Berry Set Research Articles

IMPACT OF FOLIAR APPLICATION OF CHELATED ZINC ON THE SEASONAL CHANGES OF GROWTH AND DEVELOPMENT OF GRAPE BERRIES (VITIS VINIFERA L.)

A Field experiment was conducted A Field experiment was conducted in 2019 in the growing season, to study the effect of foliar application of zinc-chelated "Zn-EDTA" at concentrations 0,50,100 and 200 mg.l-1 on the seasonal dynamic of the growth and development of some physical and chemical characteristic in berries of Halwani Lebanon grape cultivar, grown on a calcareous soil in Mosul region- Iraq. The results revealed that the foliar application of 100 mgZn.l-1 caused a significant increase of berry weight, TSS, Glucose and Fructose in berries. While spraying with 200 mgZn.l-1 caused a significant decrease in the TA and Malic acid in juice berries compared to the control. Additionally, berry weight, TSS, Glucose and Fructose were increased from the beginning of berry growth to véraison and ripening stages. Total acidity was increased from berry set to 14 June and decrease towards the end of the maturity of berries on September 6th during growth season. While Tartaric and Malic acids were increased from berry set to véraison. Whereas, decrease towards the maturity of berries. On the other hand, the interaction between zinc levels and times on growth and development of berries were also discussed.

Inflorescence temperature influences fruit set, phenology, and sink strength of Cabernet Sauvignon grape berries.

The temperature during the bloom period leading up to fruit set is a key determinant of reproductive success in plants and of harvest yield in crop plants. However, it is often unclear whether differences in yield components result from temperature effects on the whole plant or specifically on the flower or fruit sinks. We used a forced-convection, free-air cooling and heating system to manipulate the inflorescence temperature of field-grown Cabernet Sauvignon grapevines during the bloom period. Temperature regimes included cooling (ambient −7.5°C), heating (ambient +7.5°C), an ambient control, and a convective control. Cooling significantly retarded the time to fruit set and subsequent berry development, and heating shortened the time to fruit set and accelerated berry development relative to the two controls. Fruit set was decreased in cooled inflorescences, but although the cooling regime resulted in the lowest berry number per cluster, it also decreased seed and berry weight at harvest while not affecting seed number. Cooling inflorescences slightly decreased fruit soluble solids and pH, and increased titratable acidity, but did not affect color density. The inflorescence temperature did not impact leaf gas exchange and shoot growth, and shoot periderm formation occurred independently of the timing of fruit ripening. These results suggest that the temperature experienced by grape flowers during bloom time impacts fruit set and subsequent seed and berry development. Suboptimal temperatures not only reduce the proportion of flowers that set fruit but also limit the sink strength of the berries that do develop after fruit set. Shoot vigor and maturation, and leaf physiology, on the other hand, may be rather insensitive to temperature-induced changes in reproductive development.

ASSESSMENT OF SELF-FERTILITY OF BLUEBERRY VARIETIES IN THE CONDITIONS OF BELARUS

The results of a three-year study of the self-fertility of 15 varieties of highbush blueberry and one variety of lowbush blueberry are presented. The fruiting indicators (berry setting, average berry weight, average number of seeds per berry) in case of most self-pollinating highbush blueberry varieties, as a rule, are lower than with natural cross-pollination. In accordance with the average indicators of fruit set during self-pollination of flowers, blueberry varieties are ranked into five groups corresponding to the degree of self-fertility. The Spartan, Toro and Sunrise highbush blueberry varieties have a high degree of self-fertility, the best of which in terms of fruiting parameters are Spartan and Toro. Good indicators of selffertility under conditions of self-pollination were demonstrated by the Nui variety. Most of the studied blueberry varieties are characterized by unstable self-fertility rates. The Bonus and Putte varieties are classified as self-infertile taxa.

