Within-Plant Distribution of Two-Spotted Spider Mites, Tetranychus urticae Koch (Acari: Tetranychidae), on Strawberries: Decision of an Optimal Sampling Unit

It is known that two-spotted spider mite (Tetranychus urticae), a major pest of strawberry, is difficult to manage. This study was conducted to determine the optimal sampling unit to increase management efficiency of T. urticae in strawberries. The sampling unit was determined by characterizing within-strawberry distribution of T. urticae and by comparing coefficient of variation (CV) and correlation coefficient (r2) among potential sampling units. There was a significant (p < 0.05) difference in densities within a strawberry according to the leaf age. However, there was no significant difference in its density within a trifoliate leaf. More T. urticae were found on young-fully-opened (moderately old) leaves than on young and old ones. Moreover, these leaves had lower CV and r2 values than others. More specifically, optimal sampling units of T. urticae were fifth, fifth or sixth, and sixth oldest leaves for motiles (immatures and adults), all stages (motiles and eggs), and eggs, respectively. The required sampling number should be determined depending on the density. However, for management purposes, one and two leaflets would be acceptable for eggs and motiles, respectively. By using this small number of suitable sampling unit, the sampling and management for T. urticae in strawberries could be more efficient than before.

Collection, Characterizaton and Conservation of Genetic Resources of Yam Cultivars From Ekiti State, Nigeria

This study was initiated to restore the genetic resources of yam which had been decimated in a core yam-producing community in Ekiti State, Southwestern Nigeria. Twenty cultivars, consisting of Dioscorea rotundata, D. cayenensis, D. alata, and D. dumetorum were identified, collected, characterized and multiplied using an On-farm Participatory Method. The yam cultivars were characterized for quality and yield of pounded yam (iyan) as well as starch properties. They were later conserved in the Teaching and Research Farm of the Obafemi Awolowo University Ile-Ife.Morphological characterization separated Dioscorea alata (Ewura) by its winged vines while Dioscorea dumetorum (Esuru) was separated by its pubescent spines, trifoliate leaf with acute apex and base and the clustered, irregularly-shaped tuber. All the tubers of the yam cultivars had high storability. Pounded yam quality rated the Ikumo and Ajimokun cultivars as best while Odo was rated average and this was attributed to the swelling properties and amylose content of these cultivars. Yam cultivars with high granules had low swelling capacities. The Brittle Fraction Index of the starch from all the cultivars was lower than 1.0 explaining why the iyan they produced had no crust on the surface and kept for long hours after preparation.From this study, it was concluded that the local yam cultivars collected represent the core of yam genetic resources for utilization in the region. These cultivars are therefore recommended for prioritization in further studies on propagation, conservation and improvement so that a narrow genetic base of cultivars is not encouraged, for example, by promoting cultivars whose vines perform well in tuberization.

THE ACTION OF SOME CYTOKININ-TYPE COMPOUNDS ON THE ANTIOXIDANT PROTECTION CAPACITY OF PLANTS IN CONDITIONS OF UNFAVORABLE VARIATION OF HUMIDITY AND REPEATED WATER STRESS

The effect of cytokinin-type compound on the capacity of the enzymatic and non-enzymatic system of antioxidant protection by plants in conditions of humidity fluctuation and repeated drought were studied. As subjects served the plants Glycine max (Merr) L.cultivar Nadejda, grown in the Mitcherlih vegetation pots with volume of 40 kg soil and exposed to the drought stress at the phases first trifoliate leaf and flowering – pods formation. The antioxidant protection capacity of soybeans pre-treated with cytokinin, thiourea and with the composition Polyel + phytohormones (AIA, Gb, CK)is ensured both by the intensification of the activity of antioxidant enzymes and by the increase of content of non-enzymatic substances with low molecular weight.After restoring the optimal moisture content, the plants pre-treated with thiourea and Polyel + F more fully restore their functional processes.

