Seed Maturation Period Research Articles

A Comparative Review of Six Invasive Nassella Species in Australia with Implications for Their Management.

Two Nassella species, Nassella trichotoma and Nassella neesiana, have significantly reduced the carrying capacity of Australia’s south-east rangelands and agricultural systems. It is, therefore, of considerable concern that four other Nassella species have also become naturalised in Australia, and are noted to share many of the ecological features of the two currently widespread species. This paper reviews the distribution, ecology, and impacts of all six Nassella species, which are currently naturalised in Australia, and makes recommendations toward a blanket Nassella control program. The review highlights observed similarities between the species, including the time of flowering, seed type, germination requirements, and growth morphology. These common factors support the possibility that an integrated Nassella control program could be designed to integrate good grazing management with cultural control methods, such as soil cultivation, fire, and native plant competition, with treatments being implemented prior to the common annual seed maturation period. Notwithstanding the success of these integrated programs, it is recognised that seeds of all species may remain viable in the seedbank for up to 12 years, meaning ongoing monitoring and management will be required. To develop even finer control programs, further research into the ecology of these Nassella species is recommended to determine any additional weak spots in these species’ defences, and to subsequently develop and apply novel integrated control methods that target all six species.

Efficient micropropagation of Dendrobium aurantiacum from shoot explant

Embryogenic tissue culture (seed tissue culture) is a common practice in plant industry to speed up and mass production. However, the culture method is not widely adopted in most of the orchid species. Micro-size orchid seeds are difficult to obtain and collect due to ambiguous seed maturation period. Most of orchid seeds have no endosperm and highly dependent on the specific fungi for germination and survival. Micropropagation from shoot culture with meristem tissue is potentially be another alternative for mass propagation of orchid. Therefore, this study examine the potential of micropropagation technique by shoot culture in orchid, Dendrobium aurantiacum (F. Muell.) F. Muell. This study reported an effective aseptic technique to develop sterilized D. aurantiacum tissue in vitro. The callus induction and regeneration from shoot explant by utilization of different plant growth regulator had been examined in this study. Among the treatments, 20% sodium hypochlorite with 15 mins sterilization period showed the highest sterilization efficiency on explants with only 16.7±5.8% of contamination occurred after two weeks and obtained highest survival rate 73.3±5.8% after one month. Callus formed in all combinations of plant hormone treatments. Media treated with 10 mg/L 2,4-D showed the highest callus induction rate but browning condition occur after 3 months of culture. Cell count on callus proliferation showed a significant difference (p < 0.05) between control and treatments. In conclusion, micropropagation of D. aurantiacum had been shortened almost 9-12 months required for nature germination.

The Impact of Water Deficit on The Soybean (Glycine max L.) Reproductive Stage of Development

Experiment was conducted in 2014, 2015 and 2016 at the Institute of Field and Vegetable Crops, Novi Sad, Serbia, to study the effects of water deficit treatments during a soybean reproductive stage. Two water deficit treatments were conducted T1 (from beginning of blossom to seed maturation) and T2 (from beginning of seed filling to seed maturation period) and control (no water deficit). The results showed that water deficit during seed formation has a significant effect on germination energy, germination precentage and abnormal seedling. Obtained results are of great importance for farmers, because under favorable conditions, a large number of abnormal seedling has the ability to sprout, reach the reproductive stage and participate in yield formation.

Wild Seed Harvesting at Mountainous Species-Rich Grassland in Calcareous Italian Alps

