Abstract: ABSTRACT Rice (Oryza sativa L.) paddies in the Long Xuyen Quadrilateral Region of Vietnam have regularly met the increased risks under the impacts of climate change (ICC), resulting in a decline in crop productivity. The objective of this study was to determine the suitable times for broadcasting rice crops in the rice cultivation paddies belonging to Long Xuyen Quadrilateral as a mitigation solution to the negative ICC. To conduct this research, crop model namely the FAO-AquaCrop (Version 6.0) was selected to simulate grain yields of rice crops based on different scenarios of crop broadcasting calendar (CBC). The results point out that the grain yield of winter-spring (WS) and summer-autumn (SA) cropping seasons can increase up to 6.2% and 5.3% if the CBC is delayed from 7 to 14 d compared to the current broadcasting calendar (baseline) in the two experimental areas while the grain yield of the autumn-winter (AW) cropping season can increase 6.4% if the CBC is shifted 14 d compared to the baseline. In general, a shift in the CBC for all rice broadcasting crops compared to the baseline can be considered as an effective solution to minimize the negative impacts of weather factors as well as contribute to improve rice productivity.
Abstract: ABSTRACT Germination is a very sensitive stage for the harmful effect of salinity stress. Plants respond differently to different types of salt. Gibberellic acid (GA3) is the most important hormone to mitigate salt stress. A controlled germination study was conducted to evaluate the impact of different salts (0, 150 mM NaCl, and 150 mM Na2SO4) and different GA3 concentrations (0, 50, 100, 250, and 300 mg L-1) on the germination of the two most used Sudanese sorghum (Sorghum bicolor [L.] Moench) varieties Wadahmed and Tabat. The studied parameters were seed water uptake after 8 h imbibition, germination percentage, germination rate, shoot and root length, shoot and root fresh weight, shoot and root dry weight, and seed vigor index. Results showed that Na2SO4 reduced germination percentage, germination rate, shoot length, root length, root fresh weight, shoot dry weight, root dry weight, and seed vigor index by 17.0%, 50.0%, 86.99%, 89.03%, 76.8%, 54.5%, 66.6%, and 89.7%, respectively, when compared with the non-saline treatment. The maximum values for seed water uptake, germination percentage, germination rate, shoot length, and seed vigor index were achieved at 100 mg L-1 GA3. The Na2SO4 salt had a more harmful effect than NaCl. The 100 mg L-1 GA3 concentration can be recommended to improve seed water uptake, germination parameters, and seedling growth under salt stress in the two Sudanese sorghum varieties (Wadahmed and Tabat). ‘Wadahmed’ was more tolerant to salinity stress than ‘Tabat’ at the germination stage.
Abstract: ABSTRACT Genetic improvement of chickpea (Cicer arietinum L.), a recalcitrant crop, has been largely restricted owing to a lack of efficient regeneration methods. In this study, four chickpea genotypes (Giza 4, Giza 88, Giza 195, and Giza 531) were efficiently micropropagated using embryo axes and synthetic seeds developed using an encapsulation technique. Multiple shoots grew from embryo explants using 2 and 4 mg L-1 benzylaminopurine (BAP). The number of shoots for Giza 195 explants using 4 and 6 mg L-1 BAP were 5.8 and 6.2, respectively. The elongated shoots were transferred to two indole- 3-butyric acid (IBA) concentrations (50 and 100 mmol L-1) for root induction. A high rooting percentage (67%-100%) followed by successful acclimatization (70%-75%) was obtained for shoots dipped in 50 mmol L-1 IBA and cultured into an MS liquid medium. Apical buds from in vitro shoots were encapsulated in sodium alginate along with calcium chloride to produce synthetic seeds, which were successfully stored at 4 °C for 5 mo. Giza 195 and Giza 531 were better conserved than Giza 4 and Giza 88, with 70%-75% regrowth and recovery rates. These results confirmed an efficient regeneration protocol and synthetic seed production, which could be utilized for genetic transformations and crop improvement.
