Frost Injury Research Articles

Effect of increasing temperature and temperature fluctuations on alfalfa and orchardgrass in the establishment year

AbstractUnderstanding how a warmer and more variable climate will affect the productivity and stability of perennial forages in the establishment year is essential for determining forage management strategies resilient to the changing climate. We conducted an experiment from 2020–2021 and repeated it in 2021–2022 to determine how warmer and more variable temperatures affect yield of an alfalfa (Medicago sativa L.)–orchardgrass (Dactylis glomerata L.) mixture, as well as on the abundance of a winter annual weed, chickweed (Stellaria media), during the establishment year. We utilized open‐top chambers (OTCs) to manipulate air temperature in situ to impose three treatments: (1) constant warming (OTC present year‐round), (2) fluctuating warming (OTC present year‐round but temporarily removed prior to abrupt cold snaps), and (3) control (no OTC, ambient air temperature). OTCs increased air temperature within the alfalfa–orchardgrass canopy by an average of 0.45 and 0.72°C in Year 1 and Year 2, respectively; however, the effects of OTCs on air temperature varied temporally within and between years. Constant warming decreased alfalfa frost injury compared with the control, while the control and fluctuating warming resulted in similar levels of frost injury. Warmer temperature within the OTCs neither affected chickweed biomass nor the biomass of all other weed species. Both constant and fluctuating warming increased forage dry matter yield at the first harvest timepoint in the spring of both years, the period when preceding ambient air temperature tended to be cooler than other harvest timepoints. We found that the constant warming increased total forage yield (summed over the entire year) in Year 1, when precipitation was well above the 30‐year normal for our region, but decreased total forage yield in Year 2, when summer precipitation was substantially below the 30‐year normal. As global temperature continues to rise, yield loss of cool‐season perennial forages, such as alfalfa and orchardgrass, may be exacerbated in years without adequate precipitation. Therefore, exploring heat‐ and drought‐tolerant alternative forages, as well as management strategies that improve resilience to weather variability, will be increasingly important.

Greener leaves from northern trees: Latitudinal compensation in riparian cottonwoods

Narrowleaf cottonwoods (Populus angustifolia) occur in disjunct populations along rivers in a north-south corridor of the Rocky Mountain regions from Alberta, Canada, to Arizona, USA. This distribution should allow genetic divergence to provide localized ecophysiological adaptation. To test this, we compared 167 genotypes in ten source populations from across the full latitudinal range of 16° (1800 km). Replicated clonal saplings were grown for three years in a common garden at the northern range limit, where we found that shoot characteristics were correlated with the latitude of origin. Southern populations displayed increased height and stem diameter (populations: r2 = 0.489 and 0.472) due to extended in-leaf growing seasons. However, this produced a phenological mismatch, with increased fall frost injury and shoot die-back. With increasing latitude of origin there were foliar differences across the populations, with higher chlorophyll content (chl, r2 = 0.836), nitrogen (N, r2 = 0.429), and leaf mass per area (LMA, r2 = 0.474). Similar latitudinal correspondences were observed across the individual genotypes, again with the strongest correlation for chl (r2 = 0.188). Across the genotypes, chl was positively correlated with leaf length, width, area, and mass, and especially with foliar N (r2 = 0.354), which was also correlated with foliar δ13C (r2 = 0.230). The heritable correspondences between source latitude and foliar characteristics could enable vigorous photosynthesis during the shorter, northern growing season, providing latitudinal compensation. Conversely, slower photosynthesis would reduce the foliar aging rate, enabling leaf function through the longer, southern growing season. The alternate foliar strategies could accommodate the limited ‘leafspan’, or leaf lifespan. This adaptive variation in foliar physiology would impact natural or assisted northward migration of cottonwood populations in response to climate change. It could also be useful for poplar breeding, with northern genotypes contributing genes to increase photosynthetic capacity. Finally, groupings of the populations based on the combined ecophysiological traits were very consistent with genetically defined ecotypes, supporting the evolution of subspecies types within this obligate riparian tree.

