TGMB_2025v15n4

Tree Genetics and Molecular Breeding 2025, Vol.15, No.4, 161-167 http://genbreedpublisher.com/index.php/tgmb 162 2.2 Common intercropping types: grain, herb, forage, and economic crops There are many ways to grow chestnuts in the forest. Growing them together with food crops, such as chestnuts with corn, peanuts, soybeans, etc., can not only loosen the soil but also increase the nutrients in the soil (Wei et al., 2014). Pairing with cash crops, such as chestnuts with tea trees, is widely applied in many places in China. It can not only improve the quality of tea, but also enhance the environment under the chestnut forest, making the entire system more stable and profitable (Yu et al., 2006; Wan et al., 2009). In some places, chestnuts are grown together with Chinese medicinal herbs to increase income. Growing forage grass also has its benefits. It can not only improve the soil and increase organic matter, but also provide forage for the livestock industry, achieving two goals at once. 2.3 Principles of interspecific complementarity and resource use efficiency Intercropping is effective because different crops can complement each other's resources. For instance, different root systems are distributed in different soil layers and do not compete with each other when absorbing water and nutrients. Just like chestnuts and tea trees, the roots grow at different depths, do not disturb each other, and instead make both sides grow better (Yu et al., 2006; Wu et al., 2021c). Moreover, intercropping can also make the soil healthier, such as increasing organic matter, phosphorus and potassium, and also increase the variety of microorganisms (Wei et al., 2014; Wu et al., 2021b). More importantly, this approach can also regulate the light, humidity and temperature under the forest, reduce the impact of extreme weather, and improve stress resistance and the stability of the ecosystem (Wang et al., 2005; Wang et al., 2024). 3 Yield Performance of Chestnut and Companion Crops 3.1 Effects of different intercropping patterns on chestnut fruit yield and quality Research has found that growing chestnuts and tea trees together not only improves the ecological environment but also enhances the yield and quality of both chestnuts and tea. For instance, this intercropping can increase the organic matter, available phosphorus and potassium in the soil, help crops absorb nutrients better and thereby increase the yield (Wei et al., 2014; Wu et al., 2021b). Intercropping can also improve the microenvironment under the forest, such as reducing direct sunlight, lowering temperature and increasing humidity, all of which are very helpful for the growth of chestnuts and tea leaves (Wan et al., 2009). In northern regions, intercropping chestnuts and tea trees enables earlier harvest of tea leaves and better quality, and also promotes the growth of chestnuts (Wang et al., 2005; Yu et al., 2006). In addition, intercropping can also make chestnut trees grow faster and bear fruit earlier. 3.2 Productivity of intercropped species and land equivalent ratio (LER) In addition to tea trees, chestnuts can also be grown together with crops such as corn, peanuts and soybeans. These combinations can make more efficient use of land. Studies show that compared with monoculture chestnut, intercropping has richer soil nutrients, better structure and higher yield of associated crops (Wei et al., 2014). For instance, the roots of chestnuts and tea trees are distributed at different depths and do not compete for resources, which also improves the efficiency of resource utilization (Yu et al., 2006). Very often, the land utilization rate (LER) of intercropping is greater than 1. That is to say, in the same area of land, the total yield of intercropping is higher than that of monoculture (Pantera et al., 2018). Intercropping can also reduce pests and diseases and achieve more stable yields (Chadfield et al., 2022; Huss et al., 2022). 3.3 Economic return and benefit-cost ratio under each model Many studies have also pointed out that intercropping chestnuts can bring higher economic income. Compared with only growing chestnuts, intercropping can bring an additional income from companion crops, and chestnuts can bear fruit earlier, resulting in a better overall economic return. In some cases in Europe, livestock can be raised, mushrooms or beans grown under chestnut groves to further increase income sources (Pantera et al., 2018). In addition, intercropping improves the environment, reduces pests and diseases, lowers management costs and increases the input-output ratio (Figure 1) (Chadfield et al., 2022; Huss et al., 2022).

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