Effects of water stress on curly Mitchell grass, the common armyworm and the Australian plague locust

1991 ◽  
Vol 31 (3) ◽  
pp. 325 ◽  
Author(s):  
DG Phelps ◽  
PC Gregg
Keyword(s):  
Water Stress ◽  
Plant Nitrogen ◽  
Survival And Development ◽  
The Common ◽  
Plant Moisture ◽  
Australian Plague Locust ◽  
Nitrogen Relations ◽  
Common Armyworm

Temporal water and nitrogen relations of curly Mitchell grass, Astrebla lappacea (Lindl.) Domin, in response to single waterings of 0, 20, 60 and 180 mm were studied. Effects on the survival and development of the common armyworm, Mythimna convecta (Walker), and the Australian plague locust, Chortoicetes terminifera (Walker), were recorded. Glasshouse trials were conducted to ascertain the level of rainfall required for insect survival. More than 20 mm of rainfall was needed for insect survival. Even at 60 mm, development was retarded in some instances. Plant nitrogen was positively correlated (R2 = 0.51) with plant moisture. Insect survival was better correlated with plant moisture (R2 = 0.61) than with plant nitrogen (R2 = 0.41).

Optical sensing estimation of leaf nitrogen concentration in maize across a range of water-stress levels

2011 ◽  
Vol 62 (6) ◽  
pp. 474 ◽  
Author(s):  
Tong-Chao Wang ◽  
B. L. Ma ◽  
You-Cai Xiong ◽  
M. Farrukh Saleem ◽  
Feng-Min Li
Keyword(s):  
Water Stress ◽  
Vegetation Index ◽  
Optical Sensing ◽  
Leaf Nitrogen ◽  
Growth Stages ◽  
N Concentration ◽  
Leaf N Concentration ◽  
Chlorophyll Index ◽  
Plant Moisture ◽  
Leaf N

Optical sensing techniques offer an instant estimation of leaf nitrogen (N) concentration during the crop growing season. Differences in plant-moisture status, however, can obscure the detection of differences in N levels. This study presents a vegetation index that robustly measures differences in foliar N levels across a range of plant moisture levels. A controlled glasshouse study with maize (Zea mays L.) subjected to both water and N regimes was conducted in Ottawa, Canada. The purpose of the study was to identify spectral waveband(s), or indices derived from different wavebands, such as the normalised difference vegetation index (NDVI), that are capable of detecting variations in leaf N concentration in response to different water and N stresses. The experimental design includes three N rates and three water regimes in a factorial arrangement. Leaf chlorophyll content and spectral reflectance (400–1075 nm) were measured on the uppermost fully expanded leaves at the V6, V9 and V12 growth stages (6th, 9th and 12th leaves fully expanded). N concentrations of the same leaves were determined using destructive sampling. A quantitative relationship between leaf N concentration and the normalised chlorophyll index (normalised to well fertilised and well irrigated plants) was established. Leaf N concentration was also a linear function (R2 = 0.9, P < 0.01) of reflectance index (NDVI550, 760) at the V9 and V12 growth stages. Chlorophyll index increased with N nutrition, but decreased with water stress. Leaf reflectance at wavebands of 550 ± 5 nm and 760 ± 5 nm were able to separate water- and N-stressed plants from normal growing plants with sufficient water and N supply. Our results suggest that NDVI550, 760 and normalised chlorophyll index hold promise for the assessment of leaf N concentration at the leaf level of both normal and water-stressed maize plants.

Associations between host-plant nitrogen and infestations of the sugarcane borer, Eldana saccharina Walker (Lepidoptera: Pyralidae)

1989 ◽  
Vol 79 (3) ◽  
pp. 489-506 ◽  
Author(s):  
P. R. Atkinson ◽  
K. J. Nuss
Keyword(s):  
Water Stress ◽  
Field Trials ◽  
Eldana Saccharina ◽  
Plant Nitrogen ◽  
Feeding Sites ◽  
Nitrogen Levels ◽  
Natural Hosts ◽  
Cane Weight ◽  
Lepidoptera Pyralidae ◽  
Plant Trials

AbstractInfestations of Eldana saccharina Walker in South Africa are higher in intensively-grown than in peasant-grown sugarcane, and are worse in water-stressed plants. Although field trials showed negligible increases in the incidence of the pest with applied nitrogen, the degree in which the degree of water stress could not be controlled. Pot-plant trials, in which the degree of water stress was controlled as well as the amount of fertilizer, showed that the combination of nitrogen with stress resulted in increased survival of larvae and greatly increased biomass with shortened development times. Adults did not appear to choose stressed or fertilized plants in preference to normal or unfertilized ones. In every case, whether in the field or in insectary trials, increased infestation levels were associated with increased stalk total nitrogen. Amino acid determinations showed that the balance of individual acids did not appear to alter but that the balance of individual acids did not appear to alter but that glyphosate ripener had a similar effect to water stress, increasing all amino acids together. Infestations in older cane were disproportionately higher than in younger cane, weight for weight, despite reduced levels of stalk nitrogen. This anomaly may be due to the presence of phenolic compounds in younger cane, or in cane tops. Levels of nitrogen are much higher in the feeding sites of the insect in natural host-plants than in cane stalks, and the fecundity of feral moths natural hosts appeared to be higher than that of moths from sugarcane. The insect appears to have invaded sugarcane when stalk nitrogen levels reached sufficiently high levels for its survival as a result of intensive cultivation.

