Enhancement of the Photosynthesis of Chlorella pyrenoidosa as a Function of Far-Red and Short-Wave Illuminations.

in excess of the sum of the rates in the separate beams. The nature of the dependence of enhancement on far-red and short-wave illuminations, i.e., the nature of the functions E (II, I,) and D (Ii, I'), is of interest, on the one hand, for choosing optimum illuminations for subsequent studies and, on the other hand, for clarifying the essential nature an(d mechanism of the phenomenon. In previous studies, the properties of these 2 functions have not been entirely resolved. The qualitative character of E (Il, I2) is only partly known. The dependence of E on short-wave illumination, with fixed far-red illumination, is relatively wvell established (1, 2, 3, 4): E increases with I2 until P2 is several-fold greater than p1. As L, increases further, E renmains constant or (leclines gradually. In contrast, the dependence of E on far-red illumination is barely known. The only observations on this dependence seem to be those of Hoch (5) who measured enhancement in Anacystis in 3, smaller than compensating, far-red illuminations. His results seem too linited to help much in establishing the general shalpe of the surface E (I1, L)). The function D has not received any explicit attention, andI, cannot be evaluated for most studies because rates (P1, P2, P12) have not been reported along with enhancements (E). At present it is unclear whetlher D increases as illuminations rise to high levels, or whether it reaches a maximum at very low illuminations, and then remains constant, or even declines, with further increases in illumination. It is worth emphasizing that, whatever its nature, the func-