@article {88,
	title = {The use of pulse amplitude modulated fluorometry to determine fine-scale temporal and spatial variation of in situ photosynthetic activity within an Isoetes-dominated canopy},
	journal = {Aquatic Botany},
	volume = {77},
	year = {2003},
	note = {Cited By (since 1996):7Export Date: 11 November 2013Source: Scopus},
	month = {2003///},
	pages = {1 - 15},
	abstract = {We used in situ pulse amplitude modulated (PAM) fluorometry to investigate photosynthetic activity of Isoetes alpinus (Kirk) in submerged meadows of Lake Wanaka, New Zealand. We examined diel and depth-related variability in the quantum yield of photosystem II (PSII) under varying ambient light, as well as variability due to self-shading effects within the I. alpinus canopy and inter-leaf differences. We also determined the utility of short-term (minutes) irradiance versus yield estimates in assessing longer-term responses to fluctuating light. Results showed that under natural lighting, PSII yield was highly variable within the plant canopy for a given irradiance incident to that canopy, ranging from 0.02 to 0.80. This variability could be explained by relating PSII yield to irradiance within the canopy measured using a miniature scalar irradiance sensor. For individual plants, yield and irradiance were closely related, and quantitatively similar yield-irradiance (Y-E) curves were obtained for plants from a given depth by experiments using diel, short-term (seconds) and in-canopy irradiance changes. Maximum fluorescence yield consistently averaged 0.55-0.65 and the light saturation parameter (E k(Y)) at 3 m depth ranged from 189 to 247. There were water depth-related differences between mean responses of the I. alpinus canopy; individual leaves from the maximum and minimum growth depths (7 and 3 m) showed ranges of (Ek(J)) of 159-228 and 109-151 μmol m-2 s-1, respectively. Irradiance alone is the dominant determinant of PSII activity in I. alpinus in Lake Wanaka, and accurate description of light within a canopy is a pre-requisite to estimating community photosynthesis. This, combined with a comprehensive assessment of the variability of individual plant responses to irradiance, by depth, may provide a sound basis for modelling community activity. We conclude that, by its ability to obtain fine-scale activity measurements rapidly, and with no enclosure or disturbance effects, PAM fluorometry offers new insights to the activity of specific plants and parts of plants in complex submerged canopies. It remains to be determined, however, whether PAM-determined quantum yield of PSII in these plants can be directly related to carbon fixation. {\textcopyright} 2003 Elsevier B.V. All rights reserved.},
	keywords = {Irradiance, Isoetes alpinus (Kirk), Lake Wanaka, PAM fluorometry, Photosynthesis, Quantum yield},
	url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-0041739174\&partnerID=40\&md5=95dca62193f6e14eb91681e33c00b52d},
	author = {Hawes, I. and Sutherland, D. and Hanelt, D.}
}
@article {81,
	title = {Regulation of root anaerobiosis and carbon translocation by light and root aeration in Isoetes alpinus},
	journal = {Plant, Cell and Environment},
	volume = {27},
	year = {2004},
	note = {Cited By (since 1996):15Export Date: 11 November 2013Source: Scopus},
	month = {2004///},
	pages = {1102 - 1111},
	abstract = {The activity of alcohol dehydrogenase (ADH) was measured in corms and roots of the submerged freshwater macrophyte Isoetes alpinus Kirk. growing in situ, and related to its capacity for internal oxygen transport and to carbohydrate translocation. ADH activity was present in roots but not corms at uniform activity (0.15-0.35 {\texttimes} 10-6 mol g-1 fresh weight s-1) over the entire plant depth range (3-7 m depth), and was intermediate to that developed in excised roots after 1-week exposure to either dissolved oxygen at air-saturation or to anoxia. Responses of photosynthesis and root oxygen release to light intensity confirmed that shoot-to-root oxygen transport saturated at similar light intensities to photosynthetic oxygen evolution, but was positive in the dark and at irradiances below the compensation point for photosynthesis, due to contributions to transport by oxygen diffusion from the external medium. Transport of 14C-labelled photo-assimilates to roots nevertheless ceased when intact plants were exposed to a combination of leaf darkness and root external anoxia, even when high 14C concentrations were present in shoots, but remained high when the roots were provided with external oxygen. The lack of any control over permeability of the root surface to gases in this species suggested that ADH activity and reduced translocation is most likely caused by development of hypoxic tissues in the apical tissue. These results suggest that reductions in ambient light intensity may have indirect effects on I. alpinus viability by increasing the degree of root hypoxia and impairing carbon partitioning.},
	keywords = {Alcohol dehydrogenase, Anoxia, Aquatic macrophytes, Assimilates, Lacunae, Oxygen transport, Photosynthesis, Respiration},
	url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-4544301436\&partnerID=40\&md5=3f174fe3d7839650597cfe52d3369b91},
	author = {Sorrell, B.K.}
}
