To evaluate the variations of amylose content in the seed storage starch of Tartary buckwheat germplasm, we analyzed a total of 286 accessions from Nepal, China, Bhutan, Japan, Russia, Belarus, Slovakia, Estonia, and so on. As a result, these widely varied from 16.07% to 31.91%. By country, Nepal showed the widest variation (16.07% - 29.01%), followed by China (19.70% - 26.28%), Bhutan (19.38% - 26.88%), Japan (24.12% - 31.91%), and other countries (23.96% - 28.28%), although the largest number of accessions used from Nepal (n=184) should be taken into consideration. We expected to find a waxy accession or a waxy mutant from them but could not. For 164 of the 184 accessions from Nepal, information was obtained on the collection site, ranging from 950 to 3,800 m. There was a significant negative correlation between altitude and amylose content. Some of the lowest amylose accessions obtained in this study were also considered useful as breeding materials. Further clarification of their starch properties will increase their value as a new food material.

Leguminous green manure plants play an important role in increasing agricultural crop production in infertile soils as they can improve soil quality with less environmental concerns. Many studies have reported suitable green manure plants for temperate regions, but little information is available for tropical regions. Therefore, we clarified the growth response of three common tropical leguminous green manure plants, i.e., cowpea (Vigna unguiculata), sunn hemp (Crotalaria juncea), and green gram (Vigna radiata), on a Haplic Acrisol, which is strongly acidic and low in available phosphate (P) and widespread in Southeast Asia, in comparison with the other P deficient soil, a Eutric Gleysol, which is a slightly acidic and P deficient soil typically found in alluvial area, with controlling soil pH and soil available P. Cowpea was able to yield the highest dry matter production and acquire the largest amount of P among the three green manure plants in the two soils. The amount of P acquired by cowpea from the Gleysol is 6-7 times greater than that from the Acrisol. However, it was also clarified that the P acquiring ability of cowpea would be insufficient even when the Acrisol was ameliorated with CaCO₃ and P fertilizers as the Gleysol. Therefore, it would be necessary to find other green manure species which have higher P acquisition abilities enough to give suitable growth on Acrisols.

The purpose of this study was to evaluate the effect of foliar spraying of Potassium Sulfate (K₂SO₄) on the fruit growth and quality of the low-chill early ripening peach ‘KU-PP1’. K₂SO₄ concentrations of 5 g·L^-1, 10 g·L^-1, and 15 g·L^-1 were sprayed at intervals of 30, 45, and 60 days after full bloom on the leaves of ‘KU-PP1’ peach; four branches per tree during the 2020 and 2021 seasons. The largest fruit size and diameter were observed in the 15 g·L^-1 K₂SO₄ treatments. Furthermore, the TSS were observed in the 15 and 10 g·L^-1 K₂SO₄ treatments, followed by the 5 g·L^-1 K₂SO₄ treatment, which was higher than the control during both years. K₂SO₄ treatment increased the photosynthesis rate, transpiration, and stomatal conductance of ‘KU-PP1’ peach compared to the control. The results also showed that the fruit color (L*, a*, and b*) was more enhanced in the 10 and 15 g·L^-1 K₂SO₄ treatments during both years. Based on our findings of positive correlations between K₂SO₄ and fruit quality attributes, we concluded that the 15 g·L^-1 K₂SO₄ treatment produced the superior results.