Insect Control on Flue-Cured Tobacco with Systemic Insecticides, 1994

Abstract This experiment was conducted to evaluate various systemic insecticides applied as soil or transplant water treatments followed by foliar applications of Orthene for TA and TFB control on fluecured tobacco and to determine the impact of treatment on tobacco yield and price. The experiment was conducted at the VPI & SU Southern Piedmont Agricultural Research and Extension Center, Blackstone, VA. Eleven treatments and an untreated control were established in a randomized complete block design with 4 replications. Plots, 4 × 40 ft (1 row × 24 plants), were separated by single guard rows. Pretransplant soil treatments of most liquid formulations were applied broadcast with a CO2-pressurized tractor sprayer that delivered 30.4 gal/acre at 40 psi through 8003LP tips on 29 Apr (Ambient temperature, 85-89°F, soil temperature, 75°F; soil pH, 5.8; OM, 2%). Treatments were immediately incorporated by double disking. The Furadan and Temik treatments were applied during bed formation and immediately covered with 6 to 8 inches of soil on 17 May. Furadan 4F was diluted 50:50 in water and applied in a narrow stream (< 1-inch wide) in the row using a peristaltic pump. Temik was applied in a 14 inch band using a tractor mounted- Gandy granular applicator. The soil moisture was good for both the pretransplant soil and bedding treatments. ‘K-326’ flue-cured tobacco was transplanted into experimental plots in a Chesterfield-Mayodan-Bourne sandy loam soil on 18 May. A measuring cup was used to apply transplant water (TPW) treatments of Orthene and Admire in 4 fl oz/plant (204 gal/acre) at the base of each plant in the treatment plots. Virginia Cooperative Extension recommendations were followed for production of the crop. Foliar applications of Orthene and Dipel were applied on 6 Jul with a CO2-pressurized backpack sprayer that delivered 30 gal/acre through 3 TX-12 tips at 60 psi. TA populations were estimated on the upper 4 leaves of 10 plants/plot about once a week from 5 to 11 wk after transplanting. On 25 Aug, TA damage was rated on a scale of 0 to 10 where 0 = no aphid damage or sooty mold and 10 = very severe necrosis of leaves and extensive sooty mold. TFB and TFB feeding holes in the most damaged leaf were counted on 10 plants/ plot. Tobacco was harvested as it ripened, weighed, graded by a USDA/AMS inspector, and yield and price were calculated. Data were analyzed by ANOVA and significantly different means were separated by WD (K-ratio = 100). Aphid count data were transformed to Log10(x + 1) before analysis.

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Tobacco Insect Control with Insecticides Applied in the Transplant Water, 1995

Arthropod Management Tests ◽

10.1093/amt/21.1.309 ◽

1996 ◽

Vol 21 (1) ◽

pp. 309-310

Author(s):

Paul J. Semtner ◽

Surendra K. Dara ◽

William B. Wilkinson

Keyword(s):