The Effect of Spur Position and Pruning Severity on Shoot Development

Adjusting yearly pruning severity is a common vineyard management practice employed to manipulate vegetative and reproductive growth in grapevines. Although the effects of pruning on total vegetative growth are well documented, there is little research on the effects of adjusting shoots meter−1 via dormant season pruning on addressing mid-cordon shoot weakness and developmental delays. Cordon-trained, spur-pruned vines are thought, by many growers, to be especially prone to weaker positions and delayed development at mid-cordon positions. This phenomenon is also thought to become more exaggerated as the vine ages. Therefore, the effects of shoot density manipulation, implemented via dormant pruning practices, to homogenize shoot and cluster development along the length of the cordon were examined. In this research, Cabernet Sauvignon grapevines were pruned to either 5.5 shoots meter−1 (5.5) or 11.1 shoots meter−1 (11.1). To control for variations in light interception into the fruiting zone, a control of 11.1 shoots meter−1 with sensor guided leaf thinning (11.1LT) was implemented at full berry set to match the canopy light of the 5.5 shoots meter−1 treatment. It was found that individual shoot growth and yield were directly impacted by manipulation of pruning severity. Shoot growth response varied primarily by growing season, including shoot length and internode length. Yield components were significantly lower in the 5.5 treatment during the first two years of the study but were not significantly different during the last year of the study. The 5.5 treatment resulted in the highest pH and total soluble solids at harvest in 2016 and 2017.

Effect of Gibberellic Acid (GA3) on Yield and Fruit Quality of Table Grape var. Himrod in Kathmandu Valley, Nepal

The experiment was conducted at Warm Temperate Horticulture Center, Kirtipur, Kathmandu, Nepal with an aim to improve the yield and fruit quality of seedless table grape var. Himrod. Different treatments of GA3 (0 ppm,10 ppm, 20 ppm, 30 ppm, 40 ppm) were applied for two times on grape bunches after berry set. The quantitative and qualitative attributes of bunch and berry were recorded. Berry size, berry weight, berry volume, bunch weight and berry color were improved significantly in GA3 treated grape bunches whereas TA was significantly decreased. The effect of GA3 on berry diameter had significant impact on berry weight and berry volume, and thus in yield. As the yield of a vine is the product of bunch number and bunch weight, GA3 influenced the current season bunch weight by improving the berry attributes, and also affected quality attributes of grape berries in var. Himrod.

Effect of Spraying Pota Crastal Compound and Vast Trivalioum Compound on Berry Setting, Yield and Berries Quality of Superior Grapes

Effect of Spraying Pota Crastal Compound and Vast Trivalioum Compound on Berry Setting, Yield and Berries Quality of Superior Grapes

Genome-Wide Characterization of Cytokinin Response Regulator in Grape and Expression Analyses during Berry Set Process

Genome-Wide Characterization of Cytokinin Response Regulator in Grape and Expression Analyses during Berry Set Process

Flowering Behavior and Selection of Hybrid Potato Clones through LXT Breeding Approaches

Potato breeding in Bangladesh is very challenging because it is grown in the short winter season, and flowering does not occur naturally, explaining why artificial lighting and extra care are needed. In addition, the breeding scheme is mainly focused on improving potato yield, followed by tuber quality. The goal of this study was to choose male parents, as well as the effect of environment, on flowering and fruit (berry) setting and to estimate the combining ability among promising BARI-released potato varieties in the second filial generation. Lines of seven Bangladesh Agricultural Research Institute (BARI) varieties were crossed with two BARI variety potato parents as the tester (Line × tester). The BARI Alu-86, BARI Alu-72, BARI Alu-73, and BARI Alu-53 were selected as the best male parents based on the abundance of pollen and fruit set. In both years, flower initiation days varied among clones. For the majority of the traits, such as plant height, tuber number, and yield per plant, the variance of general combining ability (GCA) and specific combining ability (SCA) varied. The inheritance of the considered trait was predominant by non-additive gene action. Concerning general combining ability, for plant height, parents ‘BARI Alu-41’ and ‘BARI Alu-53’, for stem per hill, ‘BARI Alu-79′, for tuber number, ‘BARI Alu-37’, and for yield, ‘BARI Alu-37’ and ‘BARI Alu-79’ contributed complementary favorable alleles. The specific combining ability indicated ‘BARI Alu-37’ × ‘BARI Alu-86’ and ‘BARI Alu-77’ × ‘BARI Alu-72’ were the best potential hybrid families for the production of improved genotypes of tuber yield and tuber number. This study will help to design a breeding program following potato population development and the selection of progeny before their utilization as progenitors.

