Productivity of Vegetable Crops in a Region of High Solar Input. IV. Field Chamber Measurements on French Beans (Phaseolus vulgaris L.) And Cabbages (Brassica oleracea L.)

1975 ◽  
Vol 2 (4) ◽  
pp. 461 ◽  
Author(s):  
PJM Sale
Keyword(s):  
Leaf Area Index ◽  
Leaf Area ◽  
Growth Rates ◽  
Dark Respiration ◽  
Gas Analysis ◽  
Large Field ◽  
Co2 Uptake ◽  
Vegetable Crops ◽  
Area Index ◽  
French Beans

Net CO2 uptakes have been measured for crop canopies of French beans and cabbages, sown at two plant densities, using a large field assimilation chamber and a semi-closed gas-analysis system. For both species, the maximum rates of uptake were a little less than 40 mg CO2 dm-2 (ground area) h-1, and light saturation of the canopy occurred at 600-650 W m-2 (French beans) or about 800 W m-2 (cabbages). Net CO2 uptake decreased with leaf area index at values below about 5, but was relatively insensitive to temperature over the range used. Once this leaf area index was reached, the relationship between net uptake and solar radiation remained fairly constant throughout the growth period. For both species, dark respiration rates were markedly dependent on temperature, and also were lower at night than during the day when measured at the same temperature. For both French beans and cabbages, growth analyses showed the maximum growth rates to be 18-19 g dry weight m-2 (ground area) day-1. The mean growth rate from emergence to harvest for an overwintered cabbage crop was 5.5 g m-2 day-1. It is suggested that the main advantage of the region in terms of plant productivity lies in the long frost-free growing season and the ability of frost-tolerant crops to maintain fairly high growth rates throughout a mild and comparatively sunny winter.

Net Carbon Exchange Rates of Field-Grown Crops in Relation to Irradiance and Dry Weight Accumulation

1977 ◽  
Vol 4 (4) ◽  
pp. 555 ◽  
Author(s):  
PJM Sale
Keyword(s):  
Exchange Rates ◽  
Leaf Area ◽  
Growth Rates ◽  
Co2 Flux ◽  
Large Field ◽  
Co2 Uptake ◽  
Carbon Exchange ◽  
Area Index ◽  
Stages Of Growth ◽  
Net Carbon Exchange

A range of summer and winter vegetable crops has been grown under favourable conditions, and the relation between net carbon exchange and irradiance determined at several stages of growth, using large field assimilation chambers and semi-closed gas analysis systems. For all crops, leaf area index was an important determinant of net carbon exchange rate during early stages of growth, and rates increased markedly from day to day during the period of rapid vegetative development. Except for cauliflower and cucumber, for which leaf area ceased to be so important as the crops developed, maximum rates of CO2 uptake were achieved at maximum leaf areas, and were in excess of 90 mg CO2 dm-2 (ground area) h-1 for sweet corn, about 64 for rockmelon, 50 for broad bean, cauliflower and cabbage, and 45 mg dm-2 h-1 for cucumber. For both rockmelon and cucumber, net carbon exchange rates in the morning were often greater than those at the same irradiances in the afternoon, which suggests partial stomatal closure at about midday. In all crops, variations in temperature of up to 10°C either side of the ambient temperature, imposed at any time during the day, generally had little effect on negative CO2 flux (uptake), but positive CO2 flux at night was strongly influenced by temperature. In cucurbits uptake was reduced at temperatures above 35°C, but rapidly recovered when the temperature was again lowered. High growth rates were achieved by all crops for most months of the year, and the efficiency of utilization of incident energy was also high compared with other reported values. However, growth rates were not related to the maximum rates of CO2 uptake in the day, for net carbon exchange over each 24 h depended also on factors such as the ratio between day- and nightlength and night temperatures.

scholarly journals Comparisons of Herbicide Treated and Cultivated Herbicide-Resistant Corn

2010 ◽  
Vol 2010 ◽  
pp. 1-7 ◽  
Author(s):  
H. Arnold Bruns ◽  
Hamed K. Abbas
Keyword(s):  
Leaf Area Index ◽  
Leaf Area ◽  
Growth Rates ◽  
Negative Impact ◽  
Growth Yield ◽  
Yield Component ◽  
Dry Matter Accumulation ◽  
Negative Effects ◽  
Area Index ◽  
Relative Growth Rates

Four glyphosate resistant corn (Zea maysL.) hybrids, a glufosinate-ammonium resistant hybrid, and a conventional atrazine resistant hybrid gown at Stoneville, MS in 2005, 2006, and 2007 with furrow irrigation were treated with their respective herbicides and their growth, yield, and mycotoxin incidence were compared with untreated cultivated plots. Leaf area index (LAI) and dry matter accumulation (DMA) were collected on a weekly basis beginning at growth stage V3 and terminating at anthesis. Crop growth rates (CRGs) and relative growth rates (RGRs) were calculated. Plots were later harvested, yield and yield component data collected, and kernel samples analyzed for aflatoxin and fumonisin. Leaf area index, DMA, CRG, and RGR were not different among the herbicide treated plots and from those that were cultivated. Curves for LAI and DMA were similar to those previously reported. Aflatoxin and fumonisin were relatively low in all plots. Herbicide application or the lack thereof had no negative impact on the incidence of kernel contamination by these two mycotoxins. Herbicides, especially glyphosate on resistant hybrids, have no negative effects on corn yields or kernel quality in corn produced in a humid subtropical environment.

