Kareem I.

Soil phosphorus dynamics of sweet potato-based cropping system in a rainforest region of Nigeria

I. Kareem, E.A. Akinrinde, Y. Oladosu, S.Y. Abdulmaliq, E.K. Eifediyi, S.Y. Alasinrin, S.A. Kareem

ABSTRACT. To guard against soil phosphorus (P) toxicity in tuber production and have optimum tuber yield at lesser cost of P-fertilization, better understanding of the dynamics of phosphorus release in sandy loamy soil is inevitable. Therefore, this work was carried out to investigate the trend of P-release from time of application to its optimum release and its effect on sweet potato growth and tuber production. To achieve this, a 5-week incubation study under laboratory conditions was carried out to study P-release dynamics using different P sources. Similar experiment was conducted on the field using the same P sources and application rate to monitor the influence P-release rate on sweet potato production. Data on number of leaves, vine length, tuber yield, soil extractable phosphorus and phosphorus uptake of the plants were taken. Relationships between P-uptake and tuber yield, number of leaves, vine length were also established. It was found that the trend of phosphorus release was a sigmoid shape. Leaf production and vine length were improved by P-application, while yield was suppressed. It is recommended that P-fertilizer should not be applied to the soil at short intervals to avoid nutrient toxicity.

Keywords: incubation; phosphorus sources; phosphorus uptake; P-release dynamics; tuber yield.

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Salinity stress tolerance of three cowpea cultivars in a southern Guinea savannah ecological zone of Nigeria

I. Kareem, A.I. Musa

ABSTRACT. To combat the problem of food scarcity and insecurity in areas affected by salinity, crop varieties that are tolerant to the stressful conditions should be selected and used. Therefore, this study was carried out to investigate and know the effects of salinity stress on growth and yield of three cowpea cultivars to select the best salinity tolerant cultivar for optimum yield production. To achieve this, three separate experiments were concurrently carried out using ITIOK-298-15, IFE BROWN and SAMPEA 11 cowpea cultivars in the glass house of the Faculty of Agriculture, University of Ilorin, Nigeria. The salinity levels tested in each of the cultivars were 0mM (the control), 50mM, 100mM and 200mM sodium chloride (NaCl). The imposition of salinity stress was for a period of two weeks at maturity because this stage is the most sensitive stage for any crop grown under any environmental stress. The experiments were laid out in randomized complete block design (RCBD) with four replications. Data collection was centred on root length, plant height, number of leaves, leaf area, dry mass, final yield, chlorophyll content of leaves, crude protein and crude fat contents. From this work, it was found that 200mM NaCl decreased the final yield by 51% in ITIOK-298-15, 73% in IFE BROWN and 100% in SAMPEA-11 compared to the control. Furthermore, 100mM NaCl reduced crude protein contents of the leaves by 6% in ITIOK-298-15, 10% in IFE BROWN and 17% in SAMPEA-11 compared to the control. From the above results, it was found that ITIOK-298-15 was the most tolerant cultivar while SAMPEA-11 was the most susceptible cultivar to salinity stress. It is, therefore, recommended (subject to further confirmation) that ITIOK-298-15 cultivar, which is the most promising cultivar of the three cultivars experimented, be used in cowpea production in saline environments of the Southern Guinea savannah ecological areas of Nigeria.

Keywords: salinity stress; cowpea cultivars; cowpea yield; cowpea quality.

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Suitable priming for rice yield improvement

I. Kareem, M.R. Ismail, A. Pueth

ABSTRACT. Low yield of rice has made reaching self-sufficiency level in Malaysia elusive. So, Malaysia has become a target of rice exporting countries within and outside Asia. To solve this problem, a pre-sowing seed treatment was used as a physiological intervention to alleviate the impeding problems of achieving better growth and yield of Malaysian rice variety MR219. A glass house experiment, which involved the use of solutions of osmotic salts and plant hormones, was used for this investi-gation. Data on germination percentages, height, number of tillers and productive tillers, tiller efficiency and yield were taken. In both osmopriming and hormonal priming treatments, the highest number of tillers and productive tillers were from pre-germination. The tallest plants from osmopriming were from 150mM treatment, while 50 ppm GA3 had the tallest in hormonal priming. The highest tiller efficiency for osmopriming was from 150mM and and 200mM sodium chloride, while in hormonal priming it was 200 ppm salicylic acid. For yield per panicle in osmopriming, it was 50mM and 100mM magnesium chloride that had the highest, while in hormonal priming it was 200 ppm methyl jasmonate. Finally, the highest grain yield per hill was produced by 200 ppm methyl jasmonate in hormonal priming, while 50Mm magnesium chloride had the highest yield in osmotic priming. So, it is concluded that the use of 200 ppm methyl jasmonate and 50Mm magnesium chloride could be used as potential hormonal priming and osmopriming, respectively, for yield improvement of MR219 rice in Malaysia.

Keywords: osmopriming; hormonal priming; MR219 rice; growth; yield

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