Potato Minituber Production Using Aeroponics: Effect of Plant Density and Harvesting Intervals

American Journal of Potato Research, Jan/Feb 2006 by Farran, Imma, Mingo-Castel, Angel M

ABSTRACT

To optimize minituber production through aeroponics some horticultural management factors should be studied. Potato plantlets, cv Zorba, were grown aeroponically at two different plant densities (60 and 100 plants/m^sup 2^). Plants showed an extended vegetative cycle of about 5 months after planting. A higher number of stolons was obtained at low plant densities. Tuber formation hastened when supplied N was reduced. Experiments on harvesting intervals (7, 10, and 14 days) indicated that for a density of 60 plants/m^sup 2^, both number of minitubers and yield increased as harvesting interval decreased. Best results were achieved harvesting every 7 days: a total tuber yield of 118.6 g per plant was obtained (four times higher than for 100 plants/m^sup 2^). Such a yield was composed, on the average, of 13.4 tubers with a mean tuber weight of 8.1 g. Harvesting intervals did not have an effect on the number of minitubers and yield for a density of 100 plants/m^sup 2^. The best productivity obtained in this study was 800 minitubers/m^sup 2^ for weekly harvests and a low plant density (60 plants/m^sup 2^). We also studied the field performance of aeroponically produced minitubers vs those produced by hydroponics. Minituber behavior under field conditions was independent from the technique used for its production.

RESUMEN

Para optimizer la producción de mini tubérculos de papa por aeroponía, se deberían estudiar algunos factores de manejo hortícola. Se cultivaron aeropónicamente plántulas de papa del cv Zorba en dos diferentes densidades (60 y 100 plantas por m^sup 2^). Las plantas mostraron un període vegetativo extenso de cinco meses después de la siembra. Se obtuvo un gran número de estolones a baja densidad de plantas. La formación de tubérculos se aceleró cuando se redujo la aplicación de N. Los experimentos sobre intervales de cosecha (7, 10 y 14 días) indicaron que a ima densidad de 60 plantas per m^sup 2^ se incrementó el número de tubérculos y el rendimiento aumentó a medida que se fue disminuyendo el intervalo de cosecha. Los mejores resultados se obtuvieron cosechando cada 7 días, al cabo de los cuales se obtuvo un rendimiento total de 118.6g por planta (cuatro veces mayor que con 100 plantas por m^sup 2^). El rendimiento fue en promedio de 13.4 tubércules con un peso medio de 8.1g. Los intervalos de cosecha no tuvieron efecto sobre el némero de mini tubérculos y rendimiento a una densidad de 100 plantas por m^sup 2^. La mayor productividad obtenida en este estudio fue de 800 mini tubérculos por m^sup 2^ en cosechas semanales y a una baja densidad de plantas (60 plantas por m^sup 2^). También hemos estudiado el comportamiento de campo de los mini tubércules producidos aeropónicamente versus aquellos producidos por hidroponía. El comportamiento de los mini tubérculos producidos bajo condiciones de campo fue independiente de la técnica utilizada para su producción.

Accepted for publication 15 August 2005.

ADDITIONAL KEY WORDS: Solanum tuberosum, rhizotron, N supply, field behavior, hydroponics, tuber

INTRODUCTION

Producing minitubers from in vitro plantlets allows a faster multiplication rate in seed programs and reduces the number of field generations needed (Ranalli 1997). Minitubers can be obtained from high-density plantings in greenhouse beds after acclimatization (Wiersema et al. 1987) in containers using different substrate mixtures (Jones 1988), or even in hydroponics (Muro et al. 1997; Rolot and Seutin 1999). Alternatively, soil-less production techniques, such as the Nutrient Film Technique (NFT) and aeroponics have successfully been employed in tuber production, with good prospects for certified seed production (Boersig and Wagner 1988). However, Wheeler et al. (1990) described injury to periderm tissue by salt accumulation from the nutrient solution on the surface of the tuber using the NFT technique, and Tibbitts and Cao (1994) found that tuber initiation in nutrient solution without solid media was poorer than in porous media.

Aeroponic culture is an alternative method of soil-less culture in growth-controlled environments. The underground organs are enclosed in a dark chamber and supplied with a nutrient solution by way of a mist device. Aeroponics optimizes root aeration, which is a major factor leading to a yield increase as compared to classical hydroponics (Soffer and Burger 1988). It shows other advantages such as solution recirculation, a limited amount of water used, and good monitoring of nutrients and pH. The worst inconvenience relies on the low volumes available to the root system, and any losses of power to pumps can produce irreversible damages. Despite these problems, this technique has been applied successfully for the production of different horticultural and ornamental species (Biddinger et al. 1998; He and Lee 1998; Molitor et al. 1999).

An aeroponic system for seed potato production was also successfully established in Korea (Kang et al. 1996a, 1996b; Kim et al. 1997, 1999) under tropical and subtropical conditions. Although some authors reported the inhibition of tuberization in immersed organs or subjected to continuous mist culture (Tibbitts and Cao 1994), tuberization under these procedures could be promoted under certain stress conditions such as N deficiency (Krauss and Marschner 1982) and shortterm reductions in solution pH (Wan et al. 1994). Recently, Ritter et al. (2001) showed that aeroponics for producing potato minitubers under temperate weather conditions substantially improved minituber production.