Ambient Temperature ◽

Agricultural Research ◽

Sandy Loam ◽

Calculated Data ◽

Leaf Tissue ◽

Ambient Temperatures ◽

Tobacco Seedlings ◽

Loam Soil ◽

X 24 ◽

Water Treatments

Abstract Various insecticides applied as transplant water treatments were compared with foliar and soil treatments for TA and TFB control on flue-cured tobacco. Tests were conducted on a Chesterfield-Mayodan-Bourne sandy loam soil at the VPI & SU Southern Piedmont Agricultural Research and Extension Center, Blackstone, VA. Eleven treatments and an untreated control were established in a RCB design with 4 replications. Plots, 4 X 40 ft (1 row X 24 plants), were separated by single untreated guard rows. The Temik treatment was applied in a 14-inch band using a tractor mounted-Gandy granular applicator and immediately covered with 6 inches of soil at bed formation on 9 May (soil temperature, 65 °F; ambient temperature, 70 °F; soil pH, 5.6; weather, sunny; soil moisture, good). The Admire drench treatment was applied to tobacco seedlings in 288-cell float trays 24 hr before transplanting. The treatment was applied with a CO2-pressurized backpack sprayer that delivered 1 fl oz of Admire 240FS in 1.84 gal of water/1,000 plants through 8003LP tips at 20 psi. Treatments were watered in with an additional 1 gal of water immediately after application. ‘Coker 371 Gold’ flue-cured tobacco was transplanted and the transplant water (TPW) treatments were applied in 215 gal solution/acre with a Holland plunger-type transplanter on 16 May. The weather was sunny, and soil and ambient temperatures were 70 °F and 78-81 °F, respectively. Foliar applications of Orthene were applied on 3 Jul with a CO2-pressurized backpack sprayer that delivered 28 gpa at 60 psi through 3, TX-12 nozzles/row. The weather was clear, wind speed was less than 5 mph, and ambient temperature was 86 °F. Tobacco production followed Virginia Cooperative Extension recommendations for weed and disease control, fertilization, topping and sucker control. Dipel 4L was applied for tobacco hornworm control on 4 Aug. TA were counted on the upper 4 leaves of 10 plants/plot about once a wk from 6 to 10 wk after transplanting. On 22 Aug, TA damage was rated for each plot on a scale of 0 to 10 where 0 = no signs of aphid feeding and 10 = all leaves showing severe damage resulting from TA infestations including honeydew, sooty mold, necrotic leaf tissue and exuviae. TFB feeding holes were counted on 5 plants/plot on 22 May, 1 wk after transplanting. Tobacco was harvested as it ripened, weighed, graded by a USDA/AMS inspector, and yields and prices were calculated. Data were analyzed by ANOVA and significantly different means were separated by WD (K-ratio = 100). TA count data were transformed to Log10 (X+l) before analysis.

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Insect Control of Flue-Cured Tobacco with Systemic Insecticides, 1997

Arthropod Management Tests ◽

10.1093/amt/23.1.296 ◽

1998 ◽

Vol 23 (1) ◽

pp. 296-297

Author(s):

Paul J. Semtner ◽

William B. Wilkinson

Keyword(s):

Ambient Temperature ◽

Soil Temperature ◽

Sandy Loam ◽

Calculated Data ◽

Tobacco Budworm ◽

Insect Control ◽

Systemic Insecticides ◽

Control Production ◽

X 24 ◽

The Impact

Abstract This experiment was conducted at the Southern Piedmont Agric. Res. and Ext. Cntr., Blackstone, VA to evaluate TA and TFB control on flue-cured tobacco with various systemic insecticides applied as soil or transplant water treatments and to determine the impact of these treatments on tobacco yield. Thirteen treatments and an untreated check were established in a RCB design with 4 replications in a Chesterfield-Mayodan-Bourne sandy loam soil. Plots, 4 X 40 ft (1 row X 24 plants), were separately by single guard rows. Pre-transplant soil treatments of all liquid formulations except Furadan were broadcast with a CO2-pressurized tractor sprayer that delivered 32 gpa at 30 psi through 8003 LP tips on 13 May (Ambient temperature 66-68 °F, soil temperature, 65 °F; soil pH, 5.7; OM, <2%). Treatments were immediately incorporated by double disking. Band applications of Furadan and Temik were made during bed formation and immediately covered with 6 to 8 inch of soil on 15 May (Ambient temperature 75-78 °F, soil temperature, 70 °F). Furadan 4°F band treatments were applied in a 12-inch band using a CO2-pressurized backpack sprayer that delivered 16 gpa through an 8003E tip at 30 psi. Temik was applied in a 14-inch band using a tractor mounted-Gandy granular applicator. The soil was in excellent condition for both the pretransplant soil and bedding treatments. ‘Coker 371Gold’ flue-cured tobacco was transplanted into experimental plots on 19 May. A measuring cup was used to apply transplant water (TPW) treatments of Orthene and Admire in 4 fl oz/plant (204 gpa) at the base of each plant in the treatment plots. Except for insect control, production practices followed Virginia Cooperative Extension recommendations. Dipel (Bacillus thuringiensis) was applied for tobacco budworm and tobacco hornworm control on 3 Jul. Foliar applications of Orthene were applied to the Orthene TPW treatment on 5 and 31 Jul and to the Furadan treatment on 19 Jul using a CO2-pressurized back-pack sprayer that delivered 30 gpa through TX-12 tips (3 per row) at 50 psi. TA populations were estimated on the upper 4 levels of 10 plants/plot every 6 to 12 days from late Jun to mid Aug. On 25 Aug, TA damage was rated on a scale of 0 to 10: 0 = no signs of damage; 10 = very severe necrosis of leaves and extensive sooty mold. TFB and TFB feeding holes were counted on 10 plants/plot at 1 to 4 wks after transplanting. Tobacco was harvested as it ripened, weighted, and yield was calculated. Data were analyzed by ANOVA and significantly different means were separated by Waller-Duncan K-ratio t-test (K = 100). TA count data were transformed to log10 (x + 1) before analysis. Actual means are presented in the table.

