晚糯稻突变体新品种浙糯36的选育研究

采用60 Coγ射线 2 0 0Gy辐照处理 (晚粳“丙 92 1 2 4” 晚糯“绍糯选”)F2 干种子 ,经多代筛选获得晚糯稻突变体ZH2 0 6。ZH2 0 6经试种表现为产量高、籽粒大且品质优。 2年、2地区域试验比对照平均增产 9 4% ;籽粒较双亲明显增大 ,千粒重较母本丙 92 1 2 4重 4 1g ,较父本绍糯选重 3 6g ,千粒重达 30g以上。糯性优于对照祥湖 84,更优于亲本绍糯选。 2 0 0 3年通过浙江省农作物品种审定委员会审定 ,命名为“浙糯 36” ,成为近 2 0年来在浙江省 (市 )级晚粳糯稻区域试验中 ,增产幅度和籽粒均达到最大的晚糯稻审定品种。该品种的选育成功表明辐射诱变同步改良糯稻多个性状的可能性与有效性。     

粳稻耐旱突变体的诱发与鉴定

采用60Coγ射线200Gy辐照处理晚粳稻品种“浙粳20”纯系干种子,在其后代发现2个粳稻耐旱突变体G1和G2。经(生殖生长期)海南和杭州(营养生长期)耐旱性鉴定,2个突变体耐旱性明显优于原亲本“浙粳20”,也优于巴西陆稻“IAPAR-9”。普通灌溉栽培条件下的农艺性状测试表明,2个突变体对水陆环境具有较好的双重适应性。G1综合性状优良,可直接应用于生产,G2产量偏低,可作为新的优质耐旱种质利用。     

杂交稻米必需氨基酸含量与亲本的关系

根据9个不育系、5个恢复系以及由此配制的45个不完全双列杂交组合氨基酸含量的测定结果,分析了不同组合氨基酸含量的差异及其与亲本的关系。结果表明不育系和恢复系的必需氨基酸平均含量为3.202%～4.889%,占氨基酸总量的31.796%～33.394%;而杂交组合的必需氨基酸平均含量为3.616%～4.858%,占氨基酸总量的32.176%～33.016%;必需氨基酸含量依次是亮氨酸＞缬氨酸＞异亮氨酸＞苏氨酸、赖氨酸、苯丙氨酸＞蛋氨酸。平均氨基酸总量和必需氨基酸含量都有一定的杂种优势,但各组合间差异明显。     

Radiation use efficiency,N accumulation and biomass production of high-yielding rice in aerobic culture

The concept of aerobic culture is to save water resource while maintaining high productivity in irrigated rice ecosystem. This study compared nitrogen (N) accumulation and radiation use efficiency (RUE) in the biomass production of rice crops in aerobic and flooded cultures. The total water input was 800–1300 mm and 1500–3500 mm in aerobic culture and flooded culture, respectively, and four high-yielding rice cultivars were grown with a high rate of N application (180 kg N ha⁻¹) at two sites (Tokyo and Osaka) in Japan in 2007 and 2008. The aboveground biomass and N accumulation at maturity were significantly higher in aerobic culture (17.2–18.5 t ha⁻¹ and 194–233  kg N ha⁻¹, respectively) than in flooded culture (14.7–15.8 t ha⁻¹ and 142–173 kg N ha⁻¹) except in Tokyo in 2007, where the surface soil moisture content frequently declined. The crop maintained higher N uptake in aerobic culture than in flooded culture, because in aerobic culture there was a higher N accumulation rate in the reproductive stage. RUE in aerobic culture was comparable to, or higher than, that in flooded culture (1.27–1.50 g MJ⁻¹ vs. 1.20–1.37 g MJ⁻¹), except in Tokyo in 2007 (1.30 g MJ⁻¹ vs. 1.37 g MJ⁻¹). These results suggest that higher biomass production in aerobic culture was attributable to greater N accumulation, leading to higher N concentration (N%) than in flooded culture. Cultivar differences in response to water regimes were thought to reflect differences in mainly (1) early vigor and RUE under temporary declines in soil moisture in aerobic culture and (2) the ability to maintain high N% in flooded culture.     

A model explaining genotypic and environmental variation in leaf area development of rice based on biomass growth and leaf N accumulation

Leaf area index (LAI) is one of the major determinants of crop photosynthesis. The objectives of this study were to clarify the relationship between LAI development and crop growth in diverse rice genotypes grown under widely different climate conditions and to develop a model explaining genotypic and environmental variation in LAI dynamics based on environmental and plant factors. Cross-locational experiments were conducted with nine different rice genotypes at eight locations in Asia covering a wide climate range under irrigated conditions with sufficient nitrogen application. The LAI observed at the heading stage ranged from 0.85 to 8.77 among the genotypes grown at the eight locations. A fairly stable allometric relationship was observed between LAI development and above-ground biomass growth during the period from transplanting to 2 weeks before heading over all the genotypes, sites and years (r = 0.91). The allometric relationship was, however, under the influence of leaf nitrogen content per unit leaf area (LNC, g m⁻² leaf) and air temperature. On the basis of these results, we modeled the LAI development as a function of relative crop growth rate (RGR), LNC and air temperature. The rate of LAI decrease associated with leaf senescence was also described as a function of LNC.