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Stratification by chilling is the primary factor controlling germination of brodiaea (Triteleia laxa Benth.) seeds. A minimum of 8 weeks of low temperature (3C) was required for maximum germination. Soaking seeds in a solution of 1000 mg ethepho/liter for 20 h reduced the number of weeks at low temperature required for germination. Cormel size was affected by the photoperiod during seedling growth. Long days induced early leaf senescence, and cormels harvested from seedlings grown under long days weighed only half as much as those grown under short days. Chemical name used: 2-chloroethyl phosphoric acid (ethephon).
Postproduction leaf yellowing of Easter lily (Lilium longiflorum Thunb.) can be prevented by using growth regulators. Solutions containing benzyladenine (BA) reduced the percentage of yellow leaves in cold-stored plants, but solutions containing gibberellic acid (GA3) were not effective. Treatment with commercial products containing GA4+7 (Provide) or GA4+7 and BA (Promalin) nearly completely prevented the development of leaf yellowing. Concentrations as low as 25 mg·L-1 were effective. Leaf yellowing was prevented by growth regulators only on leaves that had been treated, indicating that the growth regulators were not mobilized in the plants. Growth regulator solutions halted further development of leaf yellowing when applied to plants that already had some chlorotic basal leaves. This result suggests that growth regulators need not be applied preventively. Treatment can be delayed until chlorotic lower leaves are first seen on plants. The striking effects of growth regulators in preventing leaf yellowing did not affect the development and opening of flower buds.
Leaf yellowing of excised Easter lily leaves was significantly delayed by application of gibberellic acids ≥250 mg·liter-1 or benzyladenine ≥50 mg·liter-1. Rapid development of foliar chlorosis following cold storage was delayed significantly by applying 500 mg·liter-1 of GA3 or BA before storage. Poststorage treatments were less effective. Development of chlorosis was associated with rapid loss of fresh weight and was not related to the aperture of the stomates (diffusive resistance). Respiration rates of leaves treated with growth regulators were significantly lower than those of the controls.'
The effects of the duration of cold storage, as well as the concentration, timing, and means of application of a solution containing 25 mg·L-1 each of benzyladenine (BA) and gibberellins (GA4+7) on the postharvest quality of cut Asiatic and Oriental lilies (Lilium sp.) were evaluated. Depending on the cultivar, lower leaves began to turn yellow between 1 and 2 weeks after placing non-cold-stored stems in a 20 °C room illuminated 12 h·d-1 with 8 μmol·m-2·s-1 from cool-white fluorescent lamps. Leaf yellowing continued to progress upward until the end of the vase life. Cold storage (3.3 °C) worsened the leaf disorder, particularly, on the Oriental lily `Stargazer'. The longer the duration of cold storage, the earlier the development of leaf yellowing and the higher the percentage of leaves that were chlorotic. In addition, cold storage induced bud blasting, inhibited flowers from fully opening, and reduced the longevity and fresh weight of open flowers and the vase life of cut stems. Spraying leaves with a solution containing 25 mg·L-1 each of BA and GA4+7 significantly reduced cold-storage-induced leaf yellowing, bud blasting, and vase life of three of the four cultivars tested. The development of leaf yellowing declined with increasing concentration of BA+GA4+7. The susceptibility of `Stargazer' to cold-storage-induced leaf yellowing and bud blasting can be counteracted by a concentration of growth regulators higher than that which was effective for the other cultivars. Timing of the BA+GA4+7 application was not critical, as there were no differences in leaf yellowing or bud development when the solution was sprayed before or after the cold storage. Addition of BA+GA4+7 (0.5 or 2.5 mg·L-1 of each) to the preservative solution or a pulsed treatment in solutions containing 25 mg·L-1 each of BA and GA4+7 for 4 hours prevented leaf yellowing, but increased bud blasting. For practical applications, growth regulators can be sprayed prior to or after cold storage in order to improve the postharvest leaf and flower quality of cut lilies.
Individual 'Stargazer' flowers lasted about 4.5 to 5 days and weighed ≈14 g. Addition of 2% sugar into the vase solution neither affected the longevity nor the size of the flowers but significantly enhanced anthocyanin content and, thus, the intensity of petal color. Defoliation of Oriental lilies, the common practice of retail florists, did not affect the opening, longevity, and size of the open flowers, but did result in lighter-color petals when placed in a solution without sugar. Addition of sugar to the vase solution counteracted the adverse effects of defoliation on petal color. Sugar in the vase solution did not overcome the increased bud blasting and the reduced longevity and size of flowers induced by cold storage. However, it enabled more flowers to open fully, which, without sugar, remained only partially open. Excised bud experiments revealed that bud size of 6.1 cm and 7.0 cm were critical for opening of non-cold-stored and cold-stored buds, respectively. Unlike other cut flower species in which flowers for long-term storage or long-distance transport are harvested at a tighter-bud stage than those intended for the local market, in 'Stargazer', harvesting of stems where the smallest bud is >7.0 cm would be critical in reducing cold-storage-induced bud blasting.