Abstract: ABSTRACT Herbicide residues can potentially injure sensitive crops grown in rotation. Thus, the objective of this study was to evaluate the sensitivity of six replacement crops to mesotrione residues 1 yr after herbicide application. In field bioassay, mesotrione was applied at recommended (144 g ai ha-1), twofold (288 g ai ha-1), and fourfold (576 g ai ha-1) rates at two soil types (Gleysol and Fluvisol). In field and laboratory bioassays, mesotrione residual activity was followed for a 21-d period using various measurements of phytotoxicity. No visible injuries to mesotrione residues were observed on oat (Avena sativa L.), rapeseed (Brassica napus L.), soybean (Glycine max [L.] Merr.) and sunflower (Helianthus annuus L.) in the field bioassay. Although mesotrione residues were not detected by HPLC-UV/DAD analysis, field bioassays indicated their presence due to visible injuries on field pea (Pisum sativum L.) grown in Gleysol soil with twofold and fourfold herbicide treatments. In contrast to other test crop responses, sugar beet exhibited visible injuries in both soils, and consequently, was subjected to laboratory bioassay. With increasing mesotrione rates, the reductions in sugar beet (Beta vulgaris L. var. saccharifera Alef.) fresh weight and total carotenoids content ranged from 6.2% to 18.7% and from 4.1% to 19.4% in Gleysol, and from 1.1% to 7.7% and from 0% to 11.9% in Fluvisol, respectively. Since herbicide residues could not often be detected by instrumental analysis, the bioassays seem to be a reliable tool for crop safety assessment.
Abstract: ABSTRACT Genomic selection is considered to be an important tool in plant breeding programs. However, its application in the earliness of tomato (Solanum lycopersicum L.) has not been studied. The objective of the present study was to evaluate the prediction performance of six statistical models for six quantitative characteristics related to earliness in tomato. The study used phenotypic and genotypic data belonging to an F2 population consisting of 172 tomato plants. Simple sequence repeat (SSR) markers were obtained using genotypic information, and the genomic values were estimated by the following six different statistical models: Bayesian Lasso (BL), Bayesian ridge regression (BRR), BayesA, BayesB, BayesCπ, and reproducing kernel Hilbert spaces (RKHS) regression. The correlation values ranged from 0.17 to 0.57. The highest association values were found in days to flowering of the third inflorescence and 1000-seed weight, which were greater than 0.5. In general, all the models performed in a similar manner because only slight differences were observed among the correlation values. Specifically, BL, BayesB, and RKHS exhibited the highest Pearson correlation values for most traits. According to the results, genomic selection could be a useful tool to support tomato breeding focused on earliness.
Abstract: ABSTRACT Small-scale dairy systems are important worldwide for local and national production, and an option to overcome poverty. Effects of climate change need forage options adapted to future scenarios. This research addressed the hypothesis that black-oat (Avena strigosa Schreb.), either grazing regrowth or as first-cut silage in the dry season, is a forage option for small-scale dairy farmers in the highlands of Mexico. Part I presents performance of crop and dairy cows. There were two experiments. Treatments in Experiment 1 were restricted grazing of black-oat regrowth (BKO), black-oat with red clover (Trifolium pratense L. ‘Kenland’) (BKC) or a multi-species pasture (MSP) of grasses and white clover (T. repens L.) Experiment 2 evaluated inclusion of 2.5 (T1), 5.0 (T2) or 7.5 (T3) kg DM cow-1 d-1 of black-oat silage. Nine Holstein cows were used in both experiments, organized in groups of three randomly allotted to treatment in multiple 3×3 Latin squares replicated three times. Cows received 4.6 kg DM d-1 concentrate. There were no differences (P > 0.05) in animal variables with mean milk yields of 10.8 and 15.2 kg cow-1 d-1, 37.7 and 30.0 g kg-1 milkfat, 31.1 and 32.5 g kg-1 milk protein, 512.3 and 482.2 kg live weight, and 2.6 and 2.5 body condition score, for Experiment 1 and 2 respectively. Grazing black oat regrowth was equivalent to grazing temperate pastures, and the performance of cows was independent of the amount of black oat silage supplied. Black oat is a forage resource for small-scale dairy systems for grazing and silage.