Soil plant nitrogen relations of tobacco at Mareeba, north Queensland

1965 ◽  
Vol 5 (17) ◽  
pp. 180
Author(s):  
PJ Goodman
Keyword(s):  
Nitrogen Uptake ◽  
Nitrogen Availability ◽  
Nitrogen Concentration ◽  
Leaf Nitrogen ◽  
Soil Nitrate ◽  
Nitrate Accumulation ◽  
Plant Nitrogen ◽  
Leaf Nitrogen Concentration ◽  
Red Earth ◽  
Nitrogen Relations

Nitrogen changes were studied in a red earth on which tobacco grew with very small additions of nitrogen fertilizer. Soil nitrate accumulation in the dry season before transplanting, and mineralization during the tobacco season, provided most of the plant's nitrogen requirements. Plant nitrogen uptake continued longer than in other countries, and the total amount was greater, particularly in stems and suckers. Though the plants gained nitrogen during the harvest period, leaf nitrogen concentration decreased. This resulted from translocation from lower leaves and growth of upper leaves. Decrease in leaf nitrogen concentration was essential to quality. The necessary sequence, of sufficient nitrogen for yield, followed by decreasing nitrogen availability for quality, occurs on this soil with small fertilizer additions. There is need for survey work on nitrogen availability and the time sequence of nitrogen uptake by plants on related Mareeba soils.

The Development of the 1983 Outbreak of the Common Armyworm, Mythimna convecta, in Eastern Australia

1990 ◽  
Vol 27 (3) ◽  
pp. 1001 ◽  
Author(s):  
G. McDonald ◽  
K. P. Bryceson ◽  
R. A. Farrow
Keyword(s):  
Eastern Australia ◽  
The Common ◽  
Common Armyworm

scholarly journals Deficit irrigation at different growth stages of the common bean (Phaseolus vulgaris L., cv. Imbabello)

1997 ◽  
Vol 54 (spe) ◽  
pp. 1-16 ◽  
Author(s):  
M. Calvache ◽  
K Reichardt ◽  
O.O.S. Bacchi ◽  
D. Dourado-Neto
Keyword(s):  
Water Stress ◽  
Water Use Efficiency ◽  
Water Use ◽  
Management Practice ◽  
Growth Stages ◽  
Crop Water ◽  
Traditional Management ◽  
Crop Water Use ◽  
Use Efficiency ◽  
The Common

To identify specific growth stages of the common bean crop at which the plant is less sensitive to water stress, in which irrigation could be omitted without significant decrease hi final yield, two field experiments were conducted at "La Tola" University Experimental Station, Tumbaco, Pichincha, Ecuador, on a sandy loam soil (Typic Haplustoll). The climate is tempered and dry (mean air temperature 16°C and mean relative humidity 74%, during the cropping season) 123 and 109 mm of rainfall were recorded during the experimental cropping periods (July to October), of 1992 and 1994, respectively. The treatments consisted of combinations of 7 irrigation regimes including normal watering; full stress; (traditional management practice); single stress at vegetative stage; flowering; seed formation and ripening, and of 2 levels of applied N (20 and 80 kg/ha). These 14 treatment combinations were arranged and analysed in a split-plot design with 4 replications. The plot size was 33.6 m² (8 rows, 7 m long) with a plant population of 120,000 pl/ha. Irrigation treatments were started after uniform germination and crop establishment Soil water content was monitored with a neutron probe down to 0.50 m depth, before and 24 h after each irrigation. The actual evapotranspiration of the crop was estimated by the water-balance technique. Field water efficiency and crop water use efficiency were calculated. Yield data showed that the treatments which had irrigation deficit had lower yield than those that had supplementary irrigation. The flowering stage was the most sensitive to water stress. Nitrogen fertilization significantly increased the number of pods and gram yield. Crop water use efficiency (kg/m³) was the lowest with stress at the flowering period, and the yield response factor (Ky) was higher hi treatments of full stress and stress at flowering. In relation to the traditional management practice adopted by farmers, only treatments of normal watering and stress at maturation had 13 and 10% higher crop water use efficiency, respectively.

Feeding by Distantiella theobroma (Dist.) (Heteroptera, Miridae) on Cocoa. I.—The effects of water stress in the plant

1966 ◽  
Vol 57 (1) ◽  
pp. 159-169 ◽  
Author(s):  
D. G. Gibbs ◽  
A. D. Pickett
Keyword(s):  
Water Stress ◽  
Water Status ◽  
Apical Region ◽  
Peripheral Tissues ◽  
Water Regimes ◽  
Hard Tissues ◽  
Survival And Development ◽  
Severe Infections ◽  
Reduced Rate ◽  
Cocoa Seedlings

Data were obtained on survival and development of larvae of Distantiella theobroma (Dist.) on cocoa seedlings maintained under three water régimes, high (HW), intermediate (IW) and low (LW). Recorda were taken of plant growth and damage by feeding. The water régimes of some plants were reversed in the latter part to the experiment.Larvae soon completed development on HW plants, but on LW plants a large number died, possibly because they were unable to take up fluid fast enough to offset loss by evaporation. There was intermediate mortality on IW plants.Larvae took longer to develop on IW than on HW plants, probably because they imbibed nutrients at a reduced rate.More larvae survived on LW plants that were regenerating after increase in water status than on plants that had received abundant water continuously. They fed mainly on the old wood and very little on the soft regenerative shoots, so were apparently favoured by some change in the peripheral tissues of the main stem.On HW plants, nearly all feeding took place on woody or partially hardened tissue; newly flushing tissue was not fed on if it was growing normally. On IW plants, the expansion of new terminal leaves was often slow, and these tissues were then attacked by young larvae. This happened much more on LW plants, where the apical region was killed by persistent feeding. On all plants larvae older than second instar fed only on hard tissues.Later effects of feeding were splitting of the wood where lesions had been made and sometimes the development of fungal infecdtions. The most severe infections occurred when the upper part of the old stem died back on LW plants that were regenerating after increase in water status.

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