Duration Of Anthesis Research Articles

Greenhouse evaluation of fitness-related reproductive traits in roundup®-tolerant transgenic creeping bentgrass (Agrostis Stolonifera L.)

Creeping bentgrass is a very important turfgrass species used extensively on golf course greens, fairways, and tees. One of the challenges of creeping bentgrass management is the control of grassy weeds, most of which respond to herbicides in a similar manner to that of creeping bentgrass. As part of a weed management program for golf courses, Roundup®-tolerant creeping bentgrass will be simple to employ and more effective in controlling problem weeds than currently available methods. The goal of this research was to evaluate fitness-related reproductive traits in four transgenic creeping bentgrass events modified to express a Roundup®-tolerant gene, cp4 epsps, to determine if these creeping bentgrass events had gained an unexpected reproductive fitness advantage. We compared transgenic events ASR 333, ASR801 with their nontransformed tissue culture line, C99056L and transgenic events ASR365, ASR368 with their non-transformed tissue culture line, B99061R. Populations of plants from three conventional cultivars were also included for comparison to determine whether significant variations, if present in transgenic events, were novel to the non-transformed organism, Agrostis stolonifera L. Our results showed that none of the four transgenic events surveyed were significantly different from the respective non-transformed tissue culture line plants for the following characteristics: first heading date, anthesis duration, inflorescence length, number of florets per inflorescence, pollen size, and seed-set capacity through open-pollination. One of the transgenic events, ASR333, needed significantly more days for anthesis initiation than the nontransformed tissue culture line, C99056L; while another transgenic event, ASR801, exhibited significantly shorter pollen longevity than plants of the tissue culture line, C99056L. However, ASR801 was not significantly different from the conventional cultivars ‘Penn A-4’ and ‘Penncross’ for pollen longevity. Plants of both transgenic events ASR365 and ASR368 did not differ significantly from plants of the tissue culture line, B99061R, for all characters measured.

Flowering phenology in the arid winter rainfall region of southern Africa

The impact of physical factors on the flowering phenology of a succulent karroid community in the winter rainfall region of the northwestern Cape, South Africa, based upon a three year study on permanent plots, is examined, (in the permanent plots, flowering of the shrubby species extended over a period of 4 to 4'/i months each year, while blooming ot the therophytes peaked m the first half of the flowering season. Species composition and numbers of individuals in the therophytes and geophytes offering flowers varied greatly according to the pattern and amount of seasonal precipitation. Despite these variations a consistent flowering sequence between the years was observed. Possible relations between the flowering phenology and the climatic variables are discussed in detail. The present data suggest that the onset of flowering is determined indirectly by the first drop in temperature in autumn, indicating the beginning of the rainy season and presumably the start of the growing period, and/or by the increase of temperatures in the beginning of spring. The pattern and amount of rainfall within a given season mainly influenced the duration of anthesis and the number of flowers produced.

POLLINATION ECOLOGY OF LABIATAE IN A PHRYGANIC (EAST MEDITERRANEAN) ECOSYSTEM

This study was conducted in a phryganic (East Mediterranean) ecosystem at Daphni, near Athens, Greece. The Labiatae, represented by ten species belonging to nine genera, dominate in this ecosystem type. They flower from February to July. Both flowering time and nectar quantity are related to the species ability to tolerate intense water stress. Labiatae are visited by 201 insect species. Of these, 43 are exclusively supported by the family and 37 are monotropous. Solitary bees (mainly Anthophoridae, Megachilidae, Halictidae) constitute 47.3% of pollinators. The family is important in hosting specialized bees (15 species) in phrygana, particularly late in the flowering season. Labiatae species form two equally represented groups in this system; namely, the late winter‐early spring (early) flowering, visited by relatively few pollinator species, and the late spring‐summer (late) flowering species, visited by numerous pollinators. This temporal distinction is accompanied by different pollination profiles that include duration of anthesis, reward to pollinators, floral attractiveness, and flower character differentiation. All of these attributes are maximized in the early flowering period. This strategy suggests a mechanism for resource partitioning at a time when the pollinator resource is limited and competition for the services of pollinators is expected to be intense. Contrary to the current theory concerning cornucopian species, the copiously rewarding flowers of Labiatae in phrygana are not those abundantly serviced by pollinators.

