Showing papers on "Growing season published in 1971"
TL;DR: The reflectance spectra from 500 to 2600 nm were measured for the leaves of six agronomic crops and changes in the internal structure of leaves caused increases in the near infrared wavelengths.
Abstract: Measurements of spectral reflectance characteristics during a growing season of leaves from six crops are reported. These crops include soybeans, wheat, oats, sorghum, corn, and sudangrass. The characteristics measured are related to changes in leaf structure and water content.
140 citations
Journal Article•
TL;DR: The growth of aquatic weeds in natural and man-made bodies of water has created worldwide problems and it has been recognized that there is a residue of resistant organic material that remains in the sediment.
Abstract: The growth of aquatic weeds in natural and man-made bodies of water has created worldwide problems.1-5 Although the mere presence of aquatic weeds is common, little is known about their adverse effect on water quality. During growth there are few detri mental effects because the dissolved oxygen (DO) concentration is increased and inorganic nutrients are absorbed from water. Even at the peak of the growing season, when aquatic weed densities exceed 500 g (dry weight)/ sq m, acceptable water quality may still exist.5-7 At the end of the growing season, or when the weeds are killed, their decomposition may exert heavy demands on the oxygen resources of a water. In addition, large quantities of nutrients may be released from this decaying mass. An assumption has been made that 100 percent of aquatic plant material is completely decomposed when a stand ing crop undergoes decay.8,9 However, it has been recognized that there is a residue of resistant organic material that remains in the sediment.10-11 Burkholder and Bornside12 attempted to determine the magnitude of this refractory fraction under in situ condi tions. Marine grasses suspended in seawater were enclosed in wooden con
94 citations
TL;DR: In this article, an economic model is developed for analysis of investments in irrigation, and the model encompasses the associated problem of temporal allocation of limited irrigation water within the growing season of a single crop.
Abstract: An economic model is developed for analysis of investments in irrigation. The model encompasses the associated problem of temporal allocation of limited irrigation water within the growing season of a single crop. The problem is placed in the framework of stochastic dynamic programming, and it is shown how the algebraic form of the production function for the crop determines the appropriate state variables of the decision process. An application of the model is made to conditions prevalent in Central Missouri with com the irrigated crop.
66 citations
TL;DR: Ground beetles (Coleoptera: Carabidae) found in a 4-year study of cultivated fields in South Dakota included 127 species, and adult activity started to increase rapidly between August 1 and 15, reached its peak during the 1st week of September, and by September 24–30 had dropped to early summer levels.
Abstract: Ground beetles (Coleoptera: Carabidae) found in a 4-year study of cultivated fields in South Dakota included 127 species. The 14 most common species were taken in nearly the same ratios each year. Pitfall traps yielded from 0 to 15 species from each field each week during the growing season; the mean for the season was 4.8 species per week per field.
In all 4 years, adult activity started to increase rapidly between August 1 and 15, reached its peak during the 1st week of September, and by September 24–30 had dropped to early summer levels. Maximum catches were 7–14 times the catches in early summer.
46 citations
Book Chapter•
01 Jan 1971
TL;DR: The major areas of irrigated sugarbeets are in California,Colorado, Idaho, Nebraska, Washington, and Wyoming as discussed by the authors and the major non-irrigated sugar beet areas are in the Red River Valley of Minnesota and North Dakota and in Michigan (37).
Abstract: THE SUGARBEET PLANT is adapted to a wide range in climate. It is
a major crop in irrigated areas because of its tolerance to salinity, hardiness,
and its productivity which makes it a good cash crop under various growing
seasons and soils. The major areas of irrigated sugarbeets are in California,
Colorado, Idaho, Nebraska, Washington, and Wyoming. The major non-irrigated
sugarbeet areas are in the Red River Valley of Minnesota and North Dakota and in Michigan (37).
42 citations
TL;DR: The grasses have not extracted well in the past; however, with recent improvements in agronomy and machinery, cocksfoot can be expected to yield 2000 kg/ha regularly in wetter parts of the British Isles.
