Marijuana Horticulture: The Indoor/Outdoor Medical Grower's Bible

stressful conditions that may lead to the formation of male flowers-irregular light cycle, high heat, etc. Only plants that resist intersexuality under these conditions should be considered as potential breeding parents for the creation of all-female seed lines. We call these intersex-resistant plants “true females.” Intentional selection against intersex plants is the only way to ensure intersex-free offspring.
    Clone copies of these pistillate intersex-resistant plants are then sprayed with our hormone treatment and placed into the flowering cycle and allowed to develop stamens. It typically takes three to five weeks for the plants to enter dehiscence and shed pollen. True female candidates that also resist intersexuality under typical stresses, are pollinated by pollen obtained by our hormone-treated, gender-reversed, stamen-bearing female plants. The result is a true gynoecious population, consisting entirely of female plants.
    An American company, Hybritech, was the first to introduce an effective ready-to-use hormone treatment-eliteXelite. This product is no longer available for public purchase. Another plant research firm, PG-Solutions, has since developed and released a ready-to-use hormone therapy spray, Stamen-It!. Stamen-It! is extremely effective in causing gender reversal of pistillate individuals. Some hormone sprays are able to induce staminate flower formation, but fail to produce viable pollen in any significant quantities. PG-Solutions has developed a formulation that causes significant pollen production, even in the most reversal-resistant genotypes. If you are interested in this technology, check their website, www.pgsolutions.ca .
Breeding Schemes For Cross-Pollinated Crops
    There are many types of breeding programs, some more complex than others. Which breeding method to employ depends entirely on the breeder’s goal. Ideally, potential breeders understand the benefits and drawbacks of each strategy, so a suitable strategy can be chosen to achieve the desired goal. The breeder’s personal preference always comes into play when choosing a breeding program. Previous successes may influence a breeder to use one specific breeding strategy over another. Some breeders rely heavily on science and statistics when analyzing the performance of their hybrids or progeny. Others consider breeding more of an art, and select based on feeling. Over the courseof a breeding program, a breeder will often use more than one method to achieve various aspects of the goal.
    When breeding cross-pollinators, we discuss hybrid performance in terms of combining ability–the ability of an inbred line to give characteristic performance in hybrid combinations with other lines. The progenies are tested for performance as populations and related back to the parental generation. Some often-used measures of performance are general combining ability (GCA) and specific combining ability (SCA). General combining ability is the average or overall performance of a given line in hybrid combinations open-pollinated with other lines.
    Specific combining ability is the performance of a specific line, as compared to other lines, when crossed with the same specific pollen source.
    Open pollination is a very low effort type of seed production and involves minimal, if any, selection. Seeds are planted, grown to maturity, and allowed to interbreed. Off-types, or plants that do not represent the defining characteristics of the variety, are rogued from the breeding population, to ensure the variety remains pure and true to type. Inbred lines, and other populations maintained through open pollination, are often bred by one person, and then produced for commercial production and release by others. Some breeders create true-breeding populations, then licence them to other companies who plant them and expand the seed populations by growing out many, many plants and allowing them all to fully seed. This is called a seed-increase.
Inbreeding
    Inbreeding is nothing more than crossing a group, family, or variety of plants within themselves with no additions of genetic material from an outside or unrelated population. The most severe form of inbreeding is the self-cross, in which only one individual’s genetic material forms the basis of subsequent generations. 1:1 hybrid populations are only slightly less narrow, derived from the genetic material of 2 individuals. Such tight or narrow breeding populations lead to a condition called “inbreeding