reduced ability to retain water in the floral organ as senescence begins ( Solomos and Gross, 1997 ). As such, genotypic variation in vase life may be driven by water supply or by the senescence response in the bloom. It is currently unclear whether
Aidan D. Farrell, Sarah Evelyn, Adrian M. Lennon, and Pathmanathan Umaharan
Zienab F.R. Ahmed and Jiwan P. Palta
studies conducted in our laboratory have shown that both pre- and postharvest application of LPE is able to reduce senescence and promote shelf life of fruits, cut flowers, and leaf tissue ( Farag and Palta, 1991a , 1991b ; Farag and Palta, 1993a ; Kaur
Jonathan M. Frantz, Robert J. Joly, and Cary A. Mitchell
Traditional overhead lighting of dense crop stands in controlled environments favors development of upper leaf layers to maximize interception of light incident at the top of the foliar canopy. The resultant mutual shading of lower leaves in the understory of the canopy can severely limit productivity and yield of planophile crops. Intracanopy lighting alleviated the effects of mutual shading in dense, vegetative stands of cowpea [Vigna unguiculata (L.) Walp ssp. unguiculata] growing in a controlled environment by sustaining irradiance within the understory throughout development of this edible-foliage crop. For an overhead lighting system, photosynthetic photon flux (PPF) in the understory was reduced to 1% of its initial value by 35 days of growth. PPF in an intracanopy-lighted stand remained within 30 μmol·m-2·s-1 of initial values throughout the 50-day cropping period. Spectral distribution of radiation within the intracanopy-lighted stand also remained relatively constant throughout canopy development. In the overhead-lighted stand, violet and blue radiation in the understory decreased as much as 60% from initial values. Stability of the radiation environment within the intracanopy-lighted stand delayed leaf senescence 27 days beyond when interior leaves of the overhead-lighted canopy began to turn yellow on day 16. The intracanopy-lighted stand produced twice as much edible biomass per unit electrical energy consumed by lamps as for the overhead-lighted system. The treatment differences were due to the continuous presence of understory irradiation when using intracanopy lighting but not when using overhead lighting, and they underscore the importance of the entire foliar canopy in realizing the full productivity potential of dense crop stands in controlled environments.
Vincent Russo and Aristotel Pappelis
Fungi can colonize senescent sweet corn (Zea mays var. rugosa Bonaf.) tissue. Senescence levels of tissues can be rated. Effects of four planting dates on senescence of standard (su, cv. Merit), and supersweet (sh2, cv. Florida Staysweet) corn at fresh market and seed harvest were determined. Stalk senescence was affected by cultivar (sh2 < su) and planting date (earliest was lowest). Shank senescence was affected by cultivar (fresh market < seed harvest) and planting date (lowest for plants of the earliest and latest plantings). Cob senescence was not affected by cultivar, slightly lower at fresh market than seed harvest, and lower for plants of the later than earlier planting dates. In a second experiment senescence was rated during development of sh2 cultivars. Formation of reproductive structures increased senescence rate. Cultivar had little effect on stalk and cob senescence at fresh market harvest. The cv. `Honey'n Pearl' had the lowest shank senescence rating. Delayed senescence should be incorporated in to corn genotypes.
Zhi-Rong Li, Kang-Di Hu, Fen-Qin Zhang, Shi-Ping Li, Lan-Ying Hu, Yan-Hong Li, Song-Hua Wang, and Hua Zhang
reproductive structures surrounded by immature petals and enclosed with chlorophyll-containing sepals ( Chen et al., 2008 ). Postharvest broccoli florets experience senescence similar to those seen in developmental leaf senescence at biochemical and
Laura J. Chapin, Youyoun Moon, and Michelle L. Jones
pathogen-induced cell death in young tissues, it negatively regulates senescence in older tissues. The atmc1 mutants exhibit premature leaf senescence, which is accompanied by earlier expression of the senescence marker AtSAG12 ( Coll et al., 2014
Ji-Lian Zheng, Lan-Ying Hu, Kang-Di Hu, Jun Wu, Feng Yang, and Hua Zhang
organogenesis, abiotic stress tolerance, photosynthesis, guard cell movement, and postharvest senescence, suggesting that H 2 S acts as an important gaseous regulator in plants, as do NO and CO ( Chen et al., 2011 ; García-Mata and Lamattina, 2010 ; Zhang et
Meng-Jen Wu, Lorenzo Zacarias, Mikal E. Saltveit, and Michael S. Reid
Continuous treatment with 8% ethanol doubled the vase life of `White Sim' carnation (Dianthus caryophyllus L.) flowers. Other alcohols, other concentrations of ethanol, or pulse treatments with up to 8% ethanol had little or no effect. Butanol and longer-chain alcohols shortened vase life and caused the flower stem to fold. During their eventual senescence, the petals of ethanol-treated flowers did not inroll; instead, individual petals dried slowly from their tips. Very little ethylene was produced by ethanol-treated flowers, and the normal increase in ACC content and EFE activity was also suppressed. Ethanol treatment also decreased the flowers' sensitivity to exogenous ethylene.
Dawei Shi, Xiaodong Wei, Guoxiang Chen, and Yanli Xu
Leaf senescence is characterized by programmed degradation of cellular constituents such as proteins, nucleic acids, and lipids, together with organelles and structures of leaf cell, resulting in a significant photosynthetic decline. Photosynthesis
Shunzhao Sui, Jianghui Luo, Daofeng Liu, Jing Ma, Weiting Men, Lu Fan, Yu Bai, and Mingyang Li
hindered the further expansion of commercial demand. It is known that plant hormones are implicated in the regulation of flower senescence, and may have a dramatic effect on the vase life of cut flowers. Research studies have reported that ethylene promoted