Showing papers on "Peduncle (anatomy) published in 1986"

Accumulation and Conversion of Sugars by Developing Wheat Grains : VI. Gradients Along the Transport Pathway from the Peduncle to the Endosperm Cavity during Grain Filling.

Abstract: Gradients along the transport pathway from the peduncle to the endosperm cavity were examined during grain filling in wheat. Sieve tube exudate was collected from severed aphid stylets established on the peduncle and rachis and on the vascular bundles in the creases of grains. Phloem exudate could also be collected from broken grain pedicels, and by puncturing the vascular bundle in the grain crease with a needle. Stylets on excised grains persisted exuding, indicating that grain sieve tubes are capable of loading solutes. There was little, if any, discernible gradient in osmolality or solute composition (sucrose, total amino acids) of sieve tube contents along the phloem pathway from the peduncle to the rachis or along the rachis itself. Neither was a gradient detected in osmolality along the sieve tube pathway from the rachis through the rachilla and grain stalk to the crease. Demonstrable solute gradients occurred only across those tissues of the grain crease between the crease sieve tubes and the endosperm cavity, a distance of just 1 millimeter. However, while the sucrose concentration in the sieve tubes was almost tenfold that in the endosperm cavity sap, total amino acids were only threefold higher, and the potassium concentrations of the two were equal. Our observations strongly implicate the movement of assimilates from the sieve tubes and across the crease tissues as important control points in grain filling.

The occurrence of Aspergillus flavus in vegetative tissue of cotton plants and its relation to seed infection.

Abstract: Twenty-seven mature cotton bolls with Aspergillus flavus Link colonies naturally occurring on the surface of the boll or lint were collected in the field in Arizona along with their subtending stems and peduncles. Bolls inoculated through the carpel wall 30 days after anthesis were allowed to mature in the field and were collected in the same manner. The seed and stem and peduncle sections of each boll were surface-sterilized, plated on agar media and observed for A. flavus. Seventy-eight percent of the naturally contaminated bolls with A. flavus in the seed also had the fungus in the stem and peduncle, whereas only 31% of the naturally contaminated bolls with no A. flavus in the seed had the fungus in the stem or peduncle. This difference was significant (P=0.0125), indicating a positive relationship between seed infection and stem and peduncle infection. All of the bolls inoculated through the carpel wall had A. flavus in the seed, but only 11% of the stem and peduncle sections were infected, indicating that the fungus does not readily grow downward from the boll into the supporting stem or peduncle.

Evaluation of anther-derived Streptocarpus X hybridus and their progeny

Abstract: Regeneration of plants by caulogenesis of anther derived callus of Streptocarpus X hybridus ‘Concorde’ was obtained on MS basal medium with 2.0 mg/l NAA and 0.5 mg/l BAP. All regenerated plants were diploid and of somatic cell origin as determined by chromosome counts, flower color and morphological similarity to the anther donor plant, and flower color segregation among progeny of anther-derived plants. Variation expressed as deformed and dwarfed transient morphology was observed in 2 anther-derived plants. Variation was also observed among progenies of 5 anther-derived plants from the same anther donor plant for days to flowering, flowers per peduncle, peduncle length, and leaf area. Additional morphological variation including transient leaf variegation among seedlings and twisted or inverted leaves on mature plants was also observed among progeny of anther-derived plants.

Atlatlia , a new genus of Dolichopodidae (Diptera) from Australia

Abstract: Atlatlia, a new genus with two induded new species. A. grisea from New South Wales and A. flaviseta from Western Australia, is described. The genus is placed in the dolichopodid subfamily Medeterinac. Males have an extremely long hypopygial peduncle formed of abdominal segment seven.

Dynamics of ear and stem growth and the control of grain number per ear in wheat

Abstract: The growth of the ear and stem of the main shoot of wheat was studied from the terminal spikelet stage until anthesis Floret number in a mid-ear spikelet increased to a maximum of ten at the time of flag leaf emergence Floret death occurred during the period from ear emergence until anthesis This coincided with rapid growth in length of the peduncle and with the time of maximum growth in dry mass of the ear and stem These results are consistent with the hypothesis that floret death is due to shortage of resources for growth Further improvement in floret survival and number of grains per ear may come from selection for greater partitioning of dry matter to the ear and for reduced peduncle length, relative to total stem length