Pre-bloom Period Research Articles

Effects of Prohexadione-calcium on Grape Yield Components and Fruit and Wine Composition

Prohexadione-calcium (prohexadione-Ca) was applied to field-grown Cabernet franc, Cabernet Sauvignon, Chardonnay, and Seyval to evaluate rates and timing effects on fruit yield components and on fruit and wine composition. Berries per cluster, berry weight, cluster weight, and clusters per shoot in the subsequent season were all decreased by multiple, prebloom plus postbloom, applications to Cabernet Sauvignon and Cabernet franc. Similar reductions in current season components of yield were observed with Seyval. Application (250 mg/L) to single clusters of Cabernet Sauvignon and Chardonnay at bloom, or in the one-to-two-week prebloom period decreased fruit set, whereas applications one to two weeks postbloom reduced berry weight, with no impact on fruit set. Berry weight reduction correlated to increased color intensity (420 nm + 520 nm), total anthocyanins, total phenols, and phenol-free glycosyl-glucose (PFGG) in Cabernet Sauvignon. In a separate experiment, prohexadione-Ca increased Cabernet franc must color intensity, total anthocyanins, and total phenols, despite having minimal effects on berry weight or crop yield. Aroma and flavor triangle difference tests did not distinguish treatment differences with young Cabernet franc wines. This study of prohexadione-Ca effects on grape reproductive development illustrated that berry set and berry weight were responsive to application timing, with the one-to-two-week period after bloom most sensitive to reductions in berry weight. The concurrent effects on fruit composition were generally positive, while the full impact on wine quality remains equivocal, but worthy of further evaluation.

Effects of bio-optical factors on the attenuation of ultraviolet and photosynthetically available radiation in the North Water Polynya, northern Baffin Bay: ecological implications

Recently, the Arctic has experienced a recurrent springtime thinning of the stratospheric ozone layer resulting in increasing ultraviolet-B radiation (UVBR, 280 to 320 nm). However, little is known about the effect of such UVBR enhancement on the Arctic ecosystem. In spring-summer 1998 and fall 1999, 40 stations were investigated in the North Water Polynya (NOW), High Arctic. In the course of this study, 3 periods (pre-bloom, bloom and post-bloom) were distinguished based on chlorophyll a (chl a) concentrations. The attenuation of ultraviolet radiation (UVR) and photosynthetically available radiation (PAR) are reported here. Bio-optical factors, namely particulate organic carbon (POC), dissolved organic carbon (DOC) and chl a concentrations were related to the attenuation coefficient, K d (λ), of both UVR and PAR. During the pre-bloom period (9 April to 12 May 1998), all bio-optical factors except chl a concentrations were unrelated to K d (λ). However, the absorption of colored dissolved organic matter might prevail. During the bloom period (15 May to 29 June 1998), both chl a and POC were strongly correlated to K d (λ). During the post-bloom period (27 August to 25 September 1999), POC contributed from 57 to 83 % of the K d (λ). Under stratification conditions, an inverse relationship was observed in the UVR and PAR ranges, between K d (λ) and the depth of the subsurface chlorophyll maximum (SCM). This could be a consequence of cell migration below the penetration depth of UVR where they are protected from UVR-induced physiological damages.

Seasonal Dry Matter, Starch, and Nutrient Distribution in 'Concord' Grapevine Roots

Three-year-old field-grown 'Concord' (Vitis labruscana Bailey) grapevines were destructively harvested at eight growth stages during 1998 to quantify growth, carbohydrate distribution, and nutrient concentrations of different organs. The roots were the major storage organ for carbohydrates and nutrients, accounting for 84% of the starch and 75% of nitrogen stored in the vines at the beginning of the season. About 78% of the reserve starch in the vine was used for prebloom root and shoot growth. Early-season fine-root growth was a sink for stored vine nitrogen; however, the fine roots quickly became a nitrogen uptake source, providing at least 84% of the spring growth nitrogen. Total root biomass increased from bloom to leaf fall, but reserve carbohydrates and nutrients lost in the prebloom period did not begin to recover in roots until the end of rapid shoot development in late July. Crop removal at harvest, and a late-season root flush, further increased vegetative carbohydrate and nutrient reserves in the short postharvest period.