Features fruit set higbush blueberry depending on the cultivar specifications and weather and climatic conditions

On the basis of four-year data, the features of fruit set are shown for 15 cultivars of highbush blueberry. The average yield of ripe berries from the number of flowers varies within a fairly wide range and averages from 46 % (Chandler) to 83 % (Sunrise) for highbush blueberry cultivars. The degree of variability in berry setting indices in the taxa under study varied significantly over the years: from a low level (Bluejay, Nui, Puru, Spartan, Sunrise) to a very high level (Bonus). It was revealed that the lower the level of variability of the fruit setting indicator, the higher the adaptive ability of the taxon to changing weather and climatic conditions. The setting of highbush blueberry fruits is influenced by such weather and climatic factors as humidity and air temperature. Precipitations falling within the range close to the mean annual values or slightly higher than them, and the air temperature close to the climatic norm, contribute to better fruit setting. A pronounced shortage of precipitation, especially against the background of an increased average daily temperature, during flowering and growth of fruits, as well as heavy precipitation during the period of mass flowering of blueberries, have a negative effect on berry setting. At the same time, the main limiting temperature factor during flowering and formation of blueberry fruits is a decrease in air temperature to minus indicators (freesing).

MITIGATION OF EXCESSIVE PROTON CONCENTRATIONS OF “CRIMSON” GRAPES BY THIDIAZURON AND BENZYLADENINE

The present study was conducted during the two consecutive seasons 2018 and 2019 on "Crimson Seedless" table grapes to mitigate the excessive ProTon concentration by some cytokinin use. The following treatments were used: control, thidiazuron at 50ppm (TDZ), abscisic acid at 250ppm (ABA) preceded by TDZ at 50ppm, ABA at 500ppm preceded by TDZ at 50ppm, benzyl adenine at 50ppm (6-BA), ABA at 250ppm preceded by 6-BA at 50ppm, ABA at 500ppm preceded by 6-BA at 50ppm, ABA at 250ppm and ABA at 500ppm.Treatment of TDZ and 6-BA were applied at berry set while ABA treatment was applied at 10-15% berry coloration. The results showed that pre-harvest application of TDZ or 6-BA increased cluster weight, 100 berry weight, pedicel weight, berry acidity, berry and leaves chlorophylls and decreased berry coloration, TSS, total sugars. The application of ABA at 10-15% berry coloration enhanced berry anthocyanin content, TSS, Total sugars and lowered acidity and chlorophyll. The present study recommended using either TDZ or 6-BA at 50ppm followed by ProTon at 500ppm to mitigate the excessive ProTon concentration on "Crimson Seedless" grapes.

Effects of post-veraison irrigation on the phenolic composition of <i>Vitis vinifera</i> L. cv. ‘Xinomavro’ grapes

‘Xinomavro’ (the second planted red Greek variety behind ‘Agiorgitiko’) generally produces wines that are light in colour but with increased astringency, possibly related to grape flavonoid amount and composition; although irrigation is accepted as an effective means to enhance grape phenolic maturity, its role has not yet been sufficiently studied in the case of Xinomavro. This study aimed to determine the effect of post-veraison irrigation on berry anthocyanin and proanthocyanidin amount and composition, of field-grown Xinomavro vines (Vitis vinifera L.), under the typical summer conditions of Northern Greece. In a 10-year-old Xinomavro vineyard, two post-veraison watering regimes were applied—irrigation starting 20 days after veraison (mid-ripening irrigation, MRI) and irrigation starting immediately after veraison was completed (after veraison irrigation, AVI)—alongside non irrigated vines (NI), and vines irrigated continuously from berry set through harvest (continuous irrigation, CI). Proanthocyanidin composition was determined in both skins and seeds by employing phloroglucinolysis followed by HPLC-UV and MS detection (high-performance liquid chromatographic with tandem mass spectrometric and ultraviolet absorbance detection), and the anthocyanin profile was identified only in the skin extracts by HPLC-UV (high-performance liquid chromatographic with ultraviolet absorbance detection). Post-veraison irrigation increased yield parameters and reduced anthocyanin levels and the proportion of their stable forms (acylated vs. non-acylated, tri-oxygenated and methoxylated on the B-ring vs. di-oxygenated and hydroxylated), compared to NI vines; however, these effects were more pronounced in the case of early post-veraison irrigation (AVI) than late-season irrigation (MRI). Irrigation also increased the mean Degree of Polymerization (mDP) and prodelphinidin percentage of skin tannins and decreased mDP of seed tannins. In the light of the necessity to control the accelerated ripening under the increasingly hotter and drier climatic conditions, late irrigation (MRI) might provide a solution to avoid excessive sugar levels and allow a slightly higher yield without significant reductions in berry phenolic content. The results suggest that the optimisation of the timing of irrigation could provide an effective adaptation strategy to climate change in Mediterranean viticultural areas.

