Industry standards for nutrient delivery to greenhouse-grown ornamentals are typically in excess of the plant’s needs and can be reduced without causing adverse effects. Previous studies have reduced the level of specific nutrients or suite of nutrients over the entire crop cycle or at the onset of reproductive growth. Here, two split-plot experiments (four blocks each) were conducted with subirrigated, potted, disbudded chrysanthemums (Chrysanthemum morifolium Ramat.) grown under greenhouse conditions with sulphate treatment (2.25 mmol L−1 S supplied continuously over the crop cycle in experiment 2 only and 2.25, 1.125, or 0.5625 mmol L−1 S interrupted at inflorescence emergence) as the main plot and cultivar (‘Olympia’ and ‘Covington’) as the sub-plot. Morphological characteristics of plants with fully-expanded inflorescences were unaffected by decreasing S delivery over the crop cycle. Dry mass (DM) yields and S budgets revealed that supply-based S use and S uptake efficiencies increased markedly in both cultivars with decreasing S delivery. Minor amounts of reduced-S, rather than sulphate, were lost from leaves of ‘Covington’ during inflorescence development. High quality chrysanthemums had sufficient leaf-S (0.17%–0.23% DM) at inflorescence emergence even with the lowest S supply, which would deliver an approximate 87.5% reduction in S over the crop cycle compared with industry standards. The primary mechanism to obtain sufficient S for the growth of chrysanthemums in these studies was increased uptake efficiency.

Greenhouse floriculture operations pose significant environmental risk due to extensive inputs of fertilizer, especially nitrogen and phosphorus (P). Recent evidence shows that the use efficiency for nitrogen or sulphur is markedly improved in subirrigated potted chrysanthemums (Chrysanthemum morifolium Ramat.) by supplying a moderate level of the nutrient during vegetative growth, and removing the entire nutrient suite at the onset of reproductive growth, without adverse effects on plant quality. Here, two split-plot experiments were conducted with subirrigated, potted, disbudded chrysanthemums grown in a peat:perlite mixture under greenhouse conditions (high- or low-ambient light) with inorganic orthophosphate (Pi) treatment (2.6 mmol L−1 Pi supplied during the vegetative and reproductive stages, and 2.6, 1.95, or 1.3 mmol L−1 Pi supplied during the vegetative stage only) as the main plot and cultivar (‘Olympia’ and ‘Covington’) as the subplot. Market quality plants with sufficient tissue P were produced even when Pi delivery was reduced by approximately 75% over the crop cycle, compared with industry standards. The primary mechanism for sustaining plant growth with decreasing Pi delivery was improved acquisition or uptake efficiency, although some changes in internal P-utilization efficiency were evident, including the remobilization of both organic P and Pi during inflorescence development. Differences in biomass yields, tissue P concentrations, content-based P-use efficiency (PUEC = mg shoot dry mass/mg shoot P content) with constant Pi acquisition, and uptake- versus remobilization-based P supply for inflorescence growth established that ‘Olympia’ has a greater P-utilization efficiency than ‘Covington’. This modified subirrigation practice could contribute significantly to low-input production of floricultural crops.

Two disbudded, potted chrysanthemum cultivars were subirrigated with 9.25, 12.3, and 18.5 mM N during vegetative, but not reproductive growth. At commercial harvest, visible symptoms of N deficiency or differences in plant/inflorescence quality were minimal, whereas N uptake efficiency was dramatically improved at 9.25 and 12.3 mM N.

Subirrigation systems are popular for reducing nutrient usage in indoor floricultural production. Two open subirrigation experiments were conducted in a commercial setting using multiple chrysanthemum cultivars and up to 75% less N/P/K than industry standards. The lowest N/P/K levels supplied in the nutrient solution (in mmol L-1: 5.4 N; 0.71-0.97 P; 1.9-4.1 K) up to bud break only were associated with acceptable leaf N/P/K levels (4.5-5.4% DM, 0.23-0.60% DM and 3.3-5.6% DM, respectively). These findings validate our modified delivery practice and the use of lower N/P/K inputs in the production of subirrigated pot chrysanthemums.

Summary An acid regenerated cation exchange resin (Dowex‐50, 200–400 mesh) is an effective catalyst for tallow splitting. The optimum level of catalyst was approximately 3% of the weight of fat. A two‐stage operation for 12 hr. at 100°C. gave fatty acid yields which ranged from 96% to 100% (calculated as % oleic acid). The Dowex‐50 catalyst was easily recovered after each operation, regenerated with 100 ml. of 4N. hydrochloric acid, and used again in the next operation with no appreciable decrease in catalytic activity. The original resin can be used in continued efficient tallow splitting operations if the residual resin is regenerated after each complete operation and additional fresh resin is added to make up mechanical loss.