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Open access

Mir I. Asif, Osman A. Al-Tahir, and Abdullah S. Al-Ghamdi

Abstract

The genus Phoenix is characterized by dioecious wind-pollinated woody trees. The date palm (Phoenix dactylifera L.) is one of the world’s oldest cultivated fruit trees. The date palm inflorescence consists of a compound spadix enclosed by a spathe. Flowers are produced on strands. At anthesis, the spathe splits and the strands loosen and spread to expose the flowers. Cultivated date palms are artificially pollinated. Mature male inflorescences are cut off before the spathe splits, and the strands are placed in female flower clusters to ensure pollination. In earlier studies of pollen structure and stainability (1,2), abnormally large pollen grains were noted occasionally. This study dealt with pollen size distribution in 10 male palms used to pollinate female trees in commercial groves in the Al-Hassa region of Saudi Arabia.

Open access

R. J. Henny

Abstract

Four Dieffenbachia species produced a low percentage of pollen grains with mean diameters 3244% larger than normal-sized grains.

Free access

Vikramjit S. Bajwa* and Curt Rom

Osmotic agents used to prevent apple pollen grain germination were studied in vitro by applying 10 μL of solutions to germinating apple pollen on germinating and growth media. Seven concentrations (0%, 0.25%, 0.5%, 1%, 2%, 5% and 10%) of the solution were prepared for each chemical and the characteristics of pH, EC, and osmotic potential were measured. Apple pollen was dispersed onto the media in petri dishes. Micro drops of solution were then applied to marked areas. Dishes were then placed in germination cabinets at 25 °C. Cumulative percentage pollen germination was calculated 4, 8, 12, and 24 h after treatment by microscopic observation. Generally, the cumulative percentage pollen germination decreased asymptotically with increasing chemical concentration. The most effective chemicals for restricting pollen germination and growth were CuSO4 (0.25%), CH3 COOH (0.25%), CaCl2 (10%), K2 S2 O5 (0.25%), Methyl Jasmonate (2%). The effect of these chemicals has also been tested on pistil viability both in vitro and on excised limbs.

Free access

Michael S. Stanghellini and Jonathan R. Schultheis

In 1999 and 2000, a total of 27 diploid watermelon [Citrullus lanatus (Thunb.) Matsum. & Nakai] cultivars and advanced breeding lines (hereafter referred to as cultigens) were evaluated for staminate flower and pollen grain production to assess their potential to serve as pollenizers (pollen source plants) in triploid watermelon production systems. Male reproductive output (staminate flower and pollen production) was quantified during the peak flowering and fruit setting phase of the cultigens under field conditions. The number of staminate flowers produced per plant per day, number of pollen grains produced per flower, and total number of pollen grains produced per plant per day (staminate flowers per plant × pollen grains produced per flower) differed greatly among cultigens (for all tests, P < 0.01). Staminate flower production by cultigens differed by year (P < 0.0029) and days within years (P = 0.0225), but pollen production between years by cultigens was stable (P = 0.4841). Total male reproductive output ranged from 134,206 pollen grains per plant per day for `Jamboree' to 321,905 pollen grains per plant per day for `Summer Flavor 500'. These studies demonstrate the genotypic variability in watermelon male reproductive output potential, and may assist growers in choosing a good diploid pollenizer for triploid watermelon production.

Free access

Ghodratollah Riazi, Shahrokh Khanizadeh, and Majid Rahemi

The xenial and metaxenial effects of five different male sources on cross pollination of three pistachio cultivars, were studied in 1990 and 1991 in Rafsanjan/Iran. The pollen grains used were P. atlantica Desf., P. mutica F.& M., P. vera L. (Momtaz), P. vera L. (Soltani), and an open pollination. The female cultivars chosen were `Owhadi', `Kalleh-ghuchi', and `Momtaz', which occupy the largest cultivation area. Experiment was done in two successive years in a completely randomized design. Results of this study agreed with previous studies regarding the retardance of pistachio nut development by wild pollen species rather than P. vera L. The greatest change in various characteristics of nuts, e.g., kernel weight and shell splitting, occurred when P. mutica F.& M. pollen grains used followed by P. atlantica Desf. pollen grains. Thus, some manifestations of xenia and metaxenia could be inferred. In general, larger kernels and increased shell dehiscence resulted from the use of P. vera L. pollen grains. Greater kernel weight of `Kalleh-ghuchi', higher shell splitting of `Momtaz', and higher blank of `Owhadi' produced by pollination with P. vera L. in some extent could also be cultivar characteristics.

