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The economic threshold level of Meloidogyne incognita, Alternaria dauci and Rhizoctonia solani were determined on carrot (Daucus carota L.) under greenhouse conditions. The results revealed that plant length, plant fresh weight, shoot and root dry weight, chlorophyll and carotenoid decreased progressively with the corresponding increase in the inoculum levels of each pathogen. The significant reduction in plant growth parameters, chlorophyll and carotenoid occurred when 2000 or more second stage juveniles (J2s) of M. incognita, 1.0 g or more inoculum of A. dauci or R. solani per kg soil were inoculated. Maximum reduction in plant growth attributes, chlorophyll and carotenoid occurred at the highest inoculum level of the test pathogens. Increase in the inoculum level of M. incognita caused an increase in the number of root galls, while the multiplication of nematode was found inversely related to the inoculum density. The increase in the inoculum levels of A. dauci and R. solani resulted in a progressive increase in leaf blight and crown rot indices and caused a higher reduction in plant growth parameters. The damaging threshold level of M. incognita was 2000 J2 per kg soil while 1.0 g per kg soil of A. dauci or R. solani was threshold level on carrot. The assessment of infestation levels of test pathogens will enable growers to cost-effectively select and implement the management tactics.
Effects of Meloidogyne incognita, Alternaria dauci and Fusarium solani were studied on carrot (Daucus carota L.) growth, chlorophyll, carotenoid and proline contents in different types of soil. Plants grown in 20:80 and 40:60% sand:clay soil mixtures showed a significant increase in root dry weight, chlorophyll and carotenoid contents compared to plants grown in 100% clay soil. However, use of 60:40 sand:clay resulted in a similar root dry weight, chlorophyll and carotenoid contents as was found in carrots grown in 100% clay soil. Inoculation of plants with M. incognita, A. dauci or F. solani caused a significant reduction in root dry weight, chlorophyll and carotenoid contents in all soil types as compared to their respective control. Inoculation of plants by A. dauci caused the greatest reduction in root dry weight followed by F. solani and M. incognita in different sand and clay mixtures. Use of 20:80, 40:60 or 60:40 sand:clay mixtures caused a significant increase in proline content of plants over those grown in 100% clay soil. Similarly, inoculation of M. incognita, A. dauci and F. solani caused a significant increase in proline content in all soil types compared to their respective control.
Higher plant population and nitrogen management is an adopted approach for improving crop productivity from limited land resources. Moreover, higher plant density and nitrogen regimes may increase the risk of stalk lodging, which is a consequence of complex interplant competition of individual organs. Here, we aimed to investigate the dynamic change in morphology, chemical compositions and lignin promoting enzymes of the second basal inter-nodes altering lodging risk controlled by planting density and nitrogen levels. A field trial was conducted at the Mengcheng research station (33°9′44″N, 116°32′56″E), Huaibei plain, Anhui province, China. A randomized complete block design was adopted, in which four plant densities, i.e., 180, 240, 300, and 360 × 104 ha−1 and four N levels, i.e., 0, 180, 240, and 300 kg ha−1 were studied. The two popular wheat varieties AnNong0711 and YanNong19 were cultivated. Results revealed that the culm lodging resistance (CLRI) index of the second basal internodes was positively and significantly correlated with light interception, lignin and cellulose content. The lignin and cellulose contents were significantly and positive correlated to light interception. The increased planting density and nitrogen levels declined the lignin and its related enzymes activities. The variety AnNong0711 showed more resistive response to lodging compared to YanNong19. Overall our study found that increased planting densities and nitrogen regimes resulted in poor physical strength and enzymatic activity which enhanced lodging risk in wheat varieties. The current study demonstrated that stem bending strength of the basal internode was significantly positive correlated to grains per spike. The thousand grain weight and grain yield had a positive and significant relationship with stem bending strength of the basal internode. The results suggested that the variety YanNong19 produces higher grain yield (9298 kg ha−1) at density 240 × 104 plants ha−1, and 180 kg ha−1 nitrogen, while AnNong0711 produced higher grain yield (10178.86 kg ha−1) at density 240 × 104 plants ha−1 and with 240 kg ha−1 nitrogen. Moreover, this combination of nitrogen and planting density enhanced the grain yield with better lodging resistance.
A study was conducted on the sheep farm of the Livestock Experimental Station, located in the southwestern Punjab, Pakistan, to determine the copper nutrition status of different classes of grazing sheep during two different seasons. A complete free-choice supplement (feed) was available to all animals throughout the year. The purpose of this research was to investigate, as a function of the seasons, the transfer of Cu from soil, and dietary factors to sheep grazing in this semiarid region, in order to evaluate if the Cu requirement of grazing livestock was met or if a deficiency occurred. The final goal was to maximize the production of the animals by adopting, if necessary, adequate, balanced Cu supplementation. Soil, forage, feed and water samples, and animal samples (plasma, milk, faeces and urine from lactating ewes, plasma, faeces and urine from non-lactating ewes and plasma and faeces from male animals) were taken eight times during the year (four times in each season). Soil copper was affected by the seasonal changes and sampling intervals and was significantly higher than plant needs during both seasons, while the forage copper level did not show significant seasonal fluctuations, but was only affected by the sampling intervals. The soil and forage Cu was sufficient for the requirements of the plants and the animals grazing there on during both seasons. The copper contents of the feed and water showed no seasonal or sampling interval fluctuations. The plasma Cu was affected by seasonal variations in non-lactating ewes and in rams and by sampling intervals in the lactating ewes. Faecal and urine Cu was not affected by seasonal or sampling intervals except in non-lactating ewes, where the sampling interval had a pronounced effect on faecal Cu, while milk Cu in lactating ewes was affected by seasonal changes only. In all classes of sheep plasma Cu was higher during the winter than during the summer and remained in the normal range for ruminants during both seasons. It is concluded that a mixture with high bioavailability, containing Cu, should be continuously provided to grazing sheep in this semi-arid region in order to maintain the normal level of Cu and maximize the production potential of ruminants.