Wild harvesting is an efficient option for supplying seed to be used for restoring seminatural grasslands. Several methods are currently used to implement wild harvesting, but few controlled experiments have investigated its efficiency regarding seed amount and number of species collected. A harvesting trial was conducted in a species-rich, low-productivity grassland of the calcareous Italian Alps (1 030 m above sea level [a.s.l.). Three mechanical methods were tested in three replications using a completely randomized block design: green hay (GH), dry hay (DH), and seed stripping (SS) harvesting. The number of fertile shoots, mature seeds, and species collected was recorded and compared with the standing seed yield (SSY). GH, DH, and SS harvested approximately 84%, 70%, and 29% of SSY, respectively. Forbs were harvested more efficiently than grasses in all methods but in most cases at very low seed amounts per m2 due to their low seed density for SSY. No significant difference among methods was found for the number of species collected as mature seeds, but SS, implemented on larger plots, tended to collect more forb species. Comparing the results with those of other experiments demonstrated that the relatively cool temperature of the seed maturation period at the mountain site favored stronger seed retention and therefore increased the GH and DH efficiency but decreased the SS efficiency. In cool mountain areas, wild harvesting from forb-rich grasslands should be more successful by SS implemented on wide areas and several times over the vegetative season. In less species-rich grassland, GH and DH can efficiently collect high seed amounts of the fewer species present, even if implemented over smaller areas.

When is the best time to flower and disperse? A comparative analysis of plant reproductive phenology in the Mediterranean

Abstract The phenology of organisms corresponds to the temporal match between the components of their life cycle and the seasonal distribution of resources and hazards. Flowering has been extensively studied to describe the reproductive phenology of plants, but in comparison, other key events for reproductive success such as the seed maturation period and the time of seed dispersal have been considerably less investigated. This study describes the temporal sequence of onset of flowering and seed dispersal, and the time necessary to mature seeds in 138 species growing in the strongly seasonal climate of Mediterranean southern France. Data for the three traits were compiled from several original surveys to characterize the reproductive phenology of 47 annual, 67 perennial herbaceous and 24 low stature woody species. The timing of these three phases was assessed in relation to local climatic conditions, and the degree to which they were coordinated was tested. All three phenological traits spanned a wide range of values from early spring to late summer. Annuals flowered slightly earlier than perennials but the largest difference between these groups was found for the seed maturation period, which was much shorter in annuals. This resulted in earlier dispersal dates in these species, which occurred before periods of high water deficit. Significant positive correlations were found between onset of flowering, onset of seed dispersal and seed maturation period. This suggests a consistent pattern of coordination between the different phases of reproductive phenology across species. Our results show that while the time slot for flowering appears restricted to periods with adequate temperature and water availability for most species, the seed maturation period and dispersal phase can occur during periods of substantial water deficit, at least for perennials. They also suggest that the different species can be arrayed along a fast‐slow continuum based on reproductive events, from early flowering species with short seed maturation and early dispersal to late flowering species with long seed maturation and late dispersal. Whether this relates to the postulated fast‐slow continuum identified for the functioning of vegetative organs is a promising avenue for future research. A plain language summary is available for this article.

The Isolation and Identification of Soybean Pod and Stem Blight in Taiwan

Phomopsis seed decay (PSD) caused by Diaporthe phaseolorum var. sojae (Lehman) Wehmeyer, Diaporthe phaseolorum (Cooke & Ellis) Sacc. var. caulivora Athow & Caldwell, and Phomopsis longicolla Hobbs reduces quality of soybean (Glycine max (L.) Merr.) seed when it is wet and warm condition during seed maturation period. To study of the PSD in Taiwan in March 2008, three unidentified fungal isolates (isolate1, isolate2 and isolate3) were isolated from soybean stems infected with pod and stem blight which is associated with seed decay. Based on their morphological and genotypic characteristics, three isolates were regarded as Diaporthe phaseolorum var. sojae. For PSD assay, we found that the best condition for the fungal isolates growth was on potato dextrose agar (PDA) media at 24°C temperature for 24 or 15 hr photoperiod. Leaf- stem and pods of soybean were inoculated by an atomizer with two isolates among three isolates to investigate PSD infection. In the result of two inoculation parts with two isolates, there was no significant difference in degree of pod infection and seed infection rate (%) between isolate2 and isolate3, but there was a tendency that pod inoculation than leaf- stem inoculation caused higher level of seed infection. These isolates obtained in this study would be applicable to screening of PSD resistant soybean germplasms in the breeding program.

