头季稻刈割时期对粮饲型再生稻饲草和再生稻产量、品质及经济效益的影响

【目的】探究头季稻不同刈割时期对粮饲型再生稻饲草和再生稻产量、品质及经济效益的影响,为粮饲型再生稻的高产优质高效种植及南方稻区解决粮饲争地、实现粮饲统筹提供理论依据和技术支撑。【方法】以我国南方稻区大面积作为再生稻种植的品种两优6326和桃优香占为试验材料,设开花期、乳熟期和蜡熟期3个头季刈割时期,分析头季饲草和再生季稻米的产量和品质差异,并对粮饲型再生稻模式的经济效益进行综合评价。【结果】随着刈割时期的推迟,头季干饲草产量逐渐增加,在蜡熟期刈割时最高,两优6326和桃优香占分别达9.17和10.35 t/ha。青贮饲草的饲用品质变化趋势与干饲草产量一致,刈割时期越晚,发酵品质越优,相对饲用价值越高,且在蜡熟期刈割时青贮饲草的中性洗涤纤维含量等发酵品质指标均达GB/T 25882—2010《青贮玉米品质分级》优质二级标准。再生季水稻产量在开花期刈割时最高,两优6326和桃优香占分别达8.94和8.92 t/ha,之后随着刈割时期的推迟逐渐降低。随刈割时间推迟,再生季稻米各品质指标变化趋势不尽相同,但各刈割处理下的整精米率、直链淀粉含量和垩白度表现达到或接近GB/T 17891—2017《优质稻谷》二级标准。再生季稻谷经济收益大幅高于头季饲草,2个品种的总收益、净收益和产出投入比在开花期刈割时最高,平均分别达36755元/ha、17450元/ha和1.90,并随着刈割时期的推迟逐渐降低。【结论】以高产优质饲草生产为目的,头季宜在蜡熟期刈割;以高产优质稻米生产为目的,头季宜在开花期刈割,且该模式在开花期刈割时的总体经济效益最高。

Influence of water potential and soil type on conventional japonica super rice yield and soil enzyme activities

We carried out a pool culture experiment to determine the optimal water treatment depth in loam and clay soils during the late growth stage of super rice. Three controlled water depth treatments of 0-5, 0-10 and 0-15 cm below the soil surface were established using alternate wetting and drying irrigation, and the soil water potential （0 to -25 kPa） was measured at 5, 10 and 15 cm. A 2-cm water layer was used as the control. We measured soil enzyme activities, root antioxidant enzyme activities, chlorophyll fluorescence parameters, and rice yield. The results showed that the 0-5-cm water depth treatment significantly increased root antioxidant enzyme activities in loam soil compared with the control, whereas soil enzyme activities, chlorophyll fluorescence parameters and yield did not differ from those of the control. The 0-10- and 0-15-cm water depth treatments also increased root antioxidant enzyme activities, whereas soil enzyme activities, chlorophyll fluorescence parameters and yield decreased. In clay soil, the soil enzyme activities, root antioxidant enzyme activities, chlorophyll fluorescence parameters, and yield did not change with the 0-5-cm water treatment, whereas the 0-10- and 0-15-cm water treatments improved these parameters. Therefore,the appropriate depths for soil water during the late growth period of rice with a 0 to -25 kPa water potential were 5 cm in loam and 15 cm in clay soil.

Response of grain-filling rate and grain quality of mid-season indica rice to nitrogen application

Nitrogen is one of the important factors for high yield of rice.Apart from high yield,high quality has become the current urgent demand for rice production.Grain-filling stage is crucial for rice yield and quality formation.However,the effect of nitrogen on grain-filling characteristics and the relationship of grain-filling characteristics and rice quality of mid-season indica rice were still unclear.A field experiment was carried out to ascertain the critical grain-filling characteristics that contribute to rice milling quality,appearance quality and cooking and eating quality under nitrogen applications.The results showed that nitrogen applications prolonged the duration of superior and inferior grain filling.The mean grainfilling rate(G_(mean))and the maximum grain-filling rate(G_(max))of the inferior grains were positively correlated with chalky kernel rate,chalkiness,and amylose content.The time reaching the maximum grain-filling rate(T_(max)G)of the inferior grains was positively correlated with brown rice rate,milled rice rate,and head milled rice rate.Chalky kernel rate and chalkiness were negatively correlated with peak paste viscosity and breakdown viscosity.Less amylose content and more crude protein content were detected in nitrogen application of Liangyoupei 9 and Y Liangyou 2 both in 2016 and 2017.According to the correlation analysis,better cooking and eating quality of Y Liangyou 2 which had less amylose content might result from its higher G_(max)and G_(mean)of inferior grain than that of Liangyoupei 9 in the treatments of nitrogen application.These results indicated that the prolonging grain-filling duration and increasing grain weight at the maximum grain-filling rate of inferior grains contributed to the improvement of milling quality,appearance quality,and cooking and eating quality of mid-season indica rice under appropriate nitrogen applications.

Superior grains determined by grain weight are not fully correlated with the flowering order in rice

Rice panicles are composed of many branches with two types of extreme grains,the superior and the inferior.Traditionally,it has been well accepted that earlier flowers result in superior grains and late flowers generate inferior grains.However,these correlations have never been strictly examined in practice.In order to determine the accurate relationship between superior and inferior grains and the flowering order,we localized all the seeds in a panicle in four distinct rice species and systematically documented the rice flowering order,flower locations and the final grain weight for their relationships.Our results demonstrated that the grain weight is more heavily determined by the position of the seeds than by the flowering order.Despite earlier flowering has a positive correlation with the grain weight in general,grains from flowers blooming on the second day after anthesis generally gained the highest weight.This suggests earlier flowers may not result in superior grains.Therefore,we concluded that superior and inferior grains,commonly determined by grain weight,are not fully correlated with the flowering order in rice.Following the order of the grain weight,the superior grains are generally localized at the middle parts of the primary branches,whereas inferior grains were mainly on the last two secondary branches of the lower half part of the panicle.In addition,the weight of inferior grains were affected by spikelet thinning and spraying with exogenous plant growth regulators,indicating that physiological incompetence might be the major reason for the occurrence of the inferior grains.

钢管注浆法与堆压法相结合的堵水技术在基坑堵漏中的应用

杭州某工程基坑开挖过程中出现管涌,通过钢管灌浆结合快干水泥加固并封堵基坑渗漏,为小基坑的堵漏提供一种思路,该应用能有效地解决基坑渗漏管涌问题,从而确保基坑及周边建筑安全,推进工程进度,确保施工质量。

Test of Small RNA Sequencing Repeatability in Rice

Deep sequencing of small RNAs（sR NA） is widely used in sR NAs studies in plants. In order to investigate the sequencing frequency variation of sR NAs, the same sR NA samples from rice grains were sequenced twice using deep sequencing technique. The sR NAs were classified into three categories, high abundance（〉 100 RPM）, medium abundance（10–100 RPM） and low abundance（1–10 RPM）. According to the repeat sequencing data of the same sample, highly expressed sR NAs（〉 100 RPM） were less subject to random drift, and 95% of the sR NAs Log2 ratio between two samples fell between-0.649 and 0.558. The same trend was observed in mediumly expressed sR NAs（10–100 RPM）, and 95% of the Log2 ratio fell between-0.535 and 0.759. As to lowly expressed sR NAs（1–10 RPM）, 95% of the Log2 ratio varied between-1.009 and 1.011. These results can be used as a theoretical guide to find differentially expressed s RNAs in sR NA studies in plants.