After multiplication in laboratory and greenhouse, the Chinese authorities worked with CIP scientists to evaluate the variety for drought tolerance in the field in Hebei Highland Crop Research Institute, Wumeng Agricultural Research Institute and Shanxi Highland Crop Research Institute from the late 1990s onwards. Because of its high tolerance to drought and good yield, after several years’ evaluation, the variety was put into the National Regional Trial for New Potato Varieties by Hebei Highland Crop Research Institute in 2003.
Trials in 2004 and 2005 in northern China (including Hebei, Shanxi and Inner Mongolia) showed tuber yields up 31.41 t/ha, over 40 percent higher than Zihuabai, the most popular variety in the region. Yet the Tacna variety produced these yields with almost no irrigation. Tests for disease resistance also showed that it was highly resistant to potato viruses X and Y, with some resistance to late blight. Because of this excellent performance, the Chinese authorities released Tacna as a new national potato variety in 2006, naming it Jizhangshu 8. “The performance of Tacna in China is an example of the useful diversity for stress tolerance that has been maintained in CIP’s lowland tropics population, and which we are now intently rescuing by directed selection,” said Meredith Bonierbale, CIP’s Senior Breeder.
Jizhangshu 8 has been rapidly spreading throughout China since it was registered. Planted area was over 66 000 ha in 2008 and the large-scale multiplication that is going on in the country is expected to increase that area to up to 100 000 ha in 2009. “No other new potato variety in China, maybe in the world, has ever reach a planting area near 66 666 ha so soon after it was registered,” said Xie Kaiyun, the head of CIP’s Liaison Office in Beijing. The variety has been widely planted in Hebei, Inner Mongolia, Shanxi, Gansu, Ningxia, Xinqiang, Heilongjiang, Fujian and Guizhou, from 25 to 48 degrees north latitude, in different agro-ecological regions.
CIP has developed elite potato breeding clones with resistance to virus, tolerance to heat, drought and/ or salinity in the lowland potato population. The variety Jizhangshu 8 is a product of this breeding effort. The genetic background of the variety Jizhangshu 8 is highly diverse and includes 3 wild and 2 cultivated species. Its parents had been pre-bred in INTA-Argentina, Max Planck Institute-Germany, Cornell University-USA and SPBS-Scotland and CIP. The variety Jizhangshu 8 is a clonal selection from a CIP cross, actually made in 1988 and tested during intensive research during 1989-1993 by Jorge Espinoza and Humberto Mendoza from CIP, and Rene Chavez from Universidad Jorge Basadre de Tacna. It was found outstanding in the arid areas of Peru, tolerating drought and the boron toxicity common in desert areas, and released as the variety Tacna in collaboration with Rene Chavez of the Universidad Jorge Basadre Grohmann, Peru. Results from evaluating potato crosses related to the variety Tacna in north China revealed the yield potential of such material.
Tacna, or Jizhangshu, has a growing period from 100 to 110 days after emergence, produces about six good-sized tubers per plant, with 16.4 mg vitamin C per 100 g fresh flesh, 17 percent starch content and 2.25 percent protein. Its steam-cooking quality is very good, one of the reasons for its popularity, although its drought resistance is its outstanding distinguishing quality. Northwest China is going through a severe drought now, one of the more critical constraints that China is facing in increasing food production. “With proper management and inputs, average yields could be doubled,” said Xie Kaiyun.
Because of the high tolerance to drought and high yield potential, this variety can reach about 30 t/ha under rain-fed condition with annual rainfall from 300 to 400 mm and can reach about 75 t/ha under irrigation condition. “In the early stage of extending this variety, I could get many calls everyday from farmers and my friends and they asked me to give them some seed potatoes during the harvesting season. To solve the problem, all of the nethouses in our institute were used to produce pre-basic and basic seeds of this variety,” said Mr. Ying Jiang, the vice president of Zhangjiangkou Academy of Agricultural Sciences, who got the variety registered in China and Tacna had its Chinese name, Jizhangshu 8.
“I saw Tacna growing in the field in Keshan, northeastern China, where it had been planted for several years,” said Fernando Ezeta, CIP’s regional leader in the area. “The health status of the crop was good after many years without seed renewal, possibly due to its virus resistance. It has got nice tubers and it is quite prolific and a good yielder.”