Antioxidant activity of potato compared with that of broccoli, onion, carrot and bell peppers was higher than all except broccoli. Patatin appeared to be the major water-soluble compound that showed antioxidant activity. The activity varied among potato cultivars, but was not related to flesh color or total phenolics. Antioxidant activity was evenly distributed within tuber parts and/or sections, except for skin tissue which had the greatest antioxidant activity and total phenolic content. Total phenolics varied among cultivars, with some containing twofold higher concentrations than other cultivars. Phenolic content differences were genotype dependent and not related to flesh color.

Wastewater treatment plants produce a large amount of sludge, which negatively affects our environment. The agricultural application of sludge is an environmentally friendly disposal option. The current study investigated the use of sewage sludge in the fertilisation of arid land in Al Ahsa, KSA, to reduce the need for importing fertilisers and increase plant productivity. Sewage sludge was used as an organic fertiliser in the cultivation of cucumber (Cucumis sativa) and lettuce (Lactuca sativa) through its scalable addition to sandy soil at rates of 0 (control soil), 5, 15 and 45% in a pot experiment under greenhouse conditions. Chemical and microbiological analysis was carried out using a UV spectrophotometer, flame photometer and atomic absorption spectrum. The results indicated that the application of sewage sludge significantly altered soil properties. The total dissolved salts (TDS), soluble anions (Cl, HCO 3 , NO 3 and SO 4), soluble cations (Na, K, Ca and Mg), nutrients (TKN, TP) and trace metals (Fe, Mn, Cu, Zn and Cr) increased in the sandy soil with the increasing sludge application rates. For example, the average TDS in the soil increased significantly (p<0.01) from 0.667 gm/l for the control to 1.73, 2.33 and 3.04 gm/l in soil mixed with sludge at 5, 15 and 45 %, respectively. The application of sewage sludge improved soil properties and increased organic matter from 1.72% in the control soil to 9.36% in the soil mixed with 45% sludge. In addition, the application of sewage sludge increased the growth yield of lettuce and cucumber plants. In conclusion, the current study revealed that using sewage sludge as organic manure at a low application rate of 5% can improve the soil's physical and chemical properties, provide plants with the required nutrients, and increase growth and yield.

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Studies were conducted to evaluate metolachlor for weed control and crop tolerance in sweet potatoes. Metolachlor was applied posttransplant at rates of 0.5, 1.0, or 2.0 lb/A. Tank-mix combinations of metolachlor + clomazone were also evaluated. Clomazone was the standard herbicide used for comparison. Metolachlor alone or in combination with clomazone did not cause any serious reduction in sweet potato plant vigor when applied posttransplant. Metolachlor provided excellent control of Brachiaria platyphylla, Cyperus iria, Cyperus esculentus, and Amaranthus hybridus. Tank-mixes with clomazone did not improve the weed control of metolachlor alone. Yields of No. 1 and marketable roots from metolachlortreated plots were equal to or greater than yields from plots treated with clomazone. RESISTANCE IN SWEETPOTATO TO ROOT-KNOT NEMATODE: ITS VALUE AND OTHER BENEFITS A root-knot nematode (Meloldogyne incognita) project was initiated in a field of infested sandy loam (EREC) in 1991 and continued. There were ten sweetpotato entries consisting of six cultivars (Beauregard. Excel, Georgia Jet, Jewel, Red Jewel, and Sumor), three advanced lines (W-270, W-274, and W-279) and PI 399161 which were selected for their diversity in disease reactions and other traits. Each entry was planted in the same plots each year to monitor effects of continuous cropping, disease reactions, yield and population shifts of the pathogen. Marketable yields were reduced each year for Georgia Jet and Red Jewel, but not for Beauregard. Internal necrosis in the storage roots was most severe for Beauregard. Several of the highly resistant entries, especially Sumor and W-279, performed well each year, including high yields, good quality. and little or no nematode reproduction. This study demonstrates the considerable economic benefits of a high level of durable resistance to root knot in sweetpotato.