Dry Matter Partitioning and Carbohydrate Status of 'Kawanakajima Hakuto' Peach Trees Grafted onto Different Rootstocks or with an Interstock at Pre-bloom Period

'Kawanakajima Hakuto' peach trees grafted onto Prunus tomentosa often show graft-incompatible symptoms. In relation to the tree decline, dry matter partitioning and carbohydrate status of various tree parts at pre-bloom period were investigated in 'Kawanakajima Hakuto' grafted on P. persica (PP), P. tomentosa (PT), and a compatible interstock/P. tomentosa (IS). Under non-bearing conditions of three-year-old trees, the total whole tree dry matter amount of PT was only half of PP, whereas IS was greater than PT. However, the ratio of scion to rootstock (S/R ratio) in dry matter levels was similar (0.57-0.59) in all combinations. The starch content, the major carbohydrate in various parts, was higher in the rootstock than in scion parts, that in the roots being highest in PP among the combinations. The total amount of non-structural carbohydrate (starch+simple sugars) per tree in IS and PT was half and one-third of PP, respectively. The greatest amount of non-structural carbohydrate was found in φ<2mm roots, regardless of combinations. The S/R ratio in non-structural carbohydrate levels was 0.18 for PP, 0.31 for IS, and 0.30 for PT. On bearing four-year-old trees, the S/R ratio in dry matter levels was reduced in PP (0.47) but increased in IS (0.63) and PT (0.66). The S/R ratio in non-structural carbohydrate levels was 0.16, 0.65, and 0.80 for PP, IS, and PT, respectively. These results suggest that the tree decline in PT is partially promoted by the depletion of non-structural carbohydrate reserve at the pre-bloom period. Furthermore, the use of compatible interstock improves dry matter and non-structural carbohydrate status especially in the rootstock.

Seasonal variation of bacterial production, respiration and growth efficiency in the open NW Mediterranean Sea

Bacterial growth efficiency (BGE) can have a major influence on planktonic food web structure and function; however, its controlling factors are poorly understood. Here, we report results from an annual study aimed at examining bacterial respiration (BR), production (BP), biomass (BB) and BGE in the upper 130 m of the DYFAMED station (JGOFS site, France) in the NW Mediterranean Sea. From the pre-bloom period to early summer, and with a negative gradient from sub-surface to 130 m, bacterial parameters seem to follow each other, i.e. maximum respiration in February, maximum pro- duction in March and maximum biomass in April. BGE ranged from 0.1 to 43% throughout the study period and was highest during the spring bloom and during the fall. These data clearly showed the wide range of BGE that can be experienced at 1 site on an annual timescale in the surface mixed layer and suggest that several factors (concentrations of inorganic nutrients and DOC) control BGE at this site. Our results also suggested that this oligotrophic system is net heterotrophic.

A high-frequency time series at Ocean Weather Ship Station M (Norwegian Sea): population dynamics of Calanus finmarchicus

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 219:205-219 (2001) - doi:10.3354/meps219205 A high-frequency time series at Ocean Weather Ship Station M (Norwegian Sea): population dynamics of Calanus finmarchicus Hans-Jürgen Hirche*, Thomas Brey, Barbara Niehoff Alfred Wegener Institute for Polar and Marine Research, Columbusstr. 1, 27568 Bremerhaven, Germany *E-mail: hhirche@awi-bremerhaven.de ABSTRACT: Between the end of March and mid-June 1997, net samples in the upper 100 m were taken almost daily on Weathership M (Norwegian Sea) to determine the abundance and stage composition of Calanus finmarchicus. Biomass showed high day-to-day variability with several peaks, ranging from 0.05 to 6.3 g C m-2, with an average of 0.84 g C m-2. Consequently, stage abundances were also highly variable, but stage composition was consistent. Although population egg production was almost constant throughout the study period, a clear cohort was formed. During the pre-bloom period, nauplii and Copepodite Stage I (CI) were frequently abundant, but further stage development proceeded only during the short bloom. At the end of the bloom, no young nauplii continued to grow, but older stages did. Some specimens had reached CV at the end of the investigation period. The extended seasonal presence of some stages made estimates of stage duration and production difficult. Three different numerical methods were applied to estimate productivity and production. All methods resulted in similar estimates of productivity, 0.031 to 0.055 d-1, corresponding to a production of 30 to 56 mg C m-2 d-1. These rates are considerably lower than optimum rates measured in the laboratory, suggesting strong food limitation of growth during most of the observation period. KEY WORDS: Population dynamics · Calanus finmarchicus · Norwegian Sea · Food limitation Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 219. Online publication date: September 10, 2001 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2001 Inter-Research.

