Efficacy of mulching, irrigation and nitrogen applications on bottle gourd and okra for yield improvement and crop diversification

An on-farm irrigation trial conducted on the upland of Chitwan valley of Nepal evaluated the amount and frequency of irrigation as well as the effect of nitrogen fertilizer and straw mulch applications on the performance of bottle gourd and okra vegetables. The experiment was laid out on split-split-plot design with fertilizer as main-plot factor, frequencies of irrigation as sub-plot factor, and amount of irrigation as sub-sub-plot factor. Data analysis revealed that frequency and amount of irrigation had a significant interaction effect on the number of nodes that emerge before the opening of the first flower in bottle gourd. Likewise, a significant effect of mulching was observed on the number of primary branches (P = 0.05). Number of nodes and primary branches both contributed to higher production of bottle gourd. Results also indicated that frequent application of higher amount of irrigation to bottle gourd could lead to reduced water productivity and suffer from yield losses. In the case of okra, low level of nitrogen application (30 kg N ha⁻¹) with low but daily watering had significantly higher yield (1,365 g plot⁻¹) than from higher level of nitrogen application (90 kg ha⁻¹) (P = 0.01). Interaction effect of all factors was also significant (P = 0.05) on the fruit yield of okra which implied greater value of smaller irrigation to contribute to increased returns to farmers by improving production level of okra in this area of Nepal     

Penetrance of gene I for Fusarium resistance in the tomato

Tomato seedlings were inoculated, from one to ten days after emergence, with the tomato Fusarium wilt fungus race 1. The penetrance of gene I for Fusarium resistance in the homozygous resistant variety Homestead 24 was almost complete. In the F₁ (Ii) between Homestead 24 and the susceptible Marmande penetrance was incomplete and ranged between 66.3% and 100% in different experiments. The age of seedlings at time of inoculation did not affect the final percentage of diseased plants while it influenced the nature and the time of appearance of disease symptoms. Possible consequences of incomplete penetrance for the resistance of F₁ hybrids are discussed.     

Assessing genetic resistance to spot blotch, <Emphasis Type="Italic">Stagonospora nodorum</Emphasis> blotch and tan spot in wheat from Nepal

Fungal leaf spot diseases of wheat (Triticum aestivum L.) in Nepal cause significant yield reduction. Although field testing has identified a few partially resistant cultivars, most wheat grown in Nepal lacks adequate resistance to leaf spot diseases. During 2009–2010, 116 local and commercial spring wheat cultivars and advanced breeding lines were selected from multi-year field experiments in Nepal and evaluated for seedling resistance to three leaf spot diseases: spot blotch, Stagonospora nodorum blotch (SNB) and tan spot races 1 and 5 (two of the most prevalent races) in the growth chambers at North Dakota State University, Fargo, ND, USA. The wheat cultivars and lines were artificially inoculated with individual pathogens or races at the two-leaf stage and disease reactions were evaluated 6 to 10 days after inoculation (DAI). Results indicated that 30%, 31%, 19% and 10% of the tested wheat cultivars and lines were resistant to spot blotch, SNB, tan spot races 1 and 5, respectively. Six advanced breeding lines (SW89-5422, BL 2127 = DANIAL88/HLB30//NL297, BL 3033, FILIN/IRENA/5/CNDO/R143//ENTE/MEXI-2/3/AE. SQUA (TAUS)/4WEAVER, GAN/AE.SQUARROSA (236)//DOY1/AE.SQUARROSA(447)/3/MAIZ/4/INQALAB91, Mayoor//TK SN1081/Ae. Squarrosa (222)/3/FCT, were resistant to spot blotch, SNB and tan spot race 1. Similarly, two wheat cultivars Chirya 3 and Chirya 7 were resistant to spot blotch, and tan spot races 1 and 5. The resistant wheat lines identified in this study represent potentially useful and untapped sources of resistance to multiple leaf spot diseases and should be utilized in wheat breeding programs in Nepal in order to develop wheat cultivars with broad-spectrum resistance.     

Reducing Nitrogen Leaching from Agriculture: An Essential Step toward Protecting the Environment in High Rainfall Areas of Taiwan

ABSTRACT

Reducing nitrogen (N) leaching from croplands is important to protect environmental quality and improve recovery of applied N. To contribute to this broader goal of nutrient management, a simple pot experiment evaluated the potential differences among urea (250 kg N ha^?1), urea+compost (125 kg N ha^?1 from urea + 125 kg N from 8 Mg ha^?1 of compost), compost (250 kg N from 16 Mg ha^?1 of compost) and a zero control (Ctrl), in terms of their effects on apparent N recovery (ANR), mineral N (N_min) leaching and soil retention of applied N. Cabbage (Brassica oleraceae L.) and corn (Zea mays L.) were grown in rotation where compost application was not repeated in the 2nd year. N_min leaching was monitored by adding 83 mm and 62 mm of water fortnightly to cabbage and corn crops, respectively for a total of 28 times in a two-year period. Combined (urea+compost) and independent (compost) treatment application retained 1.5 to 2 times higher N, and lowered 2.1 to 4.6 times N_min leaching, relative to independent (urea) application. We conclude that farmers’ practice of fertilization that has an inherent problem of N leaching for high rainfall areas in Taiwan could be improved by proper compost and urea combinations within agronomically recommended rates of N application.     

