Fruit Yield and Quality of ‘Valencia’ Orange Trees under Long-Term Partial Rootzone Drying

Climate, soil and tree water status, fruit yields and quality of ‘Valencia’ orange trees were monitored over five consecutive seasons (2007–2012) to study the effects of irrigation placement or volume. Three irrigation treatments were imposed: conventional irrigation (CI, 100% of crop evapotranspiration on both sides of the rootzone), partial rootzone drying (PRD, 50% of CI water only on one alternated side of the rootzone) and continuous deficit irrigation (DI, 50% of CI water on both sides of the rootzone). Yield parameters were generally not affected by PRD, and only yield per tree was lower in DI than CI trees. Fruit size and juice content were also reduced by DI, and not by PRD. Both PRD and DI increased juice soluble solids and acidity, vitamin C and carotenoid concentrations, as well as fruit, juice and sugar productivity per unit of irrigation water. Overall, the straight reduction of irrigation volumes by ~55% (DI) induced an average of 4.4% leaf dehydration, which caused significant fruit size reductions and a 3.4% reduction in juice yield, corresponding to a loss of about 2.6 tons of juice and 261 kg of sugars per hectare and year. On the other hand, water savings of about 2 mega liters per hectare and year with PRD caused a mild 2.3% leaf dehydration and mainly fruit quality improvements, indicating that PRD is a sustainable irrigation strategy for ‘Valencia’ orange.

Effect Application of Technique Partial Rootzone Drying (PRD) on the Growth, Yield and Quality of Tomatoes

The research was conducted to evaluate the performance of tomatoes varieties on growth, yield and quality through the application of partial rootzone drying. The study was conducted in green house at the Faculty of Agriculture Universitas Islam Sumatera Utara (UISU) Medan in May 2014 until September 2014. The planting media used were straw compost mixed with top soil enriched withUrea, SP ─ 36 and KCL fertilizer filled into polybeg up to 10 kg in weight. Observation variables are: the growing, yield and quality of tomato