Open access

C. G. Kuo, J. S. Peng, and J. S. Tsay

Abstract

Seed yield of Chinese cabbage (Brassica campestris ssp. pekinensis Rupr.) was studied at 34–37/22–24°C (day/night) temperatures applied at different growth stages. High temperatures at first anthesis and immediately after pollination diminished seed yield mainly through reduction in seed number. Hand pollination with pollen grains from plants reared under normal temperature improved seed yield of the plant heated at first anthesis. Both male and female gametogeneses appeared to be affected by high temperature based on seed set, but the most drastic effect of high temperature on seed yield occurred after pollination. In vitro pollen viability tests indicated that the optimum temperature for pollen grain germination and pollen tube growth was 20°. Temperatures below 16° or above 28° reduced pollen grain germination and pollen tube growth mainly because of an increase in burst pollen grains.

Free access

Mike Stanghellini and Jonathan R. Schultheis*

In 1999 and 2000, a total of 28 diploid watermelon cultigens (released cultivars and advanced breeding lines) were evaluated for staminate flower and pollen grain production to assess their potential to serve as pollenizers (pollen source plants) in triploid watermelon production systems. Male reproductive output (staminate flower and pollen production) was quantified during the peak flowering and fruit setting phase of the cultigens under field conditions. The number of staminate flowers produced per plant per day, number of pollen grains produced per flower, and total number of pollen grains produced per plant per day (staminate flowers per plant x pollen grains produced per flower) differed greatly between cultigens (for all tests, P < 0.01). Staminate flower production by cultigens differed by year (P < 0.0003) and days-within-years (P = 0.0094), but pollen production between years by cultigens was stable (P = 0.3845). Total male reproductive output ranged from 134,206 pollen grains per plant per day for `Jamboree' to 321,905 pollen grains per plant per day for `Summer Flavor 500'. These studies demonstrate the genotypic variability in watermelon male reproductive output potential, and may assist growers in selecting an optimal diploid pollenizer for triploid watermelon production.

Open access

E. Saavedra

Abstract

Preliminary research to investigate additional factors to increase results obtained by hand pollination in cherimoya (Annona cherimola Mill.) revealed that the first flowers to open gave a poorer fruit set with hand pollination than later ones. Flowers that opened earliest had the majority of the pollen grains in the tetrad stage with thick walls, full of starch and did not germinate. Flowers that opened later had a greater proportion of individual pollen grains, no starch grains, and greater cytoplasmic streaming. Many grains germinated after a few hours.

Free access

A. Talaie, B. Goleyn, A. Vezvaei, and Y. Ebrahimi

`Page' mandarin is a complex hybrid between `Minneola' tangelo and `Clementine' mandarin. Because of self-incompatibility, this cultivar severely needs pollinizers and, if a suitable pollinizer does not exist, it will produce few and small fruit. In this study, the effects of pollen grains of nine cultivars of citrus ['Sour' orange, `Duncan' grapefruit, `Sweet' lemon, `Salustiana' orange, `Local' mandarin, `Hamlin' orange, `Siavaraz III Locan' orange, `Marrs' orange, and `Shell' mahaleh (natural hybrid)] on the quantitative and qualitative characteristics of fruit (weight, diameter, length, volume, peel thickness, juice content, developed seeds, undeveloped seeds, total soluble solids, acidity, pH, vitamin C, and percentage of final fruit set) were investigated and evaluated. After artificial pollination and during fruit growth and development, seven times abscission and fruit color and diameter were recorded. Fruit were harvested 29 weeks after pollination and were analyzed. The results showed that this cultivar, in addition to the complete self-incompatibility, has the ability of week parthenocarpy, which results in small and low-quality fruit and also parthenocarpy is induced. `Page' mandarin is cross-compatible with some cultivars, such as `Marrs' orange. There is a positive and significant correlation between developed seed number and fruit weight. The pollen of `Siavaraz III Local' orange has the most effects on percentage of final fruit set. The pollen of `Shell' mahaleh (natural hybrid) has the most effect of the quantitative characteristics, and the pollen of `Marrs' orange has the most effects on qualitative characteristics. It was concluded that `Hamlin' orange is the best pollinizer for `Page' mandarin in northern Iran. The results of this study were analyzed with the use of a randomized complete-block design.

Full access

Christopher S. Cramer

Determination of ploidy is an essential plant breeding technique. Laboratory exercises for teaching students how to determine ploidy in plant tissues using various techniques are described for geranium and onion. The different methods include root tip squashes, pollen mother cell squashes, pollen grain size and germinal pore counts, stomata size and density determination, and gross morphology.