CANOPY TEMPERATURES AND ACCUMULATED DEGREE DAYS ON COTTON PLANTS UNDER WATER DEFICIT

CANOPY TEMPERATURES AND ACCUMULATED DEGREE DAYS ON COTTON PLANTS UNDER WATER DEFICIT JOÃO HENRIQUE ZONTA1; RUDAH MARQUES MANIÇOBA2; ZIANY NEIVA BRANDÃO3; MARIO ANASTASIO CARRILLO4 E JOSÉ RENATO CORTEZ BEZERRA5 1Embrapa Algodão, Rua Osvaldo Cruz, 1173, Centenário, Campina Grande – PB, CEP: 58428-095, e-mail: [email protected] 2Engenharia Agrícola, Universidade Federal Rural do Semiárido, Av. Francisco Mota, 572 - Bairro Costa e Silva, Mossoró - RN, CEP: 59625-900, e-mail: [email protected] 3Embrapa Algodão, Rua Osvaldo Cruz, 1173, Centenário, Campina Grande – PB, CEP: 58428-095, e-mail: [email protected] 4SmartFieldTM, Inc, n. 4617, 50th Street, Lubbock, Texas, 79414, e-mail: [email protected] 5Embrapa Algodão, Rua Osvaldo Cruz, 1173, Centenário, Campina Grande – PB, CEP: 58428-095, e-mail: [email protected] 1 ABSTRACT Canopy temperature is one of the best integrators of plant health and has been successfully used for irrigation scheduling. Therefore, the objective of this study was to evaluate the canopy temperature of cotton plants under water stress at different stages of the crop cycle and to determine the accumulated degree days based on canopy temperature. It was applied water deficit periods of 15 days at the following phenological stages: First Square, First Flower, Peak Bloom and Opening Bolls and control treatment. Canopy temperature was obtained using SmartCrop® wireless infrared temperature sensors. The results showed higher canopy temperatures during water deficit periods. For water deficit periods, canopy temperature values were always above the optimum temperature for cotton metabolism. As a result of the stress caused by water deficit, cotton yield was significantly reduced, with the higher yield loses recorded when applied deficit occurred during flowering stages (beginning and peak). Accumulated degree days also varied according to water stress, with a shortened phenological cycle for treatments with water deficit in comparison to the control without stress. The period for fiber thickening was also influenced by the variation in canopy temperature due to water stress, which may reflect decline in fiber quality. Keywords: Irrigation; Phenological cycle; Stress; Environmental conditions; Infrared thermometry. ZONTA, J. H.; MANIÇOBA, R. M.; BRANDÃO, Z. N.; CARRILLO, M. A. E BEZERRA, J. R. C. TEMPERATURA DO DOSSEL E GRAUS DIA ACUMULADOS EM ALGODOEIRO SOB DÉFICIT HÍDRICO 2 RESUMO A temperatura do dossel é um dos melhores assimiladores da saúde das plantas e tem sido usada com sucesso para manejo da irrigação. O objetivo deste estudo foi avaliar a temperatura do dossel do algodoeiro sob déficit hídrico em diferentes estágios fenológicos e determinar os graus dia acumulados a partir da temperatura do dossel. Foram aplicados períodos de déficit hídrico de 15 dias nos seguintes estádios fenológicos: Botão floral, Início do florescimento, Pico do florescimento e Abertura do Capulhos, além da testemunha. A temperatura do dossel foi obtida usando sensores sem fio de temperatura infravermelho SmartCrop®. Os resultados mostraram maiores temperaturas do dossel durante o déficit hídrico, quando comparados a testemunha. Para os períodos de déficit hídrico a temperatura do dossel esteve sempre acima da temperatura ótima para o metabolismo do algodoeiro. Devido ao déficit hídrico, a produtividade do algodoeiro foi significantemente reduzida, com os piores resultados para o déficit durante o florescimento (início e pico). Os graus dia acumulados variaram em função do estresse hídrico, com as plantas completando seu ciclo mais precocemente. O período de espessamento das fibras foi influenciado pela variação na temperatura do dossel devido ao estresse hídrico, podendo refletir em declínio da qualidade da fibra. Palavras-chave: Irrigação, Ciclo fenológico, Estresse, Condições ambientais, Termometria por infravermelho.