衰弱発生程度の異なるユスラウメ台木モモ樹２品種のデンプン，可溶性糖含量の季節的変化

'Kawanakajima Hakuto' peach trees often show a greater incidence of tree decline than do 'Akatsuki' trees when grafted onto Prunus tomentosa rootstock. To seek the cause of the decline, seasonal changes in carbohydrate status of root, shoots, and leaves of the two cultivars grafted on P. tomentosa and P. persica were analyzed. There were no significant differences in the starch and soluble sugar contents between 'Akatsuki' and 'Kawanakajima Hakuto' grafted on either rootstock during the dormant period but at the pre-bloom period, the root starch content in both cultivars grafted on P. tomentosa was only half that of trees grafted on P. persica. The starch content in roots and shoots of 'Kawanakajima Hakuto' on P. tomentosa continued to be lower than that on P. persica during the growing period, whereas it differed little on 'Akatsuki' on two rootstock. Similar trends were found in total sugar and sorbitol contents of the roots. No conspicuous difference between the cultivars was found in other parameters, such as sugar contents of shoots and leaves, in relation to tree decline. Therefore, the cause of decline for 'Kawanakajima Hakuto' trees grafted on P. tomentosa is attributed partly to the depletion of starch and sorbitol in the roots and starch in the shoots during the growing season.

Phytoplanktonic and Bacterial Carbon Pools and Productivities in the Gerlache Strait, Antarctica, during Early Austral Spring.

Abstract Phytoplankton and bacterial biomass and productivities were investigated at four depths in the upper 500 m of the water column in the Gerlache Strait, Antarctica, during the prebloom period of early austral spring, from October 13 to November 4, 1995. The concentrations of all carbon pools were low, with the total particulate organic carbon (POC) concentration averaging 1.9 +/- 0.9 µM. Bacterial, protozoan, and phytoplankton carbon accounted for 21% of the total POC, indicating that detritus or unenumerated organisms comprised the bulk of the POC during this period. Larger zooplankton or protozoa, such as ciliates, may account for this difference, since microzooplankton can represent a significant fraction of the total microbial biomass. Primary and bacterial secondary production rates were also low, less than 300 and 30 ng C L(-1) h(-1), respectively. However, when production was normalized to either chlorophyll or bacterial cell number, rates were similar to those recorded during the spring bloom periods. This indicates that the cells were metabolically active during the prebloom period. Chlorophyll specific primary production averaged over the upper 80 m of the water column was 1.28 +/- 0.84 µg C µg chl(-1) h(-1), whereas the mean bacterial specific growth rate over the same depth interval was 0.34 +/- 0.24 d(-1). The overall production rates were low only because of the low abundance of cells during the prebloom period. When the site was reoccupied the following year, all measures of biomass and productivity were higher [36], emphasizing the large interannual variability in the Gerlache Strait.http://link.springer-ny.com/link/service/journals/00248/bibs/38n3p296.html</hea

Effects of Low Rates of Esfenvalerate on Pest and Beneficial Species of Apple in Comparison with a Standard Program

Abstract A low rate (11.2 g·ha−1 a.i.) of esfenvalerate was tested as a single application in a seasonal program of pest control in apple orchards in comparison with the current standard program based on azinphosmethyl. The standard program provided good control of codling moth (<0.5% fruit injury) and leafrollers. Integrated control of tetranychid mites was consistent throughout the 3 years of the test. Esfenvalerate at the pink stage of apple bud development was tested to provide a rotational material for chlorpyrifos for control of leafrollers. This treatment provided suppression of leafrollers in the first year of the test and, in combination with the summer codling moth controls, maintained them at very low levels throughout the 3 years of the test. This treatment failed to provide suppression of Campylomma verbasci when substituted for chlorpyrifos in the prebloom period. Some suppression of first generation white apple leafhopper nymphs was achieved, and there was minimal impact on integrated mite ...

