水稻压致变异后代主要农艺性状的研究

用高压诱变法处理高收获指数型水稻品种粤香占 ,培育出变异材料粤压 1号、2号和 3号。通过对其主要农艺性状比较研究发现 ,3个变异材料与粤香占在生育期、株高、分蘖数、有效穗数、穗部性状、外观米质、抗病性和抗寒性等方面存在明显差异 ,表明高压诱变可能成为一种新的育种方法。     

分蘖期土壤水分对早稻矿质养分吸收的影响

在池栽条件下研究了不同水分处理对早稻吸收氮磷钾及分蘖生产效率的影响。结果表明：土壤水分对早稻吸收N、P、K矿质元素有明显影响。随着土壤水分含量的提高，植株对矿质元素的吸收量显著提高。在分蘖初期，65％水分处理的植株对N、P、K的吸收量分别只有100％的74．1％，43．9％和50．8％，而在分蘖后期，则分别只有100％的41．4％，18．6％和27．5％。早稻矿质元素的分蘖生产效率以在85％土壤含水量时最高，其N、P、K的平均分蘖生产效率分别比100％高35．7％，140％和81．8％。平均分蘖生产效率表现为P〉K〉N。     

水稻杂种后代丰产性状预测及其遗传规律的研究

通过奇选42、广二矮104等7个水稻品种,分别配制不同的杂交组合,研究了水稻主要经济性状的遗传力,F_1与两亲本的相关,杂种各世代之间的相关,F代的主要经济性状之间的相关,F_4代构成产量的经济性状与单株谷粒产量的复相关和多元回归分析。结果表明,水稻的株高、千粒重、结实率、单株谷粒重和穗粒数的遗传力较高,这些经济性状在 F_1与两亲本的相关中,在杂种各世代之间的相关中,都表现出中度或高度的显著或极显著的正相关。每株穗数和每穗实粒数与单株谷粒产量,每株穗数和每穗粒数与单株谷粒产量,每株穗数和结实率与单株谷粒产量,在复相关和多元回归中,都表现为显著或极显著的水平。     

利用标记不育系配制的高产杂交水稻新组合“丰华优2号”

“丰华优2号”系苗期携带白化转绿型叶色标记的细胞质雄性不育系白丰A与全生育期携带黄绿色叶色标记的优异恢复系NHR4配制而成,适宜在江西、浙江、安徽省作单季或连晚杂交水稻种植。     

γ射线外照射影响粳稻生育的初步研究

用~(60)Coγ射线外照射粳稻生长植株(1、2、3、4、5、6片叶、孕键、抽穗和开花期),每个时期所用照射量为2、5、10、15、20、25kR,照射量率为96.8—99.1R/min。试验表明:1—6片叶接受~(60)Coγ射线照射的植株,辐射生理损伤具有阶段性,照射后新长出的3片叶是辐射损伤最为明显的部位,通过照射后的株高增长曲线,可粗略预报辐照后减产10％、50％、90％的植株。水稻一生中孕穗期是对γ辐射最为敏感的时期,5kR便可减产80％,10kR减产100％。     

离体诱变改良杂交水稻的研究(英文)

用γ射线照射杂交籼稻保持系与恢复系的成熟胚、幼胚及愈伤组织,研究其离体培养反应。结果表明,幼胚在培养前经1kR照射处理能提高愈伤组织的诱导率和分化率。成熟胚的最佳照射量为2.5—5.0kR,而照射成熟胚的愈伤组织则以250R为佳。经照射处理的培养物,其后代体细胞无性系的变异频率显著提高。通过离体诱变方法已选得10份有希望材料,其中8份保持系和2份恢复系。     

Trade-offs between on-farm varietal diversity and highly client-oriented breeding — a case study of upland rice in India