Coriander response to potassium under its medium availability in Typic Haplustepts

Field experiments were carried out with seven levels of potassium (K) (as-1K O ha ) using coriander (var. Ajmer coriander-1) on a medium fertile2sandy loam soil (Typic Haplustepts). These results revealed that plantheight and secondary branches were lower at higher level of K, while thegrowth, yield and associated attributes were statistically (p<0.05) at parwith control. The reduction in seed yield per pot was 4.2 to 8.3 % beyond-1soil application of 40 kg K O ha . There was no significant (p<0.05)2variation in seed nutrient content, except N and K uptake. The N content in-1seed was higher at120 kg K ha , while K content in seed was more beyondthe 60 kg of applied K. Nutrient content in coriander straw increasedmarginally with increase in doses of K. Uptake of nutrients and sodium(Na) content decreased with increase in doses of K. Potassium availability-1was more with higher doses of K; beyond the 40 kg K ha and rest ofnutrient remained at par with doses of K. Soil exchangeable Na wasenhanced slightly with doses of K and soil accumulation was more than itsinitial level. Therefore, it is recommended that there is no need to apply K incoriander, if sufficient availability of K is there in soil and irrigation waterbears an appreciable amount of K. Moreover, higher application of K anddeep irrigations (>50mm) makes coriander susceptible for frost injury, if itoccurs and ultimately reduces crop yield.

Minimization of Frost Injury in Mango cv. Sindhri via Different Irrigation Levels

Mango is one of the most important fruit crops all over the world. It is the second-most significant fruit crop in Pakistan. The standardization of irrigation needs for the mango crop is one of the primary and most crucial factors for reducing frost injury, improving fruit quality, and yield, which must be taken into account. Low moisture content in the soil increases the likelihood of frost injury, so it is essential to maintain an ideal amount of moisture to mitigate such damage. To conserve valuable irrigation water, apply water only during critical stages. Research was conducted at the Experimental Orchard of Makhdom Ahmad Aalam Anwar, Mohsin Abad, during 2020-21 and 2021-22. Mango trees of the Sindhri variety were of uniform age (20 years) for this experiment. The experimental layout was a randomized complete block design. Irrigation was applied to mango trees at three different moisture levels (35-40%, 30-35%, and 25-30%) that were measured and maintained via the HH2 Moisture Meter (Version 2.3). The mango trees showed good results at the 35-40% soil moisture level compared with the rest of the treatments, especially in terms of vegetative growth. Fruit size, yield per tree, and total soluble solids of the fruit were maximum in mango trees irrigated at 35-40%. Minimum frost incidence (21%) was observed at the 35-40% moisture level, while maximal damage by frost (37%) was noticed in plants subjected to the 25-30% moisture level. This study concludes that moisture level is more important for enhancing mango yield. It will be more supportive for future work on the impact of frost injury in the mango crop.

Within- and between-population comparisons suggest independently acting selection maintaining parallel clines in Scots pine (Pinus sylvestris).

Parallel clines in traits related to adaptation in a species can be due to independent selection on a pair of traits, or due to selection in one trait resulting in a parallel cline in a correlated trait. To distinguish between the mechanisms giving rise to parallel adaptive population divergence of multiple traits along an environmental gradient we need to study variation, correlations, and selective forces within individual populations along the gradient. In many tree species, budset timing (BST) forms a latitudinal cline, and parallel clinal variation is also found in other seedling traits, such as first-year height (FYH) and fall frost injury (FFI). In this study, we set up a common garden experiment with open pollinated progeny from natural populations of Scots pine (Pinus sylvestris), with one large sample from single population (500 families) and smaller samples from across a latitudinal gradient. BST, FYH and induced FFI were first measured in a greenhouse. The seedlings were then planted in the field, where survival and height were measured at the age of 9 years as fitness proxies. We compared between- and within-population variation and genetic correlations of these three seedling traits, and estimated selection gradients at the family level in our main population, taking into account the potential effects of seed weight. Between-population genetic correlations between seedling traits were high (0.76-0.95). Within-population genetic correlations in the main population were lower (0.14-0.35), as in other populations (0.10-0.39). Within population, extensive adaptive variation persists in the seedling traits, in line with rather weak selection gradients, yet maintaining the clines. Although our sampling does not cover the whole cline equally, the results suggest that the individual clines in these traits are maintained by largely independently acting selection, which results in fewer constraints in adaptation under changing climate.

