Altitude-plant density interaction on Andean maize: contributions to decision making

DIEGO SALVE; MARÍA L. MAYDUP; EDUARDO A. TAMBUSSI; GERMÁN SALAZAR; MARIANA ANTONIETTA

Rosario

Congreso; XXXIV Reunión Argentina de Fisiología Vegetal; 2023

Sociedad Argentina de Fisiología Vegetal

In the Northwest of Argentina, yields are limited by a progressive decrease in temperature with increasing altitude, but also by a lack of specific management strategies to underpin traditional practices. Our hypothesis is that increasing plant densities could compensate for the delay in planting date and phenological development at higher altitudes. The landrace “Amarillo de ocho” was grown at two densities (5.71 pl m-2 –conventional for this area- and 8.57 pl m-2) in two field trials conducted during 2021-22 in Hornillos (HOR), Jujuy (23º39’S, 65º25’W, 2300 masl), and El Rosal (ERO), Salta (24º23’S, 65º46’W, 3350 masl) without water or nutrients limitations. Additionally, samplings in 8 farmer’s fields spanning from 2400 to 3400 masl were carried out during 2022-23 growing season where plant density and yield were registered. Average temperature during the crop cycle was 39% lower at ERO compared with HOR, but thermal time requirements from emergency to reproductive stage decreased by 30% at ERO, partially compensating for the phenological delay. Increasing altitude resulted in 50% lower biomass at harvest and 86% lower yields (1107 Kg ha-1 at ERO vs. 7912 Kg ha-1 at HOR). Higher plant densities improved yield at HOR (+29%), related with 37% higher kernel number m-2 together with a slight reduction in kernel weight (-7%) whereas at ERO, a higher yield improvement (+44%) was related with a higher increase in kernel number m-2 and a larger decrease in kernel weight (-20%). Across farmer’s fields, yield per plant negatively related with increasing plant densities (from 6 up to 16 pl m-2), with a trend towards higher improvement in kernel number m-2 and larger decrease in kernel weight in the highest altitude sites (>3000 masl). Thus, increasing plant density could improve yields in high altitude environments especially due to increased kernel number m-2.