Crop seed phosphorus (P) is primarily stored in the form of phytate, which is generally indigestible by monogastric animals. Low-phytate soybean lines have been developed to solve various problems related to seed phytate. There is little information available on the effects of P fertilization on productivity, physiological characteristics, and seed yield and quality in low-phytate soybeans. To address this knowledge gap, studies were conducted with a low-phytate line and two normal-phytate cultivars from western Japan when grown under high- and low-P fertilization. The whole plant dry weight, leaf photosynthesis, dinitrogen fixation, and nodule dry weight at the flowering stage were higher in the higher P application level, but were not different between the low-phytate line and normal-phytate cultivars. As expected, seed yield was higher in the higher level of P application for all lines. Notably, it was higher in the low-phytate line as compared with the normal-phytate cultivars at both levels of fertilizer P. The total P concentration in the seeds of the low-phytate line was the same as that of the normal-phytate cultivars, but the phytate P concentration in the low-phytate line was about 50% less than that of the normal-phytate cultivars. As a result the molar ratio of phytic acid to Zn, Fe, Mn, and Cu in seed were also significantly lower in the low-phytate line. From these results, it can be concluded that growth after germination, leaf photosynthesis, nitrogen fixation, yield and seed quality were not less in the low-phytate soybean line as compared with two unrelated normal-phytate cultivars currently grown in Japan, and that low-phytate soybeans may improve the bioavailability of microelements.

Soil salinity has emerged as one of the most prominent threats to modern intensive farming systems, and it has necessitated the cultivation of halophytes to ensure food security and human nutrition. Peucedanum japonicum Thunb. is an edible wild plant with medicinal value that is widely distributed along the Pacific coast of western Japan. However, the adaptive mechanisms of this plant with respect to salt stress tolerance have not yet to be elucidated. The purpose of this study was to compare the physiological responses of P. japonicum to salt stress with those of barley (Hordeum vulgare), which is considered a salinity-tolerant plant. Seedlings of both species at the same height were exposed to different concentrations (0, 50, 75, and 150 mM) of NaCl for 16 days, after which the leaves were analyzed with respect to different physiological parameters. The results revealed a maintenance of leaf growth in P. japonicum compared with that in barley, the growth of which was severely impaired at low concentrations of NaCl (50 and 75 mM). In response to salt stress, a higher suppression of Na+ and Cl− assimilations was observed in P. japonicum than in barley under all NaCl treatments. Moreover, P. japonicum showed a greater ability to maintain leaf K+ and Ca2+ concentrations, whereas barley exhibited a significant reduction in the concentrations of these ions under saline conditions. Thus, the superior salinity tolerance of P. japonicum could be attributed to a more efficient maintenance of ionic balances. Taken together, our results indicate that P. japonicum may be classified as a halophyte, given its superior regulation of K+, Ca2+, SO4−, and sucrose concentrations and lower NO3− concentrations compared with those of barley.