'Rourke, and E.E. Puls for their critical reviews of the manuscript. The cost of publishing this paper was defrayed in part by the payment of page charges. Under postal regulations, this paper therefore must be hereby marked advertisement solely to indicate
Pollination is essential in the production of many agricultural crops. Insufficient pollination can lead to reduced yield and lower harvest quality in many fruit and vegetables. Recent declines in insect pollinators and the use of cultural systems where compatible pollen is limiting have caused pollen-related production problems in many crops. Supplemental mass pollination (SMP) may be beneficial in such cases. However, the high cost of pollen may prohibit its use unless pollen is efficiently and uniformly applied. Our objective was to evaluate the feasibility of using selected dry particulate materials as pollen diluents for SMP. Viability was assessed in apple pollen mixed and held with selected powders (i.e., two formulations of Rilsan® nylon, polyester resin, diatomaceous earth, wheat flour, and CaCO3). Also, an assessment of inhibitory substances was made using in vitro germination tests with extracts obtained from liquid suspensions of the different particulates. Several powders, viz., Rilsan® nylon formulations, polyester resin, and wheat flour were identified as nontoxic to pollen held for 1 h as dry pollen: particle mixtures. Likewise, leachates from these diluents had no significant effect on pollen germination. Diatomaceous earth exhibited slight, but statistically significant, inhibitory effects on germination, while CaCO3 completely inhibited germination. The morphology and size of particulates were evaluated using scanning electron microscopy and will be discussed vis-a-vis pollen dispersion and metering requirements.
Abstract
Shoot tip-derived plantlets of five species of Amaranthus, A. caudatus L. cv. Pan, A. gangeticus L., A. hypochondriacus L., A. retroflexus L., and A. viridis L. flowered in vitro following 8 to 32 weeks in culture. Shoot tips were cultured on Murashige and Skoog (MS) salts and (per liter) 30 g sucrose, 100 mg myo-inositol, 0.4 mg thiamine·HCl, and 8 g agar. Additions of 0.1 mg·liter–1 NAA enhanced inflorescence production but was not necessary for flower induction. Fruits of A. gangeticus and A. retroflexus dehised and their seeds dropped on the surface of agar medium and immediately germinated. In some instances, seeds of A. gangeticus germinated while still attached to the inflorescences. Seedlings derived from sterile flowers could, in turn, give rise to inflorescences. Inflorescences could be detached from flowering plant-lets and grown successfully for several months on basal nutrient medium containing 0.1 mg·liter–1 NAA. Chemical name used: 1-naphthaleneacetic acid (NAA).
Carbohydrate energy source of various tissue culture media has an effect on growth and survival of the explants. Sucrose is the standard carbohydrate used in most tissue culture systems. The objective of the study was to determine the effect of five carbohydrate sources (fructose, glucose, maltose, sorbitol, and sucrose) at two levels (2% and 3%) on germination, growth, and survival of immature peach embryos (9.7 to 14.7mm) in vitro. Five cultivars were used. Overall, fructose, maltose, and sucrose each stimulated germination and growth as the primary carbohydrate energy source of peach embryo culture to the same degree; glucose and sorbitol were inferior. However, fructose was superior to sucrose in one cultivar. In general, sugar level did not affect survival, although cultivars did vary somewhat. Survival was found to be highly dependent upon embryo maturity.
3 Assistant professor, Department of Forest Science, Texas A&M University, MS 2135, College Station, TX 77843-2135. 1 Graduate student. 2 Professor. This study was included as part of a thesis written in partial fulfillment of the
Abstract
Aseptic culture of ovules resulted in the germination and development of abortive hybrids in 38 of 66 interspecific crosses among Impatiens. In some crosses, 6- to 11-day-old ovules had significantly higher percentages of germination than 3- to 5-day-old ovules. An average of 19.9% of the germinated seedlings was rescued, and the rest were lost through abnormal development in vitro. About 90% of the abnormal seedlings developed into hard, callus-like masses of varying sizes and shapes, and the rest developed into imperfect seedlings without roots or shoots, albinos, and soft calli. Seedlings were rescued in 25 crosses, and in 13 crosses none of the germinated seedlings was rescued. The 25 rescued progenies were derived from 8 crosses among African species, 1 among Indian species, 4 between African and Indian species, and 12 between African and New Guinea-Indonesian species. All but 2 of the progenies are new and are being reported for the 1st time. The hybrids were usually distinct and easily identified by inspection of leaves and flowers. All were sterile.
1 To whom reprint requests should be addressed. The cost of publishing this paper was defrayed in part by the payment of page charges. Under postal regulations, this paper therefore must be hereby marked
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.
orchid species. Successful in vitro seed germination has been reported for S. plicata using various medium formulations. Hossain and Dey (2013) found that the maximum seed germination percentage was observed with the Phytamax medium (95%) followed by
Abstract
Slowly growing calli were induced in vitro from nucellar explants excised from fertilized ovules of immature 4.0-4.8 cm long monoembryonic mango fruitlets. The medium consisted of Murashige and Skoog formulation that had been modified accordingly: half strength major salts, 60 g/liter sucrose, 400 mg/liter glutamine, 100 mg/liter ascorbic acid, 1.0 mg/liter 2,4-dichlorophenoxyacetic acid (2,4-D), and 8 g/liter Difco Bacto agar. Somatic embryogenesis occurred from callus on this medium and following subculture to medium without growth regulators. Maturation and limited germination of somatic embryos occurred in the absence of growth regulators.