Volume 1 Number 1 2007

CONTENTS AND ABSTRACTS

Hassine Ben Abdallah, Hager Jebari, Ali Zouba (Tunisia) Muskmelon Grafting as an Approach to Control Monosporascus cannonballus Wilt under Greenhouse and Geothermal Conditions in the South of Tunisia (pp 1-4)

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Original Research Paper: Monosporascus cannonballus is a destructive soil-borne pathogen which is able to destroy an entire muskmelon crop early in the cropping season, in greenhouses heated with geothermal water, in the south of Tunisia. Soil fumigation with methyl bromide seems to be the most common approach for controlling Monosporascus of melons in some regions of the world. Likewise, grafting melons and watermelons on Cucurbita rootstocks is successfully used to manage soil-borne pathogens (Fusarium wilt) in Tunisia and in many others countries. In this study, two muskmelon varieties “Pancha” and “Protéo” of S&G ompany were grafted on three rootstocks: Strong Tosa (S&G) and TZ 148 (Tezier) of hybrid Cucurbita type and Emphasis of Lagenaria type and planted in an early season, under greenhouse and in geothermal conditions, in the South of Tunisia. Results showed that grafting “Pancha” and “Protéo” on the rootstocks Strong Tosa and TZ 148 enhanced plant growth (leaf area and dry matter) and increased early and total production as well as the weight of fruits, compared to control treatments but grafted plants are wilted later at the end of the culture.

Mejda Daami-Remadi, Fakher Ayed, Hager Jebari, Hayfa Jabnoun-Khiareddine, Mohamed El Mahjoub (Tunisia) Variation Among Some Fusarium oxysporum f. sp. melonis Isolates as Measured by Their Effect on Muskmelon Plant Growth and Wilt Severity (pp 5-9)

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Original Research Paper: Fusarium wilt of muskmelon (Cucumis melo L.), caused by Fusarium oxysporum f. sp. melonis, is one of major constraints in melon-growing regions of Tunisia. Necrosis, gum exudates, stunting, vine death and light to dark brown vascular discoloration were recorded on diseased plants late in the season. Eight isolates of the vascular wilt pathogen obtained from different fields were identified on the basis of morphologic and cultural criteria and pathogenicity. All isolates tested showed incidence of the disease on cv. ‘Ananas d’Amérique’ plants, estimated by the disease index, height and fresh weight. A significant negative effect was observed on all the measured characteristics revealing the negative influence of Fusarium wilt on the growth of melon.

Hayfa Jabnoun-Khiareddine, Mejda Daami-Remadi, Fakher Ayed, Hager Jebari, Mohamed El Mahjoub (Tunisia) Incidence of Verticillium Wilt of Melon in Tunisia (pp 10-15)

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Original Research Paper: In the last years, melon culture in the eastern part of central Tunisia has been severely affected by a vascular wilt disease. Symptoms consist of wilting, chlorosis, necrosis, stunting and vascular discoloration. Verticillium tricorpus, V. nigrescens and mainly V. dahliae were isolated from the roots and stem tissues of affected plants. Verticillium wilt has caused significant damage in the early produce and late autumn melon cultures. Pathogenicity was established by dipping roots of 30-day old seedlings of melon cv. ‘Ananas d’Amérique’ into a suspension (10⁷ conidia/ml) of each Verticillium species for 30 min. Disease severity was assessed through the index of leaf damage, eight weeks after inoculation. In addition, plant height, above-ground fresh and dry weight and root fresh and dry weight were measured. Only V. dahliae had a negative effect on all the measured characteristics. Soil from infested fields was assayed for microsclerotia on modified Nadakavukaren and Horner medium. V. dahliae was widely distributed in the Chott Mariem region, with a density as high as 69 CFU/g of soil. Evaluation of melon cultivars in V. dahliae-infested fields indicated that all were susceptible. Verticillium wilt has become a threat to melon production in Tunisia.

