Vulnerability of sweet cherry cultivars to continuous periods of spring frosts in Plovdiv, Bulgaria

S. Malchev, S. Savchovska*

Fruit Growing Institute – Plovdiv, 12 Ostromila Str., 4004 Plovdiv, Bulgaria

(Manuscript received 31 August 2020; accepted for publication 16 October 2020)

Abstract. The periods with continuous freezing air temperatures reported during the spring of 2020 (13 incidents) affected a wide range of local and introduced sweet cherry cultivars in the region of Plovdiv. They vary from -0.6°C on March 02 to -4.9°C on March 16-17. The duration of influence of the lowest temperatures is 6 and 12 hours between March 16 and 17. The inspection of fruit buds and flowers was conducted twice (on March 26 and April 08) at different phenological stages after continuous waves of cold weather conditions alternated with high temperatures. During the phenological phase ‘bud burst’ (tight cluster or BBCH 55) some of the flowers in the buds did not develop further making the damage hardly detectable. The most damaged are hybrid El.28-21 (95.00%), ‘Van’ (91.89%) and ‘Bing’ (89.41%) and from the next group ‘Lapins’ (85.98%) and ‘Rosita’ (83.33%). A larger intermediate group form ‘Kossara’ (81.67%), ‘Rozalina’ (76.00%), ‘Sunburst’ (75.00%), ‘Bigarreau Burlat’ (69.11%) and ‘Kuklenska belitza’ (66.67%). Candidate-cultivar El.17-90 ‘Asparuh’ has the lowest frost damage values of 55.00% and El.17-37 ‘Tzvetina’ with damage of 50.60%.

Species composition and density of weeds in a grain maize crop depending of soil tillage

P. Yankov*, M. Drumeva

Department of Plant Production, Faculty of Manufacturing Engineering and Technologies,
Technical University of Varna, 1 Studentska Str., 9010 Varna, Bulgaria

(Manuscript received 5 September 2020; accepted for publication 26 October 2020)

Abstract. The study was carried out during 2014-2016 on slightly leached chernozem soil type. The species composition and density of weeds were studied in grain maize grown after previous crop wheat under the following main soil tillage types: ploughing at 24-26 cm, chisel plough at 24-26 cm and no-tillage (direct sowing). The additional tilths of the areas with ploughed and loosened soil included single disking in autumn and double pre-sowing harrowing in spring. A total herbicide was applied for control of the emerging weeds in the variant with direct sowing. The weed control was done according to the standard technology for growing of the crop in this region – treatment with herbicides at stage 3rd-5th leaf of the plants. Weed infestation was read in spring prior to the pre-sowing tillage, immediately before the vegetation treatment with herbicides, and after harvesting. The type of main soil tillage had a statistically significant effect on the species composition and the density of weeds in the grain maize crops grown after previous crop wheat. The use of ploughing, in parallel with the use of chemicals for weed control, decreased the weed infestation in the maize crops. The lower density of weeds under this main soil tillage type was related to changes in the composition and the relative percentage of the respective species in the total infestation. The use of tilths without turning the surface layer and no-tillage in the crop rotation, in spite of the application of herbicides, contributed to the increase of the amount of weeds. The reason for this was the higher variability of weed species typical for shallow tillage types.

Effects of location, gender and indole butyric acid on rooting of Laurus nobilis L. semi-hardwood stem cuttings

A. Saeed*, T. Amin

Department of Environment and Forestry, Faculty of Agriculture, Tishreen University, Latakia, Syria

(Manuscript received 15 April 2020; accepted for publication 1 July 2020)

Abstract. The research was conducted in 2018 in order to investigate the effect of location, tree gender and indole butyric acid (IBA) 4000ppm on rooting of semi-hardwood stem cuttings. Two locations (Al-Samrah and Al-Nabaeen) in Latakia province, Syria, different in latitude and above sea level (500 m and 827 m, respectively) were studied. The results showed significant effect (p<0.05) of the location and tree gender on rooting capacity. No rooting was observed in control (without IBA treatment). Location also affected the number of roots/cuttings. No effect of location or tree gender on root length and diameter was established. The highest rooting rates (%) were for cuttings taken from female trees from Al-Samrah location when treated with IBA 4000 ppm (82.2%).

