Verification and evaluation of the “Three Optimums Theory”in rice breeding for maximum yield

Rice breeding for maximum yield is a hot topic today in the rice community of the world, and a hard nut to crack into the bargain. For many years, we have been devoted to the subject. In 1987 we discussed the subject in publications at home and abroad, in which we first introduced the general strategy of combining ideal plant morphology with the use of vigor. Afterward, drawing on the wisdoms of other researchers, we experimented with test materials featuring "rather short stalks" and "rather big panicles", but the results were not very satisfactory. Then, we switched from the "two rathers" to the "three optimums" (plant height, panicle size, and tillering ability). Three years’ (1991-1993) verification, especially the demonstra

Hybrid rice achievements, development and prospect in China

This article reviews the history and progress of hybrid rice development. Hybrid rice research was initiated back in 1964, and commercialized in 1976. Three-line and two-line system hybrid rice were developed in 1974 and 1995, respectively. Research on super hybrid rice, which was first launched by Ministry of Agriculture, China in 1996, is discussed, and the great progress of super hybrid rice had been achieved with a new yield record by 15.4 t ha^-1 in the 6.84 ha demonstration location in Xupu, Hunan Province, China in 2014. And the mechanism of heterosis, the techniques of hybrid seed production and the modern field managements in hybrid rice over the past decades are also discussed. Additionally, this article dealt with the intellectual property protection（IPR） and development of hybrid rice seed industry in China. Major factors that constrain hybrid rice development are analyzed and possible solutions to this problems are proposed. Finally, the authors present methods to further increase production yield, and propose an improvement for breeding super high-yielding hybrid rice based on these methods.

Inheritance and Availability of High Grain Number Per Spike in Two Wheat Germplasm Lines

Grain number per spike （GNPS） is a major factor in wheat yield breeding. The development of high GNPS germplasm is widely emphasized in wheat-yield breeding. This paper reported two high GNPS wheat germplasm lines, Pubing 3228 and Pubing 3504, which had a stable and wide adaptability to different ecological regions. By exploring a nested cross design with reciprocals using Pubing 3228 or Pubing 3504 as a common parent and investigating the GNPS phenotypes of F1 hybrids in 2007-2008 and F2 populations in 2008-2009 of different cross combinations, the narrow-sense GNPS heritability was up to 49.58 and 52.23%, respectively. Genetic model analysis predictions suggested that GNPS in Pubing 3228 and Pubing 3504 was mainly controlled by additive genetic effects. Correlation analysis results between GNPS and 1 000- kernel weight （TKW） of F2 populations showed that TKW was not influenced with the increase of GNPS. The good coordination among three yield components of spike number per plant （SNPP）, GNPS, and TKW in the F2 segregating population implied that selection of good candidate individuals in breeding programs would be relatively straightforward. Overall, our results indicated that Pubing 3228 and Pubing 3504 are two potential germplasm lines for yield improvement of GNPS in pedigree selection of wheat breeding.

Studies on the Photosynthetic Characteristics andAssimilate's Accumulation and Transformation inHeavy Panicle Type of Rice

Using 18 indica rice varieties with different panicle weight, the photosynthetic characteristics and assimilate's accumulation and transformation in heavy panicle type of rice(HPT)were studied. The results showed that the net photosynthetic rate of the flag leaf in HPT after heading was obviously higher than that in medium panicle type(MPT)and light panicle type(LPT). The reason for the high net photosynthetic rate in HPT was the increase of Rubisco activities and chlorophyll content, and keeping high assimilate ability to CO2 under high and low light intensity, high temperature and low CO2 content, and light midday depression and wide adaptability to environmental conditions. The high net photosynthetic rate of HPT might be also the results of its excellent stomatal characteristics and higher total quantity of stomatal opening degrees(stomatal density X stomatal opening degrees). There was a large amount of dry matter production after heading and obvious high assimilate's transformation to panicle in HPT.

Development of Hybrid Rice Variety FY7206 with Blast Resistance Gene Pid3 and Cold Tolerance Gene Ctb1

Hybrid rice Fanyou 7206（FY7206）, derived from the cross between a sterile line Fanyuan A and a restorer line Fuhui 7206, was bred by the Rice Research Institute, Fujian Academy of Agricultural Sciences, China. FY7206 was characterized by moderate blast resistance, cold tolerance, as well as wide adaptability, and high yields. The blast resistance results indicated that the frequencies of blast races in race B, race C and the total resistance frequency for FY7206 were 95.5%, 100.0% and 97.2%, respectively. The disease resistance results showed that the leaf blast grade for FY7206 was level 1 and panicle blast was level 5. The indoor spray results indicated that FY7206 was resistant to 11 isolates of Magnorpathe oryzae. The blast resistance of FY7206 might be derived from the high expression of blast resistance gene Pid3. The results for simulated cold resistance in an artificial climate chamber indicated that the cold tolerance for FY7206 was moderate at the booting and flowering stages. The cold tolerance results also indicated that FY7206 could be tolerant to temperatures as low as 10 °C at the seedling stage. The q RT-PCR results showed that the expression of cold tolerance gene Ctb1 in FY7206 was relatively high. These results suggested that FY7206 is a hybrid indica rice variety with good comprehensive characteristics, including blast resistance and cold tolerance.

Relationship between the number of tapping-induced secondary laticifer lines and rubber yield among Hevea germplasm

The lack of suitable early selection parameters means that traditional rubber breeding for yield is time consuming and inefficient. Laticifer is a tissue specific fo natural rubber biosynthesis and storage in rubber tree. The number of the secondary laticifers in the trunk bark tissues is positively correlated with rubber yield in the matured rubber trees that are regularly tapped. In the present study the rubber yield from 280 of 4–5 year-old virgin trees from7 cross combinations was compared with the number o newly differentiated secondary laticifers caused by tapping. Results showed that the number of tapping induced lines of secondary laticifers varied in differen germplasm and was positively related to the rubber yield indicating this could be used as a suitable parameter fo early evaluation of yield potential of rubber trees.