Lateral Racemes Research Articles

An analysis of hormones and mineral nutrients in fruit from terminal and lateral racemes of two blueberry cultivars

BACKGROUND: In general, fruit that develops from early-opening flowers ripens earlier than fruit from late-opening flowers. However, the opposite has been observed in the rabbiteye blueberry cultivar “Brightwell” (Vaccinium ashei). OBJECTIVE: From the differences of endogenous hormones and mineral nutrition, with attempt to analyze the reasons for fruit from late-opening flowers on lateral racemes of “Brightwell” ripened earlier than fruit from early-opening flowers on terminal racemes. RESULTS: Fruit from late-opening flowers on lateral racemes of “Brightwell” ripened earlier than fruit from early-opening flowers on terminal racemes. This may be associated with the higher levels of giberellin 1, abscisic acid (ABA), salicylic acid, jasmonic acid, phosphorus, iron and boron in the early developmental stages, and the higher ABA level and lower giberellin 9 level in the fruit ripening stages on lateral racemes, compared with on terminal racemes. However, the fruit borne on the terminal racemes of “O’Neal” grew faster than fruit borne on lateral racemes, this may be correlated with the higher IAA, iron, manganese, zinc and boron levels, and the lower ABA level, in the early fruit developmental stages on terminal racemes, compared with on lateral racemes. CONCLUSIONS: The growth and ripening differences in fruit set at the two positions of the two blueberry cultivars may be associated with hormonal and nutritional control during fruit development.

Кореляція елементів насіннєвої і вегетативної продуктивності у колекційних зразків люпину білого

The aim of the study was to establish the strength and direction of the correlations between the quantitative traits that form vegetative and seed productivity of white lupine. Field, measuring-weight and mathematical-statistical research methods were used. A significant positive correlation of the average strength between seed productivity and such traits as plant height, number of lateral racemes, number of beans from the central and lateral racemes, etc. was established. A strong positive correlation was found with the vegetative development of plants, weak - with the number of seeds in one bean and the weight of 1000 seeds. A significant positive strong correlation of vegetative productivity with such quantitative features as the mass of beans from the central racemes and the mass of leaves and stems was established. A positive correlation of medium strength was found with the number of beans from the central and lateral racemes, the mass of beans from the side racemes, the mass of roots and so on. It was found that the seed productivity of white lupine plants is mainly due to the development of such traits as the number of beans from the lateral racemes, the weight of leaves and roots, the number of seeds and the weight of seeds from the central and lateral racemes. The formation of vegetative productivity primarily depends on the mass of beans from the central racemes and the mass of leaves and stems. The use of established patterns of productivity will help increase the effectiveness of selection of breeding material for the specified parameters.

Natural post-flowering photoperiod and photoperiod sensitivity: Roles in yield-determining processes in soybean

Promising yield-determining responses to artificial photoperiod manipulation during post-flowering phases have been identified in soybean [Glycine max (L.) Merrill]. These responses enhance resource capture as a result of changes in phase duration, and resource use efficiency as a result of changes in node production and pod development, alleviating intra-node pod interference. This work aims to evaluate the relevance of these responses under natural conditions and discriminate direct from indirect photoperiodic effects, that is, effects caused by changes in the capture of resources. Two field experiments were conducted with a combination of sowing dates, with similar pre- and different post-flowering photoperiod, indeterminate genotypes including near isogenic lines and commercial varieties with different photoperiod sensitivity, and shadings with different incident radiation during post-flowering. Longer post-flowering photoperiod and higher plant photoperiod sensitivity delayed crop development, particularly in lines with alleles E2, E3 or Clark background. This delay resulted in extra radiation capture and node production, which were positively related to yield. Direct photoperiodic effects on nodes per m2 were evidenced in response to changes in post-flowering photoperiod and plant photoperiod sensitivity. The distribution of available resources such as radiation in more nodes per m2 increased use efficiency. Longer post-flowering photoperiod and higher plant photoperiod sensitivity enhanced pod establishment on usually dominated positions such as lateral racemes, affecting pods per m2. Finding these relevant yield-determining effects under natural conditions suggests that processes related to post-flowering photoperiodic responses are a plausible way to enhance resource capture and use efficiency and yield in soybean production systems. In cropping systems in which the whole growing season is used to maximize yield, these post-flowering photoperiodic responses could be adopted at the expense of the pre-flowering phase duration.

