Evapotranspiration, crop coefficient and water use efficiency of onion cultivated under different irrigation depths

ABSTRACT This study aimed to determine crop evapotranspiration through the soil water balance, the crop coefficient and water use efficiency of the onion (Allium cepa L.) in a system with four irrigation regimes, cultivated in the semiarid region of northeastern Brazil. Two field experiments were carried out during the rainy and dry periods of the region in 2018, using the treatments of 100% (T1), 75% (T2), 50% (T3) and 25% (T4) of the reference evapotranspiration for daily water replacement and five replicates for each treatment. It was verified that crop evapotranspiration varies according to the water availability in the soil; however, the highest water use efficiency occurred for the T3 treatment. The T1 treatment obtained the highest estimated yield, 43.86 tons ha-1, while T4 obtained 13.47 tons ha-1, the lowest estimated yield among the treatments, and this difference was statistically significant (p ≤ 0.05) by F test. The crop coefficients obtained were 0.68, 0.89, 0.99 and 0.73 for the initial, vegetative, bulbing and maturation stages, respectively.

Contribution of water and radiation to growth and yield of pearl millet in Deccan plateau - A case study

In this study the agrometeorological data for the period from 1991 to 1997 have been used to study evapotranspiration demand and crop characteristics of pearl millet at Solapur. Crop coefficients, water use efficiency and radiation use efficiency have been worked out and discussed. This has been done for two varieties of the crop viz., ICTP-8203 and Shraddha. The study revealed that pearl millet crop consumed maximum amount of water during earhead emergence phase, followed by flowering phase. During earhead emergence and flowering phase together, ICTP-8203 variety used nearly 50% of total water used while shraddha consumed about 60%. The highest values of crop coefficient are seen during earhead emergence phase for both the varieties. Maximum photosynthetically active radiation is availed by the crop during its vegetative phase. Radiation use efficiency is more for ICTP-8203 variety than Shraddha variety.

Water requirement and growth of sorghum over semi-arid region in Deccan Plateau

Based on the result of an experiment conducted from 1978-86 during post-rainy crop season at Solapur, crop coefficients for sorghum during different stages of growth were determined. A model has been developed for relating consumptive use of water at different phenological stages in relation to climatic parameters and crop water needs. The extent to which water requirements of the crop are met and water use efficiency have been discussed. The water requirement appears to be maximum at tasseling/flowering phases of sorghum growth. It works out at 4 mm per day under Solapur environment. The seasonal rainfall in post-rainy season does not appear to furnish a reliable estimate of the yield.

EVAPOTRANSPIRAÇÃO, COEFICIENTE DE CULTURA E CRESCIMENTO DE CANA-DE-AÇÚCAR PLANTADA POR MUDAS PRÉ-BROTADAS E POR TOLETES

EVAPOTRANSPIRAÇÃO, COEFICIENTE DE CULTURA E CRESCIMENTO DE CANA-DE-AÇÚCAR PLANTADA POR MUDAS PRÉ-BROTADAS E POR TOLETES MARIA EDUARDA NAJM SANDRINI1, ALEXANDRE BARCELLOS DALRI1, ANDERSON PRATES COELHO1, ROGÉRIO TEIXEIRA DE FARIA1, LUIZ FABIANO PALARETTI1 1Departamento de Engenharia e Ciências Exatas, Faculdade de Ciências Agrárias e Veterinárias, Jaboticabal, SP, Brasil. [email protected], [email protected], [email protected], [email protected], [email protected] 1 RESUMO Atualmente, a cana-de-açúcar apresenta diversos modos de plantio, destacando-se o plantio por mudas pré-brotadas. Esse sistema necessita de novos estudos para a recomendação adequada das práticas agronômicas, como a irrigação. Objetivou-se nesse trabalho avaliar e comparar o consumo hídrico, o coeficiente de cultura e o crescimento inicial da cana-de-açúcar plantada por mudas pré-brotadas (MPB) e por toletes. Foram definidos quatro tratamentos: cana-de-açúcar plantada por MPB e por toletes, plantio de grama batatais e solo nu, todos mantidos em lisímetros de pesagem. A evapotranspiração de referência (ETo) foi medida em lisímetros com a cultura de referência (grama). A evapotranspiração da cultura (ETc) da cana-de-açúcar plantada por MPB e toletes foi estimada por meio do balanço hídrico do solo. A estimativa dos coeficientes de cultura (Kc) foi obtida pela razão entre a ETc dos lisímetros com cana e a ETo. A comparação das variáveis entre a cana-de-açúcar plantada por MPB e por toletes foi realizada por análise de regressão. O Kc da cana-de-açúcar plantada por toletes variou de 0,86 a 2,88 e do plantio por MPB de 1,12 a 3,10. A cana-de-açúcar plantada por MPB apresenta maior consumo hídrico, coeficiente de cultura e crescimento inicial do que quando plantada por toletes. Palavras-chave: arduino, consumo hídrico, irrigação, Kc, lisímetro de pesagem. SANDRINI, M.E.N; DALRI, A.B.; COELHO, A.P.; FARIA, R.T. de, PALARETTI, L.F. EVAPOTRANSPIRATION, CROP COEFFICIENT AND SUGARCANE GROWTH PLANTED BY PRE-SPROUTED SEEDLINGS AND STALKS 2 ABSTRACT Currently, the sugarcane presents several types of planting, especially the planting by pre-sprouted seedlings. This system needs new studies for the adequate recommendation of agronomic practices, such as irrigation. We aimed in this work to evaluate and compare the water consumption, crop coefficient and initial growth of sugarcane planted by pre-sprouted seedlings (PSS) and stalks. Four treatments were defined, being sugarcane planted by PSS and by stalks, bahiagrass grass and bare soil, all kept in weighing lysimeters. The reference evapotranspiration (ETo) was measured in the grass lysimeters. The crop evapotranspiration (ETc) of sugarcane planted by PSS and stalks was estimated by the water balance in the soil. The estimation of the crop coefficients (Kc) was obtained from the ratio between ETc of lysimeters with sugarcane and ETo. Comparison of the variables between planted sugarcane by PSS and by stalks was performed by regression analysis. The Kc of the sugarcane planted by stalks ranged between 0.86 to 2.88 and planting by PSS from 1.12 to 3.10. The sugarcane planted by PSS presents higher water consumption, crop coefficient and initial growth than when planted by stalks. Keywords: arduino, water consumption, irrigation, Kc, weighing lysimeter.