Abstract: Several species have been selected for their ability to synthesise protein rapidly. The main factors influencing their protein production were nitrogenous fertiliser, age at harvest, seed rate and climate. Some of the best species were grown either alone or in sequence at optimum rates of seed and N, and harvested to make maximum use of the growing season. The annual yields of extracted protein reached 2000 kg/ha in a good year with winter wheat followed by two crops of mustard or fodder radish. The grasses have not extracted well in the past; however, with recent improvements in agronomy and machinery, cocksfoot yielded 1670 kg/ha in a very dry year and can be expected to yield 2000 kg/ha regularly in wetter parts of the British Isles. It is hoped that similar knowledge will lead to much higher yields in the wet tropics.
39 citations
TL;DR: Merino sheep preferentially grazed the higher phosphate treatments under common grazing of the dry residues during the summer period, while selection continued to a higher level of phosphorus application than was needed to give maximum pasture growth.
Abstract: Nine levels of phosphorus were applied in the autumn of two seasons to 180 plots laid out in a clover pasture. Under common grazing of the dry residues during the summer period, Merino sheep preferentially grazed the higher phosphate treatments. Selection continued to a higher level of phosphorus application than was needed to give maximum pasture growth. A less marked preference was shown for high phosphate during the growing season. Chemical analysis of the dry residues within each year showed little difference due to phosphate treatment except an increase in phosphorus concentration. This ranged from 0.08 to 0.26% phosphorus at the end of the growing season, and from 0.06 to 0.17% in the dry summer residues. Above 0.10–0.15% no marked preference for higher phosphate feed was shown. A small (20–28%) but consistent and significant decrease in the free phenol content of the pasture occurred at higher phosphate levels. and could possibly have accounted for the observed preferences.
30 citations
TL;DR: In this paper, the effects of various rates and times of nitrogen application on the yield of potatoes were determined in field experiments in Michigan, both irrigated and non-irrigated trials were conducted with Katahdin, Russet Burbank, or Sebago varieties.
Abstract: The effects of various rates and times of nitrogen application on the yield of potatoes were determined in field experiments in Michigan. Both irrigated and non-irrigated trials were conducted with Katahdin, Russet Burbank, or Sebago varieties. Petioles were sampled for nitrate determinations one or more times during the growing season on each experiment, and the nitrate level in the soil was also followed throughout the season on Kent sandy loam.
26 citations
TL;DR: In this paper, a method for measuring the depth in soil from which plants absorb nutrients is descrived Radioactive tracers are injected at different depths and when allowance is made for any variations in the extent to which the added tracer is diluted hy labile ions in the soil at each depth the relative quantities of nutrient taken up from different depths can be calculated.
Abstract: A method for measuring the depth in soil from which plants absorb nutrients is descrihed Radioactive tracers are injected at different depths and when allowance is made for any variations in the extent to which the added tracer is diluted hy labile ions in the soil at each depth the relative quantities of nutrient taken up from different depths can be calculated
Results obtained with perennial ryegrass swards of contrasting age indicated that the nptake of P and Ca always occurred predominantly from within the top 125 cm of soil Apart from the initial few months of a sward's life, the proportion of both elements absorbed from different depths for a whole growing season varied little with age of sward up to 31/2 years Considerable changes in the relative contrihution of different depths of soil to uptake occurred within a season; the extent of uptake from the surface layers was primarily influenced by variations in soil-water content and the application of fertilizer to this region
23 citations
TL;DR: Increased phosphorus requirement under grazing is associated with the need for greater uptake of phosphorus under conditions where redistribution of absorbed phosphorus within the plant is prevented by defoliation, and does not appear to be due to effects of defliation on root size.
Abstract: The applied phosphorus requirement of a pasture sown to subterranean clover was measured with and without grazing. Under moderate grazing pressure, in the year of establishment, the pasture required about 50 % more phosphorus than when ungrazed. In the following season, at a higher stocking rate, the grazed areas needed twice as much phosphorus as the ungrazed to make 90% of their maximum growth. In both years this difference in requirement between stocked and unstocked treatments was present throughout the growing season. Increased phosphorus requirement under grazing is associated with the need for greater uptake of phosphorus under conditions where redistribution of absorbed phosphorus within the plant is prevented by defoliation. It does not appear to be due to effects of defoliation on root size. Nor does it depend on differential light interception or on changes in botanical composition.
