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Root oxygen deprivation and the reduction of leaf stomatal aperture and gas exchange
Get PDFThe most ubiquitous plant abiotic stress in the global
environment is generally thought to be water deficit.
The opposite of water-deficit stress. flooding, initially
involves relief of the abiotic factor of water deficit and
only becomes stressful after flooding persists long
enough to directly or indirectly interfere with a variety
of plant functions via several mechanisms. The
relief of stress with short term flooding (typically a
day or less) is the principle upon which irrigation
hinges. By contrast, the negative impacts of prolonged
flooding on ecosystems, and particularly agricultural
production systems, are substantial [I] and
may be as significant as drought, depending on one's
accounting strategy. Much of this impact is the result
of the combination of soil and plant chemical, physical,
and biological changes that cause stomata to
close after prolonged flooding. This contributes significantly
to a drastic reduction in photosynthesis and
damages many other plant functions by disrupting
transpiration and the complex system of hormonal
control of plant systems and processes
Evaluation of commercial sugarbeet hybrids for resistance to beet curly top in Canyon County, ID, 2004
Get PDFThe experiment was conducted in a commercial sprinkler-irrigated sugarbeet field near Nampa, ID in an area where
Beet curly top virus had been a problem in previous years. The field trial relied on natural infection and was planted on 19
Mar. The plots were planted to a density of 190,000 seeds/A, and thinned to 35,640 plants/A. Plots were four rows wide
(22 in-row spacing) and 36 ft long. The experimental design was a randomized complete block with eight replications.
The crop was managed by the grower according to standard cultural practices. The weather during the growing season was
cooler than normal. Disease data were recorded on 14 Sept by three raters using a disease index of 0 to 9 (no symptoms to
dead). The three ratings per plot were averaged prior to analysis. The center two rows were harvested on 20 Oct using a
small plot harvester. The sugar content of the beets was determined by the Amalgamated Sugar Co. laboratory, and the
recoverable sugar (lb/A) was estimated. Data were analyzed using the general linear models procedure (Proc GLM-SAS),
and Fisher's Protected LSD was used for mean comparisons.
Yields were above average and disease pressure was uniform and moderately severe. The commercial hybrids response
to Beet curly top virus ranged from acceptable (slight leaf curl to most leaves with moderate curling) to severely affected
(most larger leaves becoming prostrate). Analysis of variance indicated there were significant differences among hybrids for
diseases index, root yield, sugar content, and estimated recoverable sugar. Our disease ratings positively correlated (r s =
0.913, P < 0.0001) with those from the 04 Curly Top Nursery in Kimberly, ID. Based on Spearman's Coefficient of Rank
Correlation (rs = -0.737, P < 0.0001), there was an inverse relationship between estimated recoverable sugar and disease
index
Control of white mold of dry beans with foliar sprays in Jerome County, ID, 2004
Get PDFThe experiment was conducted in a commercial sprinkler-irrigated, dry edible bean field, where white mold had been
severe in previous years. The soil type was a medium silt loam (pH 7.8). Three of the treatments received early applications
on the 14 Jul when 6% of the plants had at least one open bloom. Additional materials were applied on 21 Jul when 100%
of the plants had at least one open bloom. Treatments were applied as dilute foliar sprays at 37 gal/A and 40 psi (measured
at the boom) using a nitrogen gas pressurized sprayer with two hollow cone drop nozzles (facing the sides of the plants) per
row. The mean number of plants per 10 ft of row was 34. Experimental units consisted of four rows spaced 22 in. apart
and 25 ft long, and were arranged in a randomized complete block design with four replications. The crop was managed by
the grower according to standard cultural practices. Disease incidence and severity data from two 10-ft-center row
segments per experimental unit were recorded on 3 Sep, after which the same row segments were harvested. Each plant
was placed in one of the following three categories for calculating disease severity: non-infected (NI), plants with pod
infection or upper stem infection only (P), and plants with basal stem infection (B). After drying in burlap bags in the
greenhouse, bean plants were threshed on 16 Sep with a belt thresher. Beans were screened through a 9/64 in. slotted
screen to eliminate debris and culls and weighed to determine yield. Data were analyzed using the general linear models
procedure (Proc GLM) in SAS. Fisher's Protected LSD was used for mean comparisons.
Yields were above average and not significantly different. There was very little disease pressure and therefore we were
unable to establish significant differences for both disease incidence and severity. No phytotoxicity was observed
Irrigation methods
Get PDFIrrigation is the process of applying water to soil,
primarily to meet the water needs of growing plants.
