Kernza® intermediate wheatgrass [Thinopyrum intermedium (Host) Barkworth & Dewey], the first perennial grain crop to come to market in North America, can provide a number of ecosystem services when integrated into cropping systems that are dominated by annual grain crops. However, grain yield from Kernza is lower than comparable annual cereal crops such as wheat and oats. Also, although Kernza is a long-lived perennial that can persist for decades, grain yield tends to decline over time as Kernza stands age leading most farmers to replant or rotate to a different crop after 3–5 yrs. Increased intraspecific competition as stand density increases with age has been reported to cause grain yield declines. We investigated the effect of strip-tillage applied at two different timings, between the third and fourth grain harvests, from a Kernza stand in upstate New York. Strip-tillage applied in late fall as plants were entering dormancy increased grain yield by 61% when compared to the control treatment without strip-tillage. However, total crop biomass was not reduced resulting in a greater harvest index for the fall strip-tillage treatment. Strip-tillage applied before stem elongation the following spring reduced overall tiller density and total crop biomass but did not impact tiller fertility or grain yield compared to the control treatment without strip-tillage. Increased grain yield in the fall strip-tillage treatment was due to an increase in the percentage of tillers that produced mature seedheads. This suggests that grain yield decline over time is at least partially caused by competition between tillers in dense stands. Results support further research and development of strip-tillage and other forms of managed disturbance as tools for maintaining Kernza grain yield over time.

中文翻译：

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间质小麦草（Thinopyrum intermedium）的条耕更新以保持成熟林的粮食产量

克恩扎®中间小麦草 [中间体刺麦草(Host) Barkworth & Dewey] 是北美第一种进入市场的多年生粮食作物，当整合到以一年生粮食作物为主的种植系统中时，可以提供许多生态系统服务。然而，Kernza 的谷物产量低于小麦和燕麦等可比较的一年生谷物作物。此外，虽然 Kernza 是一种长寿的多年生植物，可以持续数十年，但随着时间的推移，谷物产量往往会下降，因为 Kernza 年龄较大，导致大多数农民在 3-5 年后重新种植或轮作不同的作物。据报道，随着林分密度随着年龄的增长而增加的种内竞争会导致谷物产量下降。我们在纽约州北部的一个 Kernza 站调查了在第三次和第四次谷物收获之间的两个不同时间进行条耕的效果。与不进行条耕的对照处理相比，在植物进入休眠期时在晚秋进行的条耕使谷物产量增加了 61%。然而，作物总生物量并未减少，导致秋季条耕处理的收获指数更高。与不进行条耕的对照处理相比，次年春季在茎伸长之前进行条耕降低了总分蘖密度和总作物生物量，但不影响分蘖肥力或谷物产量。秋季条耕处理中谷物产量的增加是由于产生成熟种子头的分蘖百分比增加。这表明，随着时间的推移，谷物产量下降至少部分是由于密集林分中分蘖之间的竞争造成的。