Variation in leaf respiration in relation to growth and photosynthesis of Lolium

Abstract

Six Lolium genotypes with contrasting apparent photorespiration and CO, compensation concentration, [CO,],, were compared for net photosynthesis, dark respiration, leaf starch accumulation, rate of leaf expansion and shoot regrowth. Plants were grown in day/night temperatures of 15/10 and 25/20 "C. There were significant (P < 0'05) differences between the genotypes in all these parameters. At 25/20 "C apparent photorespiration was correlated with [COJ,. Correlation coefficients, pooled from both temperature regimes, revealed that genotypes with high rates of net photosynthesis accumulated more leaf starch during light periods than genotypes with slow photosynthesis, but rates of leaf expansion and dry matter increase were only correlated, negatively, with dark respiration. Apparent photorespiration was negatively correlated with dark respiration. These findings suggest that attributes related to photorespiration such as [CO,], and 0, uptake from C0,-free air in the light are unlikely to be useful selection criteria for growth of C, grasses, that net photosynthesis was probably not limiting growth and that maintenance respiration may have been an important determinant of genotypic differences in growth rate.Selections for slow and fast rates of dark respiration of mature leaves were therefore made at 8 and at 25 "C from within two different populations of L. perenne, S.23. This characteristic showed repeatabilities (broad-sense heritability) of from 0.41 to 0.66. Six independent comparisons of simulated swards of the slow-and fast-respiring selections were made under periodic cutting regimes, either in a growth room at 25 "C or in a glasshouse from August to May. Growth of all plots of slow-respiring genotypes was consistently more rapid than that of the fast-respiring, at 25 "C in the growth room, and during autumn and spring in the glasshouse. There was no difference in winter growth.The implications of these results for the use of gas exchange measurements as selection criteria in plant breeding programmes are discussed.

Comparative Growth Analyses of Panicum Species with Differing Rates of Photorespiration

“…Trin., is intermediate between C3 and C4 plants with respect to photorespiration. In contrast to other reports in the literature of C3 species with altered rates of photorespiration (4,12,14,(21)(22)(23), this observation has been independently confirmed in several laboratories based on a variety of CO2 exchange parameters, including reductions in the 02 inhibition of net photosynthesis, the CO2 compensation concentration (F)2, and the rate of CO2 evolution in the light (2,3,8,10,12).Although leaf anatomical studies of P. milioides have revealed some features of Kranz anatomy characteristic of C4 plants (2, 3, 9), biochemical investigations (8)(9)(10)(11)13) indicate that this species has not reduced photorespiration and the associated 02 inhibition of photosynthesis by a C4-like CO2 concentrating mechanism (5). For example, the primary products of photosynthesis in 14CO2-air are 3-P-glycerate and glycerate rather than C4 dicarboxylic acids (8,9,11).…”

“…Trin., is intermediate between C3 and C4 plants with respect to photorespiration. In contrast to other reports in the literature of C3 species with altered rates of photorespiration (4,12,14,(21)(22)(23), this observation has been independently confirmed in several laboratories based on a variety of CO2 exchange parameters, including reductions in the 02 inhibition of net photosynthesis, the CO2 compensation concentration (F)2, and the rate of CO2 evolution in the light (2,3,8,10,12).…”

Leaf Photosynthesis and Respiration of High CO2-Grown Tobacco Plants Selected for Survival under CO2 Compensation Point Conditions

“…The use of the uncoupler of oxidative phosphorylation CCCP suggested that leaf respiration of the studied lines was controlled by adenylates in a similar It is generally considered that some reduction of total plant respiration would offer the possibility of a small, but significant, increase in yield (1,15,16). In this sense, several authors (1,11,15,16,28) suggested that selection of plants for lower mature leaf respiration per unit dry weight results in significantly higher yields. Bugbee and Salisbury (9) discussed the limits ofcrop potential productivity and suggested that carbon use efficiency, which is inversely related to respiration, can still be significantly increased in plants.…”

Differences between spring wheat cultivars in early growth

“…WILSON (1975) found a CVg of21% for leaf dark respiration in perennial ryegrass and a CVg of 24% was measured by PENNING DE VRIES (pers. commun.)…”