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Effect of Intercropping on Productivity and Profitability of Sesame under Dryland Arid Conditions

Current Agriculture Research Journal ◽

10.12944/carj.8.2.11 ◽

2020 ◽

Vol 8 (2) ◽

pp. 152-156

Author(s):

Moola Ram

Keyword(s):

Agricultural Research ◽

Sandy Loam ◽

Block Design ◽

Research Station ◽

High Potassium ◽

Net Return ◽

Net Returns ◽

Randomized Block Design ◽

Loam Soil ◽

Total Productivity

An experiment on sesame intercropping system was conducted during kharif (rainy) season of 2017 on sandy loam soil (8.72 pH, 0.88 EC dS m-1), with low nitrogen (137 kg N ha-1), medium phosphorus (14.4 kg ha-1) and high potassium content (357 kg ha-1) at Agricultural Research Station, Mandor, Jodhpur in randomized block design with 3 replications. Among 7 treatments (T1 – Sole sesame, T2 – Sesame + Urdbean in 3:1, T3 – Sesame + Urdbean in 4:2, T4 – Sesame + Mungbean in 3:1, T5 – Sesame + Mungbean in 4:2, T6 – Sesame + Mothbean in 3:1, T7 – Sesame + Mothbean in 4:2 row ratio), it was found that intercropping of sesame with mungbean in ratio 3:1 resulted significantly higher total productivity and net returns (541 kg ha-1 & Rs. 18270 ha-1) over sole sesame crop (344 kg ha-1 & Rs. 6156 ha-1) followed by mungbean in 4:2 (490 kg ha-1 with net return of Rs. 15164 ha-1) being at par with urdbean in 3:1 (473 kg ha-1 with net return of Rs. 14078 ha-1). It was concluded that mungbean can be grown as a beneficial intercrop in sesame under dryland conditions of Rajasthan.

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Aphid and Flea Beetle Control on Tobacco with Insecticides Applied in the Transplant Water, 1997

Arthropod Management Tests ◽

10.1093/amt/23.1.300 ◽

1998 ◽

Vol 23 (1) ◽

pp. 300-301

Author(s):

Paul J. Semtner ◽

William B. Wilkinson

Keyword(s):