22 citations
TL;DR: The level of the teratogen cyclopamine in Veratrum californicum varied considerably among plants from various collection sites, and marked variation in both total alkaloid and percentage cyclopamines occurred as a function of stage of growth of the plant.
TL;DR: In this article, a study of barley sprayed at six different stages of development with radionuclides of Cr, Fe, Co, Zn, Hg and Pb was conducted.
TL;DR: The average water potential of all the field-grown plants were lower than levels reported from growth chamber studies as discussed by the authors, even though the soil moisture potential was kept high enough for near-optimum crop production.
Abstract: Laboratory studies have shown that plant water potential affects a number of key processes involved in growth, but there has been almost no information on what levels of water potential occur under irrigated conditions in the field. Before assessing the practical implication of laboratory results on soil and crop management, this type of information must be available. Consequently, plant water potential in irrigated crops of Zea mays, Triticum aestivum, Hordeum vulgaris, Phaseolus vulgaris, Pisum sativum, Solarium tuberosum, Beta vulgaris, and Medicago sativa, L. was measured throughout the growing season in southern Idaho. Soil moisture conditions and potential evapotranspiration were monitored. Daily changes in plant water potential varied from less than 5 bars to more than 20 bars, while random sampling of supposedly homogeneous sets of plants showed an average variation of about 2 bars. Changes due to differences in soil moisture were also detected, even though the soil moisture potential was kept high enough for near-optimum crop production. Though the crops differed widely in their response to changes in environment, the plant water potential was strongly affected by microclimatic conditions. Day-to-day changes in plant water potential generally correlated more closely with changes hi potential evapotranspiration than with changes in soil moisture content. Many of the daily changes observed in the plants remain unexplained, however. In general, the average water potential levels of all the field-grown plants were lower than levels reported from growth chamber studies. Potentials seldom rose above −8 bars and were never observed above −5 bars.
TL;DR: The paper describes in quantitative terms the vegetative spreading of clones ofTypha latifolia in natural conditions and the relations between the rhizome and shoot growth in one-year and two-year clones.
Abstract: The paper describes in quantitative terms the vegetative spreading of clones ofTypha latifolia in natural conditions. The highest rates of the formation of new shoots during the growing season were recorded in the summer (July to early August) and in the autumn (September to October): this corresponds to the two maxima in the increments in rhizome biomass. The highest rate of expansion was observed in two-year clones in which the annual increment in the colony diameter amounted up to 4 m. The relations between the rhizome and shoot growth in one-year and two-year clones are also discussed and a brief comparison of the results with data found in fully developed stands is included.
TL;DR: The composition of volatile oil from foliage of Sequoiadendron giganteum changes considerably during growth of the foliage, and data suggest that the allyl phenylethers may be involved in plant metabolism other than as passive metabolic end products.
TL;DR: No,-N in beet petioles increased to a peak concentration and then decreased exponentially during the two growing seasons on all treatments, and this rate of change approach can be used to predict N needs when adding supplemental N for sugarbeets and to characterize the N status of soil-crop systems.
Abstract: Nitrate-nitrogen in sugarbeet petioles is used to evaluate current N status of sugarbeet crops. Since the NO,-N changes rapidly during the season, better relationships are needed to interpret these data relative to sugarbeet N nutrition. Sugarbeets (Beta vulgaris, L.) were grown at four N fertilization rates and two irrigation levels to determine the root yield, sucrose percentage, sucrose yield, and N uptake in relation to the NO,-N concentration in the petioles. NO,-N in beet petioles increased to a peak concentration and then decreased exponentially during the two growing seasons on all treatments. The exponential decrease after the peak enables prediction of the NO,-N in the petioles during the remainder of the growing season. This rate of change approach can be used to predict N needs when adding supplemental N for sugarbeets and to characterize the N status of soil-crop systems.
TL;DR: Results of laboratory experiments were similar to those obtained from the field study, suggesting that the effects of non-selective vegetation control on the soil microorganisms were caused primarily by the herbicide rather than secondarily by death of the vegetation.
Abstract: Control of fescue meadow vegetation with a non-selective herbicide containing sodium cacodylate as the principal active ingredient increased the numbers of soil bacteria and decreased the numbers of fungi. Both effects were short term and failed to persist throughout the growing season. Results of laboratory experiments were similar to those obtained from the field study, suggesting that the effects of non-selective vegetation control on the soil microorganisms were caused primarily by the herbicide rather than secondarily by death of the vegetation.