Zakaria M. Sawan, Ashraf H. Fahmy, Serag E. Yousef (Egypt) Cottonseed Yield, Seed Viability and Seedling Vigour as Affected by Nitrogen, Potassium, Phosphorus, Zinc and a Plant Growth Retardant (pp 16-25)

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Original Research Paper: Seed vigour and viability are important components influencing seedling establishment, crop growth, and productivity. Cottonseed quality is affected to a large extent by the indeterminate growth habit of a cotton plant, which allows seed to set and develop over an extended period. Two field experiments were conducted at the Agricultural Research Center, Giza, Egypt, during two consecutive seasons on Egyptian cotton (Gossypium barbadense) cv. ‘Giza 86’. The aim was to identify production treatments, which may improve seed yield and quality. The first study investigated the effect of soil N-fertilization (at 95.5 and 142.8 kg N/ha) and foliar application of potassium (at 0.0, 400, 800 or 1200 ppm K₂O, applied twice; 70 and 95 days after planting) and the plant growth retardant (PGR) mepiquat chloride (applied twice; 75 days after planting at 0.0 or 50 ppm, and 90 days after planting at 0.0 and 25 ppm). The second studied the effect of soil potassium fertilization (at 0.0 and 57.1 kg K₂O/ha, eight weeks after sowing) and foliar application of chelated zinc (applied twice, at 70 and 85 days after sowing, at 0.0 and 60 ppm) and phosphorus (at 0.0, 600, 1200 and 1800 ppm P₂O_5; applied twice, 80 and 95 days after sowing). The first experiment showed that seed yield/plant and seed yield/plot, seed weight, seed viability, seedling vigour and cool germination test performance, were all found to increase due to the addition of the high N-rate (142.8 kg N/ha). Application of the three potassium concentrations and mepiquat chloride also showed similar effects. Under the conditions of this study, applying N at 142.8 kg/ha combined with spraying cotton plants with K₂O at 1200 ppm and also with mepiquat chloride at 50 and 25 ppm can be recommended to improve seed yield, as well as seed viability, and seedling vigour in the next season. In the second experiment seed yield/plant, seed yield/plot, seed weight, seed viability, seedling vigour, and cool germination test performance increased as a result of the addition of K₂O, and from the application of Zn, and P₂O₅ at different concentrations. Under the conditions of this study, applying K₂O at 57.1 kg/ha and spraying cotton plants with Zn at 60 ppm and also with P₂O₅ at 1800 ppm can be recommended to improve seed yield, as well as seed viability, and seedling vigour in the next season.

Zakaria M. Sawan, Mahmoud H. Mahmoud, Amal H. El-Guibali (Egypt) Growth, Yield components, Yield and Fiber Properties of Egyptian Cotton (Gossypium barbadense L.) as Affects by Potassium Fertilization and Foliar Application of Zinc and Phosphorus (pp 26-35)

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Original Research Paper: Two experiments were conducted at the Agricultural Research Center, Giza, Egypt, to investigate the effect of soil potassium fertilization and foliar application of chelated zinc and phosphorus on yield components, yield and fiber properties of cotton (Gossypium barbadense L.) cv. ‘Giza 86’. Potassium (0.0 and 47.4 kg of K ha^-1) was soil-applied three weeks after sowing, while chelated zinc (0.0 and 57.6 g of Zn ha^-1, applied twice at 70 and 85 days after sowing) and phosphorus (0.0, 576, 1152 and 1728 g of P ha^-1, applied twice at 80 and 95 days after sowing) were applied to the foliage. Dry matter yield of cotton plants (shoots), total chlorophyll concentration, K, Zn and P-uptake plant^-1, number of opened bolls plant^-1, boll weight, seed index, lint index, seed cotton and lint yield ha^-1 and earliness of harvest increased with the application of potassium and Zn and P at different concentration rate. Treatments generally had no significant effect on lint percentage and fiber properties, with exceptions for micronaire reading and flat bundle strength in the first season, and uniformity ratio in the second season, where the mean values of these characters increased significantly over the untreated control by applying K, and for the micronaire reading in the first season, when applying P at 1728 g ha^-1, and uniformity ratio in the second season, when applying P at 1152 and 1728 g ha^-1, where the mean values of these characters increased significantly over the untreated control by applying P. Under the conditions of this study, applying K fertilization at 47.4 kg ha^-1 combined with spraying cotton plants with zinc at 57.6 g ha^-1 and also with P at 1728 g ha^-1 improved growth and yield of Egyptian cotton.