Effect of sowing time on the yield and quality parameters of sunflower (Helianthus annuus) hybrids under semiarid irrigated conditions of northern India

To evaluate the changes in seed yield and oil quality of sunflower (Helianthus annuus L.) in response to changing environmental conditions across different planting dates and genotypic variability, a field experiment was carried out during spring 2005-2008 at PAU, Ludhiana. Planting dates affected seed yields more than any of the other characteristics measured with significant yield reduction under delayed planting conditions. An increase in oleic with decrease in linoleic acid (r = –0.993*) was observed with each progressive delay in planting time. Change in the oleic/linoleic acid ratio under different planting dates suggests a possible role of environmental factors especially temperature on the seed development processes during reproductive phase further deciding the oil quality. Total heat units accumulated during the seed maturation period had positive correlation with oleic (r = 0.697*) and negative with linoleic correlation (r = –0.578*) acid. Further investigation is needed to get deeper insight into the effects on seed oil composition of the interaction between changes in temperature regime and/or planting time under field/controlled conditions for yield maximization and better quality sunflower oil.

Ecophysiology of seed dormancy and the control of germination in early spring-floweringGalanthus nivalisandNarcissus pseudonarcissus(Amaryllidaceae)

Seed dormancy induction and alleviation in the winter-flowering moist temperate woodland species Galanthus nivalis and Narcissus pseudonarcissus are complex and poorly understood. Temperature, light and desiccation were investigated to elucidate their role in the germination ecophysiology of these species. Outdoor and laboratory experiments simulating different seasonal temperatures, seasonal durations, and temperature fluctuations; the presence of light during different seasons; and intermittent drying (during the summer period) over several ‘years’ investigated the importance of these factors in germination. Warm summer-like temperatures (20°C) were necessary for germination at subsequent cooler autumn-like temperatures (greatest at 15°C in G. nivalis and 10°C in N. pseudonarcissus). As the warm temperature duration increased so did germination at subsequent cooler temperatures; further germination occurred in subsequent ‘years’ at cooler temperatures following a second, and also third, warm period. Germination was significantly greater in darkness, particularly in G. nivalis. Dormancy increased with seed maturation period in G. nivalis, because seeds extracted from green capsules germinated more readily than those from yellow. Desiccation increased dormancy in an increasing proportion of N. pseudonarcissus seeds the later they were dried in ‘summer’. Seed viability was only slightly reduced by desiccation in N. pseudonarcissus but was poor and variable in G. nivalis. Shoot formation occurred both at the temperature at which germination was greatest and also if 5°C cooler. In summary, continuous hydration of seeds of both species during warm summer-like temperatures results in the gradual release of seed dormancy; thereafter, darkness and cooler temperatures promote germination. Cold temperatures, increased seed maturity (G. nivalis), and desiccation (N. pseudonarcissus) increase dormancy while light inhibits germination.

Non-serotinous woody plants behave as aerial seed bank species when a late-summer wildfire coincides with a mast year.

Trees which lack obvious fire-adaptive traits such as serotinous seed-bearing structures or vegetative resprouting are assumed to be at a dramatic disadvantage in recolonization via sexual recruitment after fire, because seed dispersal is invariably quite constrained. We propose an alternative strategy in masting tree species with woody cones or cone-like structures: that the large clusters of woody tissue in a mast year will sufficiently impede heat transfer that a small fraction of seeds can survive the flaming front passage; in a mast year, this small fraction would be a very large absolute number.In Kootenay National Park in British Columbia, we examined regeneration by Engelmann spruce (Picea engelmannii), a non-serotinous conifer, after two fires, both of which coincided with mast years. Coupling models of seed survivorship within cones and seed maturation schedule to a spatially realistic recruitment model, we show that (1) the spatial pattern of seedlings on a 630 m transect from the forest edge into the burn was best explained if there was in situ seed dissemination by burnt trees; (2) in areas several hundred meters from any living trees, recruitment density was well correlated with local prefire cone density; and (3) spruce was responding exactly like its serotinous codominant, lodgepole pine (Pinus contorta).We conclude that non-serotinous species can indeed behave like aerial seed bank species in mast years if the fire takes place late in the seed maturation period. Using the example of the circumpolar boreal forest, while the joint probability of a mast year and a late-season fire will make this type of event rare (we estimate P = 0.1), nonetheless, it would permit a species lacking obvious fire-adapted traits to occasionally establish a widespread and abundant cohort on a large part of the landscape.

