Introduction to the potato variety Jizhangshu No. 4

Jizhangshu No. 4 was bred by the Bashang Agricultural Science Institute of Zhangjiakou City through sexual hybridization using Kachiding as the female parent and S. chacoense as the male parent, with pedigree number: 88-1-19.

Characteristics: In 1991, it participated in a variety comparison trial, with an equivalent yield of 1947.3 kg per mu, an increase of 13.7% over the control Bashu No. 9. From 1992 to 1994, it participated in the Zhangjiakou City potato mid-maturing group regional trial, with a 3-year average yield of 1615.2 kg per mu, an increase of 11.3% over the control Bashu No. 9. In 1996, it was demonstrated and promoted in Doufuyao Village, Shangyi County on 22.5 mu, with an average yield of 1473.6 kg per mu; in Zhangming Village, Zhangbei County on 15 mu, with an average yield of 1357.5 kg per mu, an increase of 12.5% over the control Bashu No. 9.

The growth period is 95-100 days (from sowing to maturity), making it a mid-maturing variety. The plant type is semi-erect, with many branches, lush growth, and a relatively long flowering period. Plant height is 75-80 cm, flowers are white, and leaves are pale yellow, ovate. The tuber shape is long elliptical, with white skin and white flesh, shallow and evenly distributed eyes, and a large and medium tuber rate of over 75%. The tuber dormancy period is about 65-70 days, with a general yield of 1400-1500 kg per mu. Processing quality: reducing sugar 0.19%, insensitive to browning reaction, dry matter content 21.6%, crude protein 1.27%, vitamin C content 30.5 mg/100 g (fresh tuber). Resistance performance: resistant to late blight, lightly susceptible to leafroll virus disease and bunch top virus disease in the late growth stage. Judging from the tuber appearance and processing quality, this variety is a typical processing-type export-earning variety.

Economic benefits: Because it meets processing requirements, it is purchased by Beijing Simplot Food Processing Co., Ltd. as a special variety for making French fries. The marketable and main tubers above 100-150 g per mu yield 1000-1100 kg, and the selling price is 0.30-0.40 yuan per kg higher than ordinary market commodity potatoes. The income from processed commodity potatoes alone reaches 850-1100 yuan per mu, making it the only processing-type new improved variety with a per-mu income exceeding one thousand yuan in the single-cropping high-cold arid region of northern Hebei. To ensure high yield, it has now entered the stage of shoot-tip virus elimination and mass production of virus-free plantlets, and a corresponding seed propagation system has been established.

Breeder: Bashang Agricultural Science Institute of Zhangjiakou City

Region and technical adaptation scope and cultivation points: Mainly suitable for cultivation in sandy soil in single-cropping areas such as northern Hebei, Inner Mongolia, Shanxi and Northeast China. The suitable sowing period is early May, with a sowing rate of 125 kg per mu and 3500 plants per mu. Combined with sowing, apply 4000 kg of high-quality farmyard manure per mu and 35 kg of ammonium bicarbonate as chemical fertilizer. Use alternate furrow interplanting with large and small plows, dibbling seeds in the large furrow and applying chemical fertilizer in the small furrow to prevent seed burning and missing plants.

Seed tuber treatment: To improve emergence rate, prolong the growth period, and increase the rate of large and medium tubers, the seed potatoes are taken out 18 days before sowing and placed in a warm room at 18°C-20°C for sprouting. When the sprouts reach the size of a mung bean, move them outdoors to a sheltered, sunny place for sunning. Generally sun them for 7-10 days, turning them at any time during the process to ensure uniform light exposure, and remove diseased tubers at any time. Then cut them lengthwise, ensuring each mother tuber piece has 1-2 buds and weighs no less than 5 g.

Management: When 50% of the seedlings have emerged, promptly use a "V"-shaped harrow or hoe once. At the bud stage, apply 15 kg of urea per mu as a topdressing according to plant vigor. During the whole growth period, carry out 3 times of intertillage and hilling, firmly press the stolon strips, increase the tuber-setting layers, raise single-plant yield, strictly prevent the occurrence of green-headed tubers that affect the commodity tuber rate, and ensure increased yield and value.