Productivity of Vegetable Crops in a Region of High Solar Input. III. Carbon Balance of Potato Crops

1974 ◽  
Vol 1 (2) ◽  
pp. 283 ◽  
Author(s):  
PJM Sale
Keyword(s):  
Carbon Balance ◽  
Dark Respiration ◽  
Net Photosynthesis ◽  
Dry Weight ◽  
Gas Analysis ◽  
Co2 Uptake ◽  
Co2 Efflux ◽  
Vegetable Crops ◽  
Weight Changes ◽  
Potato Crops

The carbon balance of potato crops has been studied by measuring canopy net photosynthesis and dark respiration losses with a field assimilation chamber and semi-closed gas analysis system. Results are given for the latter part of growth in both a spring-planted and a summer-planted crop. Net CO2 uptake increased with solar input to reach 35–40mg dm-2 (ground area) h-1 at 400–450 W m-2, but light saturation then occurred and little or no further uptake resulted from increases in solar input up to 1000 W m-2. This supports the previous conclusion that net photosynthesis in the potato is determined by the size of the 'sink' provided by the developing tubers. The imposed experimental variables of reduced solar input (21 and 34% shade) and soil moisture were found not to affect the relation between solar input and CO2 uptake, and the effect of chamber temperature was also very small. Dark respiration rates of the canopy were markedly sensitive to temperature, and also to the solar input prior to measurement. Respiration from the below-ground plant parts accounted for a considerable part of the total plant respiration. In all, 15–20 % of the net assimilation during daylight hours was lost by night respiration. There was little variation in CO2 efflux from uncropped soil during the experiments. Dry weight changes calculated from the gasometric measurements were in accordance with those found from previous growth analysis. * Part II, Aust. J. Agric. Res., 1973, 24, 751–62.

The seasonal growth characteristics of irrigated cotton in a dry monsoonal environment

1965 ◽  
Vol 16 (3) ◽  
pp. 347 ◽  
Author(s):  
WR Stern
Keyword(s):  
Leaf Area Index ◽  
Leaf Area ◽  
Growth Rates ◽  
Dry Matter ◽  
Seasonal Effect ◽  
Cotton Yield ◽  
Seasonal Growth ◽  
Seed Cotton ◽  
Area Index ◽  
Seed Cotton Yield

Cotton plantings were made at the Kimberley Research Station (128° 36´ E., 15° 42´ S.) from September to July to give overlapping growth curves extending from September 1961 to December 1962. Crop growth was examined in relation to radiation and temperature. Beginning at the third week from sowing, each planting was sampled 12 times at intervals of 15 days. At each sampling, dry matter, leaf area index, number and dry weight of bolls, and seed cotton yield were determined. The development of total dry matter and leaf area index showed a strong seasonal trend. The number of bolls produced was less in the late plantings, and the seed cotton yield was correspondingly lower. The highest seed cotton yields and the highest ratios of seed cotton to total dry matter (30%) were obtained with January–February plantings. The growth rates between 50 and 100 days were used to analyse seasonality; the highest seasonal growth rate was 164 mg dm-2 day-1 in December–January and the lowest value was zero in early September. By using fitted harmonics, a multiple correlation was established between maximum and minimum temperatures and growth rates 30 days later. Potential rates of net photosynthesis of tops were calculated from observed radiation data with the use of the de Wit model and with allowance for light wastage, root growth, and respiration. There was good agreement between observed and potential growth rates from December to April. Midday stomatal apertures declined from November to May, and this appeared to be a seasonal effect. An annual pattern for the diffusive resistance of carbon dioxide through the leaf surface into the substomatal cavities is calculated. Radiation did not appear to be the primary limiting factor, and the seasonal growth pattern was interpreted in terms of the composite effect of maximum and minimum temperatures on extension growth, stomatal opening, and the presence or absence of suitable sinks for carbohydrates. Growth rates are evaluated against rates observed elsewhere, and means of exploiting the Kimberley environment are discussed.