English

Systematic field screening was conducted in 14 important papaya germplasm lines to observe the severity of bumpy fruit incidence. The disease severity, fruit yield and economic losses due to physiological disorders were observed. Pune Selection-3 was most sensitive (64.6%) for the disorder while Pusa Selection Red was most tolerant (4.2%). The maximum yield was obtained in Pune Selection-3 (62 kg/plant) while lowest yield in Mokama Local (20 kg/plant). The lowest market acceptability and highest economic loss were also observed in Pune Selection-3 (Rs. 3.3/kg and 11, 21,580/ha, respectively) due to highest incidence of bumpy fruit disorder as compared to other germplasm. The highest frequency of deformed seeds/fruit (83.6%) and economic loss (Rs. 84,400/ha) under fruit production for market was noticed during February, while the lowest deformed seeds/fruit (2.7%) were observed during December. The maximum incidence of vivipary and white seed disorders were observed during May (13.4 and 75.7%, respectively) while least incidence was observed in February and March (10 and 5%, respectively). The increased incidence of vivipary was observed in harvested fruits from February to May with increasing average monthly temperature. The low and high temperatures during seed maturation period aggravate deformed and vivipary seeds, respectively. Key words: Carica papaya, physiological disorders, bumpy, vivipary, white seeds.

Relationship between changes in endogenous polyamines and seed quality during development of sh2 sweet corn ( Zea mays L.) seed

Polyamines putatively affect tolerance to abiotic stresses and are believed to be important in organogenesis. Present experiments investigate the relationship between polyamines (PAs) and seed quality. Therefore, during seed development, the changes in free putrescine (Put), spermidine (Spd) and spermine (Spm) and physiological and biochemical parameters in F 1 seeds of sh 2 sweet corn were compared. Concentrations of Put, Spd and Spm increased from 14 to 30 days after pollination (DAP). After 30 DAP Put concentration declined with an opposite trend to that of Spd and Spm. The regression analysis between PAs and seed quality described by physiological and biochemical parameters including germination percentage, germination energy, germination index, seed size, seed fresh and dry weight, total soluble sugar, total soluble protein, Malondialdehyde (MDA) concentration, electrolyte leakage, peroxidase (POD) and catalase (CAT) activity were conducted. Spd was observed to have a closer relation with the comprehensive physiological changes of seeds during their development than that of Put and Spm. Moreover, the Spm concentration might be more suitable to forecast seed germinability during seed maturation period than Spd and Put. It indicated that endogenous Spd and Spm in dissociated form had more effect than Put during seed development progress of sweet corn.

Effects of Sowing Dates on the Progress of Disease Caused by Purple Stain of Soybean.

A survey of soybean fields in Hiroshima Prefecture revealed that the incidence of purple stain caused by Cercospora kikuchii in soybean (Glycine max (L.) Merr.) seeds has been significantly promoted by sowing seeds in the middle of rainy season (early-sowing) . The progress of disease on leaves of plants from early-sown seeds was more marked during the rainy reason, especially when the disease has already established before the onset of the rainy season. This promotion of disease development was recognized not only on the leaves but also on seeds and lasted until harvest time. This effect of early sowing of seeds has been attributed to the longer exposure of plants to the rainy season. Late-sowing, which is done in early July, had afforded the plants some time to escape the rainy season and hence, enabled them to be less prone to the disease. In addition, seed maturation period in early-sowing field was longer than that in late-sowing, and thus, exposing the seeds to a longer infectious period. These results indicate that late sowing of seeds can be used as a cultural practice for the control of this disease.

