Studies on the Root Characteristics of Maize Varieties of Different Eras

Experiment was conducted at the Gongzhuling Experimental Station of Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Jilin Province, China, during 2009-2010. Six representative varieties of maize （Baihe in the 1950s, Jidan 101 in the 1960s, Zhongdan 2 in the 1970s, Yedan 13 in the 1980s, Zhengdan 958 in the 1990s, and Xianyu 335 in the 2000s） were each planted under two different densities （52 500 and 82 500 plants ha-~） and two different nitrogen application levels （150 and 300 kg ha-l）. Root characteristics and distribution among soil layers were studied by the field root digging method. The results showed that root mass increased with the process of the growth and development of the plant, and it peaked at kernel filling stage, and decreased at maturity due to the root senesces. Root mass of different maize varieties from the 1950s to 1980s had a trend of increase, while it decreased for the modern varieties. Root length and root surface areas had the similar changing trend. The study suggested that early maize varieties may have root redundancy, and reducing root redundancy may be a direction for variety improvement for high yield. Root characteristics were affected by nitrogen application level and density; modern varieties were more suitable for higher fertilizer application level and density conditions. Root characteristics distribution among soil layers decreased by an exponent equation, but the regression coefficients of different varieties were different. Though the root length density （RLD） of every soil layer of different varieties also decreased by an exponent equation, there were large variations of RLD in every part of a layer.

Determination of Mangiferin and Homomangiferin in the Leaves of 93 Kinds of Mango

[Objectives]To determine the content of mangiferin and homomangiferin in mango leaves by HPLC.[Methods]The mangiferin and homomangiferin were separated and determined by Elite Hypersil C18(5μm,4.6 mm ID×250 mm)chromatographic column.Acetonitrile-0.1%(V/V)phosphoric acid solution was used as the mobile phase for gradient elution,the flow rate was 1.0 mL/min,the detection wavelength was 258 nm,the column temperature was 30℃,and the injection volume was 5μL.[Results]There was a good linear relationship between mangiferin and homomangiferin in the range of 0.0254-0.5080μg/μL(r=0.9999)and 0.000960-0.019200μg/μL(r=0.9999),respectively.The average recovery rate(n=6)of mangiferin and homomangiferin in mango leaves was 101.7%(RSD=2.0%)and 101.0%(RSD=1.7%),respectively.[Conclusions]There were great differences in the content of mangiferin and homomangiferin in the leaves of different varieties of mango.The experimental results could provide a scientific basis for further development and utilization of mango leaf resources.

Varied responses to copper for plant regeneration from calli of different rice varieties

Enrichment of copper to the culture mediumcould enhance the plant regeneration from cal-lus of indica rice variety Qiugui’ai 11. Westudied the effect of copper on plant regenera-tion of other rice varieties.Calli of 14 indica and 2 japonica varietieswere induced from disinfected mature embryoson an agar-gelled medium containing Nbasal

Simulation of Potential Productivity of Early Season Rice Varieties in Different Reqions of South China

Rice is a staple food crop in China.Since the 1950’s,many new varieties havebeen used and resulted in great increase ofyield.However there were still some barriersin the nationwide extension of new varietiesdue to the insufficient information about thecharacteristics of varieties.So,it is impor-tant to find ways of determining the potential

QTL editing confers opposing yield performance in different rice varieties

Grain yield is one of the most important and complex trait for genetic improvement in crops; it is known to be controlled by a number of genes known as quantitative trait loci（QTLs）. In the past decade, many yield-contributing QTLs have been identified in crops.However, it remains unclear whether those QTLs confer the same yield performance in different genetic backgrounds. Here, we performed CRISPR/Cas_9-mediated QTL editing in five widely-cultivated rice varieties and revealed that the same QTL can have diverse, even opposing, effects on grain yield in different genetic backgrounds.