Effects of Insect Pollination and Season on Seedling Emergence in Guayule

Mamood, A. N.; Ray, D. T.; Waller, G. D.

Effects of Insect Pollination and Season on Seedling Emergence in Guayule

1988

Mamood, A. N. | Ray, D. T. | Waller, G. D.

Stand establishment in guayule (Purthenium argentatum A. Gray) by direct seeding has not been successful due mainly to low seedling emergence. This field study was conducted in 1984 and 1985 in Tucson, AZ to evaluate the effect of honey bee (Apis melfiferu L.) pollination and different times of seed production within a season on guayule seedling emergence. The experiments involved four cultivars with four pollination treatments: plants caged with bees; plants caged without bees; plants open-pollinated (uncovered); and plants individually covered with bags. Seeds were collected monthly from July through September in 1984, and from May through September in 1985. All cultivars responded positively to honey bee pollination with increased seedling emergence. The mean percentage of seedling emergence of seed produced in plots visited by bees (56%) was significantly greater than in those from plots without bees (15%). Seeds collected in May and September had the highest emergence percentages. These results demonstrated that (i) insect pollination can increase emergence of resulting seed in guayule, and (ii) seeds produced during the warmest months have lower emergence percentages. This work was supported by a competitive research grant from the USDA. Part of a dissertation submitted by the senior author as partial fulfillment for the Ph.D. degree.

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