Estimates of outcrossing rates and of inbreeding depression in a population of the marine angiosperm Zostera marina

Despite the great diversity of pollination and fertilization mechanisms observed in marine plants, little is known about the causes or maintenance of this variation. In this study, I estimated outcrossing rates and levels of inbreeding depression in Zostera marina L. (eelgrass), providing the first empirical test of hypotheses about the evolution of breeding systems in plants with submerged flowers. This study also addressed temporal separation of female and male flowering (dichogamy) in eelgrass as a mechanism promoting an outcrossing mating system, and whether the mating system in eelgrass is related to the degree of dichogamy in the field. Outcrossing rates (0<t<1) estimated from two polymorphic allozyme loci indicate that the Z. marina population in intertidal and subtidal habitats in False Bay, Washington, USA, was highly outcrossing in both 1991 (intertidal t=0.905, subtidal t=1.0) and 1992 (intertidal t=0.775, subtidal t=0.611). The outcrossing rates were positively associated with the degree of dichogamy in 1992; intertidal plants exhibited a greater temporal separation of female and male flowering and a higher outcrossing rate than did subtidal plants. Inbreeding depression at seed set was estimated from hand pollinations (self- and outcross) on 20 reproductive individuals from the False Bay population. Averaged across all maternal parents, a greater proportion of outcrossed flowers set seed than selfed flowers; i.e., inbreeding depression was detected. Plants exhibited genetic variation for inbreeding depression, detected as a significant pollination treatment × maternal family interaction in a log-likelihood analysis. By the end of the seed-maturation period (7 mo after intial seed set) some families showed outbreeding depression, i.e., greater fitness in progeny derived from selfing than in progeny from outcrossing. The inbreeding depression in the False Bay population may be an important selective factor contributing to the maintenance of dichogamy and an outcrossing mating system, as proposed for aquatic plants.

Ubiquitous nuclear proteins bind to 5? upstream region of major Kunitz chymotrypsin inhibitor gene in winged bean

Winged bean Kunitz chymotrypsin inhibitor (WCI) accumulates abundantly in seeds and tuberous roots of winged bean plant. In seeds, the WCI mRNA is observed transiently during seed maturation period. The WCI is encoded by a multigene family and the major WCI (WCI-3) is encoded by two nearly identical genes (WCI-3a and WCI-3b genes), in which nucleotide sequences in the 1.1 kb 5' flanking regions are about 99% homologous to each other and the transcribed regions are completely identical. Here we report the detection of two types of nuclear proteins which bind to the multiple sites in the 5' upstream region of the WCI-3a gene. One of the proteins, band 1-forming protein, also bound to cauliflower mosaic virus 35S (CaMV35S) promoter, but another protein, band 3-forming protein, did not. DNaseI footprinting analysis showed that these proteins bound to AT-rich upstream regions in the WCI-3a gene. Addition of poly(dA-dT)-poly(dA-dT) to the binding reaction inhibited the formation of the retarded bands, while poly(dI-dC)-poly(dI-dC) did not. In various organs and throughout seed maturation period, proteins with invariable binding specificities were detected, and these binding proteins met some operational criteria for high-mobility-group (HMG) proteins. These results suggest that leguminous seed AT-binding proteins reported on several seed storage protein genes may be HMG-like proteins which are present ubiquitously in plant organs.

Structure and regulated expression of Kunitz chymotrypsin inhibitor genes in winged bean [Psophocarpus tetragonolobus (L.) DC

We analyzed the structure and the expression of Kunitz chymotrypsin inhibitor (WCI) genes in winged bean. WCI was encoded by a multigene family which comprised at least seven members. From their primary structures, four genes (WCI-2, WCI-3a, WCI-3b, and WCI-x) were expected to be functional ones and the other three (WCI-P1, WCI-P2, and WCI-P3) to be pseudogenes. The nucleotide sequences of the WCI-3a and WCI-3b genes were nearly identical, and they encoded the WCI-3 protein, the major chymotrypsin inhibitor in seeds. The WCI-2 gene also encoded the chymotrypsin inhibitor found in seeds and the WCI-x gene was expected to encode an unidentified chymotrypsin inhibitor. WCI messenger RNA and protein accumulated mainly in developing seeds and tuberous roots, small amounts of WCI mRNA being present in stems and pericarps. In seeds, transient accumulation of WCI mRNA was observed during the seed maturation period. These results suggest that the expression of WCI genes is regulated organ-specifically and developmentally in winged bean.