IRRIGAÇÃO LATERALMENTE ALTERNADA EM LIMA ÁCIDA 'TAHITI' NA REGIÃO NORTE DE MINAS GERAIS

IRRIGAÇÃO LATERALMENTE ALTERNADA EM LIMA ÁCIDA 'TAHITI' NA REGIÃO NORTE DE MINAS GERAIS MARCELO ROCHA DOS SANTOS1; SÉRGIO LUIZ RODRIGUES DONATO1; EUGÊNIO FERREIRA COELHO2; ALESSANDRO DE MAGALHÃES ARANTES1 E MAURÍCIO ANTÔNIO COELHO FILHO2 [1]Instituto Federal Baiano - Campus Guanambi, Distrito de Ceraíma, Caixa Postal 009, CEP 46.430-000, [email protected], [email protected], [email protected] Mandioca e Fruticultura, Rua Embrapa s/n, Caixa Postal 007, CEP 44380-000, Cruz das Almas, BA, [email protected], [email protected] 1 RESUMO As condições hídricas do solo e clima alteram as condições hídricas e fisiológicas das plantas, que influenciam o desenvolvimento e a produção. Objetivou-se com este estudo avaliar características fisiológicas, estado nutricional e produtividade em lima ácida 'Tahiti' com irrigação lateralmente alternada (partial rootzone drying – PRD). Nove tratamentos foram constituídos por diferentes reposições de lâmina de água aplicada, conforme a demanda evapotranspirométrica da cultura (ETc) e diferentes frequências de alternância no período compreendido entre a floração e a colheita, em dois ciclos produtivos da cultura, dispostos em delineamento em blocos casualizados com quatro repetições. O sistema de irrigação utilizado foi por gotejamento com duas linhas laterais e doze gotejadores por planta. Dos nutrientes analisados ficaram abaixo da faixa de suficiência apenas o teor de B nas plantas sob PRD a 50% da ETc e frequência de alternância (FA) de 7 dias, e de B e Mn sob PRD a 50% da ETc e FA de 21 dias e PRD a 75% da ETc e FA de 14 dias. Fotossíntese, transpiração, condutância estomática, concentração interna de CO2, radiação fotossinteticamente ativa e temperatura foliar variaram com a época e o horário de mensuração. Eficiência de carboxilação, eficiência quântica da fotossíntese e eficiência instantânea de uso da água (EUA) são maximizadas nos meses e horas dos dias com menores temperaturas. A PRD altera a concentração interna de CO2, transpiração, razão de carboxilação, razão de concentração de CO2 e produtividade. Há manutenção da produtividade com irrigação alternada a cada sete dias e PRD de 50% da ETc em relação à irrigação plena. Palavras-chave: Citrus, manejo da irrigação, déficit hídrico. SANTOS, M. R.; DONATO, S. L. R; COELHO, E. F.; ARANTES, A. M.; COELHO FILHO, M. A.PARTIAL ROOTZONE DRYING IN ACID LIME 'TAHITI' IN NORTHERN OF MINAS GERAIS BRAZIL 2 ABSTRACT The water conditions of the soil and climate change the water and physiological conditions of plants, influencing their development and production. This study aimed to evaluate gas exchanges, leaf temperature, nutrient levels in leaves and yield in acid lime ‘Tahiti’ under partial rootzone drying (PRD). Nine treatments were used with different percentages of crop evapotranspiration and different frequencies of alternation, from the beginning of flowering to physiological mature fruits in two productive cycles, arranged in a randomized block design with four replicates. The irrigation system was dripped with two lateral lines per row of plants, with twelve emitters per plant. Only the concentration of B was insufficient in plants under PRD with 50% ETc and frequency of alternation (FA) 7 days, PRD with 50% ETc and FA 21 days PRD and 75% ETc and FA 14 days and Mn for PRD 50% of ETc FA and 21 days PRD and 75% of ETc and FA 14 days. Photosynthesis, transpiration, stomatal conductance, internal CO2 concentration, photosynthetically active radiation and leaf temperature in Tahiti lime parameters are influenced by the period and time of measurement. The carboxylation efficiency, quantum efficiency of photosynthesis and instantaneous water use efficiency is maximized in the months and hours of days with lower temperatures. The PRD causes changes in internal CO2 concentration, transpiration, rate of carboxylation, ratio of CO2 concentration and yield. The highest yield occurred for PRD with 50% of ETc alternating irrigation every seven days in relation to full irrigation. Keyword: Citrus, irrigation management, water deficit.

Response of New Cotton Variety (Rassafa) to Nitrogen Fertilizer and Partial Rootzone Drying Drip Irrigation

Introduction: Due to the water shortage and dry Mediterranean condition, determination of water and nitrogen (N) fertilizer requirements is a major challenge for crop production and environment protection. A field experiment was carried out for two consecutive years (2014 and 2015) to evaluate the response of a new cotton variety (cv. Rassafa) to N-fertilizer and drip irrigation. Explanation: Treatments consisted of five different N-rates (0, 50, 100, 150, and 200 kg N ha-1), and three irrigation modes: full irrigation (FI), fixed partial rootzone drying irrigation (FPRD80), and alternate partial rootzone drying irrigation (APRD80). They received 100, 80, and 80% of the seasonal water use, respectively. Cotton was irrigated when soil moisture in the specified active root depth was 80% of the field capacity as designated by the neutron probe. Results: Results indicated that seed cotton yield (SCY), dry matter (DM), and water productivity (WP) could be optimized at an average N-rate of 140 kg N ha-1, for the tested cotton cultivar, whatever the irrigation mode used. In contrast to APRD80 mode, the findings showed that both FI and FPRD80 modes exhibited a consistence over years, but with an obvious preference of FI in SCY, DM, and WP.