Influence of Artichoke Antioxidant Activity in Their Susceptibility to Suffer Frost Injury.

In the northern hemisphere countries, artichoke harvest occurs in winter months; consequently, they are exposed to cold temperatures. This can lead to frost injury, such as triggering the blistering of the cuticle and detachment of outer bracts, which eventually could display brown or black discolouration. This can cause major economic and production losses. As far as we know, no literature is available about this problem in artichokes. Thus, the main aim of this study was to evaluate the effect of total phenolic content and the antioxidant potential of 'Blanca de Tudela' artichokes in their capacity to tolerate frost injury when they are exposed to low temperatures. Several factors were analysed, including floral head order, weight and size of artichokes, total phenolic content, phenolic profile and total antioxidant activity. Results showed that tertiary heads, which are the smallest in size, exhibited a greater amount of total phenolic content and antioxidant activity. As a result, these characteristics offered enhanced protection to the artichoke against frosting temperatures. In contrast, the largest artichokes, especially the primary heads, were more susceptible to suffer frostbite. Therefore, artichokes with robust antioxidant systems, characterized by elevated phenolic content, are crucial to reduce their susceptibility to frost injury.

Early ground rolling is highly effective in delaying spikelet initiation in early-sown spring wheat

ABSTRACT Ground rolling delays spikelet initiation and thus would be expected to reduce frost injury in early-sown spring wheat. To characterize the relationship between the timing of rolling and the delay of spikelet initiation, we investigated apical development of early-sown spring wheat plants (Triticum aestivum L. cv. ‘Ayahikari’) rolled at the 1-, 2-, 3-, or 4-leaf stage in three years. All rollings delayed apical development. The delay was largest in plants treated at the 1- or 2-leaf stage: spikelet initiation by 5.0 days, the start of internode elongation by 5.5 days, and jointing by 3.5 days relative to the control. Our results and recent meteorological data suggest that in early cropping of spring wheat in the Tokai region of Japan, the earliest sowing date to avoid frost injury can be advanced by 3 days by rolling.

Rapid monitoring of tea plants under cold stress based on UAV multi-sensor data

In the context of climate change, extreme weather events, represented by frost injury, are increasingly having a negative impact on the growth of tea plants. This has brought huge losses to the tea industry. Traditionally, the freezing injury of tea plants in the field was assessed by vision. This is labor-intensive and subjective. In this research, multimodal remote sensing data from different periods of natural overwintering tea plantations were collected by using unmanned aerial vehicles (UAV) equipped with multispectral (MS), thermal infrared (TIR) and RGB sensors. And the physiological data of tea leaves on the same day were obtained to construct a tea cold injury score (TCIS). Then, a convolutional neural networks-gate recurrent unit (CNN-GRU) model was improved for estimating TCIS. To better compare the performance of CNN-GRU, a single GRU model and three classical machine learning models were also used for comparison. The study found that: (1) The multimodal data fusion was superior to the unimodal data. The best prediction results were achieved for the combined bimodal MS + RGB data (Rp2 = 0.862, RMSEP = 0.138, RPD = 2.220); (2) The CNN-GRU hybrid model was superior to the other four baseline models. The best effect was achieved based on the multivariate input of MS + RGB (Rp2 = 0.862) or MS + RGB + TIR (Rp2 = 0.850); (3) The accuracy of the model after removing soil features was lower than that of the model without background removal. Therefore, the TCIS-CNN-GRU model combined with multi-source remote sensing data can objectively and accurately evaluate the cold injury phenotype of tea plants, making the CNN-GRU model more scientific and promising.

