The duration of reproductive phase (DRP) , which was defined as the number of days from panicle initiation to heading, was investigated for 8 cultivars of Oryza sativa L. including 2 japonica and 6 ...indica varieties at Kagoshima. The DRP was determined by observing the panicle initiation stage under a stereoscopic microscope and the heading stage with the naked eye. DRP of cultivars were examined under two conditions, natural day-length and constant short day-length (10h day/14h dark). Results obtained are as follows: (1) DRP was shortest in early maturing followed by medium and late maturing varieties in this order. The DRP shortened by short-day treatment also varied with the cultivar in the same order. (2) There was a significant difference in DRP among cultivars and treatments with a p 0.01 according to the analysis of valiance. These results show that the DPR varied with the cultivars and growth condition. On the other hand, in some cultivars such as TEPI, MIRITI, BINASHAIL, DPR were not differ influenced by short-day treatments suggesting that the DPR of some cultivars are not sensitive to short-day treatment.
The meteorological factors related to decreased yield of paddy rice in Kagoshima Prefecture in 2003 are discussed. A close relationship was found between meteorologically potential yield (Yp) ...estimated by growth simulation models and actual yield (Ya) at Kagoshima City. And, in 2003, the decreased yield of paddy rice occurred on early season culture at Kagoshima City were attributed to the low Yp. It was estimated from an analysis at Kagoshima City that the lower productivity on early season culture in 2003 was primarily attributable to lower solar radiation. The geographical distribution of the crop situation index in districts of Kagoshima Prefecture nearly corresponded with that of the decreased percentage of sunshine duration from the middle to the last third of June.
Germination percentages of wheat grains sampled at 3 grain-filling stages : yellow-ripe stage (water content 45-50%), dough-ripe stage (35-40%), and full-ripe stage (25-30%), and imbibed in water at ...12°C and 20°C were examined in relation to the activities of α-amylase and endoprotease. Wheat varieties studied were Chihoku-komugi, which is susceptible to pre-harvest sprouting, and Satanta, which is resistant. Germination percentage was higher at 12°C than at 20°C in all grains sampled at all stages in both varieties, and was higher in Chihoku-komugi than in Satanta at 20°C. The activity of α-amylase in the grains at the yellow-ripe stage was higher at 12°C than at 20°C in both varieties, but that at the other 2 stages was higher only in Satanta. Endoprotease increased rapidly from 7 to 10 days after the start of imbibition, and exceeded 12 units only at 12°C in Chihoku-komugi grains at the dough and full-ripe stages. The results showed that α-amylase activity was lower than the value equivalent to 300 brabender unit (BU) in amylography when the germination percentage was 0%. Endoprotease activity exceeded 6 units when the germination percentage exceeded 90%.
To investigate the possibility of estimating symbiotic nitrogen fixation through the measurements of dry matter production and evapotranspiration, we grew two isogenic lines of soybeans, ...non-nodulating line T201 and nodulating line T202 under three and five levels of nitrogen (N) application, respectively. The chlorophyll content (SPAD value) of T201 was lower than that of T202, and the difference between them expanded successively from the nil to high-N plot. As the difference in nodule dry weight (Ndw) and SPAD value became large between the two lines and among N application treatments, the difference in quantitative relationships between dry matter production (DM) and evapotranspiration (ET) became conspicuous. The value of ET (ETw=0) when DM was zero, which was determined from the regression lines, was higher in T202 than in T201, and ETw=0 found in T201 corresponded nearly to evaporation from the bare soil surface (E0). Both ET=0 and Ndw in T202, on the other hand, varied with the amount of N application, and they were connected closely with each other. The difference in DM between T201 and T202 (delta W) calculated from the difference in ETw=0 (delta ETw=0) was correlated significantly and positively with the amount of fixed nitrogen estimated from the difference between the accumulated N in the two lines (P0.001). These results suggest that the amount of symbiotic nitrogen fixation can be estimated from DM and ET by paying attention to its energy cost.
PDF