Features of the formation of sowing qualities of white lupine seeds depending on the harvest time

Purpose . To determine the optimal time for harvesting in nurseries of primary seed production of white lupine. Methods . Field, laboratory and statistical methods of material evaluation were used. Sowing qualities were studied in the laboratory separately for seeds from the central and lateral racemes in accordance with DSTU 2240-93 (State Standard of Ukraine). Results . The results of studies on determination of optimal terms for harvesting in nurseries of primary seed production are given. The studies were conducted separately for seeds from the central and lateral racemes collected in different ripe stages. It was established that the seed vigor during the first harves­ting time was minimal and ranging for varieties from 70.0 to 73.0% for the central raceme and from 58.0 to 65.0% for the lateral racemes. The best indices of seed vigor and germination capacity were established in the seeds of the central racemes harvested during the “yellow cotyledon” stage. They averaged 90.8 and 94.3% respectively for all varieties, while in the seeds of the lateral racemes these indices amounted to 84.5 and 89.3%. Agrometeorological conditions had influence on the thousand-kernel weight formation. In dry years, plants produced feeble and lightweight seeds, so their sowing qualities has been deteriorated. The highest thousand-kernel weight was obtained in the “full ripeness” stage, when it ranging from 284 to 338 g in the central racemes and from 266 to 316 in the lateral ones. The development of embryonic roots including external appearance, length was assessed. Visual assessment of germination on the third day and measurement of the length of embryonic roots on the seventh day showed that healthy, well-developed seedlings were observed in seeds of the fifth and sixth harvesting periods. Conclusions . The highest sowing qualities in most varieties with regard to lateral racemes were established in the seeds harvested in the «full ripeness» phase. For the germinating capacity, seeds of the central raceme met the requirements of DSTU for the additional category (87.0%), starting from the stage “beginning of the embryonic root yellowing”, but seeds of the lateral racemes not earlier than the phase of “yellow cotyledons”. Harvesting should be started at the “yellow cotyledons” phase of lupine seeds maturity when they were fully formed and have high sowing qualities.

Soybean fruit development and set at the node level under combined photoperiod and radiation conditions.

In soybean, long days during post-flowering increase seed number. This positive photoperiodic effect on seed number has been previously associated with increments in the amount of radiation accumulated during the crop cycle because long days extend the duration of the crop cycle. However, evidence of intra-nodal processes independent of the availability of assimilates suggests that photoperiodic effects at the node level might also contribute to pod set. This work aims to identify the main mechanisms responsible for the increase in pod number per node in response to long days; including the dynamics of flowering, pod development, growth and set at the node level. Long days increased pods per node on the main stems, by increasing pods on lateral racemes (usually dominated positions) at some main stem nodes. Long days lengthened the flowering period and thereby increased the number of opened flowers on lateral racemes. The flowering period was prolonged under long days because effective seed filling was delayed on primary racemes (dominant positions). Long days also delayed the development of flowers into pods with filling seeds, delaying the initiation of pod elongation without modifying pod elongation rate. The embryo development matched the external pod length irrespective of the pod's chronological age. These results suggest that long days during post-flowering enhance pod number per node through a relief of the competition between pods of different hierarchy within the node. The photoperiodic effect on the development of dominant pods, delaying their elongation and therefore postponing their active growth, extends flowering and allows pod set at positions that are usually dominated.