Sandy Loam ◽

Flea Beetle ◽

Calculated Data ◽

Leaf Tissue ◽

Ambient Temperatures ◽

Untreated Check ◽

Tobacco Seedlings ◽

Loam Soil ◽

X 24 ◽

The Impact

Abstract Various insecticides applied as transplant water treatments and transplant drench (TPD) were compared with foliar and soil treatments for TA and TFB control and for the impact of treatment on yield of flue-cured tobacco. Tests were conducted on a Chesterfield-Mayodan-Bourne sandy loam soil at the Southern Piedmont Agric. Res. and Ext. Cntr., Blackstone, VA. Eleven treatments and an untreated check were established in a RCB design with 4 replications Plots, 4 X 40 ft (1 row X 24 plants), were separated by single untreated guard rows. The Temik treatment was applied in a 14-inch band using a tractor-mounted-Gandy granular applicator and immediately covered with 6 inches of soil at bed formation on 15 May (Ambient temperature 75-78 °F, soil temperature, 70 °F, soil pH, 5.6; weather, sunny; soil moisture, good). The Admire drench treatment was applied to tobacco seedlings in 288-cell float trays 24 hrs before transplanting. The treatment was applied with a CO2-pressurized backpack sprayer that delivered the desired rates of Admire 240 FS in 0.46 gal of water/1,000 plants through 8003LP tips at 20 psi. Treatments were watered in with about 1 gal of water immediately after application. ‘Coker 371 Gold’ flue-cured tobacco was transplanted and the transplant water (TPW) treatments were applied in 204 gpa with a dipper at 4 fl oz/plant on 20 May. The weather was sunny, and soil and ambient temperatures were 70 °F and 78-81 °F, respectively. Foliar applications of Orthene were applied on 11 and 31 Jul with a CO2-pressurized backpack sprayer that delivered 30 gpa at 50 psi through 3 TX-12 nozzles/row. Except for insect control, tobacco production followed recommendations of the Virginia Cooperative Extension Service. Dipel 4 L (Bacillus thuringienis) was applied for tobacco hornworm control on 3 Jul. TA were counted on the upper 4 leaves of 10 plants/plot about once a week from 6 to 10 wks after transplanting. On 22 Aug, TA damage was rated for each plot on a scale of 0 to 10: 0 = no signs of TA feeding; 10 = all leaves showing severe damage resulting from TA infestations including hon-eydew, sooty mold, necrotic leaf tissue and exuviae. TFB feeding holes were counted on 10 plants/plot at 2 to 4 wk after transplanting. Tobacco was harvested as it ripened, weighed, graded by a USDA/AMS inspector, and yields and prices were calculated. Data were analyzed by ANOVA and significantly different means were separated by Waller-Duncan K-ratio t-test (K = 100). TA count data were transformed to log10 (x + 1) before analysis.

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Effect of Bio and Organic Fertilizers on Pumpkin's (Cucurbita pepo L.) Leave Content of N, P, and K

Al-Qadisiyah Journal For Agriculture Sciences (QJAS) (P-ISSN 2077-5822 E-ISSN 2617-1479) ◽

10.33794/qjas.vol10.iss1.104 ◽

2020 ◽

Vol 10 (1) ◽

pp. 241-245

Author(s):

Ammar Hameed Madi ◽

Jawad A. Kamal Al-Shibani

Keyword(s):

Cucurbita Pepo ◽

Sandy Loam ◽

Block Design ◽

Organic Fertilizers ◽

Flowering Stage ◽

College Of Agriculture ◽

Significant Difference ◽

Randomized Complete Block Design ◽

Loam Soil ◽

Four Levels

This study was conducted to investigate the effect of bacterial bio-fertilization A. chroococcum and P. putide and four levels of compost (0, 1, 2, 3) tons.h-1 on the leaves content of N.P.K elements. The experiment was carried out in one of the greenhouses of the College of Agriculture - University of Al-Qadisiyah during fall season 2018-2019. It designed in accordance with the Randomized Complete Block Design (RCBD) with three replicates in sandy loam soil. The means of treatments were compared with the least significant difference (LSD) at (5)% probability level. The results present that the treatments of A. chroococcum, P. putide and compost at (3) tons.kg-1 significantly increases the leaves content of K.P.K compared to all other treatments in the flowering stage (4.970, 0.5000, and 4.930) mg.kg-1, respectively. This treatment was followed by the effect of the treatment of A. chroococcum and compost at (3) tons.kg-1, which increases the values of all traits except the leaf content of (P). Bio-fertilizer with P. putide + A. chroococcum significantly increases the leaves' content of P.