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Single hyperspectral bands are highly sensitive to water stress in adult mandarin trees

10.5194/egusphere-egu21-12594 ◽

2021 ◽

Author(s):

Pablo Berríos ◽

Abdelmalek Temnani ◽

Susana Zapata ◽

Manuel Forcén ◽

Sandra Martínez-Pedreño ◽

...

Keyword(s):

Water Stress ◽

Water Deficit ◽

Phase Ii ◽

Irrigation Water ◽

Water Status ◽

Irrigation Scheduling ◽

Plant Water Status ◽

Phase Iii ◽

Plant Water ◽

Severe Water Stress

Mandarin is one of the most important Citrus cultivated in Spain and the sustainability of the crop is subject to a constant pressure for water resources among the productive sectors and to a high climatic demand conditions and low rainfall (about 250 mm per year). The availability of irrigation water in the Murcia Region is generally close to 3,500 m3 per ha and year, so it is only possible to satisfy 50 - 60% of the late mandarin ETc, which requires about 5,500 m3 per ha. For this reason, it is necessary to provide tools to farmers in order to control the water applied in each phenological phase without promoting levels of severe water stress to the crop that negatively affect the sustainability of farms located in semi-arid conditions. Stem water potential (SWP) is a plant water status indicator very sensitive to water deficit, although its measurement is manual, discontinuous and on a small-scale. &#160;In this way, indicators measured on a larger scale are necessary to achieve integrating the water status of the crop throughout the farm. Thus, the aim of this study was to determine the sensitivity to water deficit of different hyperspectral single bands (HSB) and their relationship with the midday SWP in mandarin trees submitted to severe water stress in different phenological phases. Four different irrigation treatments were assessed: i) a control (CTL), irrigated at 100% of the ETc throughout the growing season to satisfy plant water requirements and three water stress treatments that were irrigated at 60% of ETc throughout the season &#8211; corresponding to the real irrigation water availability &#8211; except &#160;during: ii) the end of phase I and beginning of phase II (IS IIa), iii) the first half of phase II (IS IIb) and iv) phase III of fruit growth (IS III), which irrigation was withheld until values of -1.8 MPa of SWP or a water stress integral of 60 MPa day-1. When these threshold values were reached, the spectral reflectance values were measured between 350 and 2500 nm using a leaf level spectroradiometer to 20 mature and sunny leaves on 4 trees per treatment. Twenty-four HVI and HSB were calculated and a linear correlation was made between each of them with SWP, where the &#961;940 and &#961;1250 nm single bands reflectance presented r-Pearson values of -0.78** and -0.83***, respectively. Two linear regression curves fitting were made: SWP (MPa) = -11.05 &#8729; &#961;940 + 7.8014 (R2 =0.61) and SWP (MPa) = -13.043 &#8729; &#961;1250 + 8.9757 (R2 =0.69). These relationships were obtained with three different fruit diameters (35, 50 and 65 mm) and in a range between -0.7 and -1.6 MPa of SWP. Results obtained show the possibility of using these single bands in the detection of water stress in adult mandarin trees, and thus propose a sustainable and efficient irrigation scheduling by means of unmanned aerial vehicles equipped with sensors to carry out an automated control of the plant water status and with a suitable temporal and spatial scale to apply precision irrigation.

