G. E. Clark

Assessment of tuber storage and sprouting treatments for Sandersonia aurantiaca

Abstract Temperatures of 3–5°C were suitable for the long‐term storage of sandersonia tubers. Tubers sprouted during storage at 10°C, but no sprouting occurred with up to 202 days of storage at 3–5°C. Tuber viability and subsequent sprouting were less after storage at 1°C than following 3–5°C storage temperatures. Sprouting temperatures of 20–26°C gave high sprouting percentages following long‐term storage. Tubers failed to sprout at 35°C and sprouting percentages were lower at 30°C than 20–25°C following longer storage durations (>60 days). Storage duration, storage temperatures, and sprouting temperatures influenced the time from storage removal to sprouting, storage removal to stem harvest, stem size, and daughter tuber weight. Stem length declined with increasing storage duration of 110–171 days, but was slightly greater after 202 days of storage than after 171 days. Possible reasons for these plant responses are outlined. Daughter tuber weight declined with storage duration and was less following a s...

EFFECTS OF NITROGEN NUTRITION ON SANDERSONIA CUT FLOWER AND TUBER PRODUCTION IN A SOIL-LESS MEDIUM

Abstract The effects of five nitrogen (N) application rates—14.2, 28.4, 56.8, 113.6, and 227.2 g N/ m2 (equivalent to 37.5, 75, 150, 300, and 600 ppm of N as a daily liquid feed), on greenhouse cut flower production and outdoor tuber production in Sandersonia aurantiaca (Hook.) were compared in two experiments using a peat:pumice medium. Stem length and weight declined with increasing N rate. Tuber weight declined slightly along with tuber quality with increasing N rate. High N rates resulted in an increased incidence of tuber disorders including secondary tuber formation and tuber rots. Leaf N concentration increased with N rate to a maximum of 56.8 g N/m2, but tuber N continued to increase (from 0.68 to 2.01% dry weight) with increasing N rate. The effects of the N rates on tuber storage and subsequent cut flower production were assessed at two N rates (28.4 and 113.6 g N/m2) in a third experiment. Leaf nutrient concentrations were not affected when tubers were forced at the two N rates in the third exp...

Effects of storage temperature and duration on the dormancy of Sandersonia aurantiaca tubers

Abstract The effects of three storage temperatures (1,4, and 9.5°C) and six storage durations (0, 30, 60, 90, 120, and 150 days) on tuber sprouting and stem quality of Sandersonia aurantiaca were investigated. Tubers did not sprout at lifting when given inductive conditions, but high percentages sprouted (91.7%) after only 30 days of chilling. Percent sprouting remained high (93.8%) after 90 days of storage, but decreased to 86.5% with 150 days of storage. Sprouting percentages were high for all storage durations at 4°C. Sprouting was significantly less after storage at 9.5°C than at 1 and 4°C at all storage durations. Time to initiation of sprouting and the sprouting period decreased with storage duration up to 90–120 days and were lowest at 4°C. Stem length and flower numbers per stem were significantly higher at storage durations of 90–120 days. Following 90 days of storage, stem length was greater for storage at 9.5°C than at 1 or 4°C. Storage at 4°C for 90–120 days is required to ensure rapid and eve...

Effects of growing environments, planting date, and stem treatments on sandersonia tuber weight and secondary tuber development

Abstract Sandersonia (Sandersonia aurantiaca Hook) tuber growth and secondary tuber development were assessed in two growing environments (a greenhouse and outdoors), at three planting dates (1 October, 1 December, and 1 February) and with six stem pruning treatments. Tubers of c. 1 g were used. The pruning treatments consisted of cutting the stem just above the second flower when 50% of the stems had the second flower open, or 2, 4, 6, and 8 weeks later. In another experiment the effect of stem tipping, stem pruning, flower removal, and an auxin transport inhibitor (2,3,5‐triiodobenzoic acid (TIBA)) applied 3 weeks after the second flower opened were assessed. Tuber growth and secondary tuber development were affected by the date of planting, with both tuber weight and incidence of secondary tubers declining significantly in the later planting dates. Environmental factors including temperature, radiation, and day length may have influenced the rate and type of tuber growth. Stem pruning, removal of the g...

