Competition between skeleton weed (Chondrila juncea L) and cereals in relation to nitrogen supply

1958 ◽  
Vol 9 (1) ◽  
pp. 1 ◽  
Author(s):  
LF Myers ◽  
J Lipsett
Keyword(s):  
Crop Yields ◽  
Nitrogen Supply ◽  
Weed Competition ◽  
Nitrogen Application ◽  
High Nitrogen ◽  
Nitrogen Levels ◽  
Grain Nitrogen ◽  
Low Nitrogen ◽  
Yield Of Oats ◽  
Plant Growth Regulating Substances

The effect of skeleton weed competition on the yield of wheat and oats was investigated in seasons when rainfall was plentiful. Nitrogen was found to be the major factor limiting crop yields. In soils with comparable nitrogen-supplying powers, skeleton weed density governed the crop's response to applied nitrogen. Competition between skeleton weed and crop was severe at low nitrogen levels, but minor at the high nitrogen levels achieved either by nitrogen application, or when the crop followed a legume-rich pasture. Competition had its effect early in the crop's growth. Temporary removal of competition, by spraying with plant growth regulating substances (JICPA) at different times, was used to determine when competition was critical, and measure its effects. Skeleton weed reduced nitrogen supply early in the crop's growth, and so depressed yield. An application of 1 lb MCPA per acre in the fallow 54 days before sowing, or 10 days after crop emergence, increased the yield of oats from 710 to 1350 lb grain per acre: a response equal to that from 32 lb nitrogen per acre applied at planting in the same experiment. In each case, the response to spraying at the different times was analogous to the effect of a nitrogen application at these times. Early spraying gave responses in yield; later spraying gave responses in grain nitrogen. The results provide a new estimate of the reduction in crop yield due to skeleton weed.

Effects of endophyte infection on the competitive ability of Achnatherum sibiricum depend on endophyte species and nitrogen availability

2019 ◽  
Vol 12 (5) ◽  
pp. 815-824
Author(s):  
Yong Zhou ◽  
Xia Li ◽  
Hui Liu ◽  
Yubao Gao ◽  
Wade J Mace ◽  
...  
Keyword(s):  
Dominant Species ◽  
Competitive Ability ◽  
Nitrogen Availability ◽  
Inhibitory Effect ◽  
Nitrogen Supply ◽  
Tiller Number ◽  
High Nitrogen ◽  
Nitrogen Levels ◽  
Endophyte Infection ◽  
Low Nitrogen

Abstract Aims The leaves of almost all terrestrial plant species are colonized by endophytic fungi. Compared to agronomic grasses, which usually harbor few endophytes, native grasses generally possess greater endophyte species diversity. Existing studies examining endophyte effects on natural grasses under competition normally considered the infection status (infected or uninfected), and rarely considered endophyte species. Methods We examined the effects of endophyte infection and of endophyte species on the interspecific competitive ability of a subdominant species, Achnatherum sibiricum, at two nitrogen levels (high nitrogen and low nitrogen). Achnatherum sibiricum plants infected by two different species of endophyte (Epichloë sibirica and E. gansuensis) and uninfected plants were grown in monoculture and binary mixtures with a dominant species, Stipa grandis (six individuals per species for monocultures and three + three individuals of each species in mixtures). Shoot and root biomass, tiller number and total phenolic concentration were measured after 3 months. Moreover, the aggressivity index was calculated to compare the competitive ability of A. sibiricum relative to S. grandis. Important Findings Both E. gansuensis (Eg)- and E. sibirica (Es)-infected A. sibiricum plants showed a greater competitive ability than the uninfected plants under high nitrogen supply, while the opposite result occurred under low nitrogen supply. At high nitrogen levels, Eg plants had a higher tiller number and a greater shoot biomass inhibitory effect on S. grandis than Es plants had when growing in mixture, while Es plants showed better root growth performance than Eg and uninfected plants under mixture conditions at all nitrogen levels. A higher concentration of phenolic compounds in Eg plants than in Es plants might contribute to the higher inhibitory effect of Eg plants on competing plants. Our study indicates that the interaction between endophyte infection and nitrogen availability can alter the competitive ability of the host plant A. sibiricum but that these two endophyte species work in different ways, which may influence the coexistence of A. sibiricum with the dominant species.

scholarly journals Nitrogen Levels Regulate Sugar Metabolism and Transport in the Shoot Tips of Crabapple Plants