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Tobacco Insect Control with Insecticides Applied in the Transplant Water, 1996

Arthropod Management Tests ◽

10.1093/amt/23.1.298a ◽

1998 ◽

Vol 23 (1) ◽

pp. 298-299

Author(s):

Paul J. Semtner ◽

William B. Wilkinson

Keyword(s):

Ambient Temperature ◽

Sandy Loam ◽

Leaf Tissue ◽

Insect Control ◽

Black Stone ◽

Untreated Check ◽

Tobacco Seedlings ◽

Loam Soil ◽

X 24 ◽

Water Treatments

Abstract Various insecticides applied as transplant water treatments were compared with foliar and soil treatments for TA and TFB control and for their effects on the yield of flue-cured to bacco. Tests were conducted on a Chesterfield-Mayodan-Bourne sandy loam soil at the Southern Piedmont Agricultural Agric. Res. and Ext. Cntr., Black-stone, VA. Eleven treatments and an untreated check were established in a RCB design with 4 replications. Plots, 4 X 40 ft (1 row X 24 plants), were separated by single untreated guard rows. The Temik treatment was applied in a 14-inch band using a tractor mounted-Gandy granular applicator and immediately covered with 6 inches of soil at bed formation on 21 May (soil temperature 75 °F ambient temperature, 88 °F, soil pH, 5.6; weather, sunny; soil moisture, good). The Admire drench treatment was applied to tobacco seedlings in 288-cell float trays 24 hrs before transplanting. The treatment was applied with a CO2-pressurized backpack sprayer that delivered 1 fl oz of Admire 240 FS in 1.84 gal of water/1,000 plants through 8003LP tips at 20 psi. Treatments were watered in with an additional 1 gal of water immediately after application. ‘Coker 371 Gold’ flue-cured tobacco was transplanted and the transplant water (TPW) treatments were applied in 204 gal solution/acre with a Holland plunger-type transplanter on 21 May. The weather was sunny, and soil and ambient temperature was 75 °F and 88-91 °F, respectively. Foliar applications of Orthene were applied on 3 Jul and 8 Aug with a CO2-pressurized backpack sprayer that delivered 28 gpa at 60 psi through TX-12 nozzles (3 per row. The weather was clear, wind speed was less than 5 mph, and ambient temperature was 84-86°F at each application. Except for insect control, tobacco production followed Virginia Cooperative Extension recommendations. Dipel 4 L (Bacillus thuringiensis) was applied for tobacco hornworm control on 3 Jul. TA were counted on the upper 4 leaves of 10 plants/plot about once a week from 6 to 10 wks after transplanting. On 22 Aug, TA damage was rated for each plot on a scale of 0 to 10: 0 = no signs of aphid feeding; 10 = all leaves showing severe damage resulting from TA infestations including honeydew, sooty mold, necrotic leaf tissue, and exuviae. TFB feeding holes were counted on 5 plants/plot on 2 and 26 Jun, 2 and 5 wks after transplanting. Tobacco was harvested and cured and yield was determined. Data was analyzed by ANOVA and significantly different means were separated by Waller-Duncan K-ratio t-test (K = 100). TA count data were transformed to log10 (x + 1) before analysis.

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Effect of integrated nutrient management on physical and chemical properties of soil

Agricultural Science Digest - A Research Journal ◽

10.18805/asd.v35i1.9312 ◽

2016 ◽

Vol 35 (1) ◽

Author(s):

Suman Meena ◽

Narendra Swaroop ◽

Joy Dawson

Keyword(s):