The growth and nitrogen economy of rice under sprinkler and flood irrigation in South East Australia

The agronomic implications of growing rice under sprinkler irrigation on a duplex soil in inland south east Australia were examined by comparing 3 sprinkler irrigation regimes applied once, twice and three times a week (S1W, S2W and S3W) with continuous flood irrigation (CF). Each sprinkler irrigation treatment was managed to replace evaporative loss since the previous irrigation. Each irrigation main plot was split into subplots receiving 3 levels of nitrogen (N) fertilizer −0, 80 or 120 kg N ha−1 (0N, 80N and 120N). Grain yield on all sprinkler-irrigated treatments was reduced by 50% or more when compared with CF. There was a slight decline in grain yield with lower frequency of sprinkler irrigation. The main factors contributing to the lower yields were reductions in the number of spikelets per panicle and in floret fertility. Panicle density was not significantly influenced by the irrigation treatments. Sprinkler irrigation delayed anthesis by at least 8 days, and the duration of anthesis was extended by 5 to 7 days. The lower yields under sprinkler irrigation did not appear to be due to greater N deficiency and it is uncertain whether any or all irrigation treatments suffered from P deficiency. Irrigation treatment had little effect on plant N concentration, but P concentration in the plant tops was reduced by sprinkler irrigation during the vegetative and reproductive stages. Low night temperatures throughout the reproductive phase reduced floret fertility, but all irrigation treatments at the same N rate (except SlW/120N) were affected to a similar extent. Water stress, as evidenced by leaf rolling in response to high evapotranspiration rates in this semi-arid environment, was considered to be the main factor contributing to the decline in yield on the sprinkler-irrigated treatments. The irrigation and N rate treatments did not interact significantly in their effect on any important parameter measured. Increasing the rate of applied N from 0 to 80 kg N ha−1 increased yield by about 1 t ha−1 by producing more panicles, but 120N was of no further benefit and was associated with increased floret sterility. Nitrogen fertilizer increased both the N uptake and N concentration in the plant material. We conclude that sprinkler irrigation for rice production is unlikely to be a viable strategy for water management on duplex soils in inland south east Australia. Conventional dry-seeded culture with permanent flood delayed until panicle initiation is probably a preferable alternative to sprinkler irrigation for increasing water-use efficiency.

Flower production and sexuality in Bequaertiodendron magalismontanum

Flowering propensity, flower distribution and the duration of anthesis in a natural population of Bequaertiodendron magalismontanum, located in a part of the Magalisberg mountain range, were assessed during two successive flowering seasons. Relative sex ratios and secondary sex characters of morphologically hermaphrodite and female plants are given. Selective pressures underlying the evolution of morphological gynodioecy in B. magalismontanum are discussed.

Effect of Sewage and industrial effluents on flowering behavior and yield of pea (<i>Pisum sativum</i> L. var. <i>arkel</i>)

Municipality Sewage and effluents from Shah Udyog and Dairy Farming were taken to assess the flowering behavior and yield of pea. The effluents from Dairy Farming initiated flowering earlier than the other effluents while effluents of Shah Udyog retarded comparatively. The same trend was followed for anthesis, withering and pod appearance. Duration of anthesis was found increasing in the order: Dairy Farming, Municipality Sewage, Control and Shah Udyog respectively. On the other hand, number of seed per plant and dry weight per seed was found in decreasing order from Dairy Farming to Shah Udyog through Municipality Sewage. Key words: Effluents; Flowering; Yield; Inhibition and promotion DOI: 10.3126/bibechana.v7i0.4049BIBECHANA 7 (2011) 70-75