2021 ◽  
Vol 12 ◽  
Author(s):  
Lihua Zhang ◽  
Simin Sun ◽  
Yonghui Liang ◽  
Baiyun Li ◽  
Songya Ma ◽  
...  
Keyword(s):  
Sugar Metabolism ◽  
Net Photosynthesis ◽  
Sucrose Phosphate Synthase ◽  
Nitrogen Supply ◽  
Shoot Tips ◽  
High Nitrogen ◽  
Nitrogen Levels ◽  
Nitrogen Treatment ◽  
Low Nitrogen ◽  
Growing Shoot

To comprehensively understand the responses of carbohydrate metabolism and transport to different levels of nitrogen supply in growing shoot tips of crabapple (Malus hupehensis Rehd), enzyme activities and related genes involved in the sugar metabolism pathway were investigated. The nitrogen and chlorophyll content of plants increased with increasing nitrogen supply. High nitrogen application increased the net photosynthesis rate and the growth rate of shoot tips but decreased the synthesis capability of sucrose and sorbitol in mature leaves. However, the shoot tips of plants under high-nitrogen treatment had higher contents of sucrose and sorbitol than did those under low-nitrogen treatment, while the activity of sucrose phosphate synthase and aldose-6-phosphate was increased and the transporters MdSOT and MdSUT were up-regulated. Moreover, the activities of enzymes involved in sucrose and hexose metabolism (including sucrose synthase, fructokinase, and hexokinase) were enhanced in the shoot tips of plants under high-nitrogen conditions, and the expression levels of MdSUSY3 and MdHK1 were significantly up-regulated. These findings indicate that a high nitrogen supply increases the metabolic capacity of assimilatory substances in shoot tips, accelerates the efficiency of sugar utilization and eventually leads to a rapid increase in the growth of shoot tips. Our results highlight that high nitrogen increases the capacity of sugar unloading and metabolic utilization in growing shoot tissues.

The association of dry-matter yield with nitrogen and soluble-carbohydrate concentration in perennial ryegrass (Lolium perenne L.)

1979 ◽  
Vol 93 (3) ◽  
pp. 657-667 ◽  
Author(s):  
J. Valentine ◽  
A. H. Charles
Keyword(s):  
Nitrogen Concentration ◽  
High Yield ◽  
Soluble Carbohydrate ◽  
Nitrogen Application ◽  
Simple Correlation ◽  
Nitrogen Levels ◽  
Carbohydrate Concentration ◽  
Growth Room ◽  
Selection For ◽  
Low Nitrogen

SUMMARYThe associations between yield, nitrogen and soluble-carbohydrate concentration within S. 23 perennial ryegrass were investigated at three levels of nitrogen application. Controlled growth room conditions were used.The simple correlation between yield and nitrogen concentration was negative at the low rate of nitrogen application, not present at the intermediate rate of nitrogen and positive though not significant at the high rate of nitrogen. Yield and soluble-carbohydrate concentration were only correlated (positively) at the low nitrogen rate.At low nitrogen there were ‘efficient’ genotypes with relatively high yield and low nitrogen concentration. ‘Inefficient’ genotypes had relatively low yields and high nitrogen concentration. The majority of genotypes were neither markedly efficient or inefficient. The efficient genotypes at low nitrogen maintained their yield advantage at higher nitrogen levels with average nitrogen concentration and high numbers of tillers. Inefficient genotypes remained relatively stable in yield, numbers of tillers and nitrogen concentration.Partial correlation indicated an underlying high degree of dependence between yield, nitrogen and soluble-carbohydrate concentration at all nitrogen levels. The association of yield and nitrogen concentration showed a similar trend over nitrogen levels to that obtained using simple correlation. Yield and soluble-carbohydrate concentration were positively related, and nitrogen and soluble-carbohydrate concentration inversely related, when the effects of the remaining attribute were eliminated.Data extracted from Lee et al. (1977) confirmed that yield and nitrogen concentration for varieties under field conditions varied with level of nitrogen application in a similar manner to genotypes in the controlled growth room. The variety (Melle) could be characterized as being particularly efficient.Both sets of results indicate that selection for high yield of nitrogen in herbage can best be achieved through selection for yield alone.

Effect of nitrogen fertilization on the growth of Sporobolomyces roseus on wheat leaves

1982 ◽  
Vol 60 (12) ◽  
pp. 2741-2744 ◽  
Author(s):  
R. Frossard ◽  
N. J. Fokkema
Keyword(s):  
Spring Wheat ◽  
Nitrogen Fertilization ◽  
Nitrogen Supply ◽  
Nitrogen Compounds ◽  
Controlled Environment ◽  
High Nitrogen ◽  
Flag Leaves ◽  
Sporobolomyces Roseus ◽  
Wheat Leaves ◽  
Low Nitrogen

Green flag leaves of spring wheat grown with low or high nitrogen supply in the form of Ca(NO3)2 were inoculated with Sporobolomyces roseus. Growth of the yeast in a controlled environment was followed for several days by culturing techniques. No consistent differences were found between the development of S. roseus on leaves from low or high nitrogen treated plants, suggesting that leaf exudates from low nitrogen treated plants still contain enough nitrogen compounds to support growth of S. roseus. Nitrogen fertilization obviously seems not to be an appropriate means to manipulate the phyllosphere mycoflora.