Abstract: ABSTRACT There is growing interest for health attributes in foods, and milk contains polyunsaturated fatty acids (PUFA) beneficial for human health, being forages a main source for dairy cows. This research addressed the hypothesis that black oat (Avena strigosa Schreb.), either grazing regrowth or as first-cut silage in the dry season, is a forage option for small-scale dairy farmers in the central highlands of Mexico. This study presents fatty acid profile of feeds and milk. In Experiment 1 cows grazed for 8 h d-1 black oat regrowth (BKO), black oat associated with red clover (BKC) or a multi-species pasture (MSP) of perennial ryegrass, festulolium, and white clover as treatments, and in Experiment 2 treatments were 2.5 (T1), 5.0 (T2) or 7.5 (T3) kg DM cow-1 d-1 of black oat silage (BOS) as complement to grazing. Nine Holstein cows were used in both experiments, in groups of three randomly allotted to treatment sequence in a 3×3 Latin square design replicated three times. Cows also received 4.6 kg DM d-1 commercial concentrate. In Experiment 1 there were significant differences (P < 0.05) in content of saturated fatty acids (SFA) for BKO (62.4 g 100 g-1) 2.8% lower than MSP (64.8 g 100 g-1), monounsaturated fatty acids (MUFA) in MSP (31.4 g 100 g-1) were 6.5% lower than BKO (33.6 g 100 g-1), and PUFA in BKO (4.0 g 100 g-1) were 5% higher to BKC and MSP (both with 3.8 g 100 g-1). In Experiment 2 there were nonsignificant differences (P > 0.05) between treatments in fatty acid groups. Grazing black oat regrowth resulted in milk with higher PUFA contents compared to multispecies pasture representing more benefit for health; but no effect with ensiled black oat.
Abstract: ABSTRACT Shade cloth is commonly used to reduce incident light in apple (Malus domestica [Suckow] Borkh.) orchards. Nevertheless, this technology can generate changes in plant physiology that affect tissue nutritional composition and cause fruit nutritional disorders. The effect of shade cloth on the nutritional concentration of six macroelements and six microelements on leaves, six macronutrients in the fruits of ‘Fuji’ apples, and bitter pit incidence was assessed in a study conducted in a commercial orchard in south-central Chile for three seasons. Two treatments (control without shade cloth and 30% shade cloth cover) were evaluated with five replicates in a split plot design. Averaged results for the three seasons showed that shade cloth increased Mg, Mn, and Zn concentrations in leaves by 0.02%, 40 mg kg-1, and 5.5 mg kg-1, respectively, and decreased K, Mg, and S concentrations in fruits by 12, 0.35, and 0.38 mg 100 g-1 fresh fruit, respectively. Bitter pit incidence was not affected by shade cloth (values between 0.3% and 6.6%), but seasonal conditions did affect this abiotic disorder. In conclusion, the use of shade cloth in apples did not affect bitter pit incidence, but it caused some changes in leaf and fruit nutritional concentration.
Abstract: ABSTRACT Weed control in apple tree (Malus domestica [Suckow] Borkh.) orchards continues to be a major problem. Weeds compete with fruit trees, which is manifested in production quality and quantity. The aim of this study was to determine the weed flora of apple orchards with different floor management practices and to investigate the efficacy of the diquat, oxyfluorfen, glyphosate, and fluazifop-P-butyl herbicides. Experiments were conducted during 2015 and 2016 in orchards under intensive (Ruski Krstur) and extensive (Sombor) floor management. Annual, perennial broad-leaf, and grass weeds were identified. Dominant weed species in both apple orchards were Poa annua, Hordeum murinum, Conyza canadensis, Portulaca oleracea, Cynodon dactylon, Sorghum halepense, Carduus acanthoides, Amaranthus retroflexus, Cirsium arvense, Chenopodium album, and Solanum nigrum. After the first and second assessments, the best results occurred with glyphosate in both orchards and total efficacy ranged from 88.42% to 98.32% in the orchard under intensive floor management and 90.32% to 95.55% in the orchard under extensive floor management. Diquat and oxyfluorfen have shown good results, but their efficacy was lower than for glyphosate. Fluazifop-P-butyl, as a selective herbicide, showed low efficacy at both sites; it had high efficacy on grass weeds, but no effects on broad-leaf weeds.
