Impact of Shading On Seedling Growth of Maclura Pomifera (Osage Orange)

Osage orange (Maclura pomifera (Raf.) C.K. Schneid.) shows potential for use as a biofuel feedstock. Specifically, the fruit of Osage orange is being investigated for biofuel-production due to its high percentage of oil, fermentable sugars, and other carbohydrates. Since Osage orange does not begin bearing fruit until approximately ten years of age, there is a need to evaluate the seedling stage of development. Because Osage orange is being considered for inclusion in intercropping production systems, the effect of shading on seedling growth is important. However, there is limited data describing best management practices for seedling production. The objectives of our research were to determine shade tolerance and the effects of varying shade percentages on Osage orange seedlings in a controlled greenhouse environment. Greenhouse trials were conducted in January and June of 2008, lasting for 90 and 120 days, respectively. Osage orange seedlings were grown in “cone-tainers” in each trial, sized 16 and 40 cubic inches, respectively, and set up in a randomized block design with four blocks. Treatments were a no shaded control, and shading cloth of 30%, 50%, and 70%. Plant growth parameters including height, leaf number, fresh and dry leaf, shoot, and root weights, and leaf area were measured every 30 days during each trial. Trial one, which was conducted in January, resulted in no significant differences among growth parameters, therefore the experiment was repeated during the growing season. After 120 days height, leaf area, and dry root weight were significant among treatments. Height increased linearly (P≤0.001) from 231 mm under 0% shade to 344 mm under 70% shade. Leaf area increased linearly (P≤0.001) from 178 cm² under 0% shade to 287 cm² under70% shade. Treatments did not affect number of leaves, fresh or dry leaf weight, fresh or dry shoot weight, or fresh root weight. Dry root weight, however, decreased linearly (P≤0.01) from 2.04 g under 0% shade to 1.40 g under 70% shade. These results show that Osage orange can be exposed to higher shade amounts without detriment to overall biomass, while increasing height and leaf area. Therefore, Osage orange shows promise in an intercropping system without biomass being negatively affected, although competition for water and nutrients also need to be considered.