Seasonal development of phytoplankton at a high latitude oceanic site

A three-year time series of hydrography, nutrients, chlorophyll, a, Secchi depth and phytoplankton composition taken at the Ocean Weather Station Mike (OWSM)(66°N, 2°E) was investigated. The pattern in the seasonal development of phytoplankton biomass was very similar in all three years, despite some differences in the magnitude of the spring bloom. From January to March typical winter conditions prevailed with low water mass stability, high and homogeneously depth distributed nutrient concentrations, and phytoplankton biomass below 0.05 mg m−3 chlorophyll a. During April a pre-bloom situation still prevailed, characterised by still low, but now steadily increasing biomass. The spring bloom started in May concurrent with incipient thermal stratification. Maximum phytoplankton biomass was observed between mid May and mid June, but the Chl a concentrations never exceeded 2.8 mg m−3. By July the biomass had decreased to pre-bloom levels. Generally nutrients were not depleted at this time. The decrease in phytoplankton biomass was followed by a smaller second bloom of short duration in early autumn, with Chl a concentrations around 1 mg m−3. After the autumn bloom the biomass decreased to winter levels. The winter and pre-bloom period were dominated by small nanoplankton (< 5 μm), and coccolithophorids, where Emiliania huxleyi accounted for a considerable proportion. The spring bloom was dominated by small diatoms, either Fragilariopsis pseudonana (1990, 1992) or Thalassiosira bioculata var. raripora (1991). The absence of large diatoms seemed to be a common feature of the winter and spring all three years. After the bloom, small nanoplankton (<5 μm) again became increasingly important. Dinoflagellates were also occasionally an abundant component of the phytoplankton community but the succession did not seem to reach a “dinoflagellate phase” at Stn M during summer. The autumn samples did not reveal any major changes in the composition of the phytoplankton community compared to summer.

Impact of Taedia scrupeus (Hemiptera: Miridae) Feeding on Cluster Development in Concord Grapes

Taedia scrupeus (Say) feeds on grape clusters and shoots early in the growing season. The impact of nymphal and adult feeding was assessed at the individual shoot level by confining nymphs within sleeve cages at 4 different times: prebloom, bloom, postbloom, and prebloom to postbloom. Prebloom feeding significantly reduced the number of berries per cluster and average berry weight, resulting in a 68% reduction in cluster weight. When nymphs were allowed to feed from prebloom to postbloom, cluster weight was reduced by 71%.Feeding only during bloom and postbloom did not affect cluster weight. Prebloom feeding reduced the number of florets per cluster, berries per cluster, and berry weight. The whole-vine impact of T. scrupeus was examined in a commercial Concord vineyard, where 3-vine experimental units were treated with carbaryl to remove T Scrupeus or were left untreated. Unsprayed vines, with a mean density of 20 T. scrupeus per vine, yielded 10.4 kg per vine, and sprayed vines without injury yielded 14.1 kg per vine. The yield component most strongly affected was the number of clusters per vine, which averaged 165.4 and 131.8 per vine in sprayed and unsprayed vines, respectively. Each T. scrupeus nymph was associated with 0.18kg of crop loss, suggesting that as few as 0.5 nymphs per vine can cause economic injury. Where treatment of vineyards to prevent T. scrupeus injury is warranted, it must be applied during the prebloom period.

Seasonal cycle of nitrogen and phytoplankton biomass in a well-mixed coastal system (Eastern English Channel)

The hydrological structure of the French coastal part of the eastern English Channel is strongly linked with tidal regimes and riverine input. Two distinct water masses are separated by a frontal area and drift along the coast in SW–NE direction. These two water masses are well-mixed during the entire year. We studied the seasonal dynamic of nitrogenous nutrients, chlorophyll a and organic particulate carbon and nitrogen at two stations, characteristic of these water masses, during the year 1994. Results show (i) a winter stock of nitrate and ammonium, (ii) a pre-bloom period corresponding to the use of ammonium, (iii) a high bloom period of short duration using nitrate, (iv) a post-bloom period with little phytoplanktonic activity probably limited by nutrients other than nitrogen and (v) an autumnal period of reconstitution of stock. The essential difference between the two stations is the importance of winter stock of nutrients and of bloom chlorophyll a concentration, with the coastal station richer than the offshore one. An assumption about the nitrogen available for new production in this area gives a value of 57% of the winter stock of inorganic nitrogen.

