimal treatment for PLB proliferation). Dissimilarity of 5% occurred between the mother plant and PLBs obtained after 16 weeks of culture. The range in the similarity coefficient varied from 0.80 to 1.0, and only 20% dissimilarity occurred between mother plant and PLBs after 20 weeks of culture.