Wood vinegar for control of broadleaf weeds in dormant turfgrass

Wood vinegar, a product of pyrolysis, can induce phytotoxicity on plants when applied at an adequate rate and concentration. The objective of this research was to investigate wood vinegar obtained from the pyrolysis of apple tree branches for weed control in dormant zoysiagrass. In environment-controlled growth chambers, white clover visual injury and shoot mass reduction compared to the nontreated control were evaluated after wood vinegar application at 1000, 2000, or 4000 L ha-1 under 10 or 30 C temperature conditions. Averaged across rates, wood vinegar rapidly desiccated white clover and caused 83 and 71% visual injury at 10 and 30 C, respectively, at 1 d after treatment (DAT). Averaged across temperatures, wood vinegar at 1000, 2000, and 4000 L ha-1 reduced white clover shoot mass by 56, 81, and 98% from the nontreated control at 10 DAT, respectively. In field experiments, weed control increased as wood vinegar rates increased from 1000 to 5000 L ha-1 in dormant zoysiagrass. The effective application dose of wood vinegar required to provide 90% control (ED90) of annual fleabane, Persian speedwell, and white clover was determined to be 2450, 2300, and 4020 L ha-1, respectively, at 2 weeks after treatment. Turf quality did not differ among the wood vinegar treatments and the nontreated control when zoysiagrass completely recovered from dormancy. Overall, results illustrate that wood vinegar resulting from the pyrolysis of apple tree branches can be used as a nonselective herbicide in dormant turfgrass, offering a new non-synthetic herbicide option for weed control in managed turf.

Effects of Light, N and Defoliation on Biomass Allocation in Poa annua

Plants allocate biomass to above- and below-ground organs in response to environmental conditions. While the broad patterns are well-understood, the mechanisms by which plants allocate new growth remain unclear. Modeling approaches to biomass allocation broadly split into functional equilibrium type models and more mechanistically based transport resistance type models. We grew Poa annua plants in split root boxes under high and low light levels, high and low N supplies, with N supplied equally or unequally. Our data suggest that light level had the strongest effect on root mass, with N level being more important in controlling shoot mass. Allocation of growth within the root system was compatible with phloem partitioning models. The root mass fraction was affected by both light and N levels, although within light levels the changes were primarily due to changes in shoot growth, with root mass remaining relatively invariant. Under low light conditions, plants exhibited increased specific leaf area, presumably to compensate for low light levels. In a follow-up experiment, we showed that differential root growth could be suppressed by defoliation under low light conditions. Our data were more compatible with transport resistance type models.

Influence of Bacillus subtilis strain on abscisic acid content in ABA-deficient barley mutant and its wild type

The ability to produce phytohormones and influence their metabolism in plants is an important property of rhizosphere bacteria that determines their plant growth promoting effect. Since abscisic acid (ABA) reduces stomatal conductance and increases the ability of tissues to conduct water, maintenance of water balance in lettuce plants on the background of activation of their growth was associated with the accumulation of ABA under the influence of bacteria. The aim of the study is to test the hypothesis that the growth-stimulating effect of bacteria on plants depends on their ability to synthesize the hormone ABA. The plants were grown on a light platform; seedlings were treated with a bacterial suspension simultaneously with planting. The ABA content, the relative water content, the chlorophyll content, the level of non-photochemical quenching, the leaf area and the weight of the shoots were measured. The level of transcripts of the HvNCED1, HvNCED2, and HvCYP707A1 genes responsible for ABA metabolism in barley was assessed using real-time PCR. Comparison of the ABA-deficient mutant of barley and plants of its wild type revealed the stimulation of the growth of plants of both genotypes upon bacterial treatment. The shoot mass and leaf area of the untreated mutant with bacteria were about 30 % less compared to Steptoe. The stimulating effect of bacteria was manifested in an increase in leaf area by 15 % in Steptoe and by 35 % in Az 34; shoot mass – by 18 % and 41 %, respectively. As a result, the phenotype difference between plants of two genotypes decreased. In the deficient mutant, the ABA level increased under the influence of Bacillus subtilis IB-22 more than twice. It was due to the ability of bacteria to produce ABA and reduce the activity of ABA degradation in barley plants. The results obtained in this study indicate that certain bacterial strains are able to increase the level of ABA in plants, compensating for the genetically determined deficiency of this hormone.

