Parameter identification for further utilization as selection criteria to generate new forage maize cultivars is of the utmost importance in the breeding programs. The objective of this study was to evaluate the agronomic characteristics, yield, and nutritional value of experimental maize hybrids with forage potential in the Central Highlands of Mexico. The experiment was conducted in Texcoco, State of Mexico. Treatments consisted of 11 maize cultivars planted in irrigated conditions and allocated in randomized complete block design with three replications. Results indicated differences (P<0.0001) for most variables. Earliness varied from 84 to 109 days, and plant height from 190 to 282.9 cm. In addition, cultivars with Tropical and subtropical germplasm showed an increasing incidence of common rust from 8.3 to 92%. The yield of green forage varied from 37.1 to 80 t ha-1, while the yield of dry matter was from 12.8 to 24.8 t ha-1. In conclusion, the productive potential of hybrids with Tropical germplasm is limited due to their susceptibility to rust. In contrast, hybrids with germplasm from the Highlands showed an outstanding performance. These hybrids were V-107, H157-E, H-161, and H-166E.

In Mexico, the relationship of seed size with the productive and nutritional potential of maize silage needs to be studied. Thus, this study investigated the effect of seed size on yield and the nutritional value at the cutting stage for silage of various maize varieties. The research consisted of two phases: the productivity of maize for silage and the nutritional value estimated in the laboratory. Nine maize varieties, previously classified by their seed size, were used: flat large and flat medium. The experimental design was a randomized complete block with factorial arrangement and four repetitions. The harvest was carried out at the silage-cutting stage (30-35% DM, whole plant). Results for each estimated variable showed significant differences (P<0.001) among varieties, while seed size was significant for only some variables. Based on the absolute value of the standardized coefficients, the outstanding variables were female flowering, total protein, in vitro digestibility, and dry matter yield. In conclusion, maize variety for silage affects the productivity and nutritional value in the cutting stage. In contrast, the effect of seed size on protein yield, protein content, and plant digestibility was minor. The materials Campeón, H-135, H-157, HS-2, and A-791 yielded the highest, while the nutritional value of H-135, Campeón, HS-2, VS-22, and H-358 was outstanding.

The objective of this study was to evaluate the effect of seed size on the productivity and nutritional value of maize stover and grain. Nine varieties of maize previously classified by their shape and size were produced. The investigation consisted of two phases: in the first, the agronomic and productivity characters of maize stover and grain were evaluated, and in the second, the nutritional value. The experimental design used in each phase was randomized complete blocks with factorial arrangement and four repetitions. The harvest was carried out at the cutting stage of physiological maturity. Significant differences (P ≤ 0.001) were observed between varieties for all the evaluating parameters; For seed size, there was only significance in stover protein yield per hectare, stover and grain protein content, and in vitro digestibility of stover dry matter. Based on the absolute value of the standardized coefficients, the most relevant variables were in vitro digestibility and stover protein; grain yield, protein and starch. It is concluded that the variety affects the yield and nutritional value of maize stover and grain; seed size only had a slight effect on nutritional value. The outstanding materials for their stover yield were Campeón, VS-2000, H-157E and H-358 and for grain yield, they were the hybrids HS-2, Promesa and H-157E. The most outstanding variety for its productivity and nutritional value of maize stover and grain was VS-22.