Studies on the Physiological Characteristics of C3 and C4 Crop Species
II. The effects of air temperature and solar radiation on the dry matter production of some crops
1978 Volume 47 Issue 1 Pages 90-100
Details
1978 Volume 47 Issue 1 Pages 90-100
In order to make clear the effects of temperature and solar radiation on relative growth rate, RGR, net assimilation rate, NAR, leaf area ratio, LAR, and other growth parameters as well as on differences in the pattern of dry matter production among species, 6 experiments were carried out, using the seedlings of 9 species including C3 winter crops, C3 summer crops and C4 crop species. Main results obtained are as follows:
1) There was clear difference in RGR exhibited among species and groups under the condition of high temperature and strong solar radiation. In the case of low temperature and weak solar radiation, however, difference was not so clear.
2) As a result of examination regarding the cause for the difference in RGR carried out by dividing it into two components, NAR and LAR, it has been revealed out that there is a clear difference among species and groups in NAR under the condition of high temperature and strong solar radiation, but that under the condition of low temperature and weak solar radiation, difference in NAR among species and groups is not clear.
From multiple regression analysis, evidence has been obtained that contribution of temperature and solar radiation to NAR is very high, more than 86%, in all the 3 groups.
3) Further, it has been made clear that LAR, one of the factors composing RGR, tends to be negatively affected, as a net result by the two climatic factors in the C3 winter crops, while there is no such effect recognizable in the C4 species, with intermediate response in the C3 summer crops. Besides these, by the examination on SLA and LWR which compose LAR, it has been concluded that the change in LAR was affected through both SLA and LWR.
4) Net assimilation rate is closely related with RGR in all the 9 crop species. The regression line, however, differs from C3 to C4 species. This difference is due mainly to the difference in LAR of the two groups.
5) There is an evidence for the existence of a close relationship in the C3 winter species between SLA and NAR, suggesting that in this group the climatic response and species difference in RGR may be exerted through the effect of SLA on NAR.
