EFFECTS OF INFESTATIONS BY THE CORN LEAF APHID, RHOPALOSIPHUM MAIDIS (HOMOPTERA: APHIDIDAE), ON FIELD CORN IN SOUTHWESTERN ONTARIO

1973 ◽  
Vol 105 (3) ◽  
pp. 449-458 ◽  
Author(s):  
W. H. Foott ◽  
P. R. Timmins
Keyword(s):  
Water Stress ◽  
Moisture Stress ◽  
Average Yield ◽  
Rhopalosiphum Maidis ◽  
Field Corn ◽  
Corn Leaf Aphid ◽  
Drought Conditions ◽  
Aphid Feeding ◽  
Moisture Conditions

AbstractThe effects of various levels of infestation of the corn leaf aphid, Rhopalosiphum maidis (Fitch), on yield of field corn were examined from 1965 to 1970 inclusive when all plants whose yield might have been influenced by factors other than aphid feeding were excluded from the data. A possible relationship between moisture stress in plants and degree of aphid injury was also investigated.A light infestation (maximum of 400 aphids on the tassel) caused average yield reductions up to 8.3% when plants were under moisture stress, but nil to negligible losses when moisture was adequate. Moderate infestations (many hundreds of aphids on part of the tassel) produced average losses up to 34.8% under drought conditions and up to 11.8% when moisture was abundant. Severe infestations (many hundreds of aphids on most of the tassel) caused average yield reductions ranging from 43.2 to 91.8% when plants were under water stress and up to 58.9% even with abundant moisture. Very severely infested plants (many hundreds on all of the tassel and whorl leaves) were usually barren or had ears with just a few kernels regardless of moisture conditions.Most injury from aphid feeding appeared to occur before and during pollination. No particular combination of temperature and rainfall favored aphid buildup.

BIOLOGY OF THE CORN LEAF APHID, RHOPALOSIPHUM MAIDIS (HOMOPTERA: APHIDIDAE), IN SOUTHWESTERN ONTARIO

1977 ◽  
Vol 109 (8) ◽  
pp. 1129-1135 ◽  
Author(s):  
W.H. Foott
Keyword(s):  
Constant Temperature ◽  
Minimum Temperature ◽  
Rapid Development ◽  
Winter Barley ◽  
Rhopalosiphum Maidis ◽  
Field Corn ◽  
Favorable Environment ◽  
Corn Leaf Aphid ◽  
Small Colony ◽  
Plant Emergence

AbstractThere was no evidence that the corn leaf aphid, Rhopalosiphum maidis (Fitch), can overwinter in southwestern Ontario. An alate with a small colony of nymphs was found on 26 April, indicating that migration from the south starts early in the spring. Early migrants colonized winter barley, but not winter oats, rye, or wheat. Colonization on field corn did not occur until over a month after plant emergence. Only small numbers of alatae initiated infestations on corn and the large variation in size of aphid infestations observed at pollination was due to differences in the longevity and fecundity of these few early attackers. The whorl leaves which enclosed the tassel before pollination provided a very favorable environment for rapid development of the aphids. Trapping of alatae in yellow pans of water at the periphery of a corn field in the fall showed that a minimum temperature of 13°C was required for flight. At a constant temperature of 25.5°C and a light:dark photoperiod of 14:10 h, the average prereproductive, reproductive, and postreproductive periods for 29 aphids were 5.9, 15.8, and 9.6 days, respectively. The average number of nymphs produced/female was 68.2.

scholarly journals The efficiency of different moisture and nutrition conditions in early potato growing under drip irrigation in southern Ukraine

2021 ◽  
Vol 66 (1) ◽  
pp. 1-16
Author(s):  
Raisa Vozhehova ◽  
Galina Balashova ◽  
Liubov Boiarkina ◽  
Olesya Yuzyuk ◽  
Sergey Yuzyuk ◽  
...  
Keyword(s):  
Drip Irrigation ◽  
Field Research ◽  
Early Potato ◽  
Average Yield ◽  
Irrigation Rate ◽  
The Third ◽  
Additional Control ◽  
Moisture Conditions ◽  
Tuber Treatment ◽  
Southern Ukraine

The article presents field research results on the effectiveness of different moisture and nutrition conditions at the cultivation of early potato under drip irrigation in southern Ukraine. The scheme of the experiment included the treatment with the complex Mochevyn K as an additional control and different methods and correlation of fertilizers Plantafol (treatment of tubers before planting, fertilizing, at budding and their combination), as well as different soil moisture conditions (irrigation rates of 100 and 200 m?/ha). Studies have shown that the average yield of early potato without irrigation was 10.44 t/ha. Moisture conditions significantly affected the yield of young tubers - irrigation at a rate of 200 m?/ha provided 21.61 t/ha, whereas reducing the irrigation rate to 100 m?/ha led to a decrease in yield - 19.86 t/ha. The first treatment of planting tubers, treatment of plants at sprouting and during budding provided almost the same yield. The second and the third treatments of plants and tubers did not lead to a significant increase in yield. The highest productivity of potato was provided by Plantafol treatment of tubers and combination of tuber treatment with foliar feeding at mass sprouting phase with a 200 m?/ha irrigation rate for two years: 24.16 and 23.22 t/ha.