AVALIAÇÃO AGRONÔMICA DE NOVOS CLONES DE Manihot esculenta Crantz NO SEGUNDO CICLO VEGETATIVO

O presente trabalho teve como objetivo avaliar as características agronômicas no segundo ciclo vegetativo de novos clones de mandioca de mesa oriundos de um programa de melhoramento, nas condições edafoclimáticas do município de Santarém, Oeste do Pará. O delineamento experimental utilizado foi em blocos casualizados com 13 tratamentos (novos clones de macaxeira) e três repetições. As parcelas foram constituídas por 10 plantas distribuídas em duas linhas de 5 metros, com espaçamento de 1,0 x 1,0 m. Os resultados obtidos denotam que a produtividade apresentou correlação significativa e positiva com a massa de raízes comerciais (r= 0,98), massa fresca da parte aérea (r= 0,61) e diâmetro médio das raízes (r= 0,63), com destaque para o clone C5 que obteve maiores rendimentos em relação a estas características, e consequentemente apresentou maior média de produtividade 44,70 t ha-1. Em relação ao tempo de cozimento das raízes, de treze clones testados, doze materiais obtiveram tempo médio de cozimento inferior a trinta minutos, sendo classificados como tempo de cozimento bom, com destaque para o clone C11, que apresentou média de 12,30 minutos. Todos os clones avaliados apresentam características agronômicas desejáveis tornando-se promissores para o mercado do município de Santarém, no baixo Amazonas. Palavras-chave: melhoramento; baixo amazonas; produtividade; mandioca de mesa. Agronomic evaluation of new Manihot esculenta Crantz clones in the second vegetative cycle ABSTRACT: The present work aimed to evaluate the agronomic characteristics in the second vegetative cycle of new macaxeira clones from a breeding program under the edaphoclimatic conditions of the municipality of Santarém, Western Pará. The experimental design was randomized blocks with 13 treatments (new clones of cassava) and three repetitions. The plots consisted of 10 plants distributed in two rows of 5 meters, with 1.0 x 1.0 m spacing. The results show that yield was significantly and positively correlated with commercial root mass (r = 0.98), fresh shoot mass (r = 0.61) and mean root diameter (r = 0.63). highlighting clone C5 that obtained higher yields in relation to these characteristics, and consequently presented higher average yield 44.70 t ha-1. Regarding the root cooking time, of thirteen clones tested, twelve materials had an average cooking time of less than thirty minutes, being classified as good cooking time, especially clone C11, which presented an average of 12.30 minutes. All evaluated clones have desirable agronomic characteristics making them promising for the lower Amazon market. Keywords: breeding; low amazons; productivity; table cassava.

Consistent scaling of whole-shoot respiration between Moso bamboo (Phyllostachys pubescens) and trees

Both Moso bamboo (Phyllostachys pubescens) and tree forests have a large biomass; they are considered to play an important role in ecosystem carbon budgets. The scaling relationship between individual whole-shoot (i.e., aboveground parts) respiration and whole-shoot mass provides a clue for comparing the carbon budgets of Moso bamboo and tree forests. However, nobody has empirically demonstrated whether there is a difference between these forest types in the whole-shoot scaling relationship. We developed whole-shoot chambers and measured the shoot respiration of 58 individual mature bamboo shoots from the smallest to the largest in a Moso bamboo forest, and then compared them with that of 254 tree shoots previously measured. For 30 bamboo shoots, we measured the respiration rate of leaves, branches, and culms. We found that the scaling exponent of whole-shoot respiration of bamboo fitted by a simple power function on a log–log scale was 0.843 (95 % CI 0.797–0.885), which was consistent with that of trees, 0.826 (95 % CI 0.799–0.851), but higher than 3/4, the value typifying the Kleiber’s rule. The respiration rates of leaves, branches, and culms at the whole-shoot level were proportional to their mass, revealing a constant mean mass-specific respiration of 1.19, 0.224, and 0.0978 µmol CO2 kg− 1 s− 1, respectively. These constant values suggest common traits of organs among physiologically integrated ramets within a genet. Additionally, the larger the shoots, the smaller the allocation of organ mass to the metabolically active leaves, and the larger the allocation to the metabolically inactive culms. Therefore, these shifts in shoot-mass partitioning to leaves and culms caused a negative metabolic scaling of Moso bamboo shoots. The observed convergent metabolic scaling of Moso bamboo and trees may facilitate comparisons of the ecosystem carbon budgets of Moso bamboo and tree forests.

Effects of plant species diversity on nematode community composition and diversity in a long-term biodiversity experiment

Diversity loss has been shown to change the soil community; however, little is known about long-term consequences and underlying mechanisms. Here, we investigated how nematode communities are affected by plant species richness and whether this is driven by resource quantity or quality in 15-year-old plant communities of a long-term grassland biodiversity experiment. We extracted nematodes from 93 experimental plots differing in plant species richness, and measured above- and belowground plant biomass production and soil organic carbon concentrations (Corg) as proxies for resource quantity, as well as C/Nleaf ratio and specific root length (SRL) as proxies for resource quality. We found that nematode community composition and diversity significantly differed among plant species richness levels. This was mostly due to positive plant diversity effects on the abundance and genus richness of bacterial-feeding, omnivorous, and predatory nematodes, which benefited from higher shoot mass and soil Corg in species-rich plant communities, suggesting control via resource quantity. In contrast, plant-feeding nematodes were negatively influenced by shoot mass, probably due to higher top–down control by predators, and were positively related to SRL and C/Nleaf, indicating control via resource quality. The decrease of the grazing pressure ratio (plant feeders per root mass) with plant species richness indicated a higher accumulation of plant-feeding nematodes in species-poor plant communities. Our results, therefore, support the hypothesis that soil-borne pathogens accumulate in low-diversity communities over time, while soil mutualists (bacterial-feeding, omnivorous, predatory nematodes) increase in abundance and richness in high-diversity plant communities, which may contribute to the widely-observed positive plant diversity–productivity relationship.

