Dry matter yield and interaction stability of forage barley across ten environments in Yunnan, China
This study evaluated ten forage barley genotypes across ten environments in Yunnan, China, identifying genotypes G6 and G1 as the most promising candidates for expanded testing due to their superior dry matter yield and interaction stability.
Original paper licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). This is an AI-generated explanation of the paper below. It is not written or endorsed by the authors. For technical accuracy, refer to the original paper. Read full disclaimer
In the highlands of southwestern China, farmers face a unique challenge: growing crops that must thrive in a patchwork of climates, soils, and altitudes, all while delivering a consistent harvest. For livestock farmers, the goal is often whole-crop barley, a plant harvested not just for grain but as a complete package of stems, leaves, and seed heads to feed cattle and sheep. The value of this feed depends on two things that do not always travel together: the sheer amount of dry matter the plant produces, and how reliably it produces that amount regardless of where or when it is grown. A variety that yields a massive harvest in one valley might fail in the next, or in a different year. This unpredictability is known as the interaction between the plant's genetics and its environment. To solve this, scientists must find varieties that are not just high-performing, but also stable, capable of delivering a strong crop across a wide range of conditions without needing perfect weather or soil.
A team of researchers from the Yunnan Academy of Agricultural Sciences and Yunnan Agricultural University set out to find these reliable barley varieties across the diverse landscapes of Yunnan province. They tested ten different barley entries, a mix of released cultivars and experimental breeding lines, across five distinct locations over two consecutive winter growing seasons. These locations ranged from 1,543 meters to 2,410 meters above sea level, creating ten unique combinations of place and time. In each of these environments, the team planted three small plots for every barley variety, totaling 300 plots. They managed the crops using local farming practices, which varied from site to site, and harvested them all at the same stage of growth, known as the milk stage, when the plant is full of nutrients but the grain is not yet hard. The primary measure of success was the dry matter yield, which represents the actual weight of the plant material after all the water has been removed, a critical figure for determining how much feed a farmer can store and use.
The results of this extensive trial revealed that the environment itself was the most powerful force shaping the harvest. The differences in location and season accounted for nearly 88 percent of the variation in how much barley was produced, dwarfing the differences caused by the genetics of the plants themselves. This finding underscores that no single barley variety can be judged in isolation; its performance is inextricably linked to where and when it is grown. Despite this overwhelming influence of the environment, the researchers were able to identify specific varieties that stood out. One variety, labeled G6, produced the highest average dry matter yield across all ten environments, reaching 17.81 tons per hectare. It was followed closely by G1 at 16.75 tons per hectare and G8 at 16.43 tons per hectare. However, the statistical analysis showed that while G6 had the highest average, the difference between it and the next two varieties was not large enough to be considered a definitive victory in every single comparison.
Beyond just raw production, the study looked at stability, or how little a variety's performance wavered when conditions changed. Using a method that separates the plant's average performance from its reaction to specific environments, the researchers found that a variety called G10 was the most stable, showing the least amount of fluctuation across the different sites. Yet, this stability came at a cost: G10 produced significantly less total feed than the top performers. The researchers then sought a balance, looking for a variety that offered both high yield and acceptable stability. When they weighed these two factors equally, G6 and G1 emerged as the top candidates. G6 maintained its lead even when the researchers removed one location at a time from the data or simulated thousands of different combinations of the five sites, ranking first in more than 91 percent of those scenarios. G1 consistently held the second spot, combining strong production with a very stable performance profile.
The study also examined the physical traits of the plants, such as their height, the number of stems they produced, and the amount of green leafy material. The most productive varieties, particularly G6, tended to be the ones with the most stems and the most green leaves, creating a clear picture of a robust, high-biomass plant. However, the researchers were careful to note that this study was limited to the specific conditions of Yunnan and the two years of data collected. They did not measure the nutritional quality of the feed, such as protein content or digestibility, nor did they test how well the barley would ferment for silage. The findings suggest that G6 and G1 are excellent candidates for further testing on a larger scale, but they are not yet proven to be the perfect solution for every farmer in the region. The work highlights that selecting the right crop is a complex balancing act, where the highest yield must be weighed against the risk of failure in unpredictable weather, and where the best choice depends entirely on what a farmer values most: maximum production or consistent reliability.
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