Abstract: ABSTRACT One of the main problems of rice (Oryza sativa L.) cultivation is erratic germination and crop establishment; therefore, a pre-sowing ultrasonic seed treatment was studied to improve this situation. A pot experiment was conducted to investigate the effect of ultrasonic seed treatment on rice seedlings under waterlogging conditions. Two cultivars of rice seeds, ‘Yuejingsimiao’ (YJSM) and ‘Yuxiangyouzhan’ (YXYZ), were treated with ultrasonic waves before being transferred to the pot. The ultrasonic treatment included seed treatments in the dry state (S1), wet state (S2), and a control (CK). The waterlogging treatment included three flooding levels, control (W0), 2.0-3.0 cm flooding (W1), and 3.0-4.0 cm flooding (W2). The seedling emergence rate for W1S2 was 35.07% to 64.39% higher than W1CK, while fresh weight for W2S2 increased by 54.21% to 89.98% compared with W2CK. Furthermore, W1S1 (11.74% to 15.02%) and W1S2 (7.87% to 43.29%) also increased catalase activities compared with W1CK. Malondialdehyde (MDA) decreased by 19.87% to 31.84% and 9.70% to 38.74% for YJSM and YXYZ, respectively. The results showed that under waterlogging conditions, wet seed under ultrasonic treatment significantly increased the seedling emergence rate. Both the wet and dry seed treatments improved seedling quality, antioxidant activity, but decreased the MDA content.
Abstract: ABSTRACT The evaluation of new forage genotypes under arid conditions would contribute to solving the feed shortage problem during the summer season in arid areas and identify potential candidates for particular breeding programs. The present study evaluated the yield and quality of five multi-cut pearl millet (Pennisetum glaucum [L.] R. Br.) genotypes (IP19586, IP19612, IP6105, IP13150, and Shandaweel-1) affected by three sowing dates (15 May, 1 June, and 15 June) during the 2017 and 2018 summer seasons in Alexandria, Egypt. Among the new genotypes, IP13150 maintained the desirable balance between both productivity and quality. In addition to its high DM yield (3.50 t ha-1), it was characterized by the highest crude protein (91.6 g kg-1) and N-free extract (500.5 g kg-1) contents, while it had the lowest fiber fractions. This was reflected on its organic matter digestibility (395.7 g kg-1), high gas production (24.5 mL g-1 OM), short-chain fatty acid production (47.4 Mm), microbial protein (47.8 g kg-1 OM), and the highest energy values among all the genotypes. Although DM yield of the local cv. Shandaweel-1 was moderate (3.2 t ha-1), it was inferior regarding all the tested quality attributes. Altering the sowing date exerted a limited effect on the studied parameters; early sowing on 15 May was superior to later sowing on 1 and 15 June. The superiority of the second cut over the first and third cuts in forage production highlights the success of pearl millet as a multi-cut crop in similar environments.
