Papaya seedlings growth using a low-cost, automatic watering controller

Abstract

The study assessed growth and physiological parameters of 'Sunrise Golden' and 'Tainung 01' papaya seedlings grown in 280mL plastic tubes and watered using a low-cost automatic irrigation system adjusted to operate at substrate water tension for starting irrigation (STI) of 3.0, 6.0 or 9.0 kPa. The water depths applied by the dripping system and drainage were monitored during germination and seedling growth. Germination, emergence velocity index (EVI), leaf area, plant height, shoot and root dry weight, stomatal conductance, relative water content (RWC) and relative chlorophyll content (RCC) were evaluated. Soil nutrient levels were determined by electrical conductivity (EC). Water use efficiency (WUE) corresponded to the ratio of plant dry mass to depth of water applied. STI settings did not affect papaya germination or EVI. System configuration to 3.0 and 6.0 kPa STI exhibited the highest drainage and lowest EC and RCC, indicating soil nutrient loss and plant nutrient deficiency. Drainage was greater in tubes planted with the 'Tainung 01' variety, which developed smaller root systems and lower stomatal conductance than 'Sunrise Golden' seedlings. The highest values for shoot dry weight and WEU were obtained at 6.0 kPa STI for 'Sunrise Golden' (0.62 g and 0.69 g L-1) and at 9.0 kPa in 'Tainung 01' (0.35 g and 0.82 g L-1). RWC at 9.0 kPa STI was lower than at 3.0 kPa in both varieties. The results indicate that the low-cost technology developed for irrigation automation is promising. Even so, new studies are needed to evaluate low-flow irrigation systems as well as the nutrient and water needs of different papaya varieties.

Automatically controlled deficit irrigation of lettuce in “organic potponics”

“…The values of gs recorded here were close to those obtained for lettuce by Kim et al (2004). The decrease in gs from 12h00 to 15h00 (Figure 5) was probably due to a small reduction in VPD and a sharp drop in global radiation, as observed for papaya seedlings from 12h00 to 15h00 (Dias et al, 2013).…”

“…This controller has the advantage of being built with low cost materials, even though it requires trained personnel for installation and periodic maintenance. We used and tested the Simplified Irrigation Controller (SIC, Medici et al, 2010) in the field, in pot-plant studies and in small vials for seedlings (Batista et al, 2013;Dias et al, 2013;Gomes et al, 2014;Gonçalves et al, 2014).…”

“…For papaya seedlings this range was sufficient to cause water stress (Dias et al, 2013), but not for lettuce plants (Gonçalves et al, 2014). Therefore, in this study, we are testing volumes lower than the those supplied by SIC to impose controlled stress, which can improve water use efficiency in organic potponics system for lettuce.…”

“…Therefore, in this study, we are testing volumes lower than the those supplied by SIC to impose controlled stress, which can improve water use efficiency in organic potponics system for lettuce. This system was evaluated using agronomic and physiological traits, such as stomatal conductance, chlorophyll content and chlorophyll a fluorescence, which are drought-sensitive traits (Martinazzo et al, 2011;Dias et al, 2013). This study sets the ground for a widespread use of SIC for the cultivation of plants in pots for commercial and research purposes.…”

Análise de Horário de Colheitas e Partes da Planta para Extração de Óleo Essencial de Manjericão

“…Este dispositivo pode ser construído com peças e utensílios domésticos fabricados em larga escala, de baixo custo e de fácil aquisição no mercado, e vem se mostrando eficiente na automação da irrigação, de forma a manter a umidade do solo em níveis próximos à capacidade de campo (MEDICI et al, 2010;BATISTA et al, 2013;CARVALHO et al, 2013;DIAS et al, 2013).…”