Vol. 2, No. 1, 1994

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    Towards an Optimal Resource Allocation to Forage Production in the United Arab Emirates (UAE)
    (Faculty of Agriculture, University of Khartoum, Shambat, Sudan, 1994) Ahmed, A.H.
    Forage production is one of the major agricultural activities in UAE. Forages were continuously increasing in importance, as they comprised 73% of the total area under field crops early in the eighties compared to 91% by the end of the decade, with 26% as the annual rate of increase. Alfalfa and grasses, mainly Rhodes grass, were the commonly grown crops in the UAE's four production regions. Such crops are generally classified as heavy consumers of natural agricultural resources (land and water) which are critically limiting the country's agricultural development. The major objectives of this study were to investigate allocation of natural resources to forage crops in the four regions and suggest alternative production plans. Statistical analysis of average yields revealed that the Central region has an absolute advantage in production of alfalfa and grasses over the other regions, while the Northern region has a comparative advantage in grass production. Accordingly, an LP model was constructed to determine an optimal production plan with the current restrictions on resources use and production levels. The results indicated that resources were under-utilized. Hence, it was possible to increase total alfalfa production by 26% while maintaining grasses at the current production level. Equivalently, either 47% or 27% of the total area under forage production in Southern or Central regions, respectively, could be saved. The study also suggested usage of modern technologies and improved cultural operations together with introduction of other crops that are less exhaustive to natural resources as alternative ways for improved resource utilization and conservation.
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    A Method for Determination of Volumes of Previous Thinnings and Site Productivity Using Tree Stumps
    (Faculty of Agriculture, University of Khartoum, Shambat, Sudan, 1994) El Tayeb, A.M.
    A trial was conducted to determine indirectly volumes of previous thinnings using data from four sample plots measured in Lembwa forest, south of Singa, Sudan. In each sample, plot diameters of all standing trees were measured at breast height and at ground level. In addition, diameters at ground levels of all stumps were measured. The regression analysis showed a strong relationship between diameter at ground level and at breast height of a tree. For determination of height and form factor of previously thinned trees, results of a research carried out by the author in 1985 were used. The results of this study emphasize that it is possible to determine volumes of previous thinning as well as the actual potentials of the tree species, Acacia nilotica, by using stump measurements only.
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    Abundance, Productivity and forage Quality of Umgutni (Cephalocroton cordofanus) in South Kordofan
    (Faculty of Agriculture, University of Khartoum, Shambat, Sudan, 1994) Hashim, I.M.
    Density and forage quantity and quality of umgutni (Cephalocroton cordofanus) were determined in south Kordofan. The density was 645.5 shrubs/ha, and the height of the tree was 60.6 cm and its diameter was 88 cm. Each shrub produced 99.8 g of forage/year on dry matter basis, and there was a direct relationship (r2 = 0.93, P<0.005) between the branch weight and the branch length. Leaves showed high crude protein (CP) but low neutral-detergent fibre (NDF) and acid-detergent fibre (ADF) constituents, while leaves plus stems gave low CP but high NDF and ADF constituents. Because umgutni produces nutritious food at the end of the dry season in June, it should be managed properly and propagated.
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    Possibility of Controlling Bean Yellow Mosaic Virus on Faba Bean (Vicia faba L.) by Rhizobium Inoculation
    (Faculty of Agriculture, University of Khartoum, Shambat, Sudan, 1994) Osman, A.J. ; Elsheikh, E. A.E.
    Bean Yellow Mosaic Virus (BYMV) inoculum was applied after two, three and half or five weeks from sowing to faba bean cv. Agabat which was either uninoculated or inoculated with Rhizobium leguminosarum biovar. viceae strain TAL 1397 in a pot experiment. Inoculation with the virus after two and three and half weeks significantly decreased shoot and root dry weight, nodule number, nodule dry weight, number of flowers and pods per plant, total plant nitrogen and nitrogen fixation, whereas inoculation with Rhizobium significantly increased these parameters. The reductions in plant dry weight and nodule number due to the viral treatments were correlated with the time of virus inoculation in a statistical model. The results indicate that faba bean plants suffer greatly from the virus infection when virus inocula are added early in the season. The results also indicate that Rhizobium strain TAL 1397 is effective in fixing nitrogen in normal and in virus-infected faba bean plants.
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    Accelerated Ageing as A Vigour Test for Sorghum Seed
    (Faculty of Agriculture, University of Khartoum, Shambat, Sudan, 1994) Ibrahim, A. E. ; Tekrony, D. M.
    A study was undertaken to standardize the conditions for the accelerated ageing (AA) test as a vigour test for sorghum {Sorghum bicolor (L.) Moench} seed. Three ageing temperatures (41°, 43° and 45°C) and three durations (24, 48 and 72 hours) at 100% RH were employed using 12 sorghum seed lots of different ages and treated with different chemicals. Seed moisture content increased with higher temperatures and longer durations of ageing with little variation between seed lots. Equilibrium moisture contents of 29-30% were reached after 72 hours at 43° and 45°C. Seed germination was almost unaffected by ageing at 41°C, but declined with increasing test duration at higher temperatures. Newer seed consistently had higher germination, but the chemical treatments were variable. Seeds treated with Captan fungicide showed better germination than the untreated seeds and those treated with a 'herbicide antidote or "safener" were more sensitive to ageing stress especially in older lots. Seed lots were effectively separated by ageing for 72 hours at 43°C or for 48 hours at 45°C.