Abstract: ABSTRACT Habanero pepper (Capsicum chinense Jacq.) does not have a specific fertilization. Therefore, the aim of this study was to evaluate growth, photosynthesis and accumulation of macro and micronutrients of habanero pepper plants. Plants were established in nutrient film technique (NFT) hydroponic systems. Two universal balanced solutions (Steiner and Hoagland) were compared versus a conventional solution (control: Soria solution). The concentration of macro and micronutrients in roots, stems, and leaves, photosynthetic activity of plants, total nitrate, amino acid and protein contents, and growth parameters were evaluated. According to the results, concentrations of K, Mg, Ca, Cu and Zn in plant tissues were higher in the Steiner and Hoagland treatments than control. In addition, the Steiner and Hoagland treatments increased the maximum photosynthetic rate (Amax) (81% and 80% respectively), light-saturated CO2 assimilation rate (Asat) (3.8-fold and 3-fold, respectively) and maximum catalytic activities of Rubisco (Vcmax) (51% and 30% respectively) with respect to the control. Hoagland treatment increased total nitrate content (3.66 mg g-1 FW), but Steiner treatment increased amino acids in leaves (169.97 mg g-1 FW) and control increased total proteins (1.49 mg g-1 FW). Steiner and Hoagland solutions significantly increased plant height (59% and 41% respectively), leaf area (1.26-fold and 1.02-fold, respectively), and total dry mass (80% and 69% respectively) with respect to the control solution. The results suggest that Steiner and Hoagland nutrient solutions provided nutrients that improve growth and photosynthetic activity. Moreover, total nitrate, amino acid and protein accumulation depend on the N source employed in nutrient solutions.
Abstract: ABSTRACT Quality protein maize (QPM) (Zea mays L.) is primarily used for food in countries of tropical and sub-tropical regions where maize is the main source of protein. Although its cultivation in temperate regions is hampered by residues of exotic germplasm, it could be beneficial for use in livestock feeds as it was shown that substitution of standard maize with QPM can improve livestock characteristics and decrease dietary lysine supplementation. The aim of this study was to test 11 QPM hybrids obtained by crossing adapted QPM inbred lines for their performance in field trials in 2 yr at four locations, as well as to determine their relevant biochemical components. The main reason for rejecting nine QPM hybrids was low grain yield, standard hybrids had higher yields on average for 37.8%. Hybrid ZPQPM6 had good agronomic characteristics, but its biochemical components were nonsignificantly different from the standard hybrid. Only hybrid ZPQPM13 met necessary criteria, grain yield comparable with standard hybrids, high tryptophan content in different environments (average 0.083%) and hard endosperm (average score 1.87). Lysine content, measured after mercantile production, was 0.44%. Quality index, although below the QPM threshold (which is 0.80%) was significantly higher (p < 0.05) in ZPQPM13 in comparison with standard hybrid, indicating improved nutritional quality of the protein. The results indicated that presence of exotic germplasm in these QPM hybrids is a consequential difficulty and that in their parental inbred lines at least one more backcross with temperate germplasm should be done to select better adapted QPM.
Abstract: ABSTRACT Dioscorea, commonly known as yam, is an economically, socially, and culturally-relevant tuber cropin many tropical countries. This study aimed to characterize the genetic diversity of Dioscorea alata L. and related species from Colombia (42 D. alata L., 6 D. bulbifera L., 3 D. rotundata Poir., and 3 D. trifida L. f.) through seven inter- simple sequence repeat (ISSR) markers. The plant material was collected in five departments of Colombia. The seven ISSR generated 164 bands that showed high polymorphism (83.62%). Nei-Li genetic diversity coefficient (0.66) and Shannon information index (0.2636) revealed a high level of genetic diversity. The 54 genotypes were grouped into six groups according to geographic location but not by species. We found moderate genetic differentiation (Gst = 0.13) and high gene flow (Nm = 2.7367). The analysis of molecular variance (AMOVA) showed higher variation (86%) within groups than among groups (14%). Our results suggest that the high genetic diversity in yam in Colombia can be exploited in future work on crop improvement.
