scholarly journals Studies on Matter Production of Rape Plant : IV. Diurnal changes in apparent photosynthesis and dark resiraton of rape plants under field conditions

1980 ◽  
Vol 49 (3) ◽  
pp. 489-494 ◽  
Author(s):  
Shinobu INANAGA ◽  
Atsuhiko KUMURA ◽  
Yoshio MURATA
Keyword(s):  
Field Conditions ◽  
Diurnal Changes ◽  
Rape Plant ◽  
Matter Production

scholarly journals Rapid Equilibration of Leaf and Stem Water Potential under Field Conditions in Almonds, Walnuts, and Prunes

2001 ◽  
Vol 11 (4) ◽  
pp. 609-615 ◽  
Author(s):  
Allan Fulton ◽  
Richard Buchner ◽  
Cyndi Gilles ◽  
Bill Olson ◽  
Nick Bertagna ◽  
...  
Keyword(s):  
Sample Size ◽  
Water Potential ◽  
Water Status ◽  
Irrigation Management ◽  
Irrigation Scheduling ◽  
Field Conditions ◽  
Equilibration Time ◽  
Diurnal Changes ◽  
Stem Water Potential ◽  
Stem Water

Covering a plant leaf with a reflective, water impervious bag ensures that equilibrium is reached between the nontranspiring leaf and the stem, and appears to improve the accuracy of determining plant water status under field conditions. However, the inconvenience of covering the leaf for 1 to 2 hours before measuring stem water potential (SWP) has constrained on-farm adoption of this irrigation management technique. A second constraint has been that the requirement of midafternoon determinations limits the area that can be monitored by one person with a pressure chamber. This paper reports findings from field studies in almonds (Prunus dulcis),prunes (P. domestica), and walnuts (Juglans regia) demonstrating modified procedures to measure midday SWP, making it a more convenient and practical tool for irrigation management. For routine monitoring and irrigation scheduling, an equilibration period of 10 min or longer appears to be suitable to provide accurate SWP measurements. Based on the large sample sizes in this study, we estimate that measurement error related to equilibration time for SWP can be reduced to an acceptable level [0.05 MPa (0.5 bar)] with a sample size of about 10 leaves when using a 10-min equilibration period. Under orchard conditions where tree growth and health appears uniform, a sample of one leaf per tree and 10 trees per irrigation management unit should give an accurate mean indicator of orchard water status. Under more variable orchard conditions a larger sample size may be needed. Midmorning and midday SWP both exhibited similar seasonal patterns and responded alike to irrigation events. On some occasions, midday SWP was accurately predicted from midmorning SWP and the change in air vapor pressure deficit (VPD) from midmorning to midday, but both over- and underestimate errors [to 0.3 MPa (3.0 bar)] appeared to be associated with unusually low or high diurnal changes in VPD, respectively. Hence, direct measurement of SWP under midday conditions (about 1300 to 1500 hr) is still recommended.

Effects of ambient ozone on the productivity of Populustremuloides Michx. grown under field conditions

1986 ◽  
Vol 16 (1) ◽  
pp. 47-55 ◽  
Author(s):  
Deane Wang ◽  
David F. Karnosky ◽  
F. Herbert Bormann
Keyword(s):  
Leaf Senescence ◽  
Dry Matter ◽  
Field Experiments ◽  
Ambient Air ◽  
Air Pollutant ◽  
Field Conditions ◽  
Rural Site ◽  
Ambient Ozone ◽  
Foliar Symptoms ◽  
Matter Production

Field experiments were conducted at a rural site in Millbrook, NY, to measure effects of ambient ozone on saplings of Populustremuloides Michx. Over a 3–year period, four clones representing a range of pollutant sensitivities were exposed to charcoal-filtered and ambient air in open-top chambers. Ambient ozone significantly reduced (12–24%) aboveground dry-matter production and modified tree morphology, root/shoot ratios, and rates of leaf senescence. For two clones, biomass was reduced without visible foliar symptoms. This response raises the possibility of widespread, asymptomatic depression of forest productivity under ambient air pollutant conditions.

Photothermal time describes common ragweed (Ambrosia artemisiifoliaL.) phenological development and growth

Weed Science ◽  
1998 ◽  
Vol 46 (5) ◽  
pp. 561-568 ◽  
Author(s):  
William Deen ◽  
L. Anthony Hunt ◽  
Clarence J. Swanton
Keyword(s):  
Leaf Area ◽  
Mechanistic Model ◽  
Field Conditions ◽  
Total Biomass ◽  
Common Ragweed ◽  
Matter Production ◽  
Growth Room ◽  
Time Accumulation ◽  
The Relationship ◽  
Crop Competition

The ability to predict weed phenological development under field conditions is fundamental to the development of mechanistic weed–crop competition models. We studied how phenological development of common ragweed grown under field conditions could be explained using temperature and photoperiod responses derived from growth room experiments. We also determined the relationship between phenological development and common ragweed leaf area, dry matter production, and partitioning. Phenological development of common ragweed emerging at different times in the field was described by photothermal time based on temperature and photoperiod responses derived from growth room experiments. Estimated dates of phenological events of common ragweed were within 4 d of recorded values. Common ragweed seedling density did not influence phenological development. Common ragweed leaf area development, biomass partitioning, and total biomass were related to photothermal time accumulation. The results of this study are consistent with our hypothesis that phenological development is a major factor influencing the outcome of weed–crop competition. Results obtained from this study can be incorporated into a mechanistic model of weed–crop competition.

Selection and evaluation of root nodule bacteria for Dorycnium spp.

2005 ◽  
Vol 45 (3) ◽  
pp. 241 ◽  
Author(s):  
S. R. Davies ◽  
J. G. Howieson ◽  
R. J. Yates ◽  
P. A. Lane
Keyword(s):  
Dry Matter ◽  
Root Nodule ◽  
Field Conditions ◽  
Low Fertility ◽  
Sand Culture ◽  
Nodule Bacteria ◽  
Root Nodule Bacteria ◽  
Pasture Legumes ◽  
Matter Production ◽  
Perennial Legumes

Dorycnium spp. are perennial legumes that have the ability to produce a source of forage in low fertility soils under low rainfall conditions. The inoculation of Dorycnium spp. is currently with the commercial Lotus corniculatus inoculant SU343, which until now had not been trialed against a range of alternative inoculants for Dorycnium spp. A glasshouse trial in sterile sand culture was conducted with 3 species of Dorycnium spp. along with 6 important pasture legumes to evaluate nitrogen-fixing performance, and host and rhizobia interactions. Several inoculants were selected from this trial to undergo evaluation under Tasmanian field conditions. The dry matter production of Dorycnium spp. in the glasshouse and field indicated that SU343 is a suitable inoculant for this genus. A Tasmanian isolate (WSM2338) was identified as a complimentary strain for the inoculation of Dorycnium spp., however, negative interactions with important pasture legumes require further investigation.

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