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Assessing canopy temperature-based water stress indices for soybeans under subhumid conditions

10.5194/egusphere-egu2020-16325 ◽

2020 ◽

Author(s):

Angela Morales Santos ◽

Reinhard Nolz

Keyword(s):

Water Stress ◽

Soil Water ◽

Water Status ◽

Canopy Temperature ◽

Irrigation Scheduling ◽

Stress Index ◽

Crop Water ◽

Stress Indices ◽

Soil Water Status ◽

Crop Water Stress

Sustainable irrigation water management is expected to accurately meet crop water requirements in order to avoid stress and, consequently, yield reduction, and at the same time avoid losses of water and nutrients due to deep percolation and leaching. Sensors to monitor soil water status and plant water status (in terms of canopy temperature) can help planning irrigation with respect to time and amounts accordingly. The presented study aimed at quantifying and comparing crop water stress of soybeans irrigated by means of different irrigation systems under subhumid conditions.The study site was located in Obersiebenbrunn, Lower Austria, about 30 km east of Vienna. The region is characterized by a mean temperature of 10.5&#176;C with increasing trend due to climate change and mean annual precipitation of 550 mm. The investigations covered the vegetation period of soybean in 2018, from planting in April to harvest in September. Measurement data included precipitation, air temperature, relative humidity and wind velocity. The experimental field of 120x120 m2 has been divided into four sub-areas: a plot of 14x120&#160;m2 with drip irrigation (DI), 14x120&#160;m2 without irrigation (NI), 36x120&#160;m2 with sprinkler irrigation (SI), and 56x120&#160;m2 irrigated with a hose reel boom with nozzles (BI). A total of 128, 187 and 114 mm of water were applied in three irrigation events in the plots DI, SI and BI, respectively. Soil water content was monitored in 10&#160;cm depth (HydraProbe, Stevens Water) and matric potential was monitored in 20, 40 and 60&#160;cm depth (Watermark, Irrometer). Canopy temperature was measured every 15&#160;minutes using infrared thermometers (IRT; SI-411, Apogee Instruments). The IRTs were installed with an inclination of 45&#176; at 1.8&#160;m height above ground. Canopy temperature-based water stress indices for irrigation scheduling have been successfully applied in arid environments, but their use is limited in humid areas due to low vapor pressure deficit (VPD). To quantify stress in our study, the Crop Water Stress Index (CWSI) was calculated for each plot and compared to the index resulting from the Degrees Above Canopy Threshold (DACT) method. Unlike the CWSI, the DACT method does not consider VPD to provide a stress index nor requires clear sky conditions. The purpose of the comparison was to revise an alternative method to the CWSI that can be applied in a humid environment.CWSI behaved similar for the four sub-areas. As expected, CWSI &#8805; 1 during dry periods (representing severe stress) and it decreased considerably after precipitation or irrigation (representing no stress). The plot with overall lower stress was BI, producing the highest yield of the four plots. Results show that DACT may be a more suitable index since all it requires is canopy temperature values and has strong relationship with soil water measurements. Nevertheless, attention must be paid when defining canopy temperature thresholds. Further investigations include the development and test of a decision support system for irrigation scheduling combining both, plant-based and soil water status indicators for water use efficiency analysis.

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Linking plant and soil indices for water stress management in black gram

Scientific Reports ◽

10.1038/s41598-020-79516-3 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Afshin Khorsand ◽

Vahid Rezaverdinejad ◽

Hossein Asgarzadeh ◽

Abolfazl Majnooni-Heris ◽

Amir Rahimi ◽

...

Keyword(s):

