Key Points of High-Yield Cultivation Techniques for Hybrid Napiergrass

Napiergrass (scientific name: Pennisetum alopecuroides (L.) Spreng) is perennial. The fibrous roots are relatively thick. The culms are erect, tufted, and densely covered with soft hairs below the inflorescence. The leaf sheaths are smooth, flattened on both sides, with the midrib forming a ridge; those at the base are clasping, while those on the upper part of the culm are longer than the internodes; the ligule bears cilia about 2.5 mm long; the leaf blades are linear, with papillose hairs at the base. The panicle is erect; the main axis is densely covered with soft hairs; the peduncle is 2-3(-5) mm long; the bristles are pale green or purple; the anthers have no hairs at the tip; the styles are united at the base. The caryopsis is oblong. The epidermal cell structure of the leaf blade differs between the upper and lower epidermis; the upper epidermis is long-cylindrical and wavy; the lower epidermis is long-cylindrical with thick walls. The flowering and fruiting period is summer and autumn.

It mostly grows on field banks, wasteland, roadsides and small hillsides at an altitude of 50-3200 m. It is distributed throughout the world. It has strong adaptability to soil, tolerates slight alkalinity, and also tolerates drought and poor soil. The perennial napiergrass root system is relatively well developed and has a good function of soil fixation and slope protection. The whole plant, roots or rhizomes can all be used medicinally; among them, the whole plant can clear heat, cool blood and stop bleeding; the roots or rhizomes clear heat and detoxify. In addition, it is also a forage plant and an ornamental plant.

Characteristics of hybrid napiergrass

Hybrid napiergrass has deep, dense roots and well-developed fibrous roots, with the root system distributed mainly within the 0--20 cm soil layer. The stems are round, tufted, thick, hard and erect, generally about 3.5 m tall, with about 20 tillers per plant. After repeated cuttings, tillering can increase severalfold. The leaves are long and strip-shaped, alternate, 60--80 cm long and about 2.5 cm wide. The leaf margins are densely covered with bristles, the leaf surface has sparse hairs, and the midrib is obvious. The panicle is columnar, the spike is yellowish brown, 20--30 cm long, 2--3 cm in diameter, and the spikelets are lanceolate. Because it cannot form pollen, or the pistil develops poorly, it generally does not set seed. Hybrid napiergrass originated in tropical and subtropical regions, so a warm and humid climate is most suitable for its growth. Generally speaking, it begins to grow when the daily average temperature reaches 15°C, grows fastest at 25--30°C, is obviously inhibited when the temperature is below 10°C, and is killed by frost when the temperature is below 0°C. Hybrid napiergrass has strong stress resistance and can grow on most soils, and fertile, moist soil is extremely favorable for high forage yield. It is resistant to lodging, drought, moisture and salinity-alkalinity. After being planted in Nanjing for many years, no obvious disease or pest damage has been found. The general yield is 150,000 kg/ha, and high-yield fields can produce up to 225,000 kg/ha of fresh grass.

How can hybrid napiergrass be cultivated for high yield?

Land preparation

Hybrid napiergrass has a well-developed root system and requires deep soil, so it is generally plowed 30 cm deep, preferably deep-plowed in winter and frozen to ensure loose soil. In March, harrow the land and make beds 4 m wide, and open a complete set of field ditches to avoid water accumulation in the field. This field is transplanted in mid-to-late April.

Seedling raising

When propagating with first-generation hybrid seeds, seedlings should be raised first. Use 15,000 kg/ha of organic fertilizer in the seedbed, or 300 kg/ha of pure nitrogen, plus 300 kg/ha of calcium superphosphate. In the middle and lower reaches of the Yangtze River, sowing is done in late March, with 22.5--30.0 kg/ha of seed used in the seedbed, using sparse drilling with a row spacing of 15--18 cm. First open furrows and apply insecticide to prevent underground pests from biting and eating the seeds, and after sowing set up a small shed covered with plastic film. The seedbed temperature is best controlled at 20--25°C, and the soil should be kept moist after sowing to ensure full emergence in one sowing. When the seedlings grow to 3--4 straight leaves, chemical fertilizer can be applied once, using 30--45 kg/ha of urea. After fertilizing, cultivate to bury the chemical fertilizer into the soil. If the seedbed is dry, manual irrigation should be carried out.

Reasonable close planting

When the seedlings grow to 6--8 true leaves, they can be transplanted to the field. The seedlings from 1 ha of seedbed can plant 30--40 ha of field. Field cultivation is about 45,000 plants/ha, with a row spacing of 30 cm x 60 cm and 1 seedling per hole.

Field management

When hybrid napiergrass is transplanted into the field, because the temperature is not high, it grows slowly, and weeds quickly occupy the land and suppress the napiergrass, so early weeding is very important. After the plants survive, timely cultivating and loosening the soil are needed to promote an increase in ground temperature and allow fertility to take effect.

Timely cutting

The suitable height for cutting napiergrass is about 1.3 m; too early affects yield, and too late affects quality. The stubble height is generally 15--18 cm. Too high or too low will affect regrowth and yield. After each cutting, fertilizer should be applied and cultivation should be carried out in a timely manner. Generally, cutting is done 4--5 times/a, with an annual yield of 15,000--22,500 kg/ha. In South China, the grass supply period is about 300 d/a, and in the middle and lower reaches of the Yangtze River it is 180--220 d/a. Fresh grass can be supplied from early June to the end of October.

Uses

Fresh grass cut at a height of 1.3 m can be used to feed large livestock. If it is used to feed rabbits, geese and other poultry and livestock as fish feed, the harvest height is 70--100 cm, and it can be harvested 8--10 times/a. According to experiments, 25 kg of fresh grass can produce 1.5 kg of fresh fish. Because the stems of hybrid napiergrass are relatively hard in the late growth stage, it can be cut 1--2 times in spring for feed, and then left for silage.