SEEDLING GROWTH TOLERANCE OF CUCURBITS CROPS TO HERBICIDES STOMP AND ACETOCHLOR
Summary. Several species from the Cucurbitaceae family including muskmelon, watermelon, cucumber, pumpkin, and squash were used to evaluate their tolerance in a laboratory test to two herbicides (Stomp and Acetochlor) widely used in crop cultivation. The effects of concentration and site of herbicide action on the length of primary roots and hypocotyls as well as seedling fresh weight were studied. The results showed that the cultivars differed greatly in their sensitivity to the herbicide action. The difference in the growth responses was not only species-, but also cultivar-specific. In addition, there was a difference in the herbicide acting site on plants which depended on the kind of cucurbits crops. Based on the tolerance to the action of both herbicides the studied species can be classified as follows: watermelon, squash, pumpkin, muskmelon, cucumber. The tolerance differences of the studied cucurbits crops can be used in cultivation practice.
Tolerance of egusi -melon [ Citrillus colocynthis (L.) schrad] and susceptibility of weeds to Primextra doses
Objective: The study was to evaluate melon tolerance and weeds susceptibility to Primextra {Primextra- Gold 660g/L (atrazine (370g/l) + S-metolachlor (290 g/l SC)}. Methodology and results: The Field studies were conducted in 2013 and 2014 planting seasons at Faculty of Agriculture Farm, University of Port Harcourt, Rivers State, (latitude 04 o 54 538’N, and longitude 006 o 55 329’E; 17m above sea level), Nigeria. Seven rates of primextra (0.25, 0.50, 0.75, 1.00, 1.25, 1.50, 1.98 kg ai ha -1 ), applied as pre-emergence were compared with a untreated control (no primextra).The 8 treatments were fitted into a Randomized Complete Block Design, replicated three times. Melon was planted 3 seeds per hole at a spacing of 1m ×0.5m (20,000plants/ha). Result from this study showed that both melon and weeds were susceptible to all Primextra rates but melon tolerated low doses of Primextra in the range of 0.25 – 0.75 kg ai//ha than higher rates. Weeds were more susceptible to higher Primextra rates between 1.0 and 1.98 g ai/ha. Susceptibility of weeds to Primextra rates of 0.25 – 0.75 kg ai /ha and 1.0 – 1.98 kg ai/ha accounted for about 76.2 % and 74 % weed control efficiency respectively. Results also showed that melon tolerated Primextra doses of 0.25 to 0.75 kg ai /ha and thus reached a mean ground cover of F 40 % to F 80 % when compared to the untreated plot. Melon fruit yield from the Primextra treated plots had about 23.5% (1659 Kg/ha) yield advantage over the untreated control plot (1269kg/ha). Mean fruit yield with the herbicide rates were as follows: 1959.5 kg/ha (0.25- 0.75 kg ai/ha); 1430 kg/ha (1.0 – 1.98 kg ai/ha) and 974.5kg/ha (1.50 -1.98 kg ai/ha). Susceptibility of weeds to Primextra increased as application dose increased. The implication of this result is that melon may find a tolerable dose of Primextra-Gold for integration in maize-melon cropping systems. Conclusion and application of results: Farmers can intercrop either simultaneously egusi-melon with maize or relay egusi-melon into maize and use primextra for pre-emergence weed control, at a dose not greater than 0.25-0.75 kg ai/ha for good yield and acceptable weed control. This can be applied in maize-melon cropping systems with melon either simultaneously or in relayed intercropping to reduce the effect manual weeding on melon especially during flowering and fruiting. Keywords: PrimextraGold, melon, Tolerance, weed
Mode of action of bredinin with guanylic acid on L5178Y mouse leukemia cells.
Moderate concentrations of bredinin (1.2 X 10(-5) M) strongly inhibited growth of L5178Y cells, with the effect being reversed by guanylic acid (GMP). However, at higher concentrations of breeding the inhibition was not reversed completely by GMP added in excess. Bredinin was cytocidal at concentrations above 2 X 10(-5) M, but 5 X 10(-5) M bredinin in the presence of excess GMP, bredinin was cytostatic. Bredinin inhibited nucleic acid synthesis of L5178Y cells, but bredinin itself was not incorporated into the nucleic acid. Inhibition of nucleic acid synthesis was clearly reversed by GMP. Similarly chromosomal aberrations in L5178Y cells caused by bredinin were reversed by GMP. In contrast, the effect of ahigh concentration of bredinin on cell multiplication was not reversed by GMP. The modal volume of L5178Y cells increased during incubation in the presence of bredinin and GMP for 24 hours, 5 X 10(-5) M bredinin with GMP causing a 70% increase in cell volume. This increase in cell volume was mainly due to an increase in the protein content of the cells. The cytostatic effect of bredinin with GMP was reversed completely by adenosine-3',5'-cyclic monophosphate (cyclic AMP). Other cyclic nucleotides and nucleotides were ineffective. The reversing effect of cyclic AMP on cell survival depended upon the concentration of GMP, and was not seen in the absence of GMP. It was concluded that cyclic AMP influences the secondary cytostatic effect of bredinin, and not the primary cytotoxic effect reversed by GMP.