Formation of the leaf surface and productivity of the chickling vetch (Lathyrus sativus L.) depending on the amounts of mineral fertilizers and pre-sowing inoculation of seeds

The aim of the study was to analyze the effect of different amounts of mineral fertilization, bacterization of seeds on the leaf surface area formation and the chickling vetch (Lathyrus sativus) productivity. The study engaged six NPK fertilization amounts (0 – the check (control) without fertilizers, N15P15K15, N30P30K30, N15P30K30 + N15 (top dressing), N45P45K45 and N30P45K45 + N15 (top dressing) on two backgrounds of pre-sowing seed treatment (the control, water seed treatment, seed treatment with microbiological preparation Rizogumin, which contains a suspension of nodule bacteria Rhizobium leguminosarum 31 and physiologically active substances of biological origin). The leaf surface area was determined by the cutting method (in the phase of the first trifoliate leaf, budding, flowering, pod formation), which includes the selection of 15 plants, where the leaves are quickly cut off, weighed and their wet weight is determined. After that, cuts are made with a probe of a known diameter, 5 pcs. from every leaf. The mass of all cuts was determined. After determining the surface area of the leaves of each plant, the average plant area was calculated for each variant of the experiment. The average leaf surface area was multiplied by the number of plants per square meter, and the result was multiplied by 10000 to convert it to the average leaf surface area per hectare. The yield accounting was maintained by the method of continuous threshing from the registration plot by a selected combine harvester, with cleaning from impurities, weighing and determining the moisture content of the harvested grain. The maximum leaf surface area (60.8 thousand m2 ha-1) was in the phase of grain filling when N30P45K45 + N15 was added to top dressing and seed treatment with Rizogumin. In the absence of inoculation, the leaf area was 4.1 thousand m2 ha-1 less.

Breeding strategies for soybean canopy structure optimization in dry regions

Water supply is one of the key factors limiting soybean yield. Coming from the monsoon climate region, soybean lacks effective means of leaf surface growth restriction and is prone to produce excessive leaf area that leads to undesirable transpiration increase. Reducing branching rate and, correspondingly, leaf number per plant is usually proposed to decrease leaf area. However, as far as branching ability is generally a useful trait contributing to yield stability, we have undertaken a search for possible alternative ways of leaf area reduction. Soybean canopy structure was studied in our germplasm nursery in Kursk region. We have updated an express method of soybean trifoliate leaf surface calculation. A regression index for soybean trifoliate leaf surface by central leaflet length and width product characterizes leaflet shape and depends from its length to width ratio. In the sampling studied, trifoliate leaf surface varied from 79 to 150sq. cm. Leaf area index (LAI) varied from 4.0 to 8.6 sq. m/sq. m, with optimal LAI equal to 6.0 sq. m/sq. m. Excessive LAI (over 7.7 sq. m/sq. m) decreased yield by 20 %. Optimal LAI may be achieved by various combinations of leaf size and leaf number per plant. Lines possessing good branching rate but remaining within optimal LAI values due to small leaf size were revealed. Thus, lamina size reduction may be proposed as an alternative breeding direction to solve a conflict of bushy plant type and drought tolerance.

Taxonomic studies of two trifoliate legumes of high economic importance in Ebonyi State, South-eastern Nigeria

Taxonomic studies of Sphenostylis stenocarpa and Centrosema pubescens based macro-morphology and foliar epidermises were carried out to determine their similarities and differences. The taxa are of high economic values as they are used as food and medicine in Nigeria. Standard methods were used to carry out the studies as qualitative and quantitative macromorphological characters of the taxa were obtained by visual observation and measuring with metre rule while foliar epidermal study followed standard methods previously used by other researchers. The taxa studied have trifoliate leaf type with leaf and leaflet arrangement alternate and opposite respectively. From the foliar epidermises, Sphenostylis stenocarpa possesses paracytic stomata on the abaxial surface and anisocytic stomata on the adaxial. The abaxial surface of Centrosema pubescens possesses anomocytic and paracytic stomata and anomocytic stomata on the adaxial surface. Cell shapes of the foliar epidermal surfaces are irregular with undulate anticlinal wall patterns except on the adaxial surface of Sphenostylis stenocarpa with pentagonal cell shape and straight anticlinal wall. The two taxa are similar in their leaf type and arrangement but differ greatly in their stomatal types.