The absorption and distribution of nitrogen after floret initiation in wheat

1969 ◽  
Vol 20 (5) ◽  
pp. 799 ◽  
Author(s):  
HM Rawson ◽  
CM Donald
Keyword(s):  
No Value ◽  
Wheat Plant ◽  
Nitrogen Supply ◽  
Main Stem ◽  
Fertile Plant ◽  
High Nitrogen ◽  
Plant Parts ◽  
Labelled Nitrogen ◽  
To Receive ◽  
Low Nitrogen

The pattern of absorption and distribution of nitrogen after floret initiation in wheat was examined with the aid of labelled nitrogen with a view to determining the importance of sterile tillers as a source of nitrogen for the fertile parts of the plant. Tertiary tillers were found to be of no importance as direct importers of nitrogen from the growth medium; absorption by these tillers was almost entirely via the roots of the main stem and the primary tillers. In conditions of high nitrogen supply the tertiary tillers continued to receive nitrogen from the main stem and primary tillers, but the tertiary tillers of low nitrogen plants were starved of nitrogen and soon senesced. When the sterile, tertiary tillers died there was a remobilization of most of their nitrogen, apparently to the fertile parts (main stem, primary and some secondary tillers) of the plant, but a small quantity of nitrogen was also lost to the nutrient solution. It is concluded that although sterile, tertiary tillers act as a temporary nutrient reservoir for the fertile plant parts, they are in fact of little or no value and may well be regarded as a useless vestige of perenniality in the wheat plant.

Low-temperature induced floret sterility in the rice cultivars Calrose and Inga as influenced by nitrogen supply

1984 ◽  
Vol 24 (125) ◽  
pp. 255 ◽  
Author(s):  
DP Heenan
Keyword(s):  
Low Temperature ◽  
Pollen Development ◽  
Nitrogen Supply ◽  
Nitrogen Level ◽  
Rice Cultivars ◽  
High Nitrogen ◽  
Nitrogen Levels ◽  
High Nitrogen Level ◽  
Temperature Controlled

An experiment in temperature-controlled glasshouse chambers at Yanco Agricultural Institute examined floret sterility in lnga and Calrose rice induced by low temperature and high nitrogen level. Low temperature (12�C) ,for 4 d during microsporogenesis and anthesis produced considerable sterility in both cultivars; lnga was more sensitive than Calrose. Sensitivity was greatest when florets from the mid-section of the panicle were passing through the early microspore phase of pollen development. At both stages, the amount of low-temperature induced sterility was increased by high nitrogen supply. In the absence of low temperature, high nitrogen levels induced sterility in lnga only.

Effects of varying nitrogen supply at different stages of the reproductive phase on spikelet and grain production and on grain nitrogen in wheat

1973 ◽  
Vol 24 (5) ◽  
pp. 647 ◽  
Author(s):  
RHM Langer ◽  
FKY Liew
Keyword(s):  
Leaf Area ◽  
Flag Leaf ◽  
Grain Filling ◽  
Solution Culture ◽  
Nitrogen Supply ◽  
Nitrogen Application ◽  
Stage Number ◽  
Leaf Area Duration ◽  
Three Stages ◽  
Grain Nitrogen

Plants of wheat cv. Arawa confined to the main shoot were grown in solution culture in a glasshouse. Nitrogen supply was either high (150 p.p.111.) or low (15 p.p.m.) at three stages of development: between the double-ridge stage and floret initiation, between then and ear emergence, or after ear emergence, giving eight treatment combinations. Spikelet numbers were increased only by raising nitrogen supply at the doubleridge stage. Number of grains per spikelet also responded to treatment during the same period, but was greatest when high nitrogen was given until ear emergence. This response depended on the position of the spikelet within the ear, and the basal and terminal spikelets contributed least when nitrogen supply was low. Individual grain weight responded less to treatment than grain numbers. Nitrogen application had a large effect on leaf area duration, but the grain/leaf ratio (G) was depressed. Since their appeared to be no nitrogen effects on photosynthesis per unit flag leaf area, it is suggested that grain yield was controlled mainly by the capacity of the ear to accept carbohydrate, depending on the number of sites available for grain filling. Percentage grain nitrogen increased with lateness of nitrogen application. However, raising nitrogen supply before ear emergence and then decreasing it again also affected grain nitrogen in the ear, which suggests redistribution during grain filling