Water Stress ◽

Canopy Temperature ◽

Growth Period ◽

Irrigation Scheduling ◽

Stress Index ◽

Black Gram ◽

Crop Water Stress Index ◽

Water Stress Index ◽

Relative Water ◽

Soil Indices

AbstractMeasurement of plant and soil indices as well as their combinations are generally used for irrigation scheduling and water stress management of crops and horticulture. Rapid and accurate determination of irrigation time is one of the most important issues of sustainable water management in order to prevent plant water stress. The objectives of this study are to develop baselines and provide irrigation scheduling relationships during different stages of black gram growth, determine the critical limits of plant and soil indices, and also determine the relationships between plant physiology and soil indices. This study was conducted in a randomized complete block design at the four irrigation levels 50 (I1), 75 (I2), 100 (I3 or non-stress treatment) and 125 (I4) percent of crop’s water requirement with three replications in Urmia region in Iran in order to irrigation scheduling of black gram using indices such as canopy temperature (Tc), crop water stress index (CWSI), relative water content (RWC), leaf water potential (LWP), soil water (SW) and penetration resistance (Q) of soil under one-row drip irrigation. The plant irrigation scheduling was performed by using the experimental crop water stress index (CWSI) method. The upper and lower baseline equations as well as CWSI were calculated for the three treatments of I1, I2 and I3 during the plant growth period. Using the extracted baselines, the mean CWSI values for the three treatments of I1, I2 and I3 were calculated to be 0.37, 0.23 and 0.15, respectively, during the growth season. Finally, using CWSI, the necessary equations were provided to determine the irrigation schedule for the four growing stages of black gram, i.e. floral induction-flowering, pod formation, seed and pod filling and physiological maturity, as (Tc − Ta)c = 1.9498 − 0.1579(AVPD), (Tc − Ta)c = 4.4395 − 0.1585(AVPD), (Tc − Ta)c = 2.4676 − 0.0578(AVPD) and (Tc − Ta)c = 5.7532 − 0.1462(AVPD), respectively. In this study, soil and crop indices, which were measured simultaneously at maximum stress time, were used as a complementary index to remove CWSI constraints. It should be noted that in Urmia, the critical difference between the canopy temperature and air temperature (Tc − Ta), soil penetration resistance (Q), soil water (SW) and relative water content (RWC) for the whole growth period of black gram were − 0.036 °C, 10.43 MPa and 0.14 cm3 cm−3 and 0.76, respectively. Ideal point error (IPE) was also used to estimate RWC, (Tc − Ta) and LWP as well as to select the best regression model. According to the results, black gram would reduce its RWC less through reducing its transpiration and water management. Therefore, it can be used as a low-water-consuming crop. Furthermore, in light of available facilities, the farmer can use the regression equations between the obtained soil and plant indices and the critical boundaries for the irrigation scheduling of the field.

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Physiological Changes of Wheat Varieties Under Water Deficit Condition

Bangladesh Agronomy Journal ◽

10.3329/baj.v19i2.31859 ◽

2017 ◽

Vol 19 (2) ◽

pp. 105-114 ◽

Cited By ~ 1

Author(s):

T Tasmina ◽

AR Khan ◽

A Karim ◽

N Akter ◽

R Islam

Keyword(s):

Water Stress ◽

Water Deficit ◽

Water Saturation ◽

Canopy Temperature ◽

Water Retention Capacity ◽

Retention Capacity ◽

Wheat Varieties ◽

Water Saturation Deficit ◽

Spad Value ◽

Relative Water

The experiment was carried out at the research field of the Department of Agronomy of Bangabandhu Sheikh Mujibur Rahman Agricultural University, Gazipur during November 2014 to March 2015 to assess and evaluate the physiological derivations of wheat varieties under water deficit condition. The experiment was laid out in a split plot design comprising two water regimes (irrigated or control and water stress) in main plot and three wheat varieties (BARI Gom 25, BARI Gom 26 and Sourav) in sub-plot with four replications. Surface irrigation was applied into the irrigated plots in total growing season but it was applied in water stress plots up to 21 days after sowing after that irrigation was stopped in water stress plots. It was revealed that studied parameters were significantly influenced by water regimes, variety and their interaction. The xylem exudation rate, light interception, SPAD value, leaf water potential, relative water content, water retention capacity was higher in irrigated condition where canopy temperature, water uptake capacity, water saturation deficit higher in water stress condition.The wheat var. BARI Gom 26 showed the highest PAR, SPAD value, leaf water potential, relative water content, water retention capacity where BARI Gom 25 exhibit lowest under water deficit condition. On the other hand, BARI Gom 25 showd the highest canopy temperature, water uptake capacity and water saturation deficit in water deficit condition. Therefore, considering the physiological performance and other characters BARI Gom 26 could be considered preferably for water shortage condition followed by Sourav where BARI Gom 25 was susceptible one.Bangladesh Agron. J. 2016 19(2): 105-114

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Data-Driven Models for Canopy Temperature-Based Irrigation Scheduling

Transactions of the ASABE ◽

10.13031/trans.13901 ◽

2020 ◽

Vol 63 (5) ◽

pp. 1579-1592

Author(s):

Bradely A. King ◽

Krista C. Shellie ◽

David D. Tarkalson ◽

Alexander D. Levin ◽

Vivek Sharma ◽

...