EFFECTS OF APPLICATION DATE ON THE PERSISTENCE OF CLOFENTEZINE RESIDUES: IMPLICATIONS FOR MANAGEMENT OF RESISTANCE IN THE EUROPEAN RED MITE

AbstractThe effects of timing of applications on the persistence of chemical and biologically active residues of clofentezine were tested on apple foliage during two seasons. Residues from prebloom and petal fall applications were less persistent than those in mid-season. Early season applications were toxic to European red mite for 7–21 days but mid-season applications were toxic for as long as 50–62 days. Chemical residue losses were also faster in the early season. Persistence of chemical residues was related to the rate of leaf growth and expansion. In 1991, foliage area expanded 244% per week during the prebloom period, 23% per week at petal fall, and 10% per week in July (mid-season).In a field test, applications of clofentezine at petal fall reduced European red mite populations within 7 days and mite numbers remained below economic thresholds for 6 weeks.

Testing The Validity of the Synthesis Ratio of Protein to Low Molecular Weight Metabolites as an Estimation of Phytoplankton Growth in the Field

Cholorophyll a, primary production and the patterns of 14C assimilation into the major end-products of photosynthesis were determined for phytoplankton in the coastal waters off Plymouth, in order to study their physiological ecology during spring conditions. At the end of the study period, a diatom bloom occurred after the development of a slight thermocline. Throughout the pre-bloom period, the majority of the label was found in storage products, and phytoplankton growth was not nutrient-limited. During the development of the bloom, however, an increase in protein synthesis was found, which is interpreted as a result of an active phytoplankton growth. Both synthesis ratios for protein to storage products, i.e. lipid and polysaccharide, (P/L+S) and protein to low molecular weight metabolites (P/M), summarize the variations in the physiological state of phytoplankton during this study. Comparison of the P/M synthesis ratio and different estimations of phytoplankton growth rate shows the usefulness of this index for characterising natural populations.

FEEDING PREFERENCES OF THE WESTERN FLOWER THRIPS, FRANKLINIELLA OCCIDENTALIS (PERGANDE) (THYSANOPTERA: THRIPIDAE), AND INCIDENCE OF TOMATO SPOTTED WILT VIRUS AMONG CULTIVARS OF FLORIST’S CHRYSANTHEMUM

AbstractA wide range in feeding damage as defined by leaf scars among 27 cultivars of florist’s chrysanthemum was apparent for the western flower thrips, Frankliniella occidentalis (Pergande). Assessments based on numbers of feeding scars or ranking of cultivars on the basis of the leaf area damaged by feeding were in close agreement. Cultivars with the most feeding damage under growth room conditions, such as cvs. White Marble and Polaris, were the same as those in plots within a naturally infested commercial greenhouse. Under growth room conditions, a 2- to 4-week exposure of plants to a population of thrips was sufficient to evaluate feeding damage. Closely related cultivars had similar levels of feeding damage, and foliage of yellow-flowered cultivars was significantly more attractive to thrips for feeding than foliage of white-flowered sister cultivars during the pre-bloom period. There was a low correlation between feeding damage and incidence of the tomato spotted wilt virus among cultivars in both growth room and greenhouse tests, indicating that virus susceptibility of cultivars was epidemiologically more significant than the feeding activity of western flower thrips.

Correlation of Low Seed Quality with Growing Environment of Carrot

Abstract Two surveys were conducted to evaluate the problem of low germination of carrot (Daucus carota L.) seed grown in the Columbia Basin area of Washington and Oregon. Analyses of weather data via a heat unit model demonstrated that the major difference in growing environment was the number of heat units (10C base) occurring before or during early bloom. The correlation between pre-bloom period heat units (May + June) and final percent germinability of seed lots from survey number one resulted in an r2 of 0.42 with the probability of F &gt; 0.12. The second survey showed that the greatest reason for low seed germination among seed lots in 1984 was an increased percentage of abnormal germinants compared to 1983. This indicates that the seed germination problem in carrots may be due to seed being harvested at an immature stage, which resulted in low seed germination percentage.

