Nursery performance of potentially promising rootstocks for citriculture in the south of Brazil

ABSTRACT: Diversification of rootstock varieties, with consequent reduction in phytosanitary risks, has great importance to the sustainability of citrus cultivation in the south of Brazil. This study evaluated the performance of 42 rootstocks in the nursery phase to generate ‘Valencia Late’ sweet orange seedlings. Therefore, nucellar seedlings from the rootstocks under study were analyzed in relation to plant height, stem diameter, mortality rate and percentage of bud set after grafting. The experimental design was completely randomized with four replications of 20 sample units. Not adapted genotypes had high mortality rates, and the ones of both hybrids LCR x CTSW - 009 and LVK x LCR - 038 were 100% and 90%, respectively. Other 13 genotypes had mortality rates above 30%, and ‘Sunki’ mandarin was the female genitor of ten of them. ‘Swingle’ citrumelo was the rootstock with the highest development (plant height and stem diameter), associated with low mortality rate. In relation to the other rootstocks, the best results were the fast grafting diameter, associated with low mortality rate obtained by hybrids HTR - 053, LRF x (LCR x TR) - 005, CLEO x TRBN - 245, CLEO x TRSW - 287, and citrandarins ‘Indio’, ‘Riverside’ and ‘San Diego’, as well as Trifoliate orange and ‘Rangpur’ lime. In addition to Trifoliate orange, which is widely used in Rio Grande do Sul, these rootstocks have great potential in citriculture in the south of Brazil.

Evaluating Postharvest Organic Nitrogen Fertilizer Applications in Early Fruiting Northern Highbush Blueberry

Bloom to fruit maturity is a period of rapid growth and nitrogen (N) uptake in northern highbush blueberry (Vaccinium corymbosum L.). Sufficient plant-available N is critical during this time, and growers often accomplish this through fertilizer applications from bloom through fruit development. For organic production in northern climates like Washington State, postharvest applications of N fertilizer are not recommended for northern highbush blueberry because they may stimulate excessive vegetative growth, reduce floral bud set, and increase the risk of winter injury through delayed acclimation. However, early fruiting cultivars with the potential for an extended growing season after harvest may benefit from postharvest N applications because the additional N may promote shoot and root growth that could support fruit production in future years while still allowing plants to form floral buds and acclimate to winter temperatures. The objective of this study was to evaluate the potential impacts of postharvest organic N fertilizer applications on ‘Duke’, an early fruiting northern highbush blueberry cultivar. Specific objectives were to determine the effects of postharvest organic N fertilizer application on plant growth, yield, floral bud set, fruit quality, cold hardiness, tissue macronutrient concentrations, and select soil properties. Four treatments varying in the timing of N application were evaluated in a commercial ‘Duke’ field in eastern Washington using a single fertilizer rate of 130 kg⋅ha−1 N from 2018 to 2020. The organic fertilizer N source was a liquid fertilizer derived from digested plant materials. The experimental design was a randomized complete block design with four replications and treatments included the following: control (100% of N applied preharvest); 80/20 (80% preharvest, 20% postharvest); 70/30 (70% preharvest, 30% postharvest); and 60/40 (60% preharvest, 40% postharvest). Although the year influenced measured variables, including yield, floral bud set, fruit quality, tissue nutrients, and soil properties, few treatment effects were observed across the 3-year study. Cold hardiness was only impacted once (8 Feb. 2020), and floral buds were overall hardy to extreme minimum winter temperatures for the region. This project showed that applying postharvest organic N as a liquid fertilizer had no negative consequences on productivity metrics for an early fruiting blueberry cultivar grown in a region with an extended growing season, thus providing growers with more flexibility when timing their fertilizer applications. Results may differ for other fertilizer sources, and further monitoring of soil NO3-N accumulation should be conducted to gain a better understanding of its dynamics and the potential for risks.

Pemanfaatan Tanah Mediteranian Sebagai Media Pembibitan Budset Tebu (Saccharum officinarum L.) Varietas Bululawang dengan Penambahan Pupuk Kandang pada Dosis yang Berbeda

