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  • Author or Editor: Iftikhar Ahmad x
  • HortScience x
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Effects of harvest time (morning, noon, or afternoon) on water uptake, fresh weight changes, termination symptoms, leaf relative water content (LRWC), carbohydrate status, and vase life of cut ‘ABC Purple’ lisianthus (Eustoma grandiflorum Salisb.), ‘Double Eagle’ African Gold Coin Series marigold (Tagetes erecta L.), and ‘Deep Red’ Benary’s Giant Series zinnia (Zinnia elegans Jacq.) were studied. For stems of lisianthus harvested and then stored in the dark with the basal ends in water for 2 weeks at 3 ± 1 °C, those harvested at noon (1200 hr to 1300 hr) or in the afternoon (1700 hr to 1800 hr) had longer vase life compared with stems harvested in the morning (0700 hr to 0800 hr). However, stems of lisianthus evaluated without storage had no differences in vase life. Stems of marigold harvested in the afternoon had longer vase life than morning- or noon-harvested stems. Time of harvest had no effect on cut flower longevity of zinnia. However, vase life was considerably shorter for stems of all species when tested after 2 weeks storage compared with freshly harvested stems. Stems of zinnia harvested at noon had lower LRWC than morning- or afternoon-harvested stems. Marigold stems harvested in the afternoon and evaluated without storage had lowest LRWC on Day 7 of vase life. Harvest time or storage did not influence LRWC of lisianthus. Stems of marigold and lisianthus harvested at noon or in the afternoon had higher levels of carbohydrates compared with morning-harvested stems, whereas freshly harvested stems had higher concentrations of glucose and sucrose, which decreased during storage or the vase period. Sucrose concentrations varied more significantly among various tissues than other sugars presumably as a result of translocation during vase life. In summary, carbohydrate status of stems harvested at different times of the day varied greatly and affected postharvest longevity of cut marigold and lisianthus, but not zinnia.

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Effects of paclobutrazol and ancymidol on postharvest performance and growth control of potted sunflower (Helianthus annuus L.), zinnia (Zinnia elegans Jacq.) and marigold (Tagetes erecta L.), petunia (Petunia ×hybrida Vilm.) plugs, respectively, were studied. Paclobutrazol was applied as a drench at 0, 1.0, 2.0, or 4.0 mg of a.i. per 15.2-cm pot for sunflower and 0, 0.5, 1.0, or 2.0 mg per 12.5-cm pot for zinnia, while ancymidol was applied at 0, 40, 80, and 160 mg·L−1 with a volume of 0.21 L·m−2 as a foliar spray for marigolds or petunia plug crops. With an increase in paclobutrazol dose or ancymidol concentration, plant growth (plant height and diameter, shoot fresh or dry weight) was controlled for all species tested. Use of 1.0–2.0 mg paclobutrazol per pot produced 21% to 28% shorter plants with 12% to 15% smaller plant diameter, 13% to 19% less shoot fresh weight, 15% to 21% less dry weight, and darker green foliage color for potted sunflower than nontreated plants. Treatment with 1.0–4.0 mg paclobutrazol per pot delayed first wilting by 0.7–1.4 days compared with nontreated plants. For zinnia, 0.5–1.0 mg paclobutrazol controlled plant growth, produced dark green foliage, and extended shelf life by delaying first wilting by 2.6–3.9 days and second wilting by 1.4–2.0 days than nontreated plants. For marigold and petunia plugs, 40–80 mg·L−1 ancymidol provided ample growth control with darker green foliage; however, postharvest longevity was extended only when plugs were sprayed with 160 mg·L−1 ancymidol. During simulated storage and shipping, plant growth retardants maintained darker green foliage for potted sunflower, zinnia, and marigold plugs and prevented postharvest stem elongation of petunia plugs. In summary, use of plant growth retardants effectively controlled excessive plant growth and extended shelf life of potted plants and plugs.

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