Texture properties and phenol extractability indices of the grape berry under pre- and post-veraison water deficit (Vitis vinifera L. 'Kékfrankos')

Optimal water supply is one of the most important factors in quality wine making. However, water availability is limited in several wine regions and water shortage is getting even worse due to climate change, especially under arid climate conditions. Therefore, proper water management of the vineyards, the amount and the timing of irrigation will play a crucial role in sustainable viticulture in the near future. In this study, the effect of timing of moderate water deficit on berry texture characteristics and phenolic maturity were investigated. 'Kekfrankos' grapevines were submitted to different water regimes: moderate water deficit from berry set until veraison (WD1), moderate water deficit from veraison until harvest (WD2), no water deficit (C). Concentration of the phenolic components of the grape berry skins and berry mixture for the Glories indices were measured by spectrophotometer (UVmini-1240 CE UV-VIS, Shimadzu, Japan). Cell and seed maturity indices (CMI%, SMI%) were also calculated. Berry texture characteristics were monitored by a TA.XT Plus Texture Analyser (Stable Micro System, UK). Berry skin and seed texture properties were affected by water regimes. Skin and seed hardness of WD1 were significantly lower than those of WD2. Significant differences were found in berry hardness between the treatments (C>WD1>WD2). Berry gumminess, resilience and chewiness of WD2 were lower compared to C and WD1. Anthocyanin extractability was higher when plants were not subjected to post-veraison water limitations (WD1). Furthermore, the seed maturity index was lower when water deficit occurred between berry set and veraison. Pre-veraison water deficit resulted in delayed ripening, softer seeds and thus higher phenol extractability compared to WD2 and C. Late seasonal water deficit resulted in thicker skins, which was accompanied by lower anthocyanin extractability than in WD1 and C. It seems that anthocyanin extractability is influenced by the actual water status of the grapevine rather than skin textural properties. However, there are some connections between skin texture parameters and maturity indices.

The role of auxin during early berry development in grapevine as revealed by transcript profiling from pollination to fruit set

Auxin is a key phytohormone that modulates fruit formation in many fleshy fruits through the regulation of cell division and expansion. Auxin content rapidly increases after pollination and the manipulation in its levels may lead to the parthenocarpic development. ln Vitis vinifera L., little is known about the early fruit development that encompasses from pollination to fruit set. Pollination/fertilization events trigger fruit formation, and auxin treatment mimics their effect in grape berry set. However, the role of auxin in this process at the molecular level is not well understood. To elucidate the participation of auxin in grapevine fruit formation, morphological, reproductive, and molecular events from anthesis to fruit set were described in sequential days after pollination. Exploratory RNA-seq analysis at four time points from anthesis to fruit set revealed that the highest percentage of genes induced/repressed within the hormone-related gene category were auxin-related genes. Transcript profiling showed significant transcript variations in auxin signaling and homeostasis-related genes during the early fruit development. Indole acetic acid and several auxin metabolites were present during this period. Finally, application of an inhibitor of auxin action reduced cell number and the mesocarp diameter, similarly to unpollinated berries, further confirming the key role of auxin during early berry development. This work sheds light into the molecular features of the initial fruit development and highlights the auxin participation during this stage in grapevine.

The effect of leaf removal on canopy microclimate, vine performance and grape phenolic composition of Merlot (Vitis vinifera L.) grapes in the continental part of Croatia

Leaf removal in the cluster zone is one of the commonly applied viticultural practices used to increase light penetration and to decrease humidity in dense foliage. A two- year study (2018/2019) was carried out on the Merlot variety grown in the vineyard on the Croatian hillside with continental climatic conditions, to study the effects of basal leaf removal on canopy microclimate, grape chemical composition and vine production. Leaf and lateral shoot removal was performed at berry set. Meteorological data were recorded together with microclimatic measurements: air temperature, UV radiation and relative humidity in the fruiting zone. Leaf removal altered microclimate by increasing the UV radiation within the cluster zone. Sugar concentration, bud fruitfulness and yield performance was not affect by the treatment, while leaf removal significantly reduced the concentration of titratable acidity in berry samples and increased the concentration of phenols, anthocyanins, flavonols and flavan-3-ols in berry skin. Leaf removal had a higher influence on the grape anthocyanin and flavonol composition in a season with the cooler berry ripening conditions. These results revealed important difference in leaf removal efficiency on phenolic composition of the grapes in different seasonal climatic conditions during ripening.