Water from rivers, reservoirs, lakes, or aquifers is
pumped or flows by gravity through pipes, canals,
ditches, or even natural streams. Applying water to
fields enhances the magnitude, quality, and reliability
of crop production — approximately 30% of the
world's food is grown on irrigated land, which accounts
for only about 15% of the world's land used
for crop productio
Ruminant selection among switchgrass hays cut at either sundown or sunup
Get PDFAs a result of photosynthesis, plants typically have greater concentrations of nonstructural carbohydrates at the end of the photoperiod. The preference of ruminants for hays harvested within the same 24-h period can be greater for plants harvested late in the photoperiod with increased soluble carbohydrate. To test for variation in ruminant preference for afternoon versus morning harvested hays in a C4 grass harvested in the humid east, established fields of 'Kanlow' and 'Alamo' switchgrass (Panicum virgatum L.) were used to produce hays in 1998, 1999, and 2000 near Raleigh, NC. Harvests were paired so that each cutting in the evening (PM) was followed by a cutting the next morning (AM). We harvested in this manner three times in 1998 to produce six Kanlow hays; twice with Kanlow and once with Alamo at two levels of nitrogen fertility in 1999 to produce eight hays; and three times in 2000 to produce six Alamo hays. The hays were field-dried, baled, and passed through a hydraulic bale processor. Hays from each year were tested with cattle (Bos taurus L.), goats (Capra hircus L.), and sheep (Ovis aries L.). During an adaptation phase, hays were offered individually. In the experimental phase, all possible pairs of hays were presented. Data were analyzed by multidimensional scaling and by traditional analyses. Multidimensional scaling indicated that selection was based on multiple criteria. The suite of improvements associated with PM-harvested hays in fiber content, digestibility, and nonstructural carbohydrate observed for alfalfa and fescue hays in the western USA was difficult to reproduce with switchgrass hay in the southeastern USA. This difficulty is likely related to the less favorable environment for haymaking as well as the physiology, anatomy, and morphology of this C4 grass
New furrow flume for high sediment loads
Get PDFMeasurement of water flow in furrows from either irrigation or rainfall is difficult when significant soil erosion
occurs. It can be accomplished with flumes that back up flow in the furrow, which for moderate to steeply sloping fields causes
only small changes in furrow water depth and thus has little influence on the water flow measurement. However, the ponding
of water upstream from a flume can have a significant impact on the movement of sediment down the furrow. In one research
study, measured sediment transport through the flume was reduced 40% over that measured in a furrow with only a
non– constricting metal form that matched the furrow shape. A new furrow flume has been designed that overcomes the
limitations of current v–shaped flumes or trapezoidal EEC flumes that cause significant backwater during furrow irrigation.
This new flume has a trapezoidal shape with only a side contraction. It was designed to keep flow velocities high over the
full range of flow conditions. This new flume is commercially available and has been working successfully in the field for three
seasons
Nonstructural carbohydrate and digestibility patterns in orchardgrass swards during daily defoliation sequences initiated in evening and morning
Get PDFHerbage soluble carbohydrate (SC) levels vary diurnally and livestock
intake can be higher for herbage harvested or allocated to
animals in the evening than in the morning. Few assessments of SC
and digestibility patterns have been made during sward depletion in
rotationally stocked orchardgrass (Dactylis glomerata L.). We tested
the hypothesis that simulated evening daily pasture allocation increases
24-h mean herbage SC and digestibility levels relative to morning
allocation. Total nonstructural carbohydrate (TNC) and in vitro
true dry matter digestibility (IVTDMD) levels were compared during
24-h clipping sequences initiated at 1900 h (PM) and 0700 h (AM).
Sward height was progressively reduced from 40 to 8 cm at 6-h intervals
in October, June, and August. Successively lower horizons from defoliation
sequences and also from control areas that were not under
progressive defoliation were analyzed. Digestibility and TNC levels
varied diurnally and seasonally, and were often higher for PM sequences,
but differences among 24-h means were small. Daily mean
TNC levels for defoliation sequences initiated in PM and AM were
138 vs. 132, 93 vs. 88, and 72 vs. 60 g kg' in October, June, and August,
respectively. In all periods, digestibility decreased from approximately
920 to 800 to 890 g kg' during sward depletion and displayed similar
patterns between defoliation sequences. Patterns of TNC and digestibility
during sward depletion may not be represented by those in
intact swards, and PM allocation of daily herbage may not increase
24-h mean dietary TNC density relative to AM allocation. Daily quantities
of ingested TNC could be higher for PM herbage allocation if
livestock consume proportionately more herbage in the PM than
we simulated
Seed treatments for improved stand and yield in dry beans in Twin Falls County, ID, 2004
Get PDFThe experiment was established at the Kimberly Research and Extension Center on 3 Jun. The field had been in winter
wheat (Triticum aestivum) in 2003 and was furrow irrigated. Soil type was Portneuf silt loam (20 -74-6% sand-silt-clay and
pH 7.9). Seed treatments were applied as a slurry (12 fl oz/100 lb seed) on 14 May at the rates indicated in the table below.