The decrease in the productivity of sugarcane (Saccharum officinarum L.) can be pursued through intensification with treatment in the nursery. However, it is increasingly difficult to find a good growing medium for plants, such as mediterranean soil must be managed. One of the efforts is to increase soil fertility by adding livestock manure which has the potential as organic fertilizer so that it is expected to improve soil structure and add nutrients. This study aims to determine the dose of organic fertilizer in sugarcane bud set nurseries on media with the addition of lime soil. This research was carried out at the independent farm. This study used a non-factorial Randomized Block Design (RAK) with one factor, namely the dose of organic fertilizer (0, 125, 250, 375, and 500 grams/polybag) with 3 replications. The results showed that the addition of organic fertilizer had a significant effect on plant height, number of leaves, and stem diameter of sugarcane nurseries. The best application of organic fertilizer in sugarcane bud set nurseries is a dose of 250 grams/polybag. Keywords: Sugarcane, Nurseries, Mediterranean Soil, Livestock Manure, Organic Fertilizer

Interactive Effects of Light Quality during Day Extension and Temperature on Bud Set, Bud Burst and PaFTL2, PaCOL1-2 and PaSOC1 Expression in Norway Spruce (Picea abies (L.) Karst.)

Light and temperature are crucial factors for the annual growth rhythm of tree seedlings of the boreal and temperate zone. Dormant, vegetative winter buds are formed under short days (SD) and altered light quality. In the conifer Norway spruce, expression of FTL2 increases and PaCOL1-2 and PaSOC1 decrease under light regimes, inducing bud set. Although temperature is known to modulate the timing of bud set, information about combined effects of light climate and temperature on bud phenology and gene expression is limited. We studied the interactive effects of temperature (18, 22/24 °C) and day extension with blue (B), red (R) or far-red (FR) light or different R:FR ratios compared to SD on growth–dormancy cycling and expression of FTL2, PaCOL1-2 and PaSOC1 in Norway spruce seedlings. Day-extension with B light and all treatments involving FR light sustained shoot elongation, with increased growth at higher temperature. The R light treatment resulted in delayed/prevented bud set compared to SD, with more delay/prevented bud set at 24 °C than 18 °C. This was associated with lower PaFTL2-transcript levels at 24 °C and more rapid subsequent bud burst. For the growth-sustaining treatments (long days, FR and B light), the PaFTL2-transcript levels were generally lower and those of PaCO1-2 and PaSOC1 higher compared with SD and R light. In conclusion, our results demonstrate more reduced/prevented bud set and faster bud burst with increased temperature under day extension with R light, indicating less deep dormancy than at lower temperature. Also, sustained shoot elongation under the B light treatment (27 µmol m−2 s−1) in contrast to the lower B light-irradiances tested previously (≤13 µmol m−2 s−1), demonstrates an irradiance-dependent effect of day extension with B light.

The seasonal dynamics of bud dormancy in grapevine suggest a regulated checkpoint prior to acclimation

ABSTRACTGrapevine (Vitis vinifera L.) displays wide plasticity to climate and seasonality, ranging from strongly deciduous to evergreen. Understanding the physiology of decisions to grow or quiesce is critical for improved crop management, prediction, and the adaptability of production to alternative climate scenarios. The perenniating bud (N+2) is a major economic unit and focus of study. Here we investigated the physiology and transcriptome of cv. Merlot buds grown in a temperate maritime climate from summer to spring in two consecutive years. The changes in bud respiration, hydration and internal tissue oxygen data were consistent with the transcriptome data. ABA-responsive gene processes prevailed upon the transition to a deep metabolic and cellular quiescence in the bud during autumn. Light, together with hypoxia and redox signalling presided over the resumption of nuclear and cellular growth in the transition to spring. Comparisons with transcriptome data from bud burst studies revealed a number of regulatory candidates for the orderly resumption of growth in spring, including components that may integrate light and temperature signalling. Importantly however, the bud burst forcing data, which is widely used as a measure of bud dormancy, were not consistent with the physiological and transcription data. We hypothesise the existence of a physiological checkpoint following bud set in summer, which if not met results in extreme quiescence. Collectively this is the most integrated developmental dataset of the latent bud of cultivated grapevine, and establishes a platform for systems approaches to study seasonal plasticity.One sentence summaryPhysiology and transcriptome data provide strong evidence of a regulatory checkpoint prior to acclimation and dormancy in latent grapevine buds.