Effect of Fipronil + Isoprothiolane against Onion Thrips and Purple Blotch Disease and Its Effect on Parasites and Predators

Onion (Allium cepa L.) is one of the important vegetable cum condiment crop grown throughout the world. Onion crop is infested by various insect pests and diseases right from seedling to harvesting stage. The experiment was conducted in farmer’s fields of Ranebennur (Haveri–District) to evaluate the bio-efficacy and Phytotoxicity of Fipronil + Isoprothiolane against Thrips and Purple Blotch disease in onion and its effect on parasites and predators during kharif-2018 and rabi-2019 seasons. Amongst the treatments, the formulation Fipronil 5% + Isoprothiolane 28% EC @ 1500 ml/ha was excellent in controlling thrips (2.47/trifoliate leaf) and showed the least severity of purple blotch (3.02% PDI) followed by Fipronil 5% + Isoprothiolane 28% EC@ 1250 ml/ha (2.85 and 3.25)1000 ml/ha (2.99 and 3.67 % PDI) respectively. The results revealed that amongst the treatments, Fipronil 5% + Isoprothiolane 28% EC @ 1500 ml recorded the highest bulb yield (21.52 t/ha) which was on par with the 1250 and 1000 ml/ha. The formulation Fipronil 5% + Isoprothiolane 28% EC @ 1000 ml/ha was found to be cost effective followed by treatment of Fipronil 5% + Isoprothiolane 28% EC @ 1250ml /ha for control of thrips and prevention of Purple Blotch disease hence which is recommended for control of thrips and Purple Blotch disease in onion.

Nitrogen Fertilization Management with Blends of Controlled-Release and Conventional Urea Affects Common Bean Growth and Yield during Mild Winters in Brazil

The common bean (Phaseolus vulgaris L.) requires nitrogen (N) during its vegetative and reproductive stages. A single application of a blend of polymer-sulfur coated urea (PSCU) and conventional urea (U) treated with NBPT (N-(n-butyl) thiophosphoric triamide) can meet that demand. Broadcast application could improve yield than other N management practices. This research evaluated two blends (70%PSCU + 30%U and 30%PSCU + 70%U) and three N fertilization managements (incorporated, broadcast, and split application) on soil ammonia volatilization (AV) and N mineral content (NM); plant N uptake (NU) and 15N recovery from U (NUR); and yield (GY). Irrigated field experiments were conducted in 2018 and 2019 in Rhodic Eutrustox soil. The N application rate was 90 kg ha−1. AV reached 12% (30%PSCU + 70%U, broadcast application) and 14% of the applied N (split application at the third trifoliate leaf unfolded stage (V4)). The incorporated application resulted in higher NM in the vegetative and reproductive stages than the other management practices. Broadcast application resulted in higher NU than split application at physiological maturity. Split application resulted in higher NUR (grain) and GY than broadcast application. There was a positive correlation between NUR (grain) and GY in all N fertilization management treatments. The NUR values reached 48% (30%PSCU + 70%U) and 18% (70%PSCU + 30%U). Split N application using these blends can improve NUR in grain and GY compared to broadcast application in Rhodic Eutrustox soil. This information can help farmers improve the fertilization management practices used with these blends, and thereby avoid economic losses and environmental pollution.

Yield of subterranean clover after post-emergence herbicide application for broadleaf weed control

A field experiment was established in Lincoln, Canterbury in autumn 2018 to evaluate the effect of acetolactate synthase (ALS) inhibiting herbicides on subterraneun (sub) clover. Two herbicides, imazethapyr and flumetsulam, were applied to seven sub clover cultivars at the 4-5 trifoliate leaf stage during July 2018. By December 2018, both herbicides had reduced the broadleaf weed yield by 1000 kg DM/ha. Sub clover herbage yield in spring (3 Oct 2018) increased only for ‘Antas’ and ‘Napier’ cultivars but all cultivars had an increase in total annual herbage yield when herbicides were applied. Plots were managed for seed set so re-establishment was examined. Imazethapyr had a longer residual than flumetsulam with greater control of broad-leaved dock (Rumex obtusifolius) eight months after application. Herbicide application had no effect on subsequent sub clover emergence the following year. This experiment demonstrated the potential to establish a pure sward of sub clover with the use of ALS inhibiting herbicides, which could be used to create a high legume base in pasture before overdrilling grass the following year.