Estimating Freezing Injury on Olive Trees: A Comparative Study of Computing Models Based on Electrolyte Leakage and Tetrazolium Tests

Winter frost injury is a major limiting factor for olive cultivation in temperate regions. The response of olive shoots to freezing stress can be used for selecting genotypes resistant to freezing. The electrolyte leakage (EL) and tetrazolium tests (TZ) are commonly used to evaluate dead tissues in cold stress studies. The temperature–response curve of dead tissues to lethal temperature (LT) is measured with models to calculate LT50 and LT90. In this study, we evaluated the accuracy and efficiency of eighteen nonlinear regression models (NLRs) in calculating LT50 and LT90 of freezing stress in different olive cultivars at various stages of dormancy. After evaluating the prediction performance of NLR models, it was found that only eight models were suitable for the purpose of this research out of the eighteen models examined. The 2p-logistic and Gompertz models were selected for modeling EL and TZ, respectively. Our research findings indicate that the Roughani, Kawi, and Zard varieties of olive trees exhibit the best performance under artificial temperature-controlled conditions. Our findings provide valuable insights into selecting frost-resistant cultivars and designing effective strategies for cold acclimation in olive cultivation.

Molecular Marker-Assisted Selection for Frost Tolerance in a Diallel Population of Potato.

A multi-parental population is an innovative tool for mapping large numbers of loci and genetic modifications, particularly where they have been used for breeding and pre-breeding in crops. Frost injury is an environmental stress factor that greatly affects the growth, development, production efficiency, and geographical distribution of crops. No reported study has focused on genetic mapping and molecular marker development using diallel populations of potatoes. In this study, 23 successful cross combinations, obtained by a half diallel cross among 16 parents, including eight frost-tolerant advanced breeding lines and eight cultivars, were used to map the genetic loci for frost tolerance and to create a molecular marker-assisted selection (MAS) system. Three candidate regions related to frost tolerance on chromosomes II, V, and IX were mapped by bulked segregant analysis (BSA). Furthermore, six SNP markers associated with frost tolerance from candidate regions were developed and validated. Above all, a MAS system for the frost tolerance screening of early breeding offspring was established. This study highlights the practical advantages of applying diallel populations to broaden and improve frost-tolerant germplasm resources.

Association of frost injury with tuber yield components in potato (Solanum tuberosum L.)

1In north-western and west-central sub-tropical plains of India, frost is known to influence the potato productivity by 10-50% depending upon intensity of frost and crop age. Information on frost tolerance is limited in sub-topical plains (Kang et al. 2007, Luthra et al. 2007) and association of frost injury with tuber yield components is lacking in potato. The tuber yield being complex polygenic trait is determined by interactions among various genetic as well as environmental factors. The genetic parameter gives an idea of the genetic advance to be expected from selection for a character (Johnson et al. 1955). Association among different characters helps in selection of better plant type.

Phenocam observed flowering anomaly of Rhododendron arboreum Sm. in Himalaya: a climate change impact perspective.

Flowering exhibits a significant relationship with environmental stimuli and changes. Effect of photoperiodism and vernalization have been well studied in flowering phenology; however, the effect of soil temperature on flowering is less explored which is one of the major factors of vegetation growth in alpine ecosystem. This study thus focuses on the effects of soil and air temperature on flowering response of Rhododendron arboreum Sm., a Himalayan tree species, which is also an indicator of spring initiation in high altitude regions. To monitor the flowering pattern, we employed automated phenocam, which was set up at 3356 masl in Tungnath (Indian Alpine region of Uttarakhand) for time-lapse photography of timberline ecotone. Soil and air temperature were recorded continuously at the timberline ecotone. Three years (2017 to 2020) of datasets were used for the present study. The phenocam observations displayed an interesting event in the year 2019-2020 with complete absence of flowering in R. arboreum population at Tungnath timberline ecotone. From the soil temperature data, an increase in winter (Dec-Jan, during which floral buds form) soil temperature, by > 1°C, and no accumulation of freezing degree-days were found for the year 2019-2020. Air temperature however did not display any relationship with the failure of flowering, ruling out aerial chilling or frost injury of floral buds. From the results, a possible relationship between soil temperature and flowering can be suggested pointing towards necessary root apex vernalization stimulus in shallow rooted Rhododendrons. However, the dependency of flowering in Rhododendrons on winter soil temperature further requires continuous monitoring and more observations to make concrete inferences.

