ORIGINAL PAPER ABA action on the production and redistribution of field-grown maize carbohydrates in semiarid regions Claudia Travaglia • Guillermo Balboa • Gabriel Espo ´sito • Herminda Reinoso Received: 11 October 2011 / Accepted: 19 January 2012 / Published online: 12 February 2012 Ó Springer Science+Business Media B.V. 2012 Abstract The aim of this study is to analyze the response of exogenous abscisic acid (ABA) application in plants grown under field conditions in semiarid zones in order to increase maize production. For this, it is necessary to understand the factors, such as the size and capacity of transport system involved in the mobilization and distri- bution of assimilates. The vascular transport capacity of ABA-treated and control plants was compared in terms of number of vascular bundles, phloem area per bundle, and the proportion of phloem in the ear peduncle of female inflorescences. This study showed that the application of exogenous ABA in field-grown maize under moderate drought allows a greater amount of maize production, an increase in the level of photosynthetic pigments, the car- bohydrates remobilization to grain, and the capacity of this transport by an increase in the number of vascular bundles and the phloem area in peduncle. Evidence obtained in this study suggests that ABA could help improve agricultural production in rain-fed crops in which irrigation is not possible. This will allow us to follow a new technological strategy to increase the effective filling of organs during crops in unfavorable water conditions. Keywords Abscisic acid (ABA) Á Maize Á Carbohydrates Á Phloem Á Yield Á Water stress Introduction Maize (Zea mays L.) is severely affected by drought when it occurs close to flowering, as it inhibits floral develop- ment and leads to zygote abortion and fertilization failure (Otegui et al. 1995; Saini and Westgate 2000). In this stage, grain yield is reduced more than in other stages of growth due to the fact that flowering is a critical period in the determination of the number of kernels which is, in turn, the main yield component (Andrade et al. 1999;C ¸ akir 2004). The deficiency in the translocation of photoassimilates to the spike during this period is one of the main causes of this reduction (Schussler and Westgate 1991). It has been reported that increases in the reductive sugars (glucose–fructose) in wheat (Kameli and Lo ¨sel 1993) and maize (Pelleschi et al. 1997; Schellenbaum et al. 1998) leaves are an indicative of the water stress effect. This is why the soluble sugars have been considered markers to detect genotypes tolerant to dehydration in these crops. The reduction in the number of kernels caused by water stress can happen even when the amount of viable pollen is abundant (Moss and Downey 1971; Grant et al. 1989). A close association has been made between the kernel abortion and the carbohydrate supply during flowering (Zinselmeier et al. 1999; McLaughlin and Boyer 2004). The photoassimilates produced during the photosynthesis in plants must be distributed from the zones of synthesis or storage (source) to all the organs that need the photoas- similates (sink) in order to satisfy the requirements of metabolism and growth. The amount of product to be transported and the distances they must travel require a specialized system of transport, which is the phloem. The transport through the phloem depends on the production of C. Travaglia (&) Á H. Reinoso Morfologı ´a Vegetal, Facultad de Ciencias Exactas, Fı ´sico Quı ´micas y Naturales, Universidad Nacional de Rı ´o Cuarto, Campus Universitario, 5800 Rı ´o Cuarto, Argentina e-mail: ctravaglia@exa.unrc.edu.ar G. Balboa Á G. Espo ´sito A ´ rea de Produccio ´n de Cereales, Facultad de Agronomı ´a y Veterinaria, Universidad Nacional de Rı ´o Cuarto, Campus Universitario, 5800 Rı ´o Cuarto, Argentina 123 Plant Growth Regul (2012) 67:27–34 DOI 10.1007/s10725-012-9657-7