*2.1. Field Study*

The research area was located on the east coast of Spain, in the province of Valencia (latitude 39◦2850" N, longitude 0◦2159" W). The region is characterized by an average annual temperature of 18.3 ◦C. Maximum temperatures (30.2 ◦C) are observed in the month of August, and minimum temperatures (7.1 ◦C) in January. The average rainfall is around 475 mm, with a relative humidity of 65%; the driest period corresponds with the month of August, and the rainiest with October [33]. For study purposes, a total of 108 individuals of Prunus dulcis (Mill.).

(Mill.) were selected. The procedure of each trial consisted in the selection of a minimum of 36 individuals for the different combinations of factors that could influence the generated waste: variety, pattern and fertilization type. Table 1 shows the factors studied and their different levels.


**Table 1.** Factors and levels analyzed for the characterization of almond trees biomass.

### *2.2. Vegetal Material and Treatments*

For this research, we analyzed two almond tree varieties (both of them were characterized following the UPOV norm TG/56/4 Corr): Marcona and Vayro. Marcona is an autochthonous variety from the east of Spain that is known worldwide for the high quality of its fruits. It is a highly ramified, medium-high vigor tree with low cold requirements [34]. Vayro is a late-flowering variety obtained through crosses within the IRTA (Instituto de Investigación y Tecnología Agroalimentarias) genetic hybridization program. Trees of this variety show very strong vigor and medium branch density [35].

The behavior of 3 rootstocks widely used in almond cultivation was tested. GF 305 rootstock is a medium-vigor frank peach pattern that adapts adequately to irrigated conditions [36] and is tolerant to drought. GF 677 comes from the interbreeding of peach trees (*Prunus persica* L. Batsch) and almond trees (*Prunus dulcis* Miller) obtained in France by the INRA (Institut National de la Recherche Agronomique) [37]. It is a vigorous rootstock with good agronomic behavior in both dry and irrigated conditions. Finally, GN Garnem, obtained by the Agricultural Research Service of the Government of Aragón (CITA-DGA) as the result of crossing between *Prunus dulcis* (Mill.) (cv. Garrigues) and *Prunus persica* L. Batsch (cv. Nemared). It stands out for its strong vertical growth, inducing greater vigor than GF 677 [38].

Regarding fertilization, the samples were subjected to 3 types of treatment. Biostimulant 1, which is mainly composed of saccharides and amino acids; Biostimulant 2, rich in humic and fulvic extract, and a control group of test plants that were only irrigated with water.
