Cross pollination

Kreuz, n. cross loins rump. -beeren,/.pi. Kreuzdornbeeren. -bcfruchtung, /. crossfertilization. -bein, n. sacrum, -bestau-bung, /. cross-pollination, -blume, /. milkwort (Polygala), -bliitler, m. (Bot.) crucifer, -dorn, m. buckthorn (Rhamnus). -dom-beeren, /.pi. buckthorn berries, Persian berries. 

Spanish mandarins, mostly clementines, are seedless but cross pollination with new late hybrids such as Fortune or Nova has led to an increase in the number of seeds in the clementines and this loss of quality is adversely alfecting exports. To try to identify the best pulse sequence for detecting the seeds, a... 

GM crops have been introduced rapidly, without extensive testing, on the grounds that they are similar to nonengineered crops. But the process involves creating gene combinations that could not have occurred naturally. Once released into the environment, genes that "escape" from the GM parent plant, via soil bacteria or cross-pollination, will be impossible to retrieve. Once incorporated into wild plants, we can only surmise what the outcome might be. 

For general advice, see Apples (p.294). Most European plums will set some fruit without cross-pollination, but nearly all will yield better when cross-pollinated by another European cultivar. Japanese plums must be cross-pollinated by either a Japanese or American type. American plums also need cross-pollination for best yields. Rootstock choice can further influence your plum trees success. Ask a specialty fruit nursery for help in selecting a suitable combination of trees on appropriate rootstocks. 

This North American native plant makes a fine garden shrub with lovely fall coloring. A single plant will crop reasonably well two or more bushes to cross-pollinate each other will fruit much better. Fruiting will start in the second summer after planting, reaching full cropping after five or six years. 

Cross-pollination between engineered and nonengineered plants in the field ... 

The viability of seeds produced by S. divinorum is questionable. It is apparently a self-sterile plant which will produce seed only when cross-pollinated (1). Valdes pollinated fourteen flowers and four produced seeds. Unfortunately, the seeds viability could not be assessed as they were accidentally killed when a growth chamber overheated (1). Generally, this plant is reproduced by cuttings. It is a diploid species (N=l 1) whose pollen grains are not as viable as those of other Salvia species. Out of 3027 pollen grains, Reisfield found that 53% aborted, although this fact alone does not explain why the plants do not set seed in Mexico (16). Even when 5. divinorum is hand pollinated, only 2 to 3 percent of the nutlets fully mature (8). 

Further resolution of the problem was obtained by studying pollen germination and tube growth through styles of hand-pollinated flowers. Of 39 styles observed, 13 (33%) had four or more pollen tubes that traversed the entire length of the style, reaching the ovary. Three or more pollen tubes reached the ovary in almost one half the styles observed. Of the 20 styles in which four or more pollen grains or tubes were observable at all, 14 had three or more pollen tubes that reached the ovary. Also, no difference was noted between the self- and supposed cross-pollinations. 

Others may have concerns that are more scientific. There has been much concern about the spread of pollen from GE plants and how this movement could affect non-GE crops and native plants. If organic crops cross-pollinate with GE crops, it is possible that consumers would reject the crops. There is also the concern that GE traits could be transferred and persist in wild plants in such a way as to disrupt the natural ecology. I can imagine that Rachel Carson would have been concerned about the potential disruptive effects of pollen flow. At the same time, she may have thought GE plants could be beneficial if they could help reduce pesticide use. 

Cross-pollination pollen is delivered to a flower of a different individual of... 

One model for coexistence between GE and non-GE crops is the program established for publicly owned land in Boulder County, Colorado (Byrne and Fromherz, 2003). The county leases about 4,000 acres of cropland to farmers, some of whom have chosen to grown insect resistant or herbicide tolerant GE corn. An advisory committee of farmers, scientists, and concerned citizens developed a set of protocols to minimize cross-pollination to nearby non-GE corn fields. The protocols include grower notification to the county of their planting intentions, communication among neighboring farmers to work out an acceptable coexistence plan, and establishment of a 150-foot buffer zone between fields to minimize cross-pollination. 

A more recent strategy for protecting plants from pests and disease involves the use of genetically altered plants. This method is controversial. Concerns include cross-pollination with unaltered plants and the entry of altered plants into the food supply. 

---