Responses to Ice Formation and Reasons of Frost Injury in Potato Leaves

Potato leaves are ice-tolerant but are frost-damaged at −3 °C. Freezing occurs in two steps, a first non-destructive freezing event and a second independent lethal event. Localization of ice, and whether cells freeze-dehydrate after the first freezing event remains unknown. The cause of frost damage during the second freezing event lacks experimental evidence. Cytological responses of mesophyll cells were examined during ice formation using cryo-microscopic techniques after high-pressure freeze-fixation and freeze-substitution. CO2 gas exchange on frozen leaves revealed functional responses, but also frost damage. After the first freezing event, gas exchange was uninterrupted. Consequently, intercellular spaces are free of ice, and ice may be restricted to xylem vessels. The cellular shape of the mesophyll cells was unchanged, cells did not freeze-dehydrate but were supercooled. When thawed after the first freezing event, leaves were initially photoinhibited but regained photosynthesis. During the second freezing event, cells froze intracellularly, and some palisade parenchyma cells remained intact for a prolonged time. Intracellular ice caused complete destruction of cells, and chloroplasts became invisible at the light microscopic level. When thawed after the second freezing, leaves were unable to regain photosynthesis. Consequently, freezing avoidance is the only viable strategy for potatoes to survive frost.

Ice Nucleation Active bacteria in Mount Lawu forest, Indonesia: 1. Isolation and estimation of bacterial populations on lichens

Abstract. Fu’adah K, Sari SL, Susilowati A. 2017. Ice Nucleation Active bacteria in Mount Lawu forest, Indonesia: 1. Isolation and estimation of bacterial populations on lichens. Asian J For 1: 83-91. Ice Nucleation Active (INA) bacterias cause frost injury in plants. These bacteria are also predicted to play an important role in bioprecipitation, cloud formation, and rain. Most INA bacteria studies are conducted in subtropical areas. Therefore, studies on INA bacteria from tropical areas, especially Indonesia, need to be conducted. This study aimed to isolate and determine the number of INA bacteria in lichenes. samples of lichenes were taken from the hiking pathway of Cemoro Sewu, Mount Lawu forest, Java, Indonesia, at ±2.200, ±2.400, and ±2.600 m asl. INA bacteria were isolated by the spread plate method on the NA medium with 2.5 % glycerol and King’s B medium. A tube nucleation test determined ice nucleation activity. A multiple-tube nucleation test estimated the number of INA bacteria. The data were analyzed descriptively based on colony morphology, cell morphology, biochemical tests, and analysis of the numbers of INA bacteria. The result showed that 7 isolates from Parmelia sp. at an altitude of 2.532 m asl (station 2) have been known as INA bacterias. The number of INA bacteria in lichenes was 5 x 104/g, which was very low.

Ice Nucleation Active bacteria in Mount Lawu forest, Indonesia: 2. Identification and characterization of ina gene bacteria isolated from lichens

Abstract. Arifin TN, Susilowati A, Sutarno. 2018. Ice Nucleation Active bacteria in Mount Lawu forest, Indonesia: 2. Identification and characterization of ina gene bacteria isolated from lichens. Asian J For 2: 39-46. Ice nucleation active (INA) bacteria can catalyze ice formation. Moreover, these bacteria cause frost injury in plants. This study aimed to determine the ina bacteria species of Mount Lawu forest, Java, Indonesia, based on the 16S rRNA gene and the characters of ice nucleation active gene coding of ina bacteria on lichens used ina gene primer. First, the isolates of ina bacteria were grown in NAG, and the DNA could be isolated. After that, genes coding for 16S rRNA and ina were amplified, and the amplification products were sequenced. Furthermore, the sequences were analyzed with BLAST program to know the similarity of bacteria species and ina gene characters. The result showed that the isolated ina bacteria had similarities with Pantoea, Pseudomonas, and Rahnella. The ina gene from N.2.1.B-13 isolate consists of 189 amino acids, dominated by a common amino acid found in other ina genes, like Alanine, Glycine, Tyrosine, Serine, Leucine, and Threonine. N terminal and C terminal are not found because ina gene from N.2.1.B-13 isolate is similar to the ice nucleation protein gene Pseudomonas borealis from bases 2947 bp to 3491 bp or 871 to 1060 amino acids.