Keyword(s):

Water Stress ◽

Canopy Temperature ◽

Irrigation Scheduling ◽

Data Driven ◽

Stress Index ◽

Wine Grape ◽

Crop Water ◽

Crop Water Stress Index ◽

Water Stress Index ◽

Crop Water Stress

HighlightsArtificial neural network modeling was used to predict crop water stress index lower reference canopy temperature.Root mean square error of predicted lower reference temperatures was <1.1°C for sugarbeet and Pinot noir wine grape.Energy balance model was used to dynamically predict crop water stress index upper reference canopy temperature.Crop water stress index for sugarbeet was well correlated with irrigation and soil water status.Crop water stress idex was well correlated with midday leaf water potential of wine grape.Abstract. Normalized crop canopy temperature, termed crop water stress index (CWSI), was proposed over 40 years ago as an irrigation management tool but has experienced limited adoption in production agriculture. Development of generalized crop-specific upper and lower reference temperatures is critical for implementation of CWSI-based irrigation scheduling. The objective of this study was to develop and evaluate data-driven models for predicting the reference canopy temperatures needed to compute CWSI for sugarbeet and wine grape. Reference canopy temperatures for sugarbeet and wine grape were predicted using machine learning and regression models developed from measured canopy temperatures of sugarbeet, grown in Idaho and Wyoming, and wine grape, grown in Idaho and Oregon, over five years under full and severe deficit irrigation. Lower reference temperatures (TLL) were estimated using neural network models with Nash-Sutcliffe model efficiencies exceeding 0.88 and root mean square error less than 1.1°C. The relationship between TLL minus ambient air temperature and vapor pressure deficit was represented with a linear model that maximized the regression coefficient rather than minimized the sum of squared error. The linear models were used to estimate upper reference temperatures that were nearly double the values reported in previous studies. A daily CWSI, calculated as the average of 15 min CWSI values between 13:00 and 16:00 MDT for sugarbeet and between 13:00 and 15:00 local time for wine grape, were well correlated with irrigation events and amounts. There was a significant (p < 0.001) linear relationship between the daily CWSI and midday leaf water potential of Malbec and Syrah wine grapes, with an R2 of 0.53. The data-driven models developed in this study to estimate reference temperatures enable automated calculation of the CWSI for effective assessment of crop water stress. However, measurements taken under conditions of wet canopy or low solar radiation should be disregarded as they can result in irrational values of the CWSI. Keywords: Canopy temperature, Crop water stress index, Irrigation scheduling, Leaf water potential, Sugarbeet, Wine grape.

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Simple Background Subtraction of Thermal Imagery for Canopy Temperature Measurement in Greenhouse

Applied Engineering in Agriculture ◽

10.13031/aea.13090 ◽

2019 ◽

Vol 35 (3) ◽

pp. 339-344

Author(s):

Kendall C DeJonge ◽

Huihui Huihui Zhang ◽

Sean M Gleason

Keyword(s):

Water Stress ◽

Canopy Temperature ◽

Irrigation Scheduling ◽

Small Scale ◽

Crop Water ◽

Thermal Imagery ◽

Infrared Thermometry ◽

Background Temperature ◽

Homogeneous Background ◽

Crop Water Stress

Abstract. While infrared thermometry and thermal imagery have potential to detect crop water stress and quantify evapotranspiration, both valuable in irrigation scheduling, it is often difficult to isolate plant canopy temperature from background temperatures. In this study, we demonstrate a simple technique that uses a homogeneous background temperature that contrasts with canopy temperature, thereby allowing the canopy temperature itself to be isolated in a thermal image. Analysis of pixel temperatures and their associated statistics demonstrate the potential of this method to measure small (ca. < 0.5°C) and rapid (ca. < 1 s) fluctuations in leaf energy balance. This technique has broad applicability in greenhouse, growth chamber, and other small-scale experiments where real time response of individual leaves or canopies is required. Keywords: Thermal imaging, Crop water stress, Infrared thermometry, Background masking, Deficit irrigation, Greenhouse.