Nutrient Management ◽

Particle Density ◽

Sandy Loam ◽

Pore Space ◽

Block Design ◽

Chemical Properties ◽

Available Nitrogen ◽

Randomized Block Design ◽

Loam Soil ◽

Physical And Chemical

A field experiment was conducted during <italic>Kharif</italic> season 2014 at the Research farm of Soil Science Allahabad School of Agriculture, laid out in randomized block design on sandy loam soil, containing sand 62.71%, silt 23.10% and clay 14.19% (Inceptisols). It was observed that for post harvest soil properties in treatment N20+ FYM @ 10 t ha−1 and <italic>Rhizobium</italic> P40K40 were improved significantly due to integrated use of inputs. Organic carbon-0.75%, available nitrogen- 333.23 kg ha−1, phosphorus- 34.58 kg ha−1, potassium -205.83 kg ha−1, pore space -50.80 %, pH -6.80 were found to be significant and bulk density -1.07 Mgm−3, particle density -2.62 Mgm−3, EC at 27°C -0.24 dSm−1 were found to be non-significantly improved in this treatment.

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Soil water drying and recharge rates as affected by tillage under continuous barley and barley-canola cropping systems in northwestern Canada

Canadian Journal of Soil Science ◽

10.4141/s00-029 ◽

2001 ◽

Vol 81 (1) ◽

pp. 45-52 ◽

Cited By ~ 14

Author(s):

R H Azooz ◽

M A Arshad

Keyword(s):

Soil Moisture ◽

Soil Water ◽

Sandy Loam ◽

Time Domain Reflectometry ◽

Sandy Loam Soil ◽

Soil Conditions ◽

Silt Loam ◽

Silt Loam Soil ◽

Loam Soil ◽

The Impact

In areas of the northwestern Canadian Prairies, barley and canola are grown in a short growing season with high rainfall variability. Excessively dry soil in conventional tillage (CT) in dry periods and excessively wet soil in no-tillage (NT) in wet periods could cause a significant decrease in crop production by influencing the availability of soil water. The effects of CT, NT and NT with a 7.5-cm residue-free strip on the planting rows (NTR) on soil water drying (–dW/dt) and recharge (dW/dt) rates were studied in 1992 and 1993 during wet and dry periods to evaluate the impact of NTR, NT and CT systems on soil moisture condition. The soils, Donnelly silt loam and Donnelly sandy loam (both Gray Luvisol) were selected and soil water content by depth was measured by time domain reflectometry. Water retained at 6 matric potentials from –5 to –160 kPa were observed. In the field study, –dW/dt was significantly greater in CT than in NT in the silt loam for the 0- to 30-cm layer during the first 34 d after planting in 1992. The 0- to 30-cm soil layer in CT and NTR dried faster than in NT during a period immediately following heavy rainfall in the silt loam in 1993. The drying coefficient (–Kd ) was significantly greater in CT and NTR than in NT in the silt loam soil in 1993 and in the sandy loam soil in 1992 in the top 30-cm depth. The recharge coefficient (Kr) was significantly greater in NT and NTR than in CT for the silt loam soil. The NTR system increased the –dW/dt by 1.2 × 10-2 to 12.1 × 10-2 cm d-1 in 1992 and 1993 in the silt loam soil and by 10.2 × 10-2 cm d-1 in 1993 in the sandy loam soil as compared with NT. The dW/dt was 8.1 × 10-2 cm d-1 greater in NTR in 1992 and 1993 in the silt loam soil and was 1.9 × 10-2 greater in NTR in 1992 than in CT in the sandy loam soil. The laboratory study indicated that NT soils retained more water than the CT soils. The NTR practice maintained better soil moisture conditions for crop growth than CT in dry periods than NT in wet periods. Compared with NT, the NTR avoided prolonged near-saturated soil conditions with increased soil drying rate under extremely wet soil. Key words: Water drying, water recharge, water depletion, wet and drying periods, hydraulic properties, soil capacity to retain water

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Effectiveness of Straw Mulch on Infiltration, Splash Erosion, Runoff and Sediment in Laboratory Conditions

Journal of Water and Land Development ◽

10.2478/jwld-2014-0022 ◽

2014 ◽

Vol 22 (1) ◽

pp. 51-60 ◽

Cited By ~ 11

Author(s):