Experimental units consisted of 4 rows spaced 22 in. apart x 25 ft long, and were arranged in a randomized complete block
design with 4 replicates. At planting the minimum and maximum soil temperatures at 2 in. depth were 59 and 84°F,
respectively. Fertility, weed and insect control, and irrigation management were consistent with common commercial
practices. Stand counts were recorded on 11 Jun and 16 Jun at late -emergence and primary leaf stages, respectively. Roots
from 10 plants were collected from border rows in each plot on 16 Jul when all plants had at least one open flower. The
plants were evaluated for root rot on a scale of 0-4 (0 = none; 4 = severe root rot). Beans were cut on 24 Aug and dried on
the soil surface until they were threshed on 1 Sep with a belt thresher. Beans were screened through a 9/64 in. slotted
screen to eliminate debris and culls and weighed to determine yield. Data were analyzed using the general linear model
procedure (Proc GLM) in SAS. Fisher's Protected LSD was used for mean comparisons.
Yields in the field were below average and not significantly different. Dynasty delayed emergence in the first stand
count since treatments with this product had fewer plants than the untreated check. In the second stand count 5 days later
there were no differences in stand between treatments. All treatments with mefanoxam and fludioxonil (Apron XL plus
Maxim or ApronMAXX) had reduced root disease severity
Technologies to minimize water quality impacts of irrigated agriculture
Get PDFIrrigation transformed arid land in the Pacific Northwest into productive agricultural
land. However, much of this land is prone to erosion during irrigation, which can
cause problems on and off of the field. Management practices have been developed to
control soil erosion on irrigated land and improve the quality of water returning to
streams and rivers. Applying polyacrylamide (PAM) with irrigation water can reduce
erosion from furrow irrigated fields more than 90%. Using PAM in combination with
other practices, such as applying straw mulch in furrows and installing small
sediment ponds on fields, can virtually eliminate sediment loss from fields. Once soil
runs off a field, it can be removed by settling in sediment ponds, although soluble
nutrients remain in the water. Applying 20 mg/L alum to irrigation return flow water
can remove about 50% of the soluble phosphorus that will not be removed as
suspended sediment settles in ponds. Using these management practices allows
irrigation to continue with minimal impact on water quality
Field-scale evaluation of phosphorus leaching in acid sandy soils receiving swine waste
Get PDFAccurate descriptions of P leaching are important because excess
P applied to soils can enter surface water via leaching and subsurface
transport, thereby negatively impacting water quality. The objectives
of this study were to monitor P leaching in soils with a long-term
history of waste application, relate soil solution P concentrations to
soil P status, and quantify P leaching losses. Soil solution was monitored
for 20 mo with samplers installed at 45-, 90-, and 135-cm depths
in two pits (1 X 3 X L5 m) in Autryville (loamy, siliceous, thermic
Arenic Paleudults) and Blanton (loamy, siliceous, semiactive, thermic
Grossarenic Paleudults) soils located in a grazed pasture in Sampson
County, NC, which had received swine waste for >20 yr. Maximum
soil solution P concentrations at 45 cm exceeded 18 mg L' in both
soils. Soil solution P concentrations at 90 cm in the Blanton soil were
similar to that at 45 cm indicating low P sorption. Soil solution P
concentrations at 90 cm in the Autryville soil averaged 0.05 mg L-'
compared to 10 mg L' at 45 cm. A split-line model related soil solution
P concentration to the degree of phosphorus saturation (DPS),
identifying a change point at 45% DPS. Phosphorus movement past
45 cm equaled or exceeded surplus P additions for both soils. Longterm
waste applications resulted in DPS > 90%, high soil solution
P concentrations, and substantial vertical P movement. Phosphorus
leaching should be considered when assessing long-term risk of P loss
from waste-amended soils