Effects of planting density, stem pruning treatments, and shade on secondary tuber development in Sandersonia aurantiaca

Abstract The effects of three plant densities (128, 256, and 384 tubers/m2), three stem pruning treatments, and shading on tuber weight and incidence of secondary tuber production in Sandersonia aurantiaca (Hook.) were assessed in a factorial experiment. Pruning treatments were an unpruned control, a single cut just below the lowest flower at early flowering, and a multiple cut treatment (as per single cut treatment plus 25% more stem removed every 2 weeks). Tuber weight and secondary tuber formation were significantly affected by both plant density and stem pruning treatments, but not by shading. Averaged across all pruning treatments secondary tuber formation was reduced from 25.7 to 0.6% with increasing plant densities. Mean daughter tuber weight, including the weight of tubers with attached secondary tubers, was also reduced with increasing plant density (11.4, 7.9, 6.5 g) and with increasing severity of pruning treatments (11.1, 8.4, 6.2 g). However, the effect of stem pruning on secondary tuber form...

Effects of growing media and nutrition on tuber russeting, storage, and production in Sandersonia aurantiaca.

Abstract The effects of three planting media (50:50 peat:pumice, Pinus radiata bark, and soil) at two nutrient rates (1.0 and 4.0 kg/m3 Nutricote) were assessed on sandersonia (Sandersonia aurantiaca (Hook.)) tuber production, the incidence of tuber russeting, and subsequent performance of tubers. Tuber weights were greater at the higher nutrient rate. Lighter tubers were produced in the bark medium than in the peat:pumice or soil. Tuber russeting was less, and commercially acceptable, at the low nutrient rate in all media. At the high nutrient rate russeting was greater in tubers grown in peat:pumice and soil compared to those grown in bark. At the high nutrient rate tissue concentrations of K, N, S, and P were greater. Tubers grown in bark had lower concentrations of N and S compared to tubers grown in soil and peat. At the high rate of nutrition tuber sprouting in the subsequent season was less in the tubers grown in soil and peat:pumice compared to the bark‐grown tubers. Stem length, stem weight, flower number, and vase life from tubers produced in bark at the high nutrient rate were similar to those produced in the soil and peatpumice media at the low nutrient rate. There was no improvement in production indices for the tubers grown in soil or peat:pumice at the high nutrient rate. These findings show that if grown in peat:pumice or soil, sandersonia tubers should be produced at low nutrient levels to reduce the incidence of tuber russeting and to improve subsequent forcing. If grown in bark media, higher nutrient rates can be used to maintain forcing quality without causing high levels of russeting.

Effects of soilless media pH on cut flower and tuber production in Sandersonia aurantiaca

Abstract The effects of six target media pH levels (4.5,5.0,5.5,6.0,6.5) on cut‐flower (glasshouse) and tuber production (outdoor) in Sandersonia aurantiaca (Hook.) were compared in two experiments. The effects of these pH levels on tuber storage and subsequent cut‐flower production were assessed in a third experiment in a glasshouse. Actual media pH levels achieved varied from 4.1 to 6.1 in the glasshouse and from 4.4 to 6.5 outdoors. The pH levels in the glasshouse produced small differences in stem length but no significant differences in stem weight, flower number, or vase life. At the highest pH level, the number of stems harvested was less and the number of rejected flowers greater than at lower pH levels because of decreased stem length or physiological disorders, such as leaf chlorosis and leaf tip browning on the lower leaves. Leaf concentrations of S, Mn, and Zn declined with increasing pH level whereas Mg increased in the cut‐flower experiment. The number of tubers lifted outdoors was least at the highest pH level but there was no difference in mean tuber weight. Tuber nutrient concentrations of N, Ca, Mn, Zn, and Cu declined with increasing pH level whereas Mg increased. There were no production differences at forcing with the lifted tubers. For sandersonia cut‐flower production a media pH range of 4.4–5.3 appears to be suitable, whereas for tuber production pH levels of 4.4–6.1 were best. As sandersonia production usually involves both growth phases, a range pH of 4.4–5.3 would be suitable with a target pH of 5.0–5.3 recommended for growth in peat‐pumice media. This will ensure mid‐range tuber and leaf nutrient concentrations and optimised production.