Significance to the Horticulture Industry

Significance to the Horticulture Industry

Examining the potential of Austrocedrus chilensis tree rings as indicators of past late-spring frost events in central Chile

Austrocedrus chilensis is a South American conifer broadly distributed across the subtropical and extratropical Andes that is widely utilized in tree-ring studies. This species has clear annual growth rings that are sensitive to the moisture supply and has been extensively used to reconstruct the past hydroclimate during the last millennium. Despite a great number of dendrochronological studies based on tree-ring width, little is known about the potential of the species to record intra-annual anomalies and particularly frost rings. In this study, the main traits of A. chilensis frost rings were studied and the ability of this endemic Cupressaceae to record spring frosts at five sites across a latitudinal gradient between the Mediterranean and Northern Patagonian Andes was evaluated. The average ages of trees in the study sites varied from 168 to 343 years, with minimum and maximum ages of 33 and 919 years. The results indicated that 85% of the frost rings occurred at the beginning of the earlywood and 15% showed a mid intra-ring position. Regarding the portion of the ring circumference affected by frost damage in cross sections, 59% of the injuries partially affected the entire ring, 30% affected the complete ring circumference, and 11% resulted in a ring fracture. Freezing temperatures that generated frost rings in A. chilensis from the upper treeline coincided with events below 0 °C recorded in the agricultural Central Valley of Chile. We estimated the potential time window of the formation of A. chilensis frost rings over a two and a half month period from the end of September to mid-November (early spring). Our results indicated that tree age was a determinant factor affecting the ability of trees to record frost rings. The maximum frequency of frost rings occurred at 12 years and the maximum age at which 95% of the total frost injuries occurred within our network was about 120 years. Both the exceptional longevity and the excellent state of preservation of relict wood demonstrates that A. chilensis frost rings provide a reliable proxy for monitoring and reconstructing late-spring frost events in central Chile.

Phenology, cold injury and growth of American chestnut in a Range-Wide provenance test

The primary factor limiting the distribution and growth of American chestnut (Castanea dentata (Marsh.) Borkh.) in eastern North America is tolerance to chestnut blight that is caused by the introduced fungal pathogen Cryphonectria parasitica (Murr.) Barr. However, a better understanding of how genetics and the environment influence American chestnut physiology and growth will also be needed to guide restoration as blight-tolerant growing stock becomes available. Here we describe patterns of phenology, cold injury and radial growth for American chestnut from 13 seed sources that represent three temperature zones (warm, moderate and cold) grown together in a unique provenance test in Vermont, USA. Temperature zones were established using data on the mean minimum winter temperatures over 10–30 years for weather stations nearest seed source locations; these averages were −5 °C and above for the warm temperature zone, −5 to −10 °C for the moderate temperature zone, and below −10 °C for the cold temperature zone. There was a consistent trend for trees from the warm temperature zone to break bud and leaf out earlier, and experience greater spring leaf frost damage and shoot winter injury than trees from other temperature zones. After initial establishment, woody growth (approximately 6 years of ring counts) was robust and tended to be greatest among moderate temperature zone sources and lowest for cold zone sources. Especially for trees from the warm zone, earlier budbreak was associated with greater growth. Foliar frost injury was not associated with altered growth, whereas winter shoot damage was associated with lower growth – especially following significant shoot loss. Even though warm temperature zone sources experienced more winter injury than trees from cold temperature zones, the growth of cold temperature zone sources tended to underperform that for warm and moderate zone sources – this suggests that, at least for the limited time that we evaluated growth, greater protection from the cold may come at the cost of greater growth potential. Although American chestnut is considered to be a relatively drought-tolerant species and growth was assessed during a period of historically high precipitation, higher moisture availability the year before, and occasionally during, the year of ring formation was broadly associated with greater growth across the temperature zones. Despite the negative influences of winter shoot injury on growth, the overall productivity of trees was exceptional, even at the northern edge of the species’ range provided that moisture availability was adequate.