Abstract: ABSTRACT The alternative use of plant essential oils as pesticide, repellent and/or antifeedant has been emphasized as an important tool in integrated pest management (IPM), promoted by the growing interest in methods that fulfil requirements of efficiency, safety, selectivity, technically feasible and environmentally safe. The objective of this work was to determine the pesticide potential of essential oils of rosemary pepper (Lippia origanoides Kunth; Verbenaceae), citronella (Cymbopogon winterianus Jowitt; Poaceae) and lemongrass (Cymbopogon citratus [DC.] Stapf; Poaceae) to control fall armyworm (Spodoptera frugiperda [J.E. Smith]; Lepidoptera: Noctuidae). Ovicidal, larvicidal and pupicidal activity was evaluated with five dosages (0.1%, 0.5%, 1.0%, 2.5% and 5.0% v/v) and a negative control (neutral detergent at 5.0% v/v). Unhatched eggs, mortality of caterpillars and non-emerged adults were recorded using ovicidal and pupicidal percentage, and median lethal doses (LD50) to caterpillars. The essential oils showed insecticidal activity on the egg, caterpillar 3rd instars and pupae stages, highlighting the rapid action and high mortality rates caused by the L. origanoides essential oil, which registered, at lowest dosage, average 97.8% ovicidal activity and 81.3% pupicidal activity; in addition to LD50 on 3rd instar caterpillars, 0.001% by exposure and 0.033% by topical application. Essential oils of C. citratus and C. winterianus required longer periods to act and caused significant mortality on the three stages, registering LD50 0.008% and 0.159% for exposure, and 1.151% and 1.348% for topical application, respectively. Citronella oil caused behavioral changes in caterpillars, which reflected flight and aggressiveness. Therefore, these three essential oils can be an alternative for management of fall armyworm, with the potential to hinder and reduce its biotic potential.
Abstract: ABSTRACT Salinity is a growing problem worldwide and techniques are needed to mitigate this problem. Field experiments were conducted to explore the effects of optimum N management (NM) on growth, antioxidant ability and yield performance of rice (Oryza sativa L.) in medium saline soil in the coastal area of Yancheng City, Jiangsu Province, China, during 2016 and 2017. A salt tolerant rice genotype Nangeng 9108 and N fertilizer including urea (300 kg N ha-1) were used, six levels of NM were arranged (base:tillering:panicle initiation fertilizers = 0:8:2 (T1), 0:6:4 (T2), 0:4:6 (T3), 5.6:2.4:2.0 (T4), 4.2:1.8:4.0 (T5), and 2.8:1.2:6.0 (T6), respectively). NM significantly affected plant growth, antioxidant traits, yield and yield components of rice in saline soil. On average, grain yield, panicles and spikelets per panicles were prominently higher under treatments of applied basal fertilizer (TABF; T4, T5 and T6) than treatments of non-applied basal fertilizer (TNBF; T1, T2 and T3). The TABF produced a yield advantaged of 39.7% and 54.4% over TNBF in 2016 and 2017, respectively. Bigger panicles were formed under TABF, mean spikelets per panicle was 15.7% higher than TNBF in 2016 and 20.0% in 2017. The T5 produced the highest dry weight, grain yield, panicles, spikelets per panicle, activities of catalase, peroxidase and superoxide dismutase, soluble protein, soluble sugar and sucrose at each growth period. However, the highest grain filling percentage showed under T4 had 82% and 81% advantages in each year. These results suggest that applied basal fertilizer can enhance salt tolerance and grain yield of rice, and appropriate N management can alleviate salt stress and increase grain yield.
Abstract: ABSTRACT The agroforestry activity of central Chile is developed under Mediterranean climate, characterized by long periods of water deficit conditions, particularly on hillsides with degraded and compacted soils. The objective of this study was to assess the effect of two soil and water conservation techniques on soil water content (SWC) and in plant growth and survival of three tree species. The conservation techniques evaluated were subsoiling with contour ridges (SB) and infiltration trench (IT), and a control treatment without soil management (CO). Growth and survival of Cytisus proliferus L. f. var. proliferus, Quercus suber L. and Quillaja saponaria Molina were examined. The experimental area was sown with a mixture of annual legumes. Conservation systems allowed higher SWC especially in years of higher rainfall (2008 and 2009) at 20-40 and 40-60 cm depth. SWC was higher in SB followed by IT and CO, whereas at 60-80 and 80-100 cm depth differences were significant only in the driest years. After 4 yr, plant survival of C. proliferus and Q. suber was similar in the three establishment systems (97% and 87%, respectively), but survival of Q. saponaria was lower in CO. Plant height in C. proliferus was higher in IT > SB > CO, while Q. suber was higher in SB > IT > CO; Q. saponaria had similar growth in SB and IT conservation systems but it was significantly higher (P < 0.05) than in CO. It is concluded that subsoiling with ridges has a great potential for degraded and compact soils of the Mediterranean region, allowing higher SWC in the profile and better tree establishment and growth.
