Developing cereal seeds contain photosynthetically active cells in the form of a thin green layer, the chlorenchyma, which surrounds the non-photosynthetic endosperm. The current understanding is that the chlorenchyma primarily supports endosperm respiration by supplying oxygen. However, despite the importance of such a function, photosynthetic electron transport is still poorly understood and would benefit from detailed study. This represents a technical challenge as bulky developing seeds are unsuitable for the classical spectroscopic methods routinely used for leaf material. In this study, we established a method that enables simultaneous measurement of photosystem I and photosystem II activities in dissected barley chlorenchymas with pulse amplitude modulation spectroscopy and also adapted it to measure electron transport with the electrochromic band shift. Comparative analyses of raw spectral signals and derived parameters measured on chlorenchymas and leaves demonstrate that this approach provides a reliable and detailed assessment of chlorenchyma photosynthesis. Establishing this method provides a new framework for investigating the physiological relevance of electron transport and carbon assimilation in non-foliar tissues such as chlorenchymas.