Research Findings: e-ifc No. 15, March 2008

Research work from Argentina: Nutritional evolution of drip irrigated peach (Prunus persica L.) trees

A. Bermejillo, V. Lipinski, M.F. Filippini, M. Venier, D. Cónsoli, and A. Valdés

Few studies have been made on the nutritional standards required for optimal production of fruit trees in the province of Mendoza, Argentina because of the complexity of the work and time required for these investigations.

This study describes the nutrient seasonal variations of peach trees during three to four production seasons (years 2002-2006) in two 7-year-old peach orchards in Villa Seca (Tunuyán), Mendoza.

The orchard in El Desafío was planted with the variety "Dr. Davis" and in El Porvenir the variety was "Heese". Both orchards are fertigated using a drip system and N, P, and K were applied via the fertigation system. Leaf samples were taken during the summer, twice weekly from a mean height of 1.5 m, taking the fourth leaf from the apex of each branch. These leaf samples were analysed for N, P, K, Ca, Mg, Fe, Mn, Zn and Cu and graphs describing changes in leaf nutrient status for each element were obtained. In this summary, only the graphs for K are presented.

Fig. 1. Potassium concentration in leaves of "Dr. Davis" peaches

Fig. 2. Potassium concentration in leaves of "Heese" peaches.

According to the literature, values <1% are deficient, 1-1.9% are low, 2-3% are normal, 3.1-4% are high, and >4% very high.

For all years, in El Desafío, K values were relatively low (2%) at the beginning of the season (ca 2%), probably as a consequence of a naturally poor K content of the soil. Later, when fertigation was implemented, K values rose to 3% and remained stable more or less at this value during the rest of the season (except in 2003-04).

K contents in leaves at the El Porvenir site increased from year to year, possibly reflecting good K fertigation management.

It is important to note that fertilization with K is crucial at the end of the season in order to prevent K decreases to below critical values. In both locations, K is applied from December with the purpose of improving fruit quality.

In 2005-06, foliar K values were higher than usual in December and January probably because the fruit load this season was lower than in normal years.

This occurred either because of inclement climatic conditions early in the season, or improved K fertigation management of the orchard or both these factors.