Yellowing of excised Easter lily leaves was significantly delayed by foliar application of gibberellic acids (GA3) ≥ 250 mg·1-1 or benzyladenine (BA) ≥ 50 mg·1-1. Rapid development of foliar chlorosis following cold storage was delayed significantly by applying 500 mg·1-1 of GA3 or BA before storage. Post-storage treatments were less effective. Development of chlorosis was associated with rapid loss of fresh weight and was not related to the aperture of the stomates. Respiration rate of leaves treated with growth regulators were significantly lower than that of the controls. Differences in the rate of carbohydrate depletion may explain the striking effects of growth regulators on the development of foliar chlorosis.
The development of postproduction foliar chlorosis is one of the critical problems that remains unsolved in Easter lily production. Plants at the white puffy stage were sprayed with 500 mg gibberellic acid (GA3)/liter, 500 mg benzyladenine (BA)/liter, 500 mg each GA3 and BA/liter, 500 mg ProGibb (containing 500 mg GA3/liter)/liter, and 1000 mg Promalin (containing 500 mg GA4 + GA7/liter and 500 mg BA/liter)/liter, and a water control. Development of foliar chlorosis was evaluated in a simulated interior environment at a temperature of 22.6 ± 0.2C and illuminated 12 h·d–1 with 11.2 ± 0.1 mmol·m–2·s–1 from cool-white fluorescent lamps. Results demonstrated that GA3, BA, ProGibb, and Promalin are effective in delaying the development of foliar chlorosis of cold-stored plants. Promalin was the most effective. Concentrations of Promalin as low as 50 mg· liter–1 were effective. Treatments had no effect on the development and the longevity of flower buds. This study thus suggests that application of Promalin to Easter lily plants prior to marketing is a viable solution to preventing postproduction development of foliar chlorosis.
The development of postharvest leaf yellowing affects the quality of cut Oriental and Asiatic lilies. Without cold storage, lower leaves began to turn yellow ≈1 week after placing them in an interior environment. The development of leaf yellowing continued to progress upward until the vase life was over with >25% of the leaves chlorotic. Cold storage of cut lilies worsened this leaf disorder. The longer the duration of cold storage, the sooner the development of leaf yellowing and the higher the percentage of leaves that were chlorotic. Spraying leaves with a solution containing 25 mg·L-1 each of BA and GA4+7 significantly reduced cold-stored induced leaf yellowing in both Oriental and Asiatic lily. While the growth regulator treatment completely prevented leaf yellowing of cold-stored Asiatic lilies, its effectiveness in Oriental lilies diminished with the duration of cold storage. Timing of the growth regulator application was not critical, as there were no differences in leaf yellowing when the growth regulator solution was sprayed before or after the cold storage. The concentration of the growth regulators was inversely related to the development of leaf yellowing and concentrations <5 mg·L-1 each of BA and GA4+7 were not effective. Alternative means of applying the growth regulators were evaluated, including the addition of the growth regulators to the preservative solution or as a pulsed treatment. Both methods completely prevented leaf yellowing but also induced bud abortion. For practical application, spraying the growth regulator solution on the leaves prior to or after cold storage would significantly improve postharvest quality of the cut lilies.
Effects of the duration of cold storage, as well as the concentrations, timing, and means of application of a growth regulator solution on the postharvest quality of cut Oriental and Asiatic lilies were evaluated. Without cold storage, lower leaves of Oriental lily `Stargazer' began to turn yellow ≈1 week after placing stem in an interior environment. The development of leaf yellowing continued to progress upward until the end of the vase life when there was an average of >25% chlorotic leaves. Cold storage worsened the leaf disorder. The longer the duration of cold storage, the earlier the development of leaf yellowing and the higher the percentage of leaves that were chlorotic. Spraying leaves with a solution containing 25 mg·L-1 each of BA and GA4+7 significantly reduced cold-storage-induced leaf yellowing and bud abortion in both Oriental and Asiatic lily. Concentration of the growth regulator solution was inversely related to the development of leaf yellowing. Timing of the growth regulator application was not critical, as there were no differences in leaf yellowing or bud development when the growth regulator solution was sprayed before or after the cold storage. Addition of the growth regulators to the preservative solution completely prevented leaf yellowing but also induced bud abortion. For practical application, spraying growth regulators prior to or after the cold storage would significantly improve the postharvest quality of cut lilies.
The development of greenhouse leaf yellowing in Easter lilies (Lilium longiflorum Thunb.) was significantly reduced by the application of growth regulator solutions containing gibberellins 4 and 7 (GA4+7) or benzyladenine (BA). Solutions containing BA alone significantly reduced leaf yellowing on plants caused by close spacing but were less effective than GA4+7. Application of BA alone, however, was not effective against root rot-induced leaf yellowing. When plants were treated with GA4+7 or BA + GA4+7 around the visible bud stage, nearly all of the leaves remained green until the end of the growing season. These growth regulators, however, increased the final height of the plants by 8–10 cm. The developmental rate and size of the flower buds, as well as the length of the pedicels were not affected by the growth regulator treatments. Thus application of these growth regulators greatly improved the quality of the leaves without compromising the quality and timing of the flowers. Chemical name used: N-(phenylmethyl)-1H-purine-6-amine (benzyladenine, BA).