Cold tolerance of soybean ( Glycine max (L.) Merr.) during the reproductive phase

Ten indeterminate MG00 and MG000 soybean genotypes of Swiss and North American origin, representing different levels of cold tolerance, were studied during 3 years in a total of five environments. The results showed that cold tolerance during flowering is based on three independent and synergistic traits, viz: number of flowers produced on central racemes; capacity to retain central raceme flowers despite cold stress; and capacity to compensate a loss of central raceme flowers by rapid and sustained flower development on lateral racemes. Within the material studied large genotypic variability exists for each of these traits. Particularly interesting is a 3° difference between tolerant and susceptible genotypes in the threshold below which temperatures can be considered to be damaging (15 and 18°C, respectively). The relative importance of different compensation mechanisms is discussed and the vulnerability of genotypes showing synchronous flowering of central and lateral racemes is confirmed. At harvest, susceptibility of soybean genotypes to low temperatures occurring during flowering can be distinguished by an irregular distribution of pods and seeds along the stem. Low yielding or barren nodes were the result of stress induced flower abscission. Results showed that narrow sense tolerance, i.e., reduced abscission of flowers following cold stress, can be assessed at maturity by rating pod set on central racemes of the median part of the stem.

High-frequency embryogenesis inBrassica campestris microspore culture

Microspore culture is a very important and useful tool in plant breeding for haploid production and has been developed for many years.Brassica campestris (Brassica rapa L. ssp.oleifera) is an important oilseed crop, but it is relatively recalcitrant in tissue culture including microspore culture. The microspore culture in our laboratory is based on the Canadian protocol. Thirty genotypes ofB. campestris were included in this study; twenty produced embryos. The highest yield was 5930 embryos per 100 buds from Canadian genotype Cv-2, this result was one of the best that had been reported in microspore culture inB. campestris. The buds measuring 2.0 mm to 3.9 mm in length responded best to produce embryos, the optimum timing for microspore culture was confirmed to be during the mid-late to very-late uninucleate stage. The buds could be removed from either the main raceme or lateral racemes. Activated charcoal (150 mg l-1) was added to the liquid NLN medium, it promoted embryogenesis significantly; embryo development was faster and the embryo yield was significantly higher than those cultures without activated charcoal. The donor plant condition was considered an important factor influencing embryogenesis; older donor plants (older than five weeks) and a cold treatment are recommended.

Cold and freeze stress at flowering Effects on seed yields in winter rapeseed

Winter rapeseed flowers early in spring, when freezing may injure reproductive organs. Some flowers and pods may be lost, but fruit lost at the beginning of the flowering period can be compensated by later-formed flowers. Freezing and cold stress (day/night 7/0°C) at the beginning of flowering increased branching and lengthened the flowering period. As a result, more pods were produced, but they were poorly filled. Yield was compensated by pods of the lower lateral racemes so that total seed yield was little modified by freeze stress. The observed changes could be due to an altered distribution of available assimilates, after freezing or cold treatment, which in turn modifies the plant yield architecture.

Lectotypification of Cimicifuga simplex (Ranunculaceae) and some synonyms

SummaryCompton, J. A. & Jury, S. L.: Lectotypification of Cimicifuga simplex (Ranunculaceae) and some synonyms. – Taxon 44: 401‐404. 1995. – ISSN 0040‐0262.Cimicifuga simplex (DC.) Wormsk. ex Turcz. is the correct author citation. Lectotypification on a sheet of Wormskjöld's original material at Oslo supersedes an earlier neotypification. Lectotypes are also designated for three synonyms of C. simplex: C. foetida var. intermedia Regel, C. ussuriensis Oett. and C. taquetii H. Lév.