Effect of aminoethoxyvinylglycine (AVG) on quality, berry set and coloration of ‘Alphonse Lavallée’ table grapes

AbstractThe effect of different concentrations of aminoethoxyvinylglycine (AVG; 0 (control), 250, 500, 750 and 1000 mg/l), an ethylene biosynthesis inhibitor, on grape berry set and fruit quality was evaluated under vineyard conditions. Treatments were performed on ‘Alphonse Lavallée’ grape cultivar at full bloom stage for two years. Cluster and berry growth (length, width and weight), firmness, soluble solids content, yield, berry set, anthocyanin content and colour parameters were determined on treated and untreated (control) fruits. As a result of the study, the effects of AVG concentrations on firmness were not significant. When AVG applications were compared with control, it is determined that some quality properties were statistically affected, the others were not. Fruit set was increased by lower concentrations of AVG (250 mg/l) and anthocyanin content was increased by higher concentrations of AVG (750 mg/l).

Early Defoliation Techniques Enhance Yield Components, Grape and Wine Composition of cv. Trnjak (Vitis vinifera L.) in Dalmatian Hinterland Wine Region.

Defoliation and cluster thinning are of practical importance in a control of the grapevine source-sink balance, cluster architecture, microclimate and berry composition. Nevertheless, their effectiveness on wine composition is unexplored. In this work, the impacts of preflowering (T1), after berry set (T2), and veraison defoliation (T3) and cluster thinning (T4), on yield components, grape and wine composition of cv. Trnjak are given. Implemented techniques significantly reduced yield and affected grape and wine components in comparison to untreated control (C). Despite lowest number of clusters ensured by cluster thinning, defoliation at veraison had lowest yield. Defoliations improved cluster architecture parameters. Highest berry per se was in preflowering T1 and lowest at veraison T3 defoliation. Berries of T1 had lowest sugar content (19.47 °Brix) while T3 had highest (22.3 °Brix), and the reverse is seen in total acidity highest in T1 (6.12 g/L) and lowest in T3 (5.01 g/L). Wines of early defoliations (T1 and T2) had lowest alcohol and highest anthocyanin concentration. Both techniques applied at veraison produced wines with lower anthocyanins and flavonols than those obtained without any intervention (C). In conclusion, the early defoliations (T1 and T2) improve yield and wine composition of cv. Trnjak in the Mediterranean region of Croatia.

Somatic variants for seed and fruit set in grapevine

BackgroundGrapevine reproductive development has direct implications on yield. It also impacts on berry and wine quality by affecting traits like seedlessness, berry and bunch size, cluster compactness and berry skin to pulp ratio. Seasonal fluctuations in yield, fruit composition and wine attributes, which are largely driven by climatic factors, are major challenges for worldwide table grape and wine industry. Accordingly, a better understanding of reproductive processes such as gamete development, fertilization, seed and fruit set is of paramount relevance for managing yield and quality. With the aim of providing new insights into this field, we searched for clones with contrasting seed content in two germplasm collections.ResultsWe identified eight variant pairs that seemingly differ only in seed-related characteristics while showing identical genotype when tested with the GrapeReSeq_Illumina_20K_SNP_chip and several microsatellites. We performed multi-year observations on seed and fruit set deriving from different pollination treatments, with special emphasis on the pair composed by Sangiovese and its seedless variant locally named Corinto Nero. The pollen of Corinto Nero failed to germinate in vitro and gave poor berry set when used to pollinate other varieties. Most berries from both open- and cross-pollinated Corinto Nero inflorescences did not contain seeds. The genetic analysis of seedlings derived from occasional Corinto Nero normal seeds revealed that the few Corinto Nero functional gametes are mostly unreduced. Moreover, three genotypes, including Sangiovese and Corinto Nero, were unexpectedly found to develop fruits without pollen contribution and occasionally showed normal-like seeds. Five missense single nucleotide polymorphisms were identified between Corinto Nero and Sangiovese from transcriptomic data.ConclusionsOur observations allowed us to attribute a seedlessness type to some variants for which it was not documented in the literature. Interestingly, the VvAGL11 mutation responsible for Sultanina stenospermocarpy was also discovered in a seedless mutant of Gouais Blanc. We suggest that Corinto Nero parthenocarpy is driven by pollen and/or embryo sac defects, and both events likely arise from meiotic anomalies. The single nucleotide polymorphisms identified between Sangiovese and Corinto Nero are suitable for testing as traceability markers for propagated material and as functional candidates for the seedless phenotype.

