This research was done to evaluate the growth and yield of potato plants raised from seed tuber pieces (STP) containing one, two, three and four eyes, for ascertaining whether seed tuber pieces containing two eyes will sustain potato growth and yield indifferently from those of larger seed tuber pieces containing more eyes. Results indicated that number of stolons and leaves per plant, leaf area, plant fresh and dry weight, relative growth rate, net assimilation rate, crop growth rate, chlorophyll a, b as well as total chlorophylls, Number of tubers and total tuber yield per plant were decreased with decreasing number of eyes in the STP. However, final emergence percentage and total carotenoids content were not significantly affected. Nevertheless, number of tubers and total tuber yield per plant did not differ significantly neither between whole seed tubers and half seed tubers containing four eyes nor half STP containing three eyes and quarter STP containing two eyes. However, all these parameters were significantly lower in response to single-eye STP compared with those containing two eyes or more. From the economic point of view, cultivation of quarter STP containing two eyes instead of half STP containing four eyes represents 50 % conservation in the seed tubers used for only 13.5 % loss in tubers yield. So, it could be concluded that the gain in net income became substantiated by cultivation of quarter STP containing at least two eyes instead of larger seed tuber pieces, even that represents half of the seed tuber.

Seven sunflower cytoplasmic male sterile (CMS lines) and three Rf-restorer (tester lines) were used to obtain 21 F1 hybrids according to line x tester mating design. All the 21 F1 hybrids, 7 lines, and three testers were evaluated at Sakha Agricultural Research Station, Kafer El-Sheikh Governorate during 2017 season. The results showed highly significant differences among the genotypes for all the studied traits. The major role of dominant genes was found because the degree of dominance was greater than unity. These results indicated the preponderance of dominant gene action and the feasibility of hybrid sunflower development. A5 and A9 of CMS lines and RF1 of restorer lines proved to the best general combiners for head diameter, seed yield plant -1 and seed oil content. The cross combinations of A5 x Rf1 and A7 x Rf8 were identified as the best for seed yield per plant with highly significant SCA effects and heterosis. Combining ability analysis indicated that both genetic components, additive and non-additive, were important in expression of investigated traits. The components of genetic variance indicated that the non-additive component played the main role in the inheritance of all studied traits. Heritability in broad sense (h 2 b) was larger than that in narrow sense (h 2 n) for all studied traits.