Does plant root architecture respond to potassium nutrition under water stress? A case from rice seedling root responses

2020 ◽  
Author(s):  
Dipika S. Patel ◽  
Bardhan Kirti ◽  
P Patel Dhiraji ◽  
Parekh Vipulkumar ◽  
Jena Suchismita ◽  
...  
Keyword(s):  
Water Stress ◽  
Seedling Growth ◽  
Root Architecture ◽  
Plant Root ◽  
Moisture Stress ◽  
Rice Seedling ◽  
Maximum Width ◽  
High K ◽  
Severe Water Stress ◽  
Low K

ABSTRACTThe root is the sensing organ for potassium (K) and water availability. We evaluated whether K availability influences root architecture and contributes to drought tolerance under moisture stress. Rice seedling growth was severely affected by low K availability under water stress, and the substantial reductions in root projected area, maximum width, and width to depth ratio were observed. High K availability helps maintain root top and bottom angles and reduces root steepness under mild water stress, but over K nutrition does not ensure higher seedling growth. Under severe water stress, the steepness was more regulated by water than K availability.

Effect of Application Factors on Efficacy of Fluazifop-P-Butyl in Flax

1991 ◽  
Vol 5 (3) ◽  
pp. 504-508 ◽  
Author(s):  
George H. Friesen ◽  
David A. Wall
Keyword(s):  
Growth Stage ◽  
Field Experiments ◽  
Time Of Day ◽  
Wild Oat ◽  
Spray Nozzle ◽  
Green Foxtail ◽  
Drought Conditions ◽  
Orientation Time ◽  
Moisture Conditions ◽  
Nozzle Orientation

Field experiments were conducted to determine the efficacy of fluazifop-P-butyl for the control of green foxtail, wild oat, barley, and wheat in flax as influenced by spray nozzle orientation, time of day, and growth stage. Under drought conditions in 1988, control of wild oat, wheat, and barley with fluazifop-P-butyl was enhanced 75%, 53% and 78%, respectively, when nozzles were oriented to spray forward 45°. Under adequate soil moisture conditions enhancement of control was minimal. Green foxtail control improved when fluazifop-P-butyl was applied from 1700 to 2100 h, but time of day had no effect on control of wild oat, barley, or wheat. Fluazifop-P-butyl effectiveness was reduced when applied 4 d after flax emergence due to late emerging grass seedlings. Green foxtail was the most tolerant to fluazifop-P-butyl, whereas wild oat, wheat, and barley were the most susceptible.

Effects of soil moisture and temperature on seedling emergence from natural and pre-germinated onion seeds

1986 ◽  
Vol 107 (2) ◽  
pp. 249-256 ◽  
Author(s):  
W. E. Finch-Savage
Keyword(s):  
Soil Moisture ◽  
Water Availability ◽  
Seedling Emergence ◽  
Moisture Stress ◽  
Start Time ◽  
Mean Temperature ◽  
Changing Patterns ◽  
Moisture Conditions ◽  
Germinating Seeds ◽  
Germinated Seeds

SummaryThe emergence of seedlings from natural, germinating and selected uniformlygerminated onion seeds was compared in a range of changing patterns of soil moisture. The timing, spread and amount of seedling emergence from seeds in all three treatments were affected by the timing of water availability in the seed bed and these effects differed between treatments.The rate of seedling emergence in all three treatments under non-limiting soil moisture conditions was correlated with mean temperature, but this relationship was obscured in irrigation treatments where water stress occurred. However, if the seed bed was moist at sowing irrespective of subsequent moisture stress the reciprocals of the time to the start, time to 50% and time to the end of seedling emergence from uniformly germinated seeds were correlated with mean temperature (r > 0·87, D.F. 27).The results show that if the seed bed is irrigated prior to sowing and soil moisture is maintained during the first 3 days following sowing high levels of seedling emergence with both predictable timing and uniformity can be achieved by sowing uniformlygerminated seeds. Seedling emergence from natural and germinating seeds was much less predictable.