Effect of meteorological factors on fruit maturation and the prediction of optimum harvest for apples

Apple maturation was found to be largely governed by meteorological conditions, viz. the temperature and precipitation during the pre-bloom period and the first half of the post-bloom period. The meteorological and physiological factors affecting three strains of ‘Red Delicious’ and ‘Golden Delicious’ apples cultivated in an orchard in the Simla Hills were studied during four consecutive seasons and significant correlations were established. The optimum harvest period was precisely predicted by the meteorological conditions well in advance, and the latter showed significant correlations with the actual optimum harvest period determined by starch pattern index and seed colour index. Based on these meteorological factors, a “key year” concept was evolved to reliably predict the optimum harvest period. Since this concept was based on all the interrelated meteorological conditions, a prediction would be more reliable under varying climatic conditions in any ensuing season if considered for the period of 242 days from November to June.

The effect of four early spring temperature regimes on apple fruit set, tree growth and the K and Ca level in fruits

In 2 experiments, 3-year-old ‘Cox's Orange Pippin’ apple trees, still in rest, were exposed until shortly before bloom to 4 temperature treatments giving 4 patterns of bud development, i.e. rapid or slow throughout, initially rapid followed by slow, and the reverse (first slow, then rapid). During and after bloom, until harvest, all trees were kept at the same temperature. The dates of full bloom differed between treatments by as much as 14 days, but there was little variation in the number of degree-days above 5°C until full bloom. Fruit set was distinctly better when buds developed rapidly than at “slow throughout”, the other treatments occupying an intermediate position. The treatments had little or no effect on shoot growth and fruit size. The amounts of Ca per fruit increased slightly when bud development was rapid initially or throughout the pre-bloom period. For K, the data of the 2 experiments were not consistent.

Cotton lint yield accumulation rate and quality development

Abstract Crop production management during the period of boll setting and maturation of cotton (Gossypium hirsutum L.) is critical in determining lint yield and quality. A field investigation conducted at Lubbock, Texas, during 1977–1980 included three cultivars to study the effect of temperature on factors that influence the rate of cotton yield accumulation and the development of lint quality parameters. A linear regression of physiological days (heat units) explained 93% of the variation in prebloom period expressed in days. The number of physiological days needed to complete the prebloom period was negatively related to average daily temperature in a linear manner and included a significant cultivar effect. The length of the boll setting period was determined by temperature and plant moisture stress. In the absence of plant water stress, 20–25 physiological days were needed to complete boll setting. The length of time to fully mature bolls was related to air temperature in a negative exponential manner (r2 = 0.85) with little direct influence of plant water stress or effect of cultivars. Average boll weight of crop increments fluctuated, but the only trend across years was for the mean boll weight of the last two crop increments to be smaller than the average for the total crop. However, there was a direct correlation between the percentage of total bolls set and percentage of final yield. Fiber micronaire was correlated with temperature in a positive linear manner. In the absence of significant plant water stress, temperature explained 80–90% of the micronaire values of individual cultivars compared with 60% when moisture stress conditions were included. An average crop boll temperature of 27°C appears adequate to achieve maximum development of fiber micronaire. Fiber strength also displayed a linear increase as boll period temperature increased, with coefficients of determination ranging from 0.60 to 0.77 among cultivars. Plant water stress significantly reduced micronaire values but had little effect on fiber strength. Fiber length was not affected by the range of environmental conditions during the four-year period of the study.

Influence of Air and Soil Temperatures on the Growth and Development of Lilium longiflorum Thunb. during Different Growth Phases

Abstract Yearling ‘Nellie White’ Easter lily plants were subjected to various air and soil temperature combinations to determine temperature requirements for 6 growth phases, each of one-month duration. An air and soil temperature of 24°C favored rapid leaf unfolding, stem elongation, and flower expansion with concomitant depletion of primary scales. After flower buds were visible, soil temperature had no appreciable effect on their rate of expansion; air temperature was the controlling factor. Leaf unfolding rate, stem length, and flower bud size were of equal value in monitoring crop development. Secondary scale initiation and development during the prebloom period was positively related to soil temperature rather than air temperature and was maximum at 24°. The rate of scale initiation progressively decreased from first appearance of the secondary meristem until anthesis of the primary axis. High soil temperature decreased the diameter of the secondary (daughter) axis apical meristem at any time prior to appearance of flower buds on primary axis (buds visible).