Near-isogenic wheat lines NILs carrying different alleles of vernalization response gene Vrn-D1 spring-type and winter-type NILs, in the genetic background of two early wheat cultivars, were grown in early, normal and late seasons. Spring-type NILs reached the double ridge formation stage 109–112ºC days earlier than the winter-type NILs in early-sown fields, and 88–102ºC days earlier in normal-sown fields. Spring-type NILS reached the terminal spikelet formation stage 113–214ºC days earlier than the winter-type NILs in early-sown fields, and 30-98ºC days earlier in normal-sown fields. However, the time of young spikelet development was the same in both winter- and spring-type NILs in late-sown fields, where the temperature after sowing was under 12ºC. The absolute value of the slope of the regression line showing the relationship between the number of days and average temperature from sowing to the double ridge formation stage was lower in the winter-type NILs than in the spring-type NILs, though the absolute value from the double ridge formation to terminal spikelet formation stage was the same. In early and normal-sown fields, the jointing stage of spring-type NILs was earlier than that of winter-type NILs, but there were no such differences in the flowering and maturity stages. Therefore, the acceleration effects of Vrn-D1 were prominent until around the terminal spikelet formation stage and jointing stage but became unremarkable from the heading to maturity stages under early and normal-sown field conditions, where the temperature after sowing was roughly over 12ºC.

“Minaminokaori”, a wheat cultivar for bread making in western Japan, produces protein-rich grains although its yield is moderately low. The objective of this study was to examine the effects of intensive nitrogen fertilization during stem elongation (INFSE), but no nitrogen fertilization during vegetative stages, on grain protein content (GPC) and grain yield in 2014/15 and 2015/16 in Kumamoto prefecture. In both years, spike number per unit area in INFSE-treated plants was 5–20% larger than that in conventionally fertilized plants (control). In 2014/15, grain yield of INFSE was 15% higher than in the control while GPC was not reduced. In 2015/16, although the grain yield in INFSE was identical (607 g m^–2) to the control, GPC was significantly high (13.8%) compared with the control (12.5%). The number of grains per spike and 1000 grain weight were not influenced by INFSE in both years. The increase in spike number was attributed to the increased number of spike-bearing tillers at higher nodes of the main stem. For instance, 62.2% of the third nodes on the main stem bore productive spikes in INFSE-treated plants, but only 19.1% in the control. The mean dry weight of tillers from the third nodes was 2.28 g in INFSE-treated plants and 1.67 g in the control. The aboveground part of the INFSE-treated plants accumulated more nitrogen (5.3 g m^–2) than the control (3.6 g m^–2) during full heading to maturity. Therefore, total nitrogen accumulation was significantly higher in the INFSE-treated plants (18.8 g m^–2) than in the control (15.6 g m^–2). INFSE can increase yield and GPC by increasing the uptake of nitrogen, and thus this fertilization system is suitable for cultivation of bread wheat cultivars.

We evaluated the effects of low planting density on rice grain yield and quality under a cool climate. We grew two rice cultivars (“Tsugaruroman” and “Masshigura”) at three planting densities, 21.2 hills m^–2 (normal density), 15.2 hills m^–2, and 11.2 hills m^–2, four plants per hill, transplanting in mid-May and late- May, in four consecutive years (2010–2013) in Kuroishi, Aomori Prefecture. In both mid-May and late-May transplanting, there was no significant difference in the grain yield with the planting density. However, the difference in the grain yield between 11.2 hills m^–2 and normal density (21.2 hills m^–2) was larger in the plots with late-May transplanting in 2011 and mid-May transplanting in 2012 than in the other plots. The grain quality decreased with decreasing density in the plots with “Tsugaruroman” in 2012, but not in the other plots. The grain yield was significantly correlated with the numbers of panicles and spikelets per unit area. The ratio of 11.2 hills m^–2 to normal density in grain yield and spikelet number was positively correlated with the mean air temperature from 11 and 50 days after transplanting. This suggests that the difference in the grain yield between 11.2 hills m^–2 and normal density is influenced by air temperature during the vegetative stage, and that the grain yield in 11.2 hills m^–2 might be greatly reduced under low temperature conditions, due to the difference in the number of panicles and spikelets.

Three rice varieties, “Chihominori”, “Moeminori” and “Eminoaki” for ready-made meals and restaurants bred by Tohoku Agricultural Research Center were evaluated, using the data of the performance test for breeding obtained during a 5-year period. Heavy fertilization increased the number of panicles per area and the number of spikelets per panicle, resulting in higher grain yield and similar grain quality in appearance (AGQ), compared with normal fertilization. Direct seeding increased the number of panicles per area but decreased the grain yield and indicated similar or slightly superior AGQ, compared with transplanting. The early heading variety“Chihominori” showed a significantly higher grain yield and similar AGQ in heavy fertilization and direct seeding, compared with “Akitakomachi”. The intermediate heading variety “Moeminori” showed a significantly higher grain yield but inferior AGQ. The intermediate heading variety “Eminoaki” showed a slightly higher grain yield and superior AGQ, in high fertilization transplanting and high fertilization direct seeding, compared with “Hitomebore”. These results indicate that the three varieties are suitable for rice production with high yield, low cost and less labor for ready-made meals and restaurants. The results of this study suggested that the larger number of spikelets per panicle and slightly larger thousand grain weight are important in order to breed high yield varieties for ready-made meals and restaurants.