Abstract: ABSTRACT The soil microbial communities involved in the biogeochemical cycles of plant nutrients are negatively affected by unfavorable agricultural practices. In three tillage systems (traditional tillage, TT; traditional tillage with residue incorporation, TTI; and conservation tillage, CT) with three crop rotations (cereal-cereal, C-C; legume-cereal, L-C; and cereal-legume, C-L) at three soil depths (0-5, 5-15, and 15-30 cm), the effects on the populations of bacteria, actinomycetes, and fungi over a period of six crop cycles (3 yr) were evaluated. The tillage system, crop rotation, and depth affected the concentration of microbes in the soil. Under TT/C-C (regional control), they decreased by 7.5%; in contrast, under CT/L-C and TTI/L-C, they increased by 144% and 76%, respectively. Regardless of the tillage system, rotation with legumes, especially when the legume was cultivated in the spring-summer cycle (C-L), caused significant increases in microbial populations. At the end of 3 yr, under CT and TTI the populations of actinomycetes increased, while the fungal population remained stable and the bacterial populations fluctuated in the different crop cycles. In all treatments, the concentration of microorganisms decreased with soil depth. Local practices represent a risk to the diversity of soil microbiota, and it is imperative that farmers adopt conservation practices to achieve sustainability.
Abstract: ABSTRACT There is limited information about the critical period for weed control (CPWC) in oilseed radish (Raphanus sativus L. var. oleiformis Pers.) This significantly limits the effectiveness of the applied technologies in its cultivation. The article focuses on the results of a long-term study (2013 to 2018) of the peculiarities of weed formation in oilseed radish agrophytocoenosis using different sowing technological models according to seeding rate and row spacing parameters. The study included the peculiarities of the species and generic composition of weeds and the basic attributes of the formation of species-specific amounts. The summed dominance ratio (SDR) was heterogeneous and co-oscillatory in the weed structure for both the formation of the number of individual species and their height dominance, which depended on the phenological stage of growth and crop development. In the general spectrum, the prevailing weed forms were identified with the highest potential for oilseed radish plants with an SDR greater than 1.0, which belong to groups I and VI according to environmental plasticity and stability, given the different conditions of the study period for both hydrothermal conditions and year index. In conclusion, a critical period for weed control (CPWC) in oilseed radish agrocoenosis was defined as a 5% reduction in crops ranging from 5 to 45 d after sprouting (DAS) for row sowing and a seeding rate of 4.0 million similar seeds ha-1 and 6 to 60 DAS for a variant of wide row sowing at a seeding rate of 0.5 million similar seeds ha-1.
Abstract: ABSTRACT The physicochemical properties of honey vary considerably depending on the nectar sipped by Apis mellifera bees because these characteristics are determined by environmental, geographical, and vegetational conditions in foraging areas. The aim of this study was to characterize types of honey from the Biobío Province in the Biobío Region, Chile, according to its botanical origin and physicochemical and microbiological characteristics, and thus contribute to increased knowledge about honey in the region. A total of 11 samples from different communes within the region were analyzed. Physicochemical parameters such as moisture, insoluble solids, ashes, electrical conductivity, pH, and hydroxymethylfurfural were determined, and the presence of coliforms and Escherichia coli was evaluated. Two places of provenance were characterized as monofloral of introduced plant species: the M11 sample of Melilotus indicus and the M1 sample of Echium vulgare. One place of provenance (M6 sample) was characterized as monofloral of Eucryphia glutinosa, species endemic to Chile. All types of honey complied with the physicochemical standards established by national and international food safety regulations, and none had any signs of coliforms or E. coli. Results showed that there are new types of honey in the region that meet all the required parameters; in addition, they provide a comparison of plant species that are unique in the world. This demonstrates the potential of these types of honey for national and international marketing.
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