Adaptive performance of genetically improved and unimproved seedlings of Scots pine

Our main objective was to determine whether various genetically improved reproductive materials of Scots pine ( L.) differ in growth rhythm, autumn cold acclimation and resilience from unimproved materials. The study consisted of two successive indoor experiments with Scots pine seedlings representing four levels of genetic gain (unimproved natural stands, first-generation seed orchards, 1.5-generation seed orchards and seed orchards established with freezing-tested parents) and a wide range of geographical origins within Finland. The seedlings were assessed for terminal shoot elongation, growth cessation, bud set, freezing injuries and bud flushing over the first growth period. All the adaptive traits showed a latitudinal trend regardless of the genetic level. Seed orchard progenies and natural stand progenies did not differ significantly in the timing of growth cessation, bud set, and the flushing rate of the frost-injured seedlings, after the trait variation was adjusted to the latitude of origin. The differences in autumn frost hardiness were insignificant, too, except for the somewhat higher injury rate displayed by the first-generation seed orchard materials. The finding was not conclusive due to ambiguous results from the two experiments. Overall, we did not find evidence of alarming compromises in the adaptive performance of genetically improved materials.Pinus sylvestris

Identifying and testing marker-trait associations for growth and phenology in three pine species

Identifying the additive genetic variation underlying complex traits is important for species of economic and/or ecological value. In particular, where DNA markers can be associated with trait variation they can be used to develop models to predict phenotypes as the basis of future selection and conservation programmes. Here, SNPs associated with growth (height and annual increment) and phenology (budburst and bud set) were identified in three closely related pine species including Pinus sylvestris (Scots pine). A genotyping array was used to screen 20,795 SNPs from coding regions for their association with trait variation using mixed linear model (MLM) and multilocus mixed model (MLMM) approaches: 113 SNPs located at 111 loci were significantly associated with the traits, with the majority associated with either budburst or growth increment in P. sylvestris. Common SNPs (MAF > 0.05) identified as significantly associated with bud set were found in genes putatively involved in only growth and development, whereas SNPs associated with growth and budburst were located in genes putatively involved in growth and development, response to environment and, to a lesser extent, reproduction. Predicted values estimated using the model for growth had highly significant correlations with phenotypes quantified in a P. sylvestris common environment experiment established at two sites in Scotland (YA and GS), but only at one of the sites (YA, height at 2020: r = 0.376, p < 0.001). Predicted values estimated with the model for budburst were found to be weakly but significantly correlated with duration of budburst at one of the field sites (GS, duration at 2018: r = 0.242, p = 0.012) and negatively associated with timing of budburst at the other (YA, stage six: r = −0.216, p = 0.033). Genomic prediction using the model for growth was more successful than random selection as a method of selecting tall trees at both sites. This study provides tentative support for the development of prediction models for traits that are of interest to both foresters and conservationists, while highlighting the need for caution when applying them to trees growing in different environments.

Assessing and minimizing the development and spread of fire blight following mechanical thinning and pruning in apple orchards

The adoption of mechanical thinning and pruning in commercial apple orchards has largely been limited by the risk of development and spread of fire blight. This devastating disease, caused by the bacterial pathogen Erwinia amylovora, may be transmitted by mechanical injury such as pruning, especially under warm, moist conditions conducive to bacterial growth, infection, and disease development. However, risk may be mitigated by avoiding highest risk times and applying a bactericide, such as streptomycin, following mechanical thinning or pruning. In ‘Gala’ and ‘Idared’ orchards, we evaluated the risk of fire blight development and spread following mechanical thinning early in bloom (20% bloom), when seasonal temperatures are cooler and there are few open flowers available for infection. In both orchards, we also evaluated the spread and development of fire blight by mechanical pruning in July and in August, before and after terminal bud set when shoot growth is slowed and less susceptible to infection. We also assessed the potential efficacy of a streptomycin or Bacillus subtilis biopesticide application following mechanical thinning and pruning to mitigate the spread of fire blight. In the ‘Gala’ orchard, disease never developed beyond the inoculated tree following thinning or pruning, which was unexpected for this highly susceptible cultivar. In the ‘Idared’ orchard, incidence of blossom or shoot blight from the point source, represented as relative area under the disease progress curve (rAUDPC) was rarely different for trees that received mechanical thinning or mechanical pruning compared to untreated trees, and was frequently eliminated or reduced when the antibiotic streptomycin or the B. subtilis biopesticide was applied within 24 h of mechanical thinning or pruning. For both thinning and pruning, incidence of fire blight dropped off quickly beyond the inoculated tree in the ‘Idared’ orchard and generally was not observed in trees beyond 10-15 m from the inoculated point source or predicted beyond 10 m by exponential and power law models fit to the disease progress curves. The results of this work demonstrate the low risk for fire blight development and spread by mechanical thinning and pruning when practiced under low-risk conditions—early in bloom for mechanical thinning, and after terminal bud set (in August) for mechanical pruning—especially when paired with a subsequent bactericide application. This study demonstrates the safe use of mechanical thinning and pruning in commercial apple production, corroborated by anecdotal evidence from apple growers in Western New York State.