Responses of maize × teosinte derived backcross inbred lines (BILs) to maydis leaf blight (MLB) disease

Euphytica - Rice growth and productivity are greatly affected by cold stress, which is likely to become more of a hindrance for high and stable rice yields. To identify cold tolerance at the...     

Effect of Manganese and Iron on Growth and Feeding of Juvenile Giant River Prawn, Macrobrachium rosenbergii (De-Man)

Abstract.— The effect of either manganese or iron on survival, growth, and feeding of giant river prawn, Macrobrachium rosenbergii (De-Man), juveniles was studied in two separate experiments. Survival rates of M. rosenbergii juveniles (4.58 ± 0.48 g) following 60-d exposure to 0.01 (control), 0.3, 0.6, and 1.2 mg/L of total manganese (Mn) were 100, 93.3 ± 3.4, 83.3 ± 4.3, and 83.3 ± 4.3%, respectively, while the same were 100, 83.3 ± 3.6, 73.3 ± 3.3, and 63.3 ± 4.7%, respectively, at the total iron levels of 0.02 (control), 0.32, 0.65, and 1.2 mg/L. Average daily growth of the prawn was significantly ( P  < 0.05) lower at 0.3 mg/L and higher levels of total manganese compared to control (0.01 mg/L). Average growth of the prawn exposed to 0.65 and 1.2 mg/L total iron was significantly lower ( P  < 0.05) than in control (0.02 mg/L iron) and 0.32 mg/L treatments after 60 d of exposure. Feed utilization was significantly ( P  < 0.05) reduced in M. rosenbergii juveniles exposed to 0.3 mg/L and higher levels of manganese. Feed utilization was significantly ( P  < 0.05) reduced in the prawns at all the iron treatments compared to control (0.02 mg/L iron). The accumulation of Fe and Mn was minimum in the muscle and maximum in the hepatopancreas of the prawns.     

Effect of different oil cake sources on growth, nutrient retention and digestibility, muscle nucleic acid content, gut enzyme activities and whole-body composition in silver barb, Puntius gonionotus fingerlings

Six iso‐nitrogenous (30% crude protein) and iso‐energetic (15 kJ g⁻¹) diets were prepared using different oil cake sources, viz. groundnut, soybean, sunflower, sesame, mustard and mixed oil cakes as major ingredients, and protein sources along with a minimum of 5% fish meal in each diet and were fed to silver barb Puntius gonionotus fingerlings (16.20±0.11 g) ad libitum four times a day close to an apparent satiation level for a period of 60 days to determine the effect of diets on growth, nutrient utilization, apparent digestibility coefficient (ADC) of the nutrients in the diets, gut enzyme activity, muscle nucleic acid content and whole‐body chemical composition of fish. Significantly higher (P<0.05) weight gain, specific growth rate, protein efficiency ratio, nutrient retention, ADC of nutrients in the diets, DNA:RNA ratio, protease and amylase activity with lower (P<0.05) feed:gain values were recorded in fish‐fed groundnut and soybean oil cake‐based diets than other diets tested. Among the dietary treatment groups, significantly higher (P<0.05) whole‐body protein, lipid and energy were also found in groundnut oil cake‐ and soybean oil cake‐based diets. The study suggests that the groundnut and soybean oil cake‐based diets, which led to significantly higher (P<0.05) growth and nutrient utilization than the other oil cake‐based diets in P. gonionotus fingerlings, may be used for pond culture of this species.     

A Simplified method for determining the resistance of tomato seedlings toFusarium andVerticillium wilts

A simple test for determining the resistance of tomato lines toFusarium andVerticillium wilt diseases was developed. Roots of tomato seedlings at their first true leaf stage were dipped in a heavy suspension of the pathogen for 24 h. The seedlings were then transferred to small beakers containing various concentrations of Hoagland solution. The first and most severe disease symptoms appeared on susceptible cultivars grown in 25% Hoagland nutrient solution. Final results of resistance tests were obtained 10, 8 and 16 days after inoculation withFusarium race 1, race 2, andVerticillium, respectively. The test appears to be simple, results are obtained rapidly, and greenhouse space can be saved.     

Conditioning of tomato fruit against sunscald

Tolerance to sunscald damage could be induced under controlled conditions in detached mature-green tomato fruit by gradual heating to 45.1°C, followed by a potentiation period of 10–22 h at 23–27°C. The protective effect decreased thereafter, and 34 h after the heat treatment the fruit was again fully susceptible. Exposure to light did not alter the results of the conditioning treatment. In the field, fruit exposed to the sun may undergo similar, though less drastic, daily temperature fluctuations and may thus acquire some natural resistance.     

Bacterial blight of rice and its control in Nepal

Research on Xanthomonas oryzae pv. oryzae, the bacterial blight of rice pathogen, was initiated at the Institute of Agriculture and Animal Science (IAAS) with the main objective of assessing the population structure of X. o. pv. oryzae through the use of both conventional and molecular markers in combination with virulence typing. A high DNA polymorphism was detected in the pathogen populations using different DNA probes and rep-PCR primers. Most strains were avirulent to cultivars containing the bacterial blight resistance gene Xa-21, which suggested the strategy that targets gene deployment is feasible in Nepal.