The effects of late sowing (July sowing) and dense planting on the yield and the occurrence of delayed stem senescence in soybean cultivars “Enrei”, “Tachinagaha” and “Ayakogane” were examined on the experimental farm of Nihon University. The seeds were sown in the field in June at the normal density (June-normal plot) or in July at normal, high and super high densities July-normal, July-dense and July-super dense plots, respectively. Pot experiments were carried out to analyze the amount of cytokinin at the top of the plant. In all cultivars, the yield in the July-dense plot and July-super dense plot was higher than that in the June-normal plot. The yield in the June-normal plot was the same as that in the July-normal plot, although the number of seeds per pod was higher in the latter than in the former plot. The occurrence of delayed stem senescence was more frequent in the June sowing plot than in the July-sowing plot probably due to the damage of seeds by bean bugs, smaller amount of cytokinin, and water stress after the flowering time. In conclusion, the yield was not changed by changing the sowing time from June to July in these cultivars, but the occurrence of delayed stem senescence was decreased by sowing in July.

Easy-shattering habit of the rice plant increases head loss in the Japanese head-feeding combine harvester, while the non-shattering habit increases processing loss in the conventional combine harvester. Thus, the performance of combine harvesters depends on the grain-shattering trait of the rice plant. To evaluate the effects of the grain-shattering trait on various losses at combine harvesting, we developed pairs of near-isogenic lines (NILs) for shattering habit by the selfing method. The NILs were derived from a cross between japonica rice cultivars, namely, “Asahi” and “Setokogane”; “Asahi” has an easily shattering habit, while “Setokogane” has a hard-to-shatter habit. We developed eleven pairs of NILs. Alleles at qSH1 locus were found to be associated with either easily shattering or hard-to-shatter in the pairs of NILs. Grain-shattering habits of eleven hard-to-shatter lines were not significantly different from each other, but, those of some easily shattering lines were significantly different. This shows that the genetic background affected the grain-shattering degree in the lines with shattering. These data suggest that additional loci with minor effects on the grain-shattering habit may exist in the cross between “Asahi” and “Setokogane”. Additionally, the non-functional allele at qSH1 which involves the hard-to-shatter habit, may behave epistatic to other loci. Thus, the NILs would be used to conveniently evaluate the effects of the grain-shattering trait on various losses at combine harvesting and the genetic analysis of grain-shattering in japonica rice.

We analyzed the relationship between seedling vigor and phytohormones at the seedling stage in foreign rice “Dunghan Shali” and “Italica Livorno” with vigorous initial growth under low temperature conditions, and Japanese rice “Oboroduki” and “Nipponbare”. The initial growth of “Dunghan Shali” and “Italica Livorno” was superior to that of “Oboroduki” and “Nipponbare” at both 27ºC and 12ºC. The phytohormone gibberellin supports vigorous initial growth of “Dunghan Shali”. The vigorous initial growth of “Italica Livorno” at 27ºC could be induced by the effects of gibberellin since we noted increased expression of OsGA20ox1, a gene that promotes gibberellin biosynthesis. Both “Dunghan Shali” and “Italica Livorno” harbor common mutations in the promoter region of OsGA20ox1. At 12ºC, the vigorous initial growth of “Italica Livorno” was because of the increased expression of OsGA20ox1. In “Dunghan Shali”, although the expression of OsGA20ox1 was not high, the level of abscisic acid, which suppresses plant growth, was lower than that in the three other varieties. We conclude that the effect of gibberellin was important for the vigorous initial growth of rice seedlings at 27ºC, but a balance of multiple phytohormones may be important for the seedling vigor in rice at 12ºC.


In Yamaguchi Prefecture, nitrogen topdressing is commonly applied at the flowering stage to maintain appropriate grain protein content (GPC) in the bread wheat cultivar “Setokirara”. We examined whether it is possible to replace nitrogen topdressing, such as ammonium sulfate at the flowering stage, with the application of a coated urea fertilizer at the spikelet formation stage. A field experiment was conducted in 2013/2014 and 2014/2015 at the Yamaguchi Prefectural Agriculture and Forestry General Technology Center. The GPC of “Setokirara” treated with coated urea at the spikelet formation stage was lower than that of “Setokirara” treated with ammonium sulfate at the flowering stage. In contrast, the yield of “Setokirara” treated with coated urea was higher than that of “Setokirara” treated with ammonium sulfate. The GPC of “Setokirara” was significantly correlated with yield. Nineteen to sixty percent of nitrogen was released from the coated urea fertilizer before the flowering stage. In contrast, the amount of nitrogen released from coated urea fertilizer was low around the flowering stage, which is known to be the most effective period to apply nitrogen topdressing for an increase in GPC. This may be why “Setokirara” treated with coated urea had a higher yield and lower GPC. Even when the dose of the coated urea fertilizer applied was doubled, the GPC of “Setokirara” remained lower than that of “Setokirara” treated with ammonium sulfate at the flowering stage.