Origin

‘Lipin 2’ was preliminarily selected as a desirable genotype based on its thin nutshell and high kernel percentage. The first selection was during the 1977 season (April–November) and was identified as ‘77104’ from the seedling (Wang et al. 1996). After 18 years of evaluation, ‘77104’ was renamed ‘Lipin 2’ and was authorized as the most promising walnut selection by the Department of Science and Technology of Liaoning Province in 1995. From 2001 to 2023, ‘Lipin 2’ was evaluated in national regional experiments in Dalian city (Liaoning province), Fenyang city (Shanxi province), and Zanhuang county (Hebei province). In Oct 2018, it was approved by the Liaoning Provincial Forest Tree Certification Committee with the cultivar number Liao S-SV-JR-005-2018. In Sep 2024, it was approved by the China National Forest Tree Certification Committee with the cultivar number Nation S-SV-JR-013-2024.

Description and Performance

‘Lipin 2’, as an early-maturing variety, is usually harvested in late August to early September in Shanxi and in the middle of September in Hebei and Liaoning. However, ‘Lipin 2’, as a fresh food product, began to be available for sale in a series of batches in mid-July. Fully mature ‘Lipin 2’ produces large-sized nuts weighing 8.1 g per kernel (Table 1). Shell seal is good. The obround-shaped nut averages 67.2% kernel. The popularity of ‘Lipin 2’ is due to its early maturity, large nuts, high kernel percentage, ease of kernel removal, and high yield. The nuts of ‘Lipin 2’ are usually sold as fresh-eating walnuts.

Table 1. Main characteristics of ‘Lipin 2’ compared with Chinese main cultivated walnut cultivars, as well as an American cultivar Chandler.

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The cultivar is characterized by a rounded canopy with a half-spreading growth habit (Fig. 1A). Female flowers usually appear 4 to 5 years after the grafted seedlings are planted. Female flower clusters generally consist of up to two to three flowers (Fig. 1B) and usually two fruits set (Fig. 1C). This is a terminal fruitful cultivar made up of 31% lateral buds. The flowering is protogynous, with male and female flowers overlapping for 3 to 5 d. In the region of Dalian in Northeast China, leafing is in the middle of April, and leaf shedding occurs in early November. The female flower blooming period is at the beginning of May and the pollen-shedding period is in mid-May.

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The nut shape is obround (Fig. 1D) with round apex and bottom. The suture is flat and looser in combination. The nutshell is 0.7 mm on average and the inner fold totally degenerates, thus the whole kernel is very easy to remove. The color of the kernel is classified as light.

Feld trials for ‘Lipin 2’ have been conducted at three locations in China (Table 2). One-year-old grafted trees were arranged in a randomized complete block design, with each location containing three blocks and at least 10 trees for each block (Table 2). The yield of ‘Lipin 2’ in the three locations from 2020 to 2023 was superior to ‘Lipin 1’ tested (Table 2).

Table 2. In-shell nut yield of ‘Lipin 2’ walnut compared with ‘Lipin 1’ in three field trial locations.

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‘Lipin 2’ has performed well in walnut-producing areas in northern China, such as Hebei, Shanxi, Shaaxi, Henan, Shandong, and Liaoning provinces. ‘Lipin 2’ walnut can survive the winter normally in the colder Liaoning region. Today in China, the development of the walnut industry is relatively stable. Growers often use techniques such as high-position grafting or budding to transform other varieties into the ‘Lipin 2’ (Wang et al. 2022).

Availability

Small amounts of hardwood scion are available for research purposes from the author, Zhao baojun (agroforestry@163.com).