Introduction to the Improved Yam Variety Guihuai No. 6

Variety approval number: Gui Shen Shu 2004006

Breeding unit: Cash Crops Research Institute, Guangxi Academy of Agricultural Sciences

Variety source: Systematically selected and bred from yam germplasm resources collected in Hongshi Village, Yangmei Town, Rong County.

Applicant unit: Cash Crops Research Institute, Guangxi Academy of Agricultural Sciences

Characteristics: An early-maturing variety with a growth period of 170-190 days in central and southern Guangxi. Stem right-twining, four-angled, 0.4 cm in diameter, stem wings obvious, no thorns, no purple coloration, main stem 3.0-4.5 m long; leaves broad and large, main stem leaves 15.0-18.0 cm long, 10.5-12.0 cm wide, broadly cordate, base deeply cordate, apex acute, leaf color light green, smooth, relatively thin, waxy layer inconspicuous, no gloss; reticulate venation, 7-9 basal veins, both ends of the petiole purplish-red; phyllotaxy alternate in the lower part, mostly opposite in the middle and upper parts and on branches, a few alternate; aerial tubers rarely or not formed in leaf axils. Tuber long cylindrical, 70.0-85.0 cm long, tuber weight per plant 0.8-1.3 kg; tuber base with more root hairs, top with few and short root hairs; tuber skin bright red, smooth; tuber cross-section white; good viscosity. At 7 months of age, dry sample tuber zinc and iron contents were 20.2 mg/kgDM and 12.0 mg/kgDM respectively, copper (Cu) content 7.17 mg/kgDM, starch content 70.5%DM, crude protein content 11.2%DM, total amino acids 7.83%DM, total saponins 0.72%DM, soluble total sugar content 26.3%DM, crude fat content 0.28%DM. Fresh tuber moisture content 78.8%.

Yield performance: In a variety comparison trial conducted in Nanning in 2002, the average yield was 1856.3 kg/667 sq m, 24.61% higher than the control variety (from Yangmei Town, Rong County); in the 2003 repeat trial, the average yield was 1760.3 kg/667 sq m, 24.87% higher than the control. In 2003, production demonstrations were carried out in Rong County, Luzhai and Beiliu, with average yields of 1665.2 kg/667 sq m, 1782.7 kg/667 sq m and 1755.4 kg/667 sq m respectively.

Key cultivation techniques: 1. Choose sandy loam soil with convenient drainage and irrigation and deep soil layers for planting. 2. Select disease-free and pest-free tubers as seed, cut into 5 cm-8 cm sections; large tubers can be further cut lengthwise into two pieces, then dip the cut surfaces in plant ash. 3. Planting method and density: with a row spacing of 1.3-1.5 m, dig deep furrows, then backfill soil to form high ridges, ridge height 30-40 cm, width 60 cm, punch holes at a plant spacing of about 20 cm and fill with sand, hole depth 80-100 cm. Plant the seed tubers on the sand holes. The suitable sowing season is early March to early April in southern Guangxi, and mid-March to mid-April in central Guangxi. Plant 2500-3000 plants per 667 sq m. 4. Fertilizer and water management: apply 1000-1500 kg of decomposed farmyard manure or 40-50 kg of compound fertilizer and 50 kg of superphosphate per 667 sq m as base fertilizer. After emergence, set up trellises in time to guide the vines, properly prune side branches and weed during the mid-growth period, apply one application of manure water when seedlings are 10-15 cm tall; during the mid-period, combine weeding and earthing up with a topdressing of 7.5-10 kg/667 sq m of compound fertilizer; during the peak tuber enlargement period, pay attention to applying compound fertilizer solution 2-3 times. Keep the soil moist throughout the growing period. 5. Pay attention to the control of black spot disease, anthracnose, tobacco cutworm and other diseases and pests.

Approval opinion of the autonomous region variety approval committee: Upon review, this variety has good application value in production, has passed approval, and can be planted according to local conditions.