To analyze the extent of variations in salt tolerance in soybean, 170 genotypes were screened against salinity stress at the vegetative stage at the Department of Agronomy of Bangabandhu Sheikh Mujubur Rahman Agricultural University in Bangladesh. The plants were grown in pots, subjected to saline irrigation of 150 mM NaCl solution, from 14 to 30 days after sowing; then plant height and dry weight of different plant parts were measured. The genotypes showed a wide variation in different plant characters. Relative plant height (percent value to the control) ranged from 43.2 % to 98.3 % with a mean of 73.0 %, the relative stem dry weight from 24.7 % to 99.4 % with a mean of 59.4 %, the relative leaf dry weight ranged from 6.9 % to 98.7 % with an average value of 48.9 % and the relative root dry weight from 9.8 % to 96.4 % with a mean of 65.3 %. Similarly, the relative shoot dry weight (RSDW), which is the sum of the dry weight of stem, leaf and petiole, ranged from 20.4 % to 93 % with an average value of 52.2%. The genotypes were grouped into different salt-tolerance categories based on their RSDW value and salinity susceptibility index (SSI). Among the 170 genotypes, 13 which showed a low SSI (0.265) and high RSDW (> 80 % of the control) under salinity were grouped into tolerant category, 36 into the medium-tolerant category with a SSI of 0.666 and RSDW in the range of 60-80 %, while 83 genotypes were medium-susceptible with a SSI of 1.052 and 40-60% RSDW, and the remaining 38 genotypes were grouped into the susceptible category with a SSI of 1.376 and <40% RSDW. The wide genotypic variations in salinity tolerance might be useful for improving the salinity tolerance level of this crop through genetic manipulation programs.
In passion fruit, little information is available about the effect of the form of N fertilizer on vegetative growth and flowering. Nutrient solutions containing 5, 10, 25, or 50 mM N with an NH4-N:NO3-N ratio of 100:0, 75:25, 50:50, 25:75, or 0:100 were applied to passion fruit grown in sand to determine the appropriate ratio for vegetative growth and flowering. Vegetative growth, SPAD value, photosynthetic and transpiration rates, flower number, and leaf mineral contents were examined. SPAD value and photosynthetic rate decreased and necrosis was observed following the pure application of 25 and 50 mM NH4-N; in addition, the vine dry weight decreased at 50 mM. With additional NO3-N, the plants were able to avoid the detrimental effects of NH4-N. The N ratio did not affect vegetative growth except for the application of NH4-N alone, and no visible damage was observed, while the photosynthetic rate increased as the NO3-N ratio increased at N concentrations of ≥25 mM. At less than 10 mM N, symptoms of N deficiency were observed. The flower number increased as the NH4-N ratio increased. NH4-N should not be applied alone to passion fruit; however, an NH4-N-dominant fertilizer consisting of ≥50% NH4-N is recommended to promote reproductive growth without reducing vegetative growth.
Several options to reduce methane (CH4) emission from rice fields have been reported including straw management, soil amended with Fe(OH)3 and iron slag, encapsulated calcium carbide, and water management by drainage-flooding. In the present paper, field experiments were conducted to determine whether controlled water level below 3 cm and 6 cm might affect CH4 and nitrous oxide (N2O) emissions compared to local rice farmer practice (water level mostly above 6 cm but basically uncontrolled) in Maros area, South Sulawesi, Indonesia. CH4 and N2O fluxes were measured at one-week intervals throughout two cropping seasons using a closed chamber method. Grain yield was determined at the end of cultivation. The results showed that CH4 emission in the 1st cultivation was reduced by 36.5% and 33.8% in the plots with 3 cm and 6 cm water levels, respectively, whereas, in the 2nd cultivation, it was reduced by 63.6% and 44.6%, compared to farmer practice plots. N2O emission from paddy fields was not detected and tended to decrease in both cropping seasons. We concluded that controlled water level lower than that in farmer practice could significantly reduce CH4 emission without affecting rice grain yield and N2O emission.
Vegetable production is one of small-scale farmer transforming strategies from subsistence farming to a business enterprise in Ethiopia. Nonetheless, the focus of research and extension placed on boosting production without due consideration on the costs and returns. This paper takes a step forward in examining the cost and benefit of small-scale onion and tomato farming using data obtained from randomly sampled households. Net returns were employed to determine the cost-benefit of vegetable farming. Likewise, sensitivity analysis was introduced to account for any major fluctuations and risks envisaged. Small-scale vegetable farming was found a profitable enterprise and the local average yield is well above the national average yield. Returns from onion was more sensitive to yield variation and an average marginal yield increase by 5-10% would compensate for price fluctuations of up to 50% drop from a normal season price. Onion fetched more net income and the profit margins of both crops were high. Onion production is more labor intensive and this shows high potential for consistently supporting farm household and rural labor while tomato production tends to be chemical intensive. Research and extension services need to provide information on the cost-benefits hand in hand with the promotion of yield increase. The findings have a far-reaching implication that onion and tomato farming can be sustainably pursued with the available open pollinated varieties and improved management practices without hastily resorting to high yielding and imported inputs such as hybrid seeds.
We would like to correct mistakes found in a research article, “Effects of Excess NH4-N or NO3-N Fertilizer Applications on Leaf Injury, Vegetative Growth, and Leaf Mineral Contents in Passion Fruit”, published in Tropical Agriculture and Development Vol.56 No.3.
We would like to correct mistakes found in a research article, “An Assessment of Farm Household Diverse Common Bean Seed Sources and the Seed Quality in Central Ethiopia”, published in Tropical Agriculture and Development Vol.56 No.3.