Abstract
Experimental determination of the more restricted development of specific ion effect has been cleared in understanding the nature of saline injufy to crops. In this paper, the chlorophyll content was used in giving expression to the degree of saline injury, on which observations at this laboratory had indicated the darker green color, the tip-burn, or the chlorosis on a leaf. The responses of rice plants (Norin No, 22) grown on sand medium to additions of 0.4, 0.8, and 1.2% of NaCl to a base nutrient solution were compared with that of unsalinized plants. Chlorophyll was assayed colorimetrically in the extract with 80% acetone solution from the 10 sq. cm of tissues that were randomly selected from the leaves classified by the leaf-order and the severity of injury, and also that were absolutely necessary to be externally normal. Addition of NaCl to the substrate actually tended to enhance the chlorophyll content, but with elapsed time, there was a general tendency toward an inverse relation between the chlorophyll content and the level of sodium or chloride content, though significant quantities of these ions were not determined, presumably as a result of the leachability on these ions. In observations on the components of chlorophylls, the differences were comparatively small. Marked changes in the mineral components, viz. total nitrogen, protein nitrogen, and phosphorus, took place with changing chlorophyll content, but soluble nitrogen and potassium components were found to have no relation. And also the water content or dry matter weight per unit area in these samples was not connected with changes of chlorophyll content. Coefiicients of correlation between the chlorophyll content and each component were shown in Table 1. Now, these figures emphasize that it is important for the light of saline-injury mechanism to consider the behaviour of both nitrogen compounds and phosphorus in saline crops. In interpreting the stability of chlorophyll-protein complex, the fluctuation of electrophoretic protein in saline leaves was investigated. It was found that the electrophoretic proteins were altered selectively with changing leaf-order and severity, but after dialysis against distilled water, no difference between the electrophoretic patterns from control and saline leaves which were externally normal was observed and also that the protein consistency detected by paper electrophresis reduced generally on all fractions or specific protein fraction in the saline leaves, containing so much amount of salt that had done enough of development of saline injury. Accordingly, an accentuated accumulation of these ions seems to effect on metabolic function with protein and to be the one directly associated with saline injury to crops.