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Water and thermal regimes for field pea in Australia and their implications for breeding

Crop and Pasture Science ◽

10.1071/cp11321 ◽

2012 ◽

Vol 63 (1) ◽

pp. 33 ◽

Cited By ~ 33

Author(s):

V. O. Sadras ◽

L. Lake ◽

K. Chenu ◽

L. S. McMurray ◽

A. Leonforte

Keyword(s):

Water Stress ◽

Water Deficit ◽

Minimum Temperature ◽

Growth Period ◽

Field Pea ◽

Maximum Temperature ◽

Mild Stress ◽

Degree Days ◽

Spatial And Temporal Patterns ◽

Stressful Condition

There is a large gap between the refined approaches to characterise genotypes and the common use of location and season as a coarse surrogate for environmental characterisation of breeding trials. As a framework for breeding, the aim of this paper is quantifying the spatial and temporal patterns of thermal and water stress for field pea in Australia. We compiled a dataset for yield of the cv. Kaspa measured in 185 environments, and investigated the associations between yield and seasonal patterns of actual temperature and modelled water stress. Correlations between yield and temperature indicated two distinct stages. In the first stage, during crop establishment and canopy expansion before flowering, yield was positively associated with minimum temperature. Mean minimum temperature below ~7°C suggests that crops were under suboptimal temperature for both canopy expansion and radiation-use efficiency during a significant part of this early growth period. In the second stage, during critical reproductive phases, grain yield was negatively associated with maximum temperature over 25°C. Correlations between yield and modelled water supply/demand ratio showed a consistent pattern with three phases: no correlation at early stages of the growth cycle, a progressive increase in the association that peaked as the crop approached the flowering window, and a progressive decline at later reproductive stages. Using long-term weather records (1957–2010) and modelled water stress for 104 locations, we identified three major patterns of water deficit nation wide. Environment type 1 (ET1) represents the most favourable condition, with no stress during most of the pre-flowering phase and gradual development of mild stress after flowering. Type 2 is characterised by increasing water deficit between 400 degree-days before flowering and 200 degree-days after flowering and rainfall that relieves stress late in the season. Type 3 represents the more stressful condition with increasing water deficit between 400 degree-days before flowering and maturity. Across Australia, the frequency of occurrence was 24% for ET1, 32% for ET2 and 43% for ET3, highlighting the dominance of the most stressful condition. Actual yield averaged 2.2 t/ha for ET1, 1.9 t/ha for ET2 and 1.4 t/ha for ET3, and the frequency of each pattern varied substantially among locations. Shifting from a nominal (i.e. location and season) to a quantitative (i.e. stress type) characterisation of environments could help improving breeding efficiency of field pea in Australia.

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Vapour pressure deficit aids the interpretation of cotton canopy temperature response to water deficit

Functional Plant Biology ◽

10.1071/fp13223 ◽

2014 ◽

Vol 41 (5) ◽

pp. 535 ◽

Cited By ~ 10

Author(s):

Warren C. Conaty ◽

James R. Mahan ◽

James E. Neilsen ◽

Greg A. Constable

Keyword(s):