Root and Shoot Traits of Spring Wheat Cultivars with Wild-Type and Semi-Dwarf Rht Alleles at Early and Late Growth Stages

Roots play an important role in improving crop yield by affecting the amount of water uptake and nutrient acquisition. The objective of this study was to characterize variability in root and above-ground characteristics among three diverse semi-dwarf spring wheat cultivars, ‘Vida’, ‘Oneal’ and ‘Duclair’ and a wild-type cultivar, ‘Scholar’ at early and late growth stages in a greenhouse. Plants were grown in 45-cm long tree pots in a greenhouse under optimal growth conditions. As soil-less media, a mixture of peat (70%) and perlite (30%) was used. Plants were harvested at tillering (GS25-26) with 5-6 tillers, booting (GS43-45), and maturity (GS92). Root and shoot traits indicated significant variability among wild-type and semi-dwarf spring wheat cultivars at those growth stages. The study results showed that root mass per plant at tillering, booting, and maturity ranged from 0.10 to 0.14 g, 0.47 to 0.9 g, and 0.55 to 0.85 g, respectively, while shoot mass per plant varied from 1.7 to 2.5 g, 6.5 to 10.7 g, and 21.2 to 24.5 g, respectively. From booting to maturity, root mass was relatively constant, however, shoot mass increased considerably. Moreover, the average root mass of semi-dwarf spring wheat cultivars was 37% lower at booting and 30% lower at maturity compared to the wild-type cultivar, even though there was no significant variation among the cultivars at the early growth stage. Based on the results of the variability identified in this research, wild-type cultivar, Scholar can be evaluated for the improvement of genotypes with superior root system in breeding programs.

Trichoderma spp. in growth promotion of Jacaranda mimosifolia D. Don

The low volume of information related to the interaction of Trichoderma fungi with seeds and seedlings represents a limitation to forest production, and it is important to carry out studies focusing on its effect on plant germinability and formation. The aim was to evaluate commercial products based on Trichoderma spp. in promoting growth of Jacaranda mimosifolia. For initial seedling growth assay, seeds were treated with Trichoderma spp. suspension and placed on germinating paper sheets. At 28 days after sowing (DAS) the following evaluations were: percentage germination (PG), root length (RL), shoot length (SL), total length (TL), fresh root mass (FRM), fresh shoot mass (FSM), fresh total mass (FTM), root dry mass (RDM), shoot dry mass (SDM) and total dry mass (BIO). To evaluate the development of Jacaranda mimosifolia plants, the experiment was conducted in a greenhouse, wherein the soil of each pot (10 L) was treated with five strains of the Trichoderma spp. (Trichoderma asperellum URM 5911; T. harzianum ESALQ 1306; T. harzianum IBLF 006 WP; T. harzianum SIMBI T5 and T. harzianum T-22 WG. Then, Jacaranda mimosifolia seeds were sown and the evaluations performed at 120 DAS. The variables were: PG at 120 DAS, shoot height (SH), stem diameter (SD), and Dickson quality index (DQI). The strains SIMBI T5, ESALQ 1306 and T-22 WG stood out in relation to RL; while ESALQ 1306 and SIMBI T5 stood out performed the RL and TL. In greenhouse, SIMBI T5 and ESALQ1306 presented higher values of ALT, CR, DC, MFT. Meanwhile, only the SIMBI T5 strain stood out for MSPA, MSR, BIO and DQI.

Effect of biofuel waste, urea, deer browsing and vegetation control on Pinus banksiana seedling growth on a dry upland site in central Canada

Ash from biofuels and nitrogen fertilizer are increasingly being used as soil amendments. While this can increase tree growth, it can also increase mammalian grazing and competition with vegetation. We applied moderate amounts (1.5 t ha^-1 y^-1) of ash and 74 kg N ha^-1 y^-1 of urea in each of two years to a well-drained site in southeastern Manitoba, planted with <i>Pinus banksiana</i>. Subplots received deer browsing and/or vegetation control. The ash resulted in an increase in pH in the upper 15m of mineral soil from ca. 5.7 to 6.6, and the urea created short-term spikes in soil inorganic N (NH₄ and NO₃) levels. Urea combined with ash significantly increased seedling relative growth rates in the first two years, with seedlings being largest with urea, with or without ash. However, by the fourth year seedling growth and size did not differ between the amendments. Urea application increased browsing damage to 91 %, but only when vegetation was mowed. Browsing guards resulted in seedlings having 1.6 times greater shoot mass by the end of the fourth growing season. These results suggest that on sandy soils in the dry region of central Canada, <i>P. banksiana</i> may get little benefit from ash applications.