Factors Affecting Yield and Yield Components of Main and Ratoon Rice：A Review

Rice ratooning refers to the production of second crop from the stubble after the harvest of main crop. Main and ratoon rice growth and development are affected by different factors. These factors include varieties selection, water management,fertilizer management, stubble height, plant protection practices and external environmental factors such as temperature and light.In this review, we discussed the different factors affecting the yield and yield components of main and ratoon rice. Among these factors the most important and first one is varietal selection. Varieties should be selected according to the requirement of specific area and prefer varieties resistant to insects/pests and diseases. Sufficient amount of water and fertilizer should be supplied.Stubble height of 10-20 cm will resulted in high production of ratoon rice. Too low or too high temperature and light would reduce the grain yield and quality of rice. Optimal temperature is useful for higher yield. It was concluded that by keeping the management practices more efficiently, the yield of main rice as well as ratoon rice could be increased. There is a need of more studies focusing on improvement of the quality of ratoon rice.

Long Period Grating Imprinted on a Flat-Shaped Plastic Optical Fiber for Refractive Index Sensing

A corrugated surface long period grating(LPG)was fabricated on a flat-shaped plastic optical fiber(POF)as a refractive index(RI)sensor by a simple pressing with the heat pressure and mechanical die press print method.The light propagation characteristics of an LPG imprinted on a multi-mode POF were analyzed by the method of geometrical optics.Theoretical and experimental results showed that the structural parameters of the sensor affected the RI sensing performance,and the sensor with a thinner flat thickness,a deeper groove depth of the corrugated surface LPG,and a longer LPG exhibited better RI sensing performance.When the POF with a diameter of 1 mm was pressed with the heat pressure to a flat shape with a thickness of 600μm,an LPG with a period of 300μm,a groove depth of 200μm,and a length of 6 cm was fabricated on it,and the RI sensitivity of 1447%/RIU was obtained with a resolution of 5.494×10^(−6) RIU.In addition,the influences of the POF cladding,tilting of LPG,and bending of the sensing structure were investigated.The results demonstrated that after removing the cladding and tilting or bending the LPG,the RI sensing performance was improved.When the LPG imprinted on the flat-shaped POF was bent with a curvature radius of 6/πcm,the highest sensitivity of 6563%/RIU was achieved with a resolution of 2.487×10^(−9) RIU in the RI range of 1.3330–1.4230.The proposed sensor is a low-cost solution for RI measurement with the features of easy fabrication,high sensitivity,and intensity modulation at the visible wavelengths.

Effects of Epichloë endophyte on antioxidant enzymes activities, photosynthesis and growth of three ecotypes of Elymus dahuricus

Fungal endophytes of some cultivated grasses can increase plant performance and competitive abilities,especially under stress. Far less is known about the influence of Epichlo? infections in wild populations of wild grasses. In this study, plants of three Elymus dahuricus ecotypes(WLS, QY and WTS) either infected with Epichlo? endophyte(E+) or uninfected(E–) were grown in the field. The activities of the antioxidant enzymes ascorbate peroxidase, catalase, peroxidase and superoxide dismutase, and concentrations of H_2O_2 and malondialdehyde were examined in the leaves of E+ and E– plants. We also determined photosynthesis parameters,leaf blade and sheath carbohydrate concentration and plant growth parameters of both E+ and E– plants. E+ plants from the WLS and QY populations had significantly higher antioxidant enzyme activities and photosynthetic capability(P < 0.05), superior growth characteristics including more abundant carbohydrate concentration than E– plants. In contrast, in plants from the WTS population,the endophyte had no significant effect on reactive oxygen species scavenging capability and growth performance(P > 0.05), and even displayed some negative effects on plant photosynthetic capability. Thus, endophyte infection significantly affected E. dahuricus antioxidant enzyme activities(P < 0.05), photosynthesis and growth capability,although, the effects varied with plant ecotypes.

Grass phasiRNAs and male fertility

Recent studies have indicated that a special type of small noncoding RNAs, phased small-interfering RNAs(phasiRNAs) play crucial roles in many cellular processes of plant development. PhasiRNAs are generated from long RNA precursors at intervals of 21 or 24 nt in plants, and they are produced from both protein-coding gene and long noncoding RNA genes. Different from those in eudicots, grass phasiRNAs include a special class of small RNAs that are specifically expressed in reproductive organs.These grass phasiRNAs are associated with gametogenesis, especially with anther development and male fertility. In this review,we summarized current knowledge on these small noncoding RNAs in male germ cells and their possible biological functions and mechanisms in grass species.