TL;DR: In this paper, the authors compared a fixed growing season, from May to September, with those for growing seasons defined as the periods when either the mean air temperature in the screen or the soil temperature at a 50 cm depth exceeds 5 ǫC.
Abstract: Climatic moisture indices for a fixed growing season, from May to September, are compared with those for growing seasons defined as the periods when either the mean air temperature in the screen or the soil temperature at a 50-cm depth exceeds 5 C. Indices for the longer growing seasons based on soil and air temperatures have small differences at individual stations, but are larger than those for the May–September period. When arranged according to increasing index values, the orders of the stations are essentially the same when growing seasons are based on soil and air temperatures. These differ from the May–September order only in cases where late spring and early fall rains are heavy in relation to summer precipitation. Indices based on data for the May–September period adequately describe the water demand-water supply relationships during the period in which water deficits develop. When moisture conditions outside the May–September period are needed the accumulated water surpluses should be considered.
01 Jan 1971
TL;DR: Fertilization resulted in increased height and top weight of red pine seedlings by the end of the second growing season, but also resulted in considerable seedling mortality.
Abstract: Fertilization resulted in increased height and top weight of red pine seedlings by the end of the second growing season, but also resulted in considerable seedling mortality. A high level of watering also increased seedling growth but to a much less extent than fertilization. Fertilization of 1-year-old seedlings resulted in dramatic changes in their chemical composition after one growing season.
Dissertation•
01 Aug 1971
TL;DR: The dominant grass species of the Kamloops area of British Columbia is Agropyron spicatum, but throughout this area there are localized regions where Stipa comata is dominant as mentioned in this paper.
Abstract: The dominant range grass species of climax stands in the Kamloops area of British Columbia is Agropyron spicatum, but throughout this area there are localized regions where Stipa comata is dominant. It was believed that certain edaphic factors influenced the composition of the two grassland stand types. Stipa comata was observed to be growing on gravelly and coarse textured soils with low available water storage capacity, while Agropyron spicatum grew on finer soils with higher water storage capacities. At the beginning of the growing season, soils supporting Agropyron had a higher field moisture content than did nearby soils supporting Stipa. However, Stipa was observed to develop faster and is believed to be more highly adapted to droughty soil conditions.
TL;DR: In this article, a critic of the concept of growing seasons is presented, arguing that it is not the right way to describe the seasons of the year. The Professional Geographer: Vol. 23, No. 4, pp. 337-340.
Abstract: (1971). A CRITIQUE OF THE CONCEPT OF GROWING SEASON. The Professional Geographer: Vol. 23, No. 4, pp. 337-340.
TL;DR: Eight fertilizer experiments were conducted at five locations in the Mallee from 1963 to 1966, following both lucerne and volunteer pastures, to study responses to applied phosphorus and nitrogen in wheat on sandy soils infested with skeleton weed.
Abstract: Eight fertilizer experiments were conducted at five locations in the Mallee from 1963 to 1966, following both lucerne and volunteer pastures, to study responses to applied phosphorus and nitrogen in wheat on sandy soils infested with skeleton weed (Chondrilla juncea). Each year two separate sites were selected-one having no history of sown pasture, the other having supported a poor, but typical lucerne stand for several years. In most years, grain yields were markedly increased by both nutrients following either lucerne or volunteer pasture, and a large positive interaction occurred between phosphorus and nitrogen at five sites. The response to nitrogen obtained after lucerne was due to the low density of the lucerne stands, which had had little effect on skeleton weed populations and soil nitrogen levels. Total yield variation depended mainly on the number of fertile tillers (66 per cent) and grain number per ear (19 per cent). On the other hand, the yield increases to phosphorus and nitrogen were attributed mainly to increases in the number of grains per ear, although increased tiller number also contributed. Grain weight was of little importance in both total yield and yield response. The level of grain protein content depended mainly on the growing season rainfall (r = -0.832). Application of phosphorus reduced grain protein content, and nitrogen increased it. The response to applied nitrogen was related to growing season rainfall (r = 0.783) and the difficulty of determining optimum rates of application is discussed.