Detection of Potato virus Y associated with African nightshade leafy vegetable (Solanum scabrum miller) in Kenya

S.L.Kimaru*, D.C. Kilalo, J.W. Kimenju, W.M. Muiru

1Department of Plant Science and Crop Protection, University of Nairobi, P.O. box 30197, Nairobi, Kenya

(Manuscript received 20 June 2020; accepted for publication 27 August 2020)

Abstract. The African nightshades (ANS) have been part of the food systems in sub-Saharan Africa for generations. They are particularly attractive to small scale farmers because the risks of crop losses are much lower compared to the exotic vegetables. Plant viruses are economically important pathogens affecting African nightshade production. More than 200 plant viruses are reported to infest solanaceous family crops. This study was carried out to detect Potato virus Y associated with African nightshade. Symptomatic leaf samples were obtained from four agro-ecological zones in Kenya. The viral pathogens were detected using serology and molecular techniques. Laboratory experiments were carried out at the University of Nairobi and Kenya Plant Health Inspectorate Service (KEPHIS) from February 2017 to August, 2018. Field samples had the highest mean viral percentage frequency of 44.8% compared to greenhouse samples having 29.8% using serology methods. Molecular testing revealed that greenhouse and farm field sample were positive for the three Potato virus Y strains PVYN:O (necrotic recombinant), PVYO (ordinary) and PVYNTN (necrotic). Detection of Potato virus Y in ANS suggests that it is prevalent in the sampled regions and could cause problems to other solanaceous crops.

Machine learning model for estimating agricultural crop insurance payout based on air temperature, rainfall, and relative humidity

K.P. Mangani1*, R. Kousalya2

1Department of Computer Science, Dr.N.G.P Arts and Science College, Coimbatore, Tamilnadu, India
2Research Supervisor, Head of the Department of Computer Application, Dr.N.G.P Arts and Science College, Coimbatore, Tamilnadu, India

(Manuscript received 17 March 2020; accepted for publication 7 May 2020)

Abstract. In Agriculture, the weather-based variations are deliberated to estimate the crop insurance payout. This research model includes linear regression technique (LR) for air temperature payout prediction and fuzzy based choquistic regression (FCR) technique for rainfall payout prediction of agricultural blocks. Then the combined indices of rainfall, relative humidity and air temperature are considered as input to the proposed model named fuzzy based Quasi Poisson Regression technique (FQPR) implementing the multi-indices evaluation function that performs the total payout prediction per hectare of the specified block. The deviations in weather indices determine the insurance payout value with the threshold parameter specified as per policy makers. Thus, the proposed techniques can support the prediction of the total insurance payout with additional weather parameters for the seasonal period of the selected crop for selected five districts with reduced error rate. The results show that the proposed work is appropriate for combining weather indices and predicting the total insurance payout of the groundnut crop of the selected districts.

Fall Armyworm, Spodoptera frugiperda (Lepidoptera: Noctuidae): A recent threat and future management strategy in Nepal

S. Gahatraj1*, S. Tiwari1,2, S. Sharma3, L. Kafle4

1Faculty of Agriculture, Agriculture and Forestry University, Rampur-44209, Chitwan, Nepal
2Bio-Protection Research Centre, Lincoln University, P.O.Box 85084, Lincoln-7647, New Zealand
3Entomology Division, Nepal Agricultural Research Council, Khumaltar-44700, Nepal
4National Pingtung University of Science and Technology, Shuefu Road, Neipu, Pingtung 912, Taiwan

(Manuscript received 31 March 2020; accepted for publication 10 May 2020)

