Treatment of seed with gibberellic acid (GA) resulted in significant increases in germination percent for Penstemon ambiguous, P. barbatus, P. eatoni, P. palmeri, P. parryi. P. pseudospectabilis, P. secundiflorus, and P. strictus in one or both of two experiments which were conducted. Germination of several other species increased with GA treatment, but differences were not significant.

Several species of low -water requiring species have been successfully propagated through vegetative and sexual means. Auxin treatments and bottom healing were beneficial in many cases. Development of improved propagation schemes, and subsequent growing practices, will increase grower success and profitability, eventually increasing availability of new low water use plants to the Arizona consumer. The long-term result of this work will be the availability of new, low-water use plant species which may be utilized by the homeowner and landscape contractor. The addition of new and exciting plant materials to the consumer market, it is hoped will accelerate the use of arid species in the Arizona landscape, resulting in water savings throughout the state, particularly in urban areas.

Jojoba stem tip cuttings were stored under refrigerated conditions of 34° and 42°F for up to 2 months with no loss in rooting potential. Rooting percent for cuttings of two clones which were rooted with no prior storage was 64.8%. Rooting after 7, 14, 28 and 56 days of storage was 81.7, 72.9, 71.7 and 81.2 %, respectively.

When Lilium longiflorum bulb scales we removed and placed in a moist environment, new bulbs ("scalets") arise from the base of the original scale, providing a practical means of clonal propagation. To determine which region of the scale is responsible for the early development of the new scalet, investigations were conducted on the localization of stanch hydrolysis and accumulation of soluble sugars in basal distal and central regions. Over a six week period starch concentration decreases initially in the distal regions, followed by the central region. Soluble sugars increased in distal areas over this same time period These findings indicate the distal regions of a lily scale are important in the early development of the new scalet, in contrast to the adjacen4 basal region.

Bulbs of three varieties of oriental hybrid lilies were stored at 4 °C for 6 to 12 weeks prior to greenhouse forcing at 18 °C night temperature. Increasing duration of storage reduced the number of days to shoot emergence, visible flower buck and anthesis for each variety. The number of days from planting to anthesis ranged from 70 to 102 and varied with cultivar and storage duration. Increasing durations of storage had no commercially significant effect on the number of flowers reaching anthesis, number of leaves or aborted flower buds. The varieties used in this study flower earlier than commercially established cultivars and may be successfully forced in Arizona for early spring holidays.

Treatment of jojoba plants with foliar sprays of benzyladenine (BA) alone, or in combination with gibberellin(4+7) (GA(4+7)) fatly increased branching frequency compared to untreated control plants and to plants from which all shoot tips were removed (pinched). Use of BA by itself resulted in an adverse reduction in intemode elongation. This was overcome in treatments which included GA(4+7) Use of GA(4+7) by itself resulted in reduced branching and abnormal shoot elongation. Pruning (pinching) of all shoot tips resulted in a slight increase in branching over untreated plants, but it had much less effect on branching than did treatments with BA. Results were very similar on two different clones tested.

Sucrose was identified by high performance liquid chromatography (HPLC) as the only phloem-mobile carbohydrate in the Boojum tree. This result has implications for carbohydrate metabolism in the desert adapted Boojum and ocotillo, as discussed below.

The alkaline nature of most Arizona soils contributes to widespread iron deficiency in exotic ornamental plants, such as pyracantha. An experiment was conducted in 1987 to evaluate the effectiveness of two soil-applied iron fertilizers (FeEDDHA chelate and a jarosite-type iron silicate, Ironite\) and three rates of foliar- applied FeEDDHA in controlling iron chlorosis symptoms in established pyracantha vines. Soil-applied FeEDDHA was the most effective in reducing iron chlorosis symptoms, followed by the foliar chelate treatments. The iron silicate material had no significant effect on iron chloroses symptoms compared to the untreated control. Both soil and foliar applications of FeEDDHA chelate made in the fall can effectively control iron chlorosis symptoms in established pyracantha.

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Call number: LD2668 .T4 1978 B45 / Master of Landscape Architecture