Effects of Different Nitrogen Treatments on N use Efficiency and Grain Yield of Mechanically-transplanted Hybrid Rice

In order to investigate effects of topdressing on grain yield and N use efficiency of mechanically-transplanted hybrid rice, this experiment was conducted with 2-line hybrid rice cultivars, Quanliangyou 1 and Quanliangyou 681 with 3 application levels of N fertilizer, N_0, N_1, N_2, respectively. The results showed that there were no significant differences in grain yields of the 2 varieties between treatments N_1 and N_2. It was indicated that N is not the factor which could limit grain yield within limited application levels of N fertilizer. High N fertilizer treatment could contribute to the formation of effective panicles and spikelets per panicle, but it could also lead to the decline in grain filling rate. It was suggested that lowering the amount of Nfertilizer could facilitate improvement of N-use efficiency.

Structural and Histochemical Features of the Slow-Growing Perennial Coptis chinensis Franch.(Ranunculaceae)

Huanglian(Coptis chinensis Franch.)is a slow-growing perennial medicinal herb with considerable economic value.This study aimed to determine the structural characteristics and the levels of berberine deposits in the organs and tissues of Huanglian using light and epifluorescence microscopy.The adventitious roots are composed of primary and secondary structures with endodermis,exodermis,and phellem.The rhizome structures are composed of primary and secondary structures with cuticle and phellem.The leaves are composed of sclerenchymatous rings,isolateral mesophyll,and thin cuticles.We detected berberine in the xylem walls of the roots and rhizomes as well as in the sclerenchymatous rings of the petioles.We postulate that as the exodermis is developed,the deposition of berberine in the xylem closest to the root tips may affect water and nutrient absorption and transfer.Leaf blades had a thin cuticle and isolateral mesophyll,suggesting shade tolerance.These structural and histochemical features suggest that Huanglian is adapted to the slow growing nature of a shady environment.

Effects of nitrogen supply methods on fate of nitrogen in maize under alternate partial root-zone irrigation

Partial root-zone irrigation(PRI)has been practiced worldwide,but little information is available on nitrogen(N)supply methods influence on fate of applied N fertilizer for crop production under PRI.A field experiment was conducted to investigate effect of N supply methods on the uptake,residual,and loss of applied N fertilizer in maize(Zea mays L.)under alternate PRI at Wuwei,northwest China in 2014.15N-labeled urea was used as N fertilizer.Two irrigation methods included alternate furrow irrigation(AI)and conventional furrow irrigation(CI).Two N fertilizer supply methods included conventional N supply(CN)and alternate N supply(AN),were applied in combination with each irrigation method.Grain yield,root length density(RLD),N uptake by maize at the maturity stage,and atom%of 15N excess,residual 15N and residual NO3-N in the 0-100 cm soil layer after maize harvest were determined.Results shown that compared to CI coupled with CN,AI coupled with AN or CN significantly increased the grain yield,harvest index,RLD,N uptake by maize,15N accumulation in grain,atom%of 15N excess in the 0-60 cm soil layer,the residual 15N and 15N uptake rates;but significantly decreased the residual NO3-N in the 0-100 cm soil layers and 15N loss rate.Moreover,the synchronized rather than separation supply of N fertilizer and water enhanced the most above parameters under AI.15N uptake rate was positively correlated with RLD in the 0-40 cm soil layer,suggesting that the enhanced RLD contributed to the improved 15N uptake rate.Therefore,alternate furrow irrigation coupled with conventional or alternate nitrogen supply(synchronized supply of N fertilizer and water)could help improve 15N uptake rate and reduce the 15N loss rate.