Abstract:

Forage maize (Zea mays×Z. perennis) is a new type of perennial forage grass bred by maize-perennial teosinte substitution line (2n=20) and Z. perennis (2n=40). It can be harvested for silage or green feed several times in one growth period, and has high nutritive value, regenerative ability, and environmental adaptation. To understand the growth regularity and confirm the best harvest time of forage maize, its growth rate, fresh and dry matter accumulation and distribution during different stages in a field experiment were investgated, and evaluated its nutient values. The results indicated that the dynamic growth of forage maize fits Logistic model, and the growth rate was slow from the 30th to 50th day after sowing, fast from the 51st to 70th day (4.4 cm d^-1), slow from the 71st to 90th day, fast from the 91st to 110th day, and slow after 111st day (productive stage). Biomass and the ratio of stem to leaf of forage maize increased while palatability and nutritive value declined from tillering to silking stages. After tasseling stage, the nutrient value declined faster. Gross energy (GE), digestible energy (DE), metabolizable energy (ME), and total digestible nutrient (TDN) were the highest at booting or initial tasseling stage, which were 18.5 MJ kg^-1, 12.2 MJ kg^-1, 10.0 MJ kg^-1, and 0.66 kg, respectively. At initial tasseling stage, the fresh and dry matter yields were 101.4 t ha^-1 and 18.35 t ha^-1, crude protein (CP), crude fiber (CF), ether extract (EE), crude ash (CA) and nitrogen-free extract (NFE) were 14.2%, 24.3%, 3.9%, 6.3%, and 51.3%, respectively. It is suggested that forage maize should be harvested in initial tasseling stage in order to produce better biomass and nutritive value.

Key words: Forage maize, Growth dynamics, Harvest time