Search Results

You are looking at 1 - 10 of 1,637 items for :

  • "seasonality" x
Clear All
Free access

Park S. Nobel and Miguel Castañeda

Detached, unrooted cladodes (stem segments) of the widely cultivated prickly pear cactus Opuntia ficus-indica (L.) Miller (Cactaceae), which remain alive for at least 12 months, provide a model system for investigating stem responses to environmental factors. Initiation of organs varied seasonally; on average 2.14 new organs were initiated per cladode over a 16-week period in a glasshouse for cladodes detached in winter, 0.76 when detached in late spring, and only 0.07 when detached in late summer. Shading by 45% halved new organ initiation and shading by 95% decreased it by 96%. The seasonal and light responses for new organ initiation are consistent with field observations on O. ficus-indica. For detached cladodes maintained in environmental chambers for 14 weeks, the new organs were 10 times more likely to be fruit than daughter cladodes at day/night temperatures of 15/5 °C, equally likely to be either organ at 25/15 °C, and 10 times more likely to be daughter cladodes than fruit at 35/25 °C. Decreasing the shading or the temperature favored stomatal opening, as shown by increases in the dry mass/fresh mass ratio of the detached cladodes. Such increased stomatal opening was accompanied by increased photosynthetic activity, as shown by greater starch content and higher concentrations of sucrose, glucose, and fructose. Why low day/night temperatures favored reproductive structures and high temperatures favored vegetative ones is not clear, but future research using unrooted cladodes may help elucidate the mechanisms involved.

Open access

Amalie B. Kurzer, Rose Bechtel and Jean-Xavier Guinard

cost proportionately more often ( P ≤ 0.05), as well as farm to fork, purchasing preferences, and seasonality. This lower proportion of instances discussing these topics could be either there is less awareness of these topics in children or that they

Free access

Suphasuk Pradubsuk and Joan R. Davenport

for ≈50% of the U.S. production ( U.S. Department of Agriculture, 2008 ). ‘Concord’ grape does not reach full production until about the fifth year after planting ( Aegerter and Folwell, 1996 ). Size and seasonal duration of vegetative, reproductive

Free access

Mark G. Lefsrud, John C. Sorochan, Dean A. Kopsell and J. Scott McElroy

. Therefore, proper N management is critical for optimum plant performance. Seasonality effects caused by increases in irradiance, photoperiod, temperature, and rainfall can directly influence the growth and photosynthetic rate of plants, resulting in

Free access

Chris Gottschalk and Steve van Nocker

One of the most important plant traits, in terms of both ecology and agricultural production, is seasonal timing of flowering. Seasonal flowering is driven by the interaction of endogenous genetic pathways with environmental cues such as photoperiod

Free access

Suphasuk Pradubsuk and Joan R. Davenport

vine in Oregon ‘Pinot Noir’ wine grape ( Vitis vinifera L.) and did not show clear seasonal trends. Colugnati et al. (1995) studied vine Fe, Mn, and B content in four different grape cultivars and found total B absorption increased continuously

Full access

Kenneth Cropper, Gregg Munshaw and Michael Barrett

fall for cool-season grasses would increase stand density sufficiently to limit smooth crabgrass encroachment. The second objective was to determine if seasonal changes in mowing heights on tall fescue would allow a reduced rate of prodiamine to provide

Free access

Julie M. Tarara, Paul E. Blom, Bahman Shafii, William J. Price and Mercy A. Olmstead

., 1993 ; Reynolds et al., 2005 ) and previously we investigated its seasonal dynamics in grapevine ( Blom and Tarara, 2007 ). Another commonly measured static variable, the mass of dormant cane prunings (e.g., Bennett et al., 2005 ; Naor et al., 2002

Restricted access

Elias A. Moura, Pollyana C. Chagas, Edvan A. Chagas, Railin R. Oliveira, Raphael H. Siqueira, Daniel L.L. Taveira, Wellington F. Araújo, Maria R. Araújo and Maria L. Grigio

, climatic conditions of the cultivation site, and the incidence of pests and diseases ( Araújo et al., 2008 ). Depending on the seasonal variations of each biome, the crop may have an early or late cycle. The climate can also affect viability of flower set

Free access

Yali Song, Patrick Burgess, Hairong Han and Bingru Huang

CO 2 uptake by photosynthesis and CO 2 release by shoot, root, and soil respiration, which can vary with seasonal temperature changes and plant/soil conditions ( Lohila et al., 2003 ). There has been significant previous research regarding carbon