Chia (Salvia hispanica L.) grain is rich in omega-3 and omega-6 fatty acids, which are important for human nutrition and prevention of cardiovascular disease, as well as dietary fibre and quality protein. Demand for chia grain is increasing worldwide driven by the interest in functional food; however, large gaps exist in our understanding of chia physiology. The objective of this study was to determine the critical period for grain yield in chia. A field experiment was conducted under well-watered conditions during four growing seasons, using sequential shading periods of 7–10 days during the season. Yield of unshaded controls varied from 1418 to 2148 kg ha^–1 among seasons. Chia’s critical period for grain yield spanned from 550 degree-days before flowering to 250 degree-days after flowering. Seed number fully accounted for reductions in grain yield, with no responses in grain weight to shading. Shading from 550 to 250 degree-days before flowering reduced yield by as much as 40% and this reduction was associated with reductions in the number of verticillasters on second and third order branches. Shading from 50 degree-days before flowering to 250 degree-days after flowering reduced yield by at least 20% and this reduction was associated with reductions in both the number of verticillasters on second and third order branches and the number of grains per verticillaster on branches of all orders. The findings from this study will aid development of management practices to avoid stresses during periods when grain yield would be penalised, and will contribute to breeding for yield potential and stress adaptation by targeting the critical physiological stages.

Chia（S alvia hispanica L.）谷物富含omega-3和omega-6脂肪酸，它们对人体营养和预防心血管疾病以及膳食纤维和优质蛋白质非常重要。由于人们对功能性食品的兴趣，全球对奇亚籽的需求正在增长。但是，在我们对Chia生理学的理解上存在很大的差距。这项研究的目的是确定Chia谷物产量的关键时期。在四个生长季节中，在灌溉条件良好的条件下进行了田间试验，该季节中连续遮光时间为7-10天。无遮荫对照的产量从1418到2148 kg ha ^–1在各个季节之间。Chia的谷物产量的关键时期从开花前的550度到开花后的250度。种子数量充分说明了谷物产量的下降，而谷物重量对遮光没有反应。从开花前的550天至250度天遮阴使产量降低多达40％，并且这种减少与二阶和三阶分支上的小白菊数量减少有关。从开花前的50天到开花后的250天的阴影会使产量降低至少20％，并且这种减少与二阶和三阶分支上的小白菊数量减少以及分支上每个小插图的谷物数量减少有关所有订单中。