Yield Stability of Cassava During Prolonged Mid-Season Water Stress

1992 ◽  
Vol 28 (2) ◽  
pp. 165-174 ◽  
Author(s):  
Mabrouk A. El-Sharkawy ◽  
Anna Del Pilar Hernández ◽  
Clair Hershey
Keyword(s):  
Water Stress ◽  
Growth Cycle ◽  
Yield Stability ◽  
High Yield ◽  
Shoot Biomass ◽  
Deep Soil ◽  
Leaf Formation ◽  
Plant Characteristics ◽  
Moisture Conditions ◽  
Field Drainage

SUMMARYYield stability in cassava requires genotypes that produce well under the variable moisture conditions encountered during the growth cycle. Plant characteristics related to yield stability were studied in two cassava clones subjected to 105 days of water stress in a field drainage lysimeter. Stress conditions commenced 117 days after planting, and the plants were allowed to recover at the end of the stress period for the rest of the growth cycle. Water stress restricted the growth of leaves and stems, but root yields were increased or remained unaffected. Leaf water potential varied little with stress, but gas exchange rates were about 75% those of the control throughout the stress period in both cultivars. Under stress, the plants partially closed their stomata and extracted deep soil moisture slowly. A high yield in both wet and stressed environments was associated with high mean LAI, better leaf retention, and greater partitioning of shoot biomass into leaf formation.

EFFECTS OF MOISTURE STRESS AT EARLY HEADING AND OF NITROGEN FERTILIZER ON THREE SPRING WHEAT CULTIVARS

1973 ◽  
Vol 53 (1) ◽  
pp. 1-5 ◽  
Author(s):  
S. DUBETZ ◽  
J. B. BOLE
Keyword(s):  
Water Stress ◽  
Soil Water ◽  
Spring Wheat ◽  
High Stress ◽  
Moisture Stress ◽  
Triticum Aestivum L ◽  
Kernel Weight ◽  
Soil Water Stress ◽  
Boot Stage ◽  
Four Levels

Three cultivars of spring wheat (Triticum aestivum L.) were grown at four levels of N fertilizer in metal lysimeters protected from rain by an automatic rain shelter. A soil water stress of 8 bars was developed in one-half of the lysimeters at the early boot stage. Water stress reduced yield by severely decreasing the number of kernels per spike. Tillering was not affected and kernel weight was increased. Pitic 62 withstood the high stress better than Manitou or Kenhi. N enhanced yield by increasing tillering. Kernel weight was unaffected by N, and the number of kernels per spike was decreased. Pitic, which had a higher number of kernels per spike, outyielded Manitou and Kenhi. The protein content of Manitou was higher than that of the other two cultivars. The cultivars differed in their reaction to soil water stress and N.

Assessment of Drought Tolerance Indices in Bread Wheat Genotypes Under Different Sowing Dates

2012 ◽  
Vol 45 (3) ◽  
pp. 25-39 ◽  
Author(s):  
S. Mohammadi ◽  
M. Janmohammadi ◽  
A. Javanmard ◽  
N. Sabaghnia ◽  
M. Rezaie ◽  
...  
Keyword(s):  
Drought Stress ◽  
Drought Tolerance ◽  
Grain Yield ◽  
High Performance ◽  
Wheat Yield ◽  
Moisture Stress ◽  
Drought Indices ◽  
Terminal Drought ◽  
Sowing Dates ◽  
Moisture Conditions

Abstract The capability of a genotype to achieve acceptable yield over a broad range of sub-optimum and suitable conditions is extremely imperative. Late planting and end-season drought stress are two main factors limiting wheat yield in northwest of Iran. In a 2-year field experiment at Miandoab, Iran, the ability of several selection indices to identify drought resistant genotypes under different sowing dates and moisture conditions were evaluated. Six genotypes of differing response to water scarcity were planted at 20-d intervals on three dates from 11 October to 20 November. Drought resistance indices were utilized on the basis of grain yield under end-season drought (Ys) and normal (YN) conditions. Evaluation of MP, HARM, GM, STI, TOL, SSI, RDI, YSI and Yr indicated that late sowing (20 Nov) significantly decreased drought tolerance in all investigated genotypes. However, yield comparisons under normal and terminal drought stress conditions revealed that promising lines (C-81-4, C-81- 10, C-81-14 and C-82-12) had better performance than local checks (Zarrin and Alvand). Furthermore under both moisture conditions C-81-10 genotype had the greatest grain yield. Based on drought indices like as MP, GMP, STI and HARM C-81-10 genotype introduced as the most tolerant genotype to end-season drought stress. Grain yield showed a positive and significant correlation with HARM, GMP, MP, STI and YI indices were more efficient for recognizing high performance genotypes under different sowing dates and diverse moisture stress.

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