Cyrtanthus: an evaluation of cut flower performance and of treatments to maximise vase life

Abstract In the current study two Cyrtanthus cultivars (one red flowered and one orange flowered) were grown at three locations in New Zealand. Flowering stems were harvested when the florets were in tight bud, pulsed for 24 h at 5–7°C with commercially available postharvest solutions or water, then packaged and stored to simulate transport before assessment of postharvest performance. In two experiments the vase life of the orange flowered cultivar was 15 and 18 days in water, whereas in other experiments the maximum vase life of the red flowered cultivar in water was 11 days. The majority (>90%) of the florets on the orange cultivar were fully open before the initiation of floret senescence on the same stem, whereas 40% of the florets of the red cultivar were starting to senesce when only 80% of the florets on the stem were open. In addition, bud abortion was more prevalent for the red flowered cultivar, which had an average rate of 9.2% bud abortion for stems treated with water compared to 0.1% for the orange flowered cultivar. Chrysal‐SVB was the only effective solution tested for extending the vase life of these cultivars, giving an extension of 2 days for both the orange and red Cyrtanthus flowers. Treatment of less mature stems of the orange flowered cultivar with a double rate of Chrysal‐SVB increased the vase life by 4 days. Stems were held in water after harvest and cool stored for up to 72 h before packing without affecting the subsequent vase life. In addition, we have shown that the orange flowered cultivar can be held dry in a cool store for up to 4 days after packaging with a subsequent vase life of 15 days in water.

Effects of nutrition, planting density, and stem pruning treatments on tuber weight and secondary tuber development in Sandersonia aurantiaca

Abstract The effects of two nutrient rates (Nutricote at 1.0 or 3.0 kg/m3 of potting mix), three plant densities (128, 256, and 384 tubers/m2), and three stem pruning/leaf removal treatments on tuber weight and the incidence of secondary tuber production in Sandersonia aurantiaca (Hook.) were assessed in a factorial experiment. The pruning/leaf removal treatments were an unpruned control, stem pruning just below the lowest flower at early flowering, and a leaf removal treatment (leaves stripped from below the lowest flower at early flowering). Secondary tuber formation was significantly affected by both nutrient rate and plant density, but not by the pruning treatments. The higher plant density reduced mean secondary tuber formation from 75 to 45%, and the lower nutrient rate decreased secondary tuber numbers from 64 to 55%. There was no significant interaction between plant density and nutrient rate. At the lowest density and high nutrient rate the incidence of secondary tubers was 79% compared to 38% at...

Effects of bulb storage, leaf and root pruning, on flower production in Cyrtanthus elatus

Abstract The effects of combinations of duration of bulb storage, storage temperature, and leaf and root pruning regimes before storage on flower production in Cyrtanthus elatus were studied in three experiments. In the first experiment, bulb viability was 93% after 49 days and declined at 98 and 147 days of storage at 1°C to 3%. Storage at 5°C for 147 days did not affect viability but flowering date was delayed 24 days. In subsequent experiments storage at 5°C did not delay flowering after 50 days, but after 100 days flowering was up to 23 days earlier and produced stems 17–22% shorter. Increasing severity of leaf and root pruning reduced the number of flower stems/bulb 46–60%, but did not affect stem length. With storage at 5°C it may be possible to spread the flowering season.