On-farm varietal diversity is now highest in marginal agricultural environments because, unlike the case in more favourable areas, modern varieties have not been a sufficiently attractive option for farmers to replace their landraces. However, the continued survival of landraces on farm is dependent on the continuing failure of plant breeding to provide better alternatives. Highly client-oriented breeding can produce suitable modern varieties for areas that were dominated by landraces. We examine here the case of the adoption of two upland rice varieties in three states in eastern India, Jharkhand, West Bengal and Orissa, where our surveys had confirmed low adoption of modern varieties in the upland ecosystem. The two new upland varieties were readily accepted by farmers who rapidly adopted them on large proportions of their land. On-farm diversity is maintained by the need to trade-off among varieties but once a variety with overall superiority was found this incentive was removed. The new varieties from the client-oriented breeding did not have weaknesses that farmers had to trade-off against their landraces so they were more likely to replace them. They also replaced older modern varieties. Farmers had previously maintained them along with landraces because they had to trade-off the higher yield of Kalinga III against the more stable yield of landraces or the higher yield of Vandana against the higher gain quality of the landraces. Only mean count per household could be used to test the significance of the differences between individual years. In all states, this revealed a significant reduction in landrace diversity with the adopting farmers when the addition of the two new varieties was not considered. Trends across years for mean varietal count, total count and Shannon–Wiener index showed a significant decline in Orissa, irrespective of whether the two new varieties were included in the analysis or not. In Jharkhand there was a significant decline only for mean count when the new varieties were not included. In Orissa, it was possible to test if rare landraces were as readily replaced as more common ones. Landrace replacement was unmitigated by increasing rarity yet the most rare landraces have the highest priority for genetic conservation. Some landraces were completely replaced by the farmers in the sample despite a diverse variety portfolio being a risk-reducing strategy in a region where there is a high risk of crop failure. There was little environmental heterogeneity in the marginal, drought-prone areas to slow this decline. The new varieties had an impact on the farming system because sometimes farmers brought additional upland into cultivation. They also introduced these varieties into more favourable, medium land. The strategy of releasing two new upland varieties met with some success in maintaining diversity.     

Effects of ambient air pollution on wheat and rice yield in Pakistan

Open-top chambers ventilated with ambient or chiarcoal-filtered air were used to assess the impact of air pollution on the yield of local cultivars of wheat and rice, at a site on the outskirts of Lahore. At this location, 6-h mean O₃ concentrations reach 60 ppb in certain months, and annual mean NO₂ concentrations are 20–25 ppb. The experiments showed significant yield reduction in two successive seasons which ranged from 33% to 46% in wheat and from 37% to 51% in rice. The major yield parameter affected was the number of ears or panicles per plant, although there was also evidence of small effects on 1000 grain weight and on the number of grains per ear/panicle. These results have significance in terms of the maintenance of agricultural yields as pollution emissions rise in south and south-east Asia.     

水稻黄叶突变体光合特性的日变化

对水稻黄叶突变体黄玉B及其亲本龙特甫B孕穗期的光合速率和叶绿素荧光参数的日变化所进行的研究表明:(1)在自然日照条件下,当光强上升到1043.4μmol/m2.s时,野生型出现光饱和点并表现出光抑制现象,而突变体没有出现光饱和点;(2)在野生型出现光抑制阶段(12:00—14:00),突变体的光合速率(Pn)、PSⅡ原初光化学效率(Fv/Fm)、PSⅡ光量子效率(фPSⅡ)、非循环光合电子传递速率(ETR)和热耗散(NPQ)均高于野生型。突变体在强光条件下(PFD>1149.2μmol/m2.s)能有效利用光能并耗散过剩光能,其对强光光响应能力优于野生型亲本。     

杂交水稻氮、钾肥施用技术研究

在杂交水稻高产栽培中,根据杂交水稻需肥规律,合理分配和运筹肥料是关键技术。连续2年田间试验结果表明,在杂交水稻前期基蘖肥、中期长粗肥、后期穗肥施氮比例为8∶2∶0和施钾比例为10∶0∶0的习惯比例上,减少总氮量的12%,使前、中、后期用氮比例为8∶0∶2,用钾比例为3∶7∶0,有利于塑造一个稳发缓降的群体,提高水稻的群体质量,培育壮秆大穗而获高产,较习惯比例施肥增产13 4%。