Abstract. Fall Armyworm (FAW), Spodoptera frugiperda, is an invasive pest of maize including other cultivated crops such as rice, wheat, and many other vegetables. This invasive species was initially noticed in North-America and later reported in many countries of Africa in early 2016. In South Asia, this has been reported for the first time in India followed by Srilanka in 2018 and Bangladesh, China, Taiwan and Nepal in 2019. It is polyphagous in nature and damage has been reported in more than 80 plant species. The loss has to lead up to 50-80% in maize in severe situation. FAW is a distant flyer and can fly more than 100 km in a night and spread well in crop fields. As this pest is already invasive in many states of India and the likelihood of entry and spreading in Nepal is higher because of the open border between the countries and flexible government quarantine policy. The great socio-economic loss has been forecasted once this pest has received invasive status in Nepal. Recently, this crop has been confirmed by Nepal Agricultural Research Council (NARC) in Gaidakot area of Nawalpur district, Nepal and has been noticed in almost all parts of Nepal such as Sidhuli, Chitwan, Nawalparasi, Tanahun and Rupendehi districts. However, this information has not been endorsed by Nepal Plant Protection Office (NPPO), an official invasive species endorsing organization in Nepal. This species is spreading rapidly in maize growing areas and significant losses have been reported in maize crop by the farmers. The regular scouting, surveillance, and monitoring can be suggested to evaluate the pest status in the crop field. Habitat manipulation with the deployment of deterring crops ‘push’ such as desmodium (Desmodium uncinatum) and pest-attracting crop ‘pull’ such as Napier (Pennisetum purpureum) and Sudan grass (Sorghum vulgare sudanense) is suggested in a ‘push-pull strategy’, the most popular and successful method of FAW management in the maize field. Field sanitation, and conserving pest’s natural enemies are other integrated approaches. However, in a commercial maize field, a group of ‘soft’ and selective chemicals have been suggested for immediate control of this pest. This review compiled the recent informations available on FAW and is useful for farmers, researchers and policy makers to draw a roadmap for the future FAW management in Nepal.

Soil structure indices under different tillage systems of sandy loam soil in Hadejia, Jigawa state, Nigeria

A. Nabayi1*, H.A. Santuraki1, A.H. Girei1, N.G. Hayatu2, F.D. Haruna3, S.A. Yusif2, S.A. Lukman2

1Department of Soil Science, Faculty of Agriculture, Federal University Dutse, Jigawa state, PMB 7156, Nigeria
2Department of Soil Science and Agricultural Engineering, Faculty of Agriculture, Usmanu Danfodiyo University, Sokoto, PMB 2346 Sokoto state, Nigeria
3Department of Soil Science, Faculty of Agriculture, Federal University Dutsinma, Katsina State, PMB 5001, Nigeria

(Manuscript received 10 January 2020; accepted for publication 4 March 2020)

Abstract. Soil structural indices have a significant effect on the nutrients retention and crop yield. Studies on soil structure indices in the semi-arid zone are minimal despite their importance in controlling water and water transmission, root elongation and erosion. A study was conducted in the area of Hadejia to evaluate the influence of tillage systems (TS) and sampling depths on some selected soil structure indices. The TS were four (4); conventional tillage (CT), reduced tillage (RT), zero tillage (ZT) and chisel plough (CP), while the sampling depths were two – 0-15cm and 15-30cm. Randomised complete block design (RCBD) was used in factorial arrangement. The result showed that the soil is sandy loam in texture irrespective of the TS. Lower dispersion ratio (DR) was observed in ZT with greater aggregate silt + clay (ASC) and water stability index (WSI) which differed significantly (p<0.01) from one another. Pearson’s correlation and simple linear regression analysis revealed a significant (p<0.01) positive and negative relationships between organic matter (OM) content of the soil with ASC, WSI and DR, respectively. Negative correlation of OM with DR stressed the significance of OM in decreasing DR of the soil which further explains lower DR by ZT because of greater OM content (p<0.05). Sodium (Na), sodium absorption ratio (SAR) and exchangeable sodium percentage (ESP) were in the order of RT>ZT>CT>CP with RT having the highest that differed significantly (p<0.05) from other TS. Lower values in CT and CP could be a result of leaching due to the lower surface residues relative to conservational tillage systems. Conclusively, the best tillage systems to improved soil structural indices are conservation tillage (ZT and RT) systems, particularly ZT.