Shoot biomass in wheat is the driver for nitrogen uptake under low nitrogen supply, but not under high nitrogen supply

2014 ◽  
Vol 165 ◽  
pp. 92-98 ◽  
Author(s):  
Yoshiaki Kamiji ◽  
Jiayin Pang ◽  
Stephen P. Milroy ◽  
Jairo A. Palta
Keyword(s):  
Nitrogen Uptake ◽  
Nitrogen Supply ◽  
Shoot Biomass ◽  
High Nitrogen ◽  
Low Nitrogen

scholarly journals The ESX-1 secretion system senses bacterial contact and prepares mycobacteria for environmental adaptation

2021 ◽  
Author(s):  
Nadia Herrera ◽  
Pascal D Odermatt ◽  
Mark Voorhies ◽  
Rachel Nakagawa ◽  
Anita Sil ◽  
...  
Keyword(s):  
Mycobacterium Smegmatis ◽  
Transcriptional Profiling ◽  
Secretion System ◽  
Environmental Adaptation ◽  
High Nitrogen ◽  
Nitrogen Levels ◽  
Genome Wide ◽  
Early Secretory Antigenic Target ◽  
System 1 ◽  
Low Nitrogen

The ESX-1 system (6-kDa early secretory antigenic target (ESAT-6) secretion system-1) is essential for Mycobacterium tuberculosis pathogenesis and conjugal transfer in Mycobacterium smegmatis, yet little is known about how its function is regulated. Live-cell fluorescence microscopy showed natively expressed ESX-1 was organized into distinct foci predominantly observed at cell-cell contacts. These foci formed when two cells touched and required a fully assembled ESX-1 system in both bacteria, suggesting the generation of an ESX-1 megacomplex across multiple membranes. The emergence of ESX-1 foci and ESX-1 secretion was environmentally dependent: foci formed in low nitrogen environments in which secretion was suppressed, yet with increasing concentrations of nitrogen, ESX-1 systems diffused along the plasma membrane and secretion was activated. Genome-wide transcriptional profiling revealed ESX-1 dependent induction of genes required for the SOS response and error prone DNA replication in high nitrogen. Based on these findings, we propose a new model of ESX-1 function where ESX-1 localization and secretion are responsive to nitrogen levels and form an integral node in the mycobacterial response to neighboring cells and environmental adaptation.

The comparative phosphate requirements of four annual pastures and two crops

1976 ◽  
Vol 27 (4) ◽  
pp. 479 ◽  
Author(s):  
PG Ozanne ◽  
KMW Howes ◽  
A Petch
Keyword(s):  
Unit Area ◽  
Maximum Yield ◽  
Subterranean Clover ◽  
Single Species ◽  
Nitrogen Supply ◽  
High Nitrogen ◽  
Direct Response ◽  
Phosphorus Requirement ◽  
Wimmera Ryegrass ◽  
Low Nitrogen

The levels of broadcast phosphate needed for 90% of maximum production by subterranean clover, Wimmera ryegrass at two levels of nitrogen, wheat and lupins are compared in a field experiment. Two seeding rates, one five times the other, were used to vary the stand densities and yields per unit area of the swards. A total of 180 kg nitrogen/ha was supplied to the wheat and high nitrogen grass plots; the low nitrogen grass plots received 30 kg/ha. Although both the high seeding rates and the high nitrogen applications gave up to double the yield per unit area, they did not significantly change the level of phosphate required for 90% of maximum yield by a given species or mixture. Grown as single species, lupins had the highest phosphorus requirement (202 kg/ha); wheat (118 kg/ha) and clover (107 kg/ha) had similar requirements; while grass with either a low nitrogen supply (58 kg/ha) or a high nitrogen supply (56 kg/ha) had the lowest requirement when measured during flowering. When clover and ryegrass were grown as a mixed sward, the phosphorus requirement (84 kg/ha) was close to the average of those for the pure clover and grass. Both the grass and clover responded to approximately the same level of phosphate when grown as a mixture. The amount of nitrogen fixed by the clover, either as a pure sward or when mixed with grass, increased with increasing phosphate application. We think that the phosphate level required by the grass when grown with clover rather than as a pure sward was an expression of this increased nitrogen supply and not a direct response to phosphate. The levels of phosphate required to produce 90% of the maximum grain yield in the lupin and ear yield in the wheat were similar to the phosphate requirement for 90% of maximum vegetative yield.

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