L.N. Ukiwe Lugard, C.E. Ogukwe (Nigeria) Potassium Ion Uptake by Water Hycinth (Eichhornia crassipes) on The Lower Reaches of the Niger River, Nigeria (pp 36-39)

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Short Communication: The concentration of potassium ion in water hyacinth (Eichhornia crassipes), a free-floating aquatic weed, was studied. Field trips were made to sample stations and harvested water hyacinth digestate were analyzed using Atomic Absorption Spectrophotometry. Investigations showed that the concentration of potassium ion in January to June 2003 ranged from 0.52 mg/l to 0.59 mg/l and that the cumulative mean average of the ion concentration for the six months was 0.55 mg/l. From January to June in 2004, the ion concentration ranged from 0.55 mg/l to 0.62 mg/l. The cumulative ion mean average within this period was 0.59 mg/l indicating an increasing trend in potassium ion uptake from January to June in 2003 and 2004 in the Lower Reaches of the Niger River, Nigeria. This was likely as a result of increased agricultural, industrial and human waste activities around the sample areas. Run-off from these activities is washed into the river by rainfall, which coincided with an increase in average rainfall level during the sampling periods, thus creating an upsurge in nutrient levels.

Ndubuisi J. Aneke, Emeka E. Oguzie, Luke N. Ukiwe (Nigeria) Physicochemical Properties of Choloform Extract of Water Hyacinth (Eichhornia crassipes) (pp 40-42)

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Short Communication: Physiochemical examinations were carried out on the chloroform extract of Eichhornia crassipes leaves. Preliminary phytochemical analysis of the extract revealed the presence of saponins, alkaloids, glycosides and anthraquinones in the extract. Fractionation of the extract constituents by column chromatography and thin layer chromatography yielded three distinct compounds designated I, II and III with R_f values 0.89, 0.69 and 0.49 respectively. The UV/visible spectra for compounds I, II, and III showed maximum absorbance at three-point wavelength maxima respectively. Chemical tests for the presence of alkaloid and phenolic hydroxide in the three compounds were negative. The IR absorption bands for compound I, II, and III respectively were recorded. Relating the UV/visible and IR results, the presence of unique nitro aromatic esters were revealed in compounds I, II, and III, hence their distinct R_f values.

Wafaa M. Shukry (Egypt) Fatty Acids and Stress in Three Oil-Producing Plants: Canola (Brassica napus L.), Safflower (Carthamus tinctorius L.) and Sunflower (Helianthus annus L.) (pp 43-56)

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Original Research Paper: The effect of salinity- and drought-stressed soils collected from different sites in Egypt (Suez road; North Coastal area; El-Kantra East) on yield parameters of three oil plants canola (Brassica napus L.), safflower (Carthamus tinctorius L.) and sunflower (Helianthus annus L) was assessed. The plants were subjected to a pot experiment in which pots contained an equal amount of each soil-type either alone or supplemented with composted plant residue (wheat straw and Eichhornia crassipes) at three concentrations (0.25, 0.5, 1.0% v/v) as organic fertilizers and ammonium sulphate at three levels (5, 10, 15 g/pot) as inorganic fertilizer. All three soil types resulted in a decrease in all yield and yield attributes for all three plants when grown in these different soil types compared to the control garden soil although yield parameters improved when soils were supplemented with organic fertilizers rather than inorganic ones. Oil contents and the saturated and unsaturated fatty acid profile varied considerably among treatments.