The effect of laundry grey water irrigation on the growth response of selected local bean species in Nigeria

B. Ikhajiagbe1,2, E.O. Ohanmu1,3*, P.O. Ekhator1, P.A. Victor1

1Environmental Biotechnology and Sustainability Research Group, Department of Plant Biology and Biotechnology, University of Benin, Benin City, Nigeria
2Applied Environmental Biosciences and Public Health Research Group, Department of Plant Biology and Biotechnology, University of Benin, Benin City, Nigeria

3Department of Biological Sciences, Faculty of Science, Edo University Iyamho, Edo State, Nigeria

(Manuscript received 25 July 2019; accepted for publication 5 February 2020)

Abstract. This study examined the growth responses of some selected local bean (pulses) varieties in Nigeria; Vigna unguiculata (Ife brown), Vigna unguiculata (Ekpoma Local), Phaseolus vulgaris, Cajanus cajan and Glycine max, cultivated on soil irrigated with laundry-based grey water. Healthy seeds of all bean species were sown in plastic bowls of three replicates each and irrigated daily with similar quantities of the respective grey water. The effect of the grey water on the germination, growth and yield of all the beans was observed for a period of four months. The result obtained revealed that grey water had a negative effect on the growth and yield of all the beans as there was a decrease in the percentage emergence of all seedlings, height of emergent seedlings and number of flowers and pods produced. Grey water also altered the chlorophyll content and total crude protein of all the beans subjected to the treatment. The effect of grey water on plant is as a result of accumulation of excess salts contained in grey water on the soil.

Efficacy of different herbicide combinations for weed control in irrigated maize silage

R. Bazitov*

Agricultural Institute, 6000 Stara Zagora, Bulgaria

(Manuscript received 1 October 2019; accepted for publication 13 January 2020)

Abstract: The aim of this study was to establish the efficacy of herbicide combinations between Tender EC and Titus + Magneto SL, and Wing P and Mistral Opti applied in a field of maize under the conditions of mixed irrigation. The study has been carried out with maize cultivated on meadow-cinnamon soil at the experimental field of the Agricultural Institute – Stara Zagora for the period 2014-2016. The research was conducted with a mid-grade hybrid corn LG35.62 with the same background of fertilization and irrigation with the following variants: 1) Control (without herbicides); 2) Wing P – 4000 ml/ha and Mistral Opti – 210 ml/ha, and 3) Tender EC – 1500 ml/ha and a mixture of Titus – 40 g/ha + Magnet SL – 1200 ml/ha. Increasе of maize yield by 41.6% (on average) in comparison with the control variant and by 28.9% compared to the variant Wing P and Mistral Opti was found.

Phytoplankton blooms in front of cape Galata (Black Sea) during the period 2008-2017

D. Klisarova*, D. Gerdzhikov
Institute of Fish Resources, 4 Primorski Blvd., 9000 Varna, Bulgaria
(Manuscript received 7 November 2019; accepted for publication 21 January 2020)

Abstract. The aim of the study was to identify the peculiarities of the development of phytoplankton blooms (annual and seasonal dynamics) in front of cape Galata, Bulgarian Black Sea coast in the period 2008-2017. In that area up to 30 nautical miles (nm), from 6 stations (G-1, G-3, G-5, G-10, G-20 and G-30, respectively at 1, 3, 5, 10, 20 and 30 nm from the coast), 187 phytoplankton samples were collected. A total of six phytoplankton species were recorded, developing with the following blooming concentrations: Emiliania huxleyi, Oscillatoria sp., Merismopedia sp., small Flagellates (Cryptophyceae), Prorocentrum cordatum (minimum) and Pseudo-nitzschia delicatissima. It was found that the reported in previous periods trend of increasing phytoplankton biomass in front of cape Galata had already changed. Compared to the observed quantities in the period 1993-2007, the current phytoplankton values in the surface layer (up to 30 nm in front of cape Galata) were 1.63 times lower in abundance and 5.60 times lower in biomass.