Photosynthesis in Artificial Communities of Wheat, Lucerne, and Subterranean Clover Plants

1967 ◽  
Vol 20 (3) ◽  
pp. 623 ◽  
Author(s):  
RW King ◽  
LT Evans
Keyword(s):  
Leaf Area Index ◽  
Leaf Area ◽  
Dark Respiration ◽  
Subterranean Clover ◽  
Net Photosynthesis ◽  
Area Index ◽  
Light Intensities

The relation between leaf area index (L.A.I.) and rates of net photosynthesis at three light intensities, and of dark respiration, was examined throughout the course of growth of artificial communities of wheat and lucerne at 20�C, and of subterranean clover at 25� /20�C.

scholarly journals Study of a Non-destructive Method for Estimating the Leaf Area Index in Vegetable Crops Using Digital Images

HortScience ◽  
2010 ◽  
Vol 45 (10) ◽  
pp. 1459-1463 ◽  
Author(s):  
Carlos Campillo ◽  
M.I. García ◽  
C. Daza ◽  
M.H. Prieto
Keyword(s):  
Leaf Area Index ◽  
Leaf Area ◽  
Digital Images ◽  
Direct Methods ◽  
Vegetable Crops ◽  
Simple Method ◽  
Area Index ◽  
Skilled Operator ◽  
Significant Area ◽  
Non Destructive

One estimate of a crop's ability to capture light energy is the leaf area index (LAI), which is defined as the proportion of leaf area per unit of land area. Direct methods of estimation involve determining the LAI in a significant area of cultivation and individually measuring the leaf surface, which is often tedious. The objective of this study was to develop a cheap and simple method for determining LAI based on the percentage of groundcover (PGC) measured in two vegetable crops with notable differences in leaf type and plant architecture using digital images obtained with a commercial camera and applying open-source software. The PGC values obtained from digital image analysis in cauliflower and tomato crops and the measurements of LAI obtained by destructive sampling (measured with a planimeter) allowed us to obtain a relationship between two variables (r2 > 0.88). In all cases, the extinction coefficients were obtained from comparisons of LAI and PGC with values ranging between 0.75 and 0.85 for processing tomato and 0.60 and 0.70 for cauliflower. The method used allows non-destructive estimations of LAI that are comparable with other more expensive indirect methods that require a skilled operator.

scholarly journals Photosynthesis in Artificial Communities of Cotton Plants in Relation to Leaf Area I. Experiments with Progressive Defoliation of Mature Plants

1965 ◽  
Vol 18 (6) ◽  
pp. 1103 ◽  
Author(s):  
LJ Ludwig ◽  
T Saeki ◽  
LT Evans
Keyword(s):  
Leaf Area Index ◽  
Leaf Area ◽  
Dark Respiration ◽  
Net Photosynthesis ◽  
Area Index ◽  
Light Intensities ◽  
Cotton Plants

The relation between the leaf area index (L.A.I.) of artificial communities of cotton plants and their rates of dark respiration and of net photosynthesis at three light intensities was examined. The L.A.I. was varied by the removal of successive layers of leaves, working from the base of the canopy upwards. Experiments were carried out at 20, 30, and 40�0 to vary the relative magnitudes of respiration and photosynthesis.

The interrelationship of solar radiation and leaf area index in determining the rate of dry matter production of swards of subterranean clover (Trifolium subterraneum L.)

1963 ◽  
Vol 14 (1) ◽  
pp. 20 ◽  
Author(s):  
JN Black
Keyword(s):  
Growth Rate ◽  
Solar Radiation ◽  
Leaf Area Index ◽  
Leaf Area ◽  
Growth Rates ◽  
Subterranean Clover ◽  
Crop Growth ◽  
Area Index ◽  
Specific Level ◽  
Crop Growth Rate

The relationship of crop growth rate, leaf area index, and solar radiation has been examined for swards of subterranean clover, of the variety Bacchus Marsh. Leaf area index was varied by growing swards at eight densities of sowing, and radiation varied by two levels of shading, in addition to full daylight; the whole experiment was done three times—in summer, early winter, and spring—at the Waite Agricultural Research Institute, Adelaide. Crop growth rate was measured as the difference between the dry weights of the swards on two harvest occasions, and was calculated from smoothed values obtained by fitting an appropriate equation to the yield : density relationship. Thus a set of nine curves were available, each showing the response of growth rate to varying leaf area index at a specific level of radiation. These nine curves formed a consistent series, the growth rate rising with leaf area index until a maximal value was reached at the "optimum leaf area index", thereafter falling. At low levels of radiation, growth rate fell to zero at high leaf area indices. Both the maximal growth rate and the optimum leaf area index increased with radiation, and an analysis of the data indicated that these growth indices were dependent on radiation, the effect of temperature being negligible. A generalized series of curves was calculated by extrapolation, so that crop growth rates can be derived for any combination of leaf area index and radiation. A comparison of maximal crop growth rates and percentage utilization of light energy of subterranean clover and other crops suggests that this clover is relatively inefficient in integrating its environment.

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