EVALUATION OF ROMANIAN APPLE CULTIVARS IN LATVIA

Commercial apple growing in Latvia feels some lack of climate adapted modern cultivars. Development of fruits and trees is limited by active growth period (temperatures over 10 °C) of 135-150 days and active temperature sum of 1700-2100 °C. Winter hardiness also is essential, as temperatures below −30°C occur each 10 years, and winter thaws are frequent. Annual precipitation 692 mm favours development of fungal diseases. In 2016, a trial of four Romanian apple cultivars resistant to scab - ‘Aura’, ‘Ciprian’, ‘Jonaprim’ and ‘Romus 3’ was established in Latvia. Trees were grafted on dwarfing rootstock B.396 and planted as 1-year old whips in 3 replications with 2-3 trees in each replication, and trained as slender spindle. Commercial cultivars ‘Auksis’ (midseason) and ‘Ligol’ (late) were used as controls. Most trees of all cultivars in the 2nd year (2017) developed a well branched frame, from 37.5% trees of ‘Ciprian’ to 90% trees of ‘Jonaprim’. The first fruits were harvested in 2017, and commercially significant yield was achieved in 2018, except ‘Jonaprim’, which had the slowest yield increase. By the sum of yield in 2017-2021 ‘Aura’ and ‘Jonaprim’ surpassed commercial cultivar ’Auksis’, but were less productive than ‘Ligol’. Only slightly lower summary yield was obtained from ‘Ciprian’, while ‘Romus 3’ showed the lowest productivity and strong premature fruit drop. Very good taste panel results were obtained for ‘Aura’ and ‘Ciprian’, 7 to 8 points in average. Their fruits also kept well, to 5 months in common storage at 2 ±1oC. Fruits of the other two cultivars were too small and had mediocre or poor taste. The weather conditions in the trial years allowed to test susceptibility to spring frosts and drought. All cultivars showed good tree health after over-wintering. ‘Jonaprim’ and ‘Auksis’ in 2019 had the highest spring frost injury, 60-70% of fruits, while least injured were ‘Aura’ (21.5%) and ‘Ciprian’ (27.7%). Extreme drought in summer of 2021 led to low average fruit mass of all cultivars including the normally large fruited ‘Ligol’ (120-130 g), while in other years ‘Aura’ had fruits over 180 g, very attractive yellow with red stripes. Fruits of ‘Ciprian’ also had good size, but in some years too dark over-colour. ‘Aura’ and ‘Ciprian’ showed good adaptation to the climate of Latvia and can be recommended for wider trials at farms.

Chemical Composition of Gmelina arborea: A Review

Gmelina arborea is a fast-growing tree, which grows on different localities and prefers moist fertile valleys with 750–4500 mm rainfall. It does not thrive on ill-drained soils and remains stunted on dry, sandy or poor soils; drought also reduces it to a shrubby form. The tree attains moderate to large heights of up to 30 m, with a girth of 1.2 to 4 m. It has a chlorophyll layer just under the outer bark, which is pale yellow on the outside and white inside.Gmelina arborea wood is pale yellow to cream-coloured or pinkish-buff when fresh, turning yellowish brown on exposure and is soft to moderately hard, light to moderately heavy, lustrous when fresh, usually straight to irregular or rarely wavy grained and medium course textured. Flowering takes place during February to April when the tree is more or less leafless whereas fruiting starts from May onwards up to June. The fruit is up to 2.5 cm long, smooth, dark green, turning yellow when ripe and has a fruity smell. The fruit is edible and has a bitter-sweet taste.4 This tree is commonly planted as a garden and an avenue tree; growing in villages along agricultural land and on village community lands and wastelands. It is light demander, tolerant of excessive drought, but moderately frost hardy. It has good capacity to recover from frost injury. Gamhar trees coppices very well with vigorous growth. Saplings and young plants need protection from deer and cattle. Gmelina arborea grows naturally throughout India, Myanmar, Thailand, Laos, Cambodia, Vietnam and in southern provinces of China