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DNA fingerprints of four Taxa of black seeds (Nigella sativa L.) from Qassim (Saudi Arabia), Ethiopia, Egypt, and Syria were studied. The results showed that there are several genetic differences between these different black seeds Taxa, which could be considered as genotypic characteristics and lead to classifying them as varieties under the sativa species. To study the DNA fingerprinting of these Taxa, the Inter Simple Sequence Repeat (ISSR) method was employed in the PCR technique to determine the levels of polymorphism between their genetic makeups. The ISSR-PCR investigated the intermicrosatellites sequences in their three types (Di, Tri, and Tetra) of the Short Tandem Repeats. Seventeen proper primers representing these three primers' types were used. The obtained banding pattern indicated a high level of polymorphism. The scored bands of the DNA fingerprints in these Taxa were 108, 106, 100 and 81 in Qassim, Ethiopia, Syria, and Egypt, respectively. When the percentages of dissimilarity between them were computed, the range was between 21.5-36.3%. Such a relatively high level of polymorphism substantiated the objectives of the present study which supposed that black seeds grown in the different localities in the world over time have undergone genetic changes to the level that could make them different varieties. Twenty four genes representing 24 different enzymes and isozymes were selected and scanned via PCR technique using suitable SSR primers. The obtained results, showed some changes in the genetic structure of some of these genes. The differences in the DNA fingerprints and the number of comparable genes should be reflected on the gene expression manifested in the protein homology and hence on the metabolism.

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The effect of different shading densities on some chemical composition of the roots of two sugarbeet cultivars was studied out during 1984/1985 season. Plants were grown under 0, 37, 50 and 70 % shading treatments. Results showed that the capacity of root tissue in production or storage of sucrose was not directly dependent on light intensity as all the shading treatments did not change the sugar percentage. Therefore, it was suggested that the sucrose percentage in the root was a genetically‐dependent character more than an environmental one. Also, shading had no significant effects on the chemical composition (protein, fiber, fat, ash and dry matter) of fresh roots at maturity, except the fiber percentage which was significantly increased only under the 70 % shading treatment.

This study was carried out at the Agricultural Experiment Station of King Saud University near Riyadh (26° N, 46° E) during the 1984/85 season to study the effect of shading densities on the agronomic and growth parameters of sugarbeet. Two cultivars were grown under three shading nets with densities of 37, 50 and 70 % in addition to the control (0 % shading = normal sunlight condition). The results indicated that shading affected the growth and the weight of sugarbeet plants and the effects were function of shading density. Root weights were drastically reduced by increasing shading density, whereas top weights were less affected. Increasing shading density resulted in a significant increase in specific leaf area, leaf area ratio while it decreased leaf area index, root weight ration, net assimilation rate and crop growth rate for both cultivars. The interaction between shading densities and sampling dates was significant for most of the studied characters, while that between cultivars and shading densities was significant for root weight and crop growth rates only.