Crop-coefficients of tomato as derived using monolithic weighing type lysimeter in mid hill region of Meghalaya

Crop coefficients (kc) was determined for tomato (Lycopersicon esculentum Mill.) with the help of UMS-GmBH cylindrical field lysimeter of 30 cm diameter and 120 cm deep and Penman-Monteith FAO-56 model. Eight other models viz. Modified Penman Method, Hargreaves equation, Samani-Hargreaves equation, Thornthwaite equation, Solar Radiation Method, Net Radiation Method, Blaney-Criddle Method and Radiation Method were also used for estimation of ET0­ and compared with Penman-Monteith model to find out the accuracy of prediction with limited weather parameters. Scatter plot and paired t-test were used for comparison. Out of all these models, Blaney-Criddle method, Solar and Net Radiation method were found to yield similar results as given by Penman-Monteith model. The values of crop evapo-transpiration (ETc) were varying from 2.54 mm d-1 to 6.70 mm d-1. The crop-coefficients (kc) for three growth stages of tomato viz., initial, mid and maturity were found to be 0.55, 1.07 and 0.78, respectively.

Crop coefficient estimated by degree-days for ‘Marandu’ palisadegrass and mixed forage

Considering profitability in pasture-based systems, investigating parameters affecting crop coefficients for irrigation management becomes important. In this experiment, we determined the crop coefficient of ‘Marandu’ palisadegrass based on accumulated degree-days and estimated plant water consumption under single (‘Marandu’ alisadegrass) and mixed (‘Marandu’ palisadegrass + black oats + Italian ryegrass) cropping regimes. The research was conducted at the Luiz de Queiroz College of Agriculture in Piracicaba, São Paulo, Brazil, between 2016 and 2017. Evapotranspiration was assessed using weighing lysimeters while crop evapotranspiration was calculated using mean weight variation. Reference evapotranspiration and degree-days were estimated. Data were obtained from an automated weather station. Equations and regression models relating crop coefficient with accumulated degree-days were generated for two seasons (spring/summer and autumn/winter) and evaluated for two year-cycles, from 2015 to 2018. The results showed better prediction accuracy for the single cropping system in spring/summer 2017–18. Highlights The model for determinating crop coefficient (Kc) by accumulated degree-days showed efficient for use in determination local. The use of the degree days for determination Kc is more vantage because only necessary to measure the air temperature (maximum and minimum). The equations for determining crop coefficient by accumulated degree days for the spring/summer season in Marandu palisade grass cultive show more precision that in mixture forage system.

Crop coefficient and water requirement of Okra (Abelmoschus Esculentus L. Moench)

Based on the result of an experiment conducted from 1997 to 1999 during March-July, a model has been developed for relating crop coefficient of okra with time at Bangalore. The peak value of crop co-efficient was found to be 1.16 on the 9th week after sowing. On an average okra crop consumed about 547 mm of water during the growth. The mean values of crop coefficients are found to be 0.46, 1.29 and 0.66 during seedling, pod development and maturity stages respectively.

Evapotranspiration Partition and Dual Crop Coefficients in Apple Orchard with Dwarf Stocks and Dense Planting in Arid Region, Aksu Oasis, Southern Xinjiang

Crop coefficients are critical to developing irrigation scheduling and improving agricultural water management in farmland ecosystems. Interest in dwarf cultivation with high density (DCHD) for apple production increases in Aksu oasis, southern Xinjiang. The lack of micro-irrigation scheduling limits apple yield and water productivity of the DCHD-cultivated orchard. A two-year experiment with the DCHD-cultivated apple (Malus × domestica ‘Royal Gala’) orchard was conducted to determine crop coefficients and evapotranspiration (ETa) with the SIMDualKc model, and to investigate apple yield and water productivity (WP) in response to different irrigation scheduling. The five levels of irrigation rate were designed as W1 of 13.5 mm, W2 of 18.0 mm, W3 of 22.5 mm, W4 of 27.0 mm, and W5 of 31.5 mm. The mean value of basal crop coefficient (Kcb) at the initial-, mid-, and late-season was 1.00, 1.30, and 0.89, respectively. The Kc-local (ETa/ET0) range for apple orchard with DCHD was 1.11–1.20, 1.33–1.43, and 1.09–1.22 at the initial, middle, and late season, respectively. ETa of apple orchard in this study ranged between 415.55–989.71 mm, and soil evaporation accounted for 13.85–29.97% of ETa. Relationships between total irrigation amount and apple yield and WP were developed, and W3 was suggested as an optimum irrigation schedule with an average apple yield of 30,540.8 kg/ha and WP of 4.45 kg/m3 in 2019–2020. The results have implications in developing irrigation schedules and improving water management for apple production in arid regions.