Cold tolerance in soybean (Glycine max L. Merr.) in relation to flowering habit, pod set and compensation for lost reproductive organs

Soybean genotypes judged to be cold tolerant can be distinguished at maturity by the regularity of pod distribution along the main stem. They have few or no barren nodes following cold stress. Good productivity of individual nodes is associated with reduced abscission after a low temperature stress and/or with a rapid compensation on the injured nodes. By removal of all flowers present on two nodes at stage beginning bloom, the function of lateral racemes was studied on five genotypes judged sensitive (S) and five judged cold tolerant (T) at two locations in Switzerland in 1990 and 1991. In all experiments, four cold tolerant genotypes produced flowers abundantly on lateral racemes. This profuse flowering began normally some days after the central raceme had finished flowering on control plants. In contrast, cold sensitive genotypes had sparse flowering on the lateral racemes and, for one of them, nearly synchronous flowering of central and lateral racemes. The correlation coefficient between the number of flowers appearing after flower removal and final compensatory pods was 0.85 in the most favourable environment. Moreover, the broad sense heritability for number of lateral flowers was 0.69, which suggests that it may be possible to select for cold tolerance indirectly by observing the flowering habit.

Study of Astragalus inflorescences by the method of logical opportunities

The giant genus Astragalus can be considered an appropriate model for applying Z avarzin's approach known as "space of logical opportunities". In the present paper, the attempt is made to analyze the diversity of flower arrangement types in this genus, constructing such a "space" on the basis of independent combinations of 5 parameters: 1) continuity vs. discontinuity of the floral zone; 2) many lateral racemes vs. 1-2 lateral racemes in a floral zone; 3) rosette vs. semi-rosette vs. elongated main axis; 4) racemes multiflorous vs. pauciflorous; 5) racemes with long vs. short peduncles. The overall number of the theoretically possible combinations of these parameters is 48, but only 37 really do occur. The absence of the other 11 variants is probably due to morphogenetic constraints.

Glucosinolates in oilseed rape (Brassica napus) and the incidence of pollen beetles (Meligethes aeneus)

SummaryDuring an early stage of migration into a field of oilseed rape in the spring of 1988, more pollen beetles were observed on the double‐low variety, Ariana, than on the adjacent single‐low varieties, Bienvenu and Mikado. More beetles were found on open flowers on terminal racemes than on yellow and green flower buds on lateral racemes.Five alkenyl, three indolyl and two aromatic glucosinolates were identified in the floral tissues of oilseed rape. The major compounds were progoitrin (2‐OH, 3‐butenyl) and glucobrassicanapin (4‐pentenyl). There were no differences in the types and concentrations of glucosinolates present in the terminal and lateral racemes of any variety, and only small differences between single‐ and double‐low varieties. Concentrations of glucosinolates in floral tissues of crops grown with a little nitrogen were twice those of well‐fertilised crops. There was no association between the number and distribution of pollen beetles on plants and the amounts or types of glucosinolates present in floral tissues.

Effects of donor genotype and bud sampling on microspore culture of Brassica napus

The effects of genotype, intravarietal donor plants, planting density, inflorescence age, bud position, and bud developmental stage on embryo production in Brassica napus L. were investigated. Embryo yields, frequency of normal embryo production, and direct plantlet regeneration were genotype dependent. Embryo yield ranged from 4 to 196 embryos/anther equivalent, normal cotyledonous embryos varied from 6 to 72% of total embryos produced, and direct plantlet regeneration from embryos occurred from 1 to 47% of embryos subcultured. The G231 line was superior in all three factors Embryo production also was affected by the physiological condition of individual donor plants. Dense plantings reduced plant and bud size, leading to reduced microspore production. In some genotypes embryo production was affected negatively at dense planting densities (3 plants/pot), while in others the rate was unchanged, the plants maintaining high embryogenic potential. The highest frequency of embryogenesis was obtained from cultures of buds sampled at approximately 1 week after first flowering and decreased with the aging of the inflorescence. Buds from 2-week-old inflorescences produced fewer embryos and these were generally small, multilobed structures that never developed further into plants. Buds from the lateral racemes and from the primary raceme appeared to be equally capable of embryo production if selected at the appropriate stage of development. Embryogenic microspores commonly were found in buds with a petal/anther length ratio between 1/4 and 3/4, although the optimum embryo yield was from microspores of buds around the 1/2 ratio. Microspores from later bud stages became oval in culture and did not develop further, while uninucleate microspores remained round, and enlarged prior to division.