Effectiveness of sequential herbicide application Flex with graminicides in soybean crops

В Дальневосточном НИИ защиты растений в условиях деляночного эксперимента изучена биологическая и хозяйственная эффективность нового гербицида Флекс в посевах сои сорта Асука. Гербицид применялся при достижении культурой фазы развития два тройчатых листа. Исследования проведены в 2019 г. по общепринятым методикам на лугово-бурых оподзоленных почвах, типичных для Приморского края. Установлена одинаково высокая эффективность последовательного внесения препарата Флекс 1,5 л/га с ПАВ Тренд 90 0,2 л/га и граминицидов Фюзилад Форте 1,5 л/га и Центурион 0,3 л/га в смеси с Амиго Стар 0,6 л/га в отношении комплекса однолетних двудольных и злаковых сорняков в течение всего периода вегетации сои. Снижение общей биомассы сорных растений в этих вариантах опыта составило 97–99 %. Высокую чувствительность к гербициду Флекс (снижение массы на 99–100 %) проявила амброзия полыннолистная, занимающая лидирующее положение среди однолетних широколистных сорняков по частоте встречаемости и плотности произрастания в регионе. Новый препарат эффективно подавлял также жерушник болотный, марь белую и акалифу южную. Наложение граминицидов Фюзилад Форте и Центурион в смеси с Амиго Стар через 3 сут после обработки посевов сои препаратом Флекс способствовало эффективному контролю однолетних злаковых сорных растений: ежовника обыкновенного, видов щетинника и шерстняка мохнатого (снижение массы на 75–100 %). Токсическое действие препарата Флекс на двудольные многолетние виды сорняков проявлялось главным образом в торможении нарастания надземной растительной массы, которая в опытных вариантах при первом после обработки учете была ниже контроля на 55–88 %. К моменту уборки сои действие гербицидов на эту группу сорняков ослабло, в основном за счет наращивания массы щавельником курчавым. Высокая биологическая активность нового гербицида и граминицидов обеспечила сохранение значительной части урожая. В опытных вариантах урожайность сои выросла на 0,41–0,44 т/га и достигла 1,28–1,31 т/га в сравнении с контролем (0,87 т/га). Экономическая эффективность применения гербицида Флекс с последующим наложением граминицидов составила 3,64–3,96 тыс. руб./га. In the Far-Eastern Scientific Research Institute of Plant Protection in plot experiment studied the biological and economic efficiency of new herbicide Flex in crops of soybean varieties Asuka when the culture development phase was two trifoliate leaf. The research was carried out in 2019 using generally accepted methods on meadow-brown podzol soils typical for the Primorsky territory. An equally high efficiency of sequential application of the Flex preparation 1.5 l/ha with surfactant Trend 90 0.2 l/ha and graminicides Fusilade Forte 1.5 l/ha and Centurion 0.3 l/ha in a mixture with Amigo Star 0.6 l/ha for a complex of annual dicotyledonous and cereal weeds during the entire growing season of soy was established. The decrease in the total biomass of weeds in these variants of the experiment was 97–99 %. High sensitivity to the Flex herbicide (weight reduction by 99–100 %) was shown by ragweed, which occupies a leading position among annual broad-leaved weeds in frequency of occurrence and density of growth in the region. The new product was also effective in suppressing marsh cress, common lambsquarter, and Asian copperleaf. The imposition of graminicides Fusilade Forte and Centurion with Amigo Star three days after treatment of soybean crops with Flex preparation contributed to the effective control of annual cereal weeds: cockspur grass, species of bristlegrass and hairy cupgrass (weight reduction by 75–100 %). The toxic effect of the Flex preparation on dicotyledonous perennial species was mainly manifested in inhibiting the growth of aboveground plant mass, which in the experimental versions was 55–88 % lower than the control one when taken into account for the first time after treatment. By harvesting soybeans, the herbicidal effect on this group of weeds was weakened, mainly due to the mass build-up of curled dock. The high biological activity of the new herbicide and graminicides ensured the preservation of a significant part of the crop. In the experimental versions, the yield of soybean seeds increased by 0.41–0.44 t/ha compared to the control (0.87 t/ha). The economic efficiency of using the Flex herbicide with subsequent application of graminicides was 3.64–3.96 thousand rubles/ha.