Physiological role of glucosinolates in brassica napus. Concentration and distribution pattern of glucosinolates among plant organs during a complete life cycle

AbstractConcentrations and distribution of glucosinolates in various organs of rape (Brassica napus L) were examined during major stages of development. Fluctuations in the total content as well as in the individual levels of glucosinolates were investigated in double low Drakkar and high glucosinolate Chine 32 cultivars. The distribution pattern of aliphatic and aromatic glucosinolates between the various organs, as well as the variation in the concentrations of individual glucosinolates during plant development were quite similar between the two cultivars. Peculiar stages of accumulation during the vegetative growth period and the seed maturation period were identified. These stages were followed by periods of intense degradation during flowering, germination and early growth stages of seedlings. Fluctuations in the amount and structure of the glucosinolates in each of these periods suggest a storage function for these compounds which are required at specific stages of development. The involvement of some of these compounds in hormonal control of flowering is also discussed.

Growth and Productivity of Cotton Grown from Seed Produced Under Four Night Temperatures1

The seeds used in this study were produced by growing cotton (Gossypium hirsutum L.) plants from first flower through boll maturation in growth chambers where tire night temperatures were 11, 15, 21, and 27 C. These seeds were used to evaluate the effect of seed quality on the growth and productivity of matured plants. The cultivars used were ‘Acala 1517 Br2,’ ‘Stoneville 7A,’ ‘Lankart Sel 57,’ ‘Stripper 31,’ and ‘CA 491.’ Characters or traits measured were 1) seed weight and percentage of germination of the seed produced in the temperature controlled growth chambers; and 2) rate of seedling emergence, vegetative growth rates, seed cotton per plant, bolls per plant, and production rate index of the plants grown from the seed produced in the chambers.Low night temperatures during the seed maturation period had a detrimental effect upon seed quality (seed weight and percentage of germination). In field plantings, seedlings from seeds produced under low night temperatures (11 and 15 C) emerged more slowly than those from seeds produced under high night temperatures (21 and 27 C). The plants that developed from seeds produced under low night temperatures (11 C) grew more slowly and were less productive than plants from seeds produced under high night temperatures (21 and 27 C).

Embryo dormancy in subterranean clover seeds. II. Its value relative to impermeability in field germination regulation

Less than 20% of the viable seeds of three subterranean clover cultivars survived exposure to typical summer field environments in the absence of protection from embryo dormancy and impermeability. The survival rate of seeds was no higher when protected by embryo dormancy only. By contrast, when the seeds were protected by both embryo dormancy and impermeability the survival rate of viable seeds was 70% or higher. It is concluded that fully mature dry seeds of subterranean clover receive little protection from embryo dormancy during the summer, although the mechanism may well be important in preventing germination during the late seed maturation period. It is suggested that in breeding and selection programmes impermeability should receive priority as a germination-regulating mechanism.

The effect of time of planting and nitrogen fertilizer on yield attributes of Brassica oilseed crops in the Ord River Valley

At Kimberley Research Station in the 1962 dry season, two varieties of Brassica ca.mpe.rtris and one of B. juncea were sown under irrigation at four dates from May 1 to July 2 with six nitrogen fertilizer treatments. Seed yield was reduced with later date of sowing. There was a small linear response to nitrogen fertilizer up to 80 lb an acre nitrogen. Applying half the nitrogen at sowing and half at budding showed no advantage over applying all the nitrogen at sowing. Oil content was also reduced with later date of sowing. Nitrogen fertilizer at the highest level reduced oil content slightly. Although seed and oil yield were highest at the first sowing, dry matter and nitrogen yield of tops were highest at the second sowing. The fall in seed and oil yield with later date of sowing appeared to be associated more with rising temperature during the seed maturation period than with general vegetative performance.