Leila Gholami ◽

Kazimierz Banasik ◽

Seyed Hamidreza Sadeghi ◽

Abdulvahed Khaledi Darvishan ◽

Leszek Hejduk

Keyword(s):

Soil Loss ◽

Sandy Loam ◽

Soil Aggregates ◽

Sediment Concentration ◽

Runoff Coefficient ◽

Splash Erosion ◽

Straw Mulch ◽

Conservation Treatment ◽

Loam Soil ◽

The Impact

Abstract Mulches have extraordinary potential in reducing surface runoff, increasing infiltration of water into the soil and decreasing soil erosion. The straw mulches as a biological material, has the ability to be a significant physical barrier against the impact of raindrops and reduce the detachment of soil aggregates. The present study is an attempt to determine the efficiency of straw mulch as conservation treatment in changes in the splash erosion, time-to-runoff, runoff coefficient, infiltration coefficient, time-to-drainage, drainage coefficient, sediment concentration and soil loss. The laboratory experiments have been conducted for sandy-loam soil taken from deforested area, about 15 km of Warsaw west, Poland under lab conditions with simulated rainfall intensities of 60 and 120 mmh–1, in 4 soil moistures of 12, 25, 33 and 40% and the slope of 9%. Compared with bare treatments, results of straw mulch application showed the significant conservation effects on splash erosion, runoff coefficient, sediment concentration and soil loss and significant enhancement effects on infiltration and drainage. The results of Spearman-Rho correlation showed the significant (p < 0.05) correlation with r = –0.873, 0.873, 0.878 and 0.764 between rainfall intensity and drainage coefficient, downstream splash, sediment concentration and soil loss and with r = –0.976, 0.927 and –0.927 between initial soil moisture content and time-to-runoff, runoff coefficient and infiltration coefficient, respectively.

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MITIGATION OF HEAT STRESS EFFECTS ON POTATO GROWTH BY CALCIUM AND NITROGEN APPLICATION DURING STRESS

HortScience ◽

10.21273/hortsci.27.6.596f ◽

1992 ◽

Vol 27 (6) ◽

pp. 596f-596 ◽

Cited By ~ 1

Author(s):

Ahmed A. Tawfik ◽

Jiwan P. Palta

Keyword(s):

Heat Stress ◽

Sandy Loam ◽

Leaf Tissue ◽

Maximum Temperature ◽

N Application ◽

Total N ◽

Stress Effects ◽

Loam Soil ◽

Potato Growth ◽

The Impact

The optimum temperature regime for Solanum tuberosum cv. Russet Burbank is usually 20/15°C day/night. We studied the impact of heat stress (30/25°C, day/night) on the growth of this heat sensitive cultivar under controlled conditions (UW-Biotron). Plants were grown in sandy-loam soil which tested at 1500 Kg/ha Ca. Plants were at the maximum temperature for 6h during the middle of the day with a photoperiod of 14 hrs. All pots received identical amounts of total N (rate: 225 Kg N ha1.). The treatments were: (1) NSN: non-split N (N application 1/2 emergence, 1/2 two wks later): (2) SPN: split-N (1/2 emergence 1/6 at 2, 5 and 8 wks later); (3) SPN+Ca: Split-N+Ca (Ca at 2, 5 and 8 wks after emergence, total Ca from CaNO3 was 113 Kg ha1). Total leaf FWT and DWT was significantly reduced in NS treatment by heat stress at 13 wks as compared to optimum conditions. However, this was not reduced in SPN and SPN+Ca. Under heat stress: (a) SPN + Ca gave the highest leaf FWT and DWT, stomatal conductance, transpiration rate, and leaflet tissue Ca content; (b) Young expanding leaflets gave higher growth rate with SPN and SPN + Ca than NSN; (c) Ca content of mature leaflet decreased progressively in both NSN and SPN but not in SPN + Ca. Our results show that application of Ca and N during heat stress can mitigate stress effects and that maintenance of a certain level of calcium in leaf tissue is important under heat stress.

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