CPPU-induced changes in energy status and respiration metabolism of grape young berry development in relation to Berry setting

The energy status, the level of respiration metabolism are improtant index reflecting plant growth state, participates in many growth processes. However, their relationship to berry setting remain unclear. In this study, the grape of ‘kyoho’ of CPPU [CPPU, N-(2-coloro-4-pyridinyl)-N-phenylurea] treated were used to measurement physiological indicators. The results showed that CPPU treatment reduced respiratory rate, reduced Cytochrome C oxidase (CCO) and ascorbic acid oxidase (AAO) activity, reduced NAD kinase (NADK) activity, maintained low nicotinamide adenine denucleotie phosphate (NADP) and nicotinamide adenine denucleotie phosphate reduced form (NADPH) levels, reduced nicotinamide adenine denucleotie (NADH) levels, and slowed down the reduction of energy charge. These results provided strong evidence that CPPU treatment promoted grape berry setting due to increased energy status, increased Embden-Meyerhof pathway (EMP) and the tricarboxylic acid (TCA) cycle respiratory metabolic pathways, decreased pentose phosphate pathway (PPP), and decreased CCO and AAO activity of respiratory terminal oxidase.

The Effects of Bagging Applications on Maturation, Yield and Quality in cv. Italia Grape

Araştırmada Italia çeşidinde 2012 ve 2013 yıllarında üç farklı torbalama uygulamasının (Mogul 19 g m-2, Mogul 30 g m-2 ve Tyvek) olgunluk, verim ve kalite üzerine etkileri incelenmiştir. Torbalama uygulamaları tane tutumu döneminde gerçekleştirilmiştir. Çalışmanın yürütüldüğü her iki yılda da Mogul tip torbalarda torba içi sıcaklıklarının dış koşullara göre daha yüksek olduğu, Tyvek tip torbalarda ise torba içi sıcaklıkların dış koşullara yakın seyrettiği belirlenmiştir. Torba içi nem değerleri tüm torbalarda dış koşullara göre düşük bulunmuş, Mogul tip torbalarda bu değer Tyvek tip torbalara göre daha düşük ortaya çıkmıştır. Araştırma bulgularına göre tane yarılma direnci ölçümlerinde açıkta geliştirilen tanelerin torbalama uygulanmış tanelere göre daha sağlam olduğu belirlenmiştir. Özellikle Mogul tip torbaların ise olgunlaşmayı hızlandırıcı etki gösterdiği belirlenmiştir.

The Effect of Grapevine Age (Vitis vinifera L. cv. Zinfandel) on Phenology and Gas Exchange Parameters over Consecutive Growing Seasons.

Unlike most crop industries, there is a strongly held belief within the wine industry that increased vine age correlates with quality. Considering this perception could be explained by vine physiological differences, the purpose of this study was to evaluate the effect of vine age on phenology and gas exchange parameters. An interplanted, dry farmed, Zinfandel vineyard block under consistent management practices in the Central Coast of California was evaluated over two consecutive growing seasons. Treatments included Young vines (5 to 12 years old), Control (representative proportion of young to old vines in the block), and Old vines (40 to 60 years old). Phenology, leaf water potential, and gas exchange parameters were tracked. Results indicated a difference in phenological progression after berry set between Young and Old vines. Young vines progressed more slowly during berry formation and more rapidly during berry ripening, resulting in Young vines being harvested before Old vines due to variation in the timing of sugar accumulation. No differences in leaf water potential were found. Young vines had higher mid-day stomatal conductance and tended to have higher mid-day photosynthetic rates. The results of this study suggest vine age is a factor in phenological timing and growing season length.