Water Stress ◽

Soil Water ◽

Vapour Pressure ◽

Water Status ◽

Canopy Temperature ◽

Vapour Pressure Deficit ◽

Irrigation Scheduling ◽

Plant Water ◽

Stress Detection ◽

Water Fraction

Crop canopy temperature (Tc) is coupled with transpiration, which is a function of soil and atmospheric conditions and plant water status. Thus, Tc has been identified as a real-time, plant-based tool for crop water stress detection. Such plant-based methods theoretically integrate the water status of both the plant and its environment. However, previous studies have highlighted the limitations and difficulty of interpreting the Tc response to plant and soil water stress. This study investigates the links between cotton Tc, established measures of plant water relations and atmospheric vapour pressure deficit (VPDa). Concurrent measures of carbon assimilation (A), stomatal conductance (gs), leaf water potential (Ψl), soil water (fraction of transpirable soil water (FTSW)) and Tc were conducted in surface drip irrigated cotton over two growing seasons. Associations between A, gs, Ψl, FTSW and Tc are presented, which are significantly improved with the inclusion of VPDa. It was concluded that utilising the strong associations between Ψl, VPDa and Tc, an adjustment of 1.8°C for each unit of VPDa should be made to the critical Tc for irrigation. This will improve the precision of irrigation in Tc based irrigation scheduling protocols. Improved accuracy in water stress detection with Tc, and an understanding of the interaction the environment plays in this response, can potentially improve the efficiency of irrigation.

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Estimates of genetic parameters in diallelic populations of cotton subjected to water stress

Revista Brasileira de Engenharia Agrícola e Ambiental ◽

10.1590/1807-1929/agriambi.v24n8p541-546 ◽

2020 ◽

Vol 24 (8) ◽

pp. 541-546

Author(s):

Walmir S. Vasconcelos ◽

Roseane C. dos Santos ◽

Ubieli A. A. Vasconcelos ◽

José J. V. Cavalcanti ◽

Francisco J. C. Farias

Keyword(s):

Water Stress ◽

Combining Ability ◽

Genetic Parameters ◽

Fiber Quality ◽

Semiarid Region ◽

Flowering Stage ◽

Fiber Quality Traits ◽

Cotton Plants ◽

Cotton Genotypes ◽

Partial Diallel

ABSTRACT The objective of this study was to estimate the general combining ability (GCA) and specific combining ability (SCA) of cotton genotypes subjected to water stress, based on fiber quality traits. Irrigated cotton plants were grown in the dry season in the Northeast region of Brazil and subjected to 23 days without irrigation at the beginning of the flowering stage. GCA and SCA analyses were based on the partial diallel model. Significant differences were found for GCA for all traits, with predominance of additive effects. The crossing between the genotypes FM-966 and CNPA-5M was the most promising hybrid combination, showing great potential for improvements in fiber quality in environments subjected to water stress, such as the Semiarid region of the Northeast of Brazil.

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Assessing the Water-Stress Baselines by Thermal Imaging for Irrigation Management in Almond Plantations under Water Scarcity Conditions

Water ◽

10.3390/w12051298 ◽

2020 ◽

Vol 12 (5) ◽

pp. 1298

Author(s):

Saray Gutiérrez-Gordillo ◽

Iván Francisco García-Tejero ◽

Víctor Hugo Durán Zuazo ◽

Amelia García Escalera ◽

Fernando Ferrera Gil ◽

...

Keyword(s):

Water Stress ◽

Thermal Imaging ◽

Water Status ◽

Irrigation Management ◽

Irrigation Treatment ◽

Canopy Temperature ◽

Irrigation Scheduling ◽

Stress Index ◽

Crop Water ◽

Crop Water Stress Index

This work examines the use of thermal imaging to determine the crop water status in young almond trees under sustained deficit irrigation strategies (SDIs). The research was carried out during two seasons (2018–2019) in three cultivars (Prunus dulcis Mill., cvs. Guara, Lauranne, and Marta) subjected to three irrigation treatments: a full irrigation treatment (FI) at 100% of irrigation requirements (IR), and two SDIs that received 75% and 65% of the IR, respectively. Crop water monitoring was done by measurements of canopy temperature, leaf water potential (Ψleaf), and stomatal conductance. Thermal readings were used to define the non-water-stress baselines (NWSB) and water-stress baselines (WSB) for each treatment and cultivar. According to our findings, Ψleaf was the most responsive parameter to reflect differences in almond water status. In addition, NWSB and WSB allowed the determination of the crop water-stress index (CWSI) and the increment of canopy temperature (ITC) for each SDI treatment, obtaining threshold values of CWSI (0.12–0.15) and ITC (~1 °C) that would ensure maximum water savings by minimizing the effects on yield. The findings highlight the importance of determining the different NWSB and WSB for different almond cultivars and its potential use for proper irrigation scheduling.

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