稻米表观直链淀粉含量由两对非等位基因控制

利用籼粳交(02428/特青)花培DH群体,研究了稻米表观直链淀粉含量(AAC)及其组成因子——热水不溶性直链淀粉含量(HISAC)和热水可溶性直链淀粉含量(HSAC)的遗传特性。结果表明,HSAC和HISAC都表现为一对主效基因遗传,且两者表现为连锁遗传关系。用Amy-s(t)表示控制HSAC的基因,用Amy-i(t)表示控制HISAC的基因,两基因的连锁遗传距离为12.9 cM。由于Amy-s(t) 和Amy-i(t)相互连锁,因此AAC在总体上表现为一对基因遗传。     

水稻弱势籽粒淀粉形成对稻米品质影响研究进展

随着社会的发展和经济水平的提高,人们的消费习惯和消费结构发生了巨大变化,人们对优质稻米的需求越来越高,有关稻米品质的研究也越发得到重视。本文综述了影响水稻弱势籽粒淀粉品质形成的机理与相应调控途径,基于此,提出了通过调控水稻弱势籽粒淀粉形成来提高稻米整体营养品质的新思路。     

不同收获时期对稻米品质的影响

水稻在最适时期收获可获得高的精米率和好的蒸煮品质,1989和1990年我们利用6个生产上广泛应用的品种为材料,每个品种种植600m2的小区,不设重复,研究了不同成熟期收获对稻米品质的影响。试验在淹水栽培下进行,记载抽穗期(50%抽穗的日期)。在抽穗期后27～42天,每3天收获1次,每亚区6m2,重复3次。收后在太阳光下晒干,2个月后用Satake水稻去壳机(型号THU-35A)和BurrowsMcGill3号精米机碾成精米,然后用过量水法煮成米饭。稻谷成熟期对稻米品质有很大的影响(见表)。我们观察到当稻谷含水量在20%～23%时收获,可获得较高的总精米率和整精米率,较…     

国审杂交籼稻组合的稻米品质分析

分析了2003—2013年通过国审的378份杂交籼稻的主要米质性状表现以及各米质指标间的相关性。结果表明,杂交早籼稻的垩白、整精米率和胶稠度在11 a间均有明显改善,但其米质性状仍然差于杂交中、晚籼;垩白性状仍是今后杂交籼稻米质改良的重点。垩白度和垩白粒率与整精米率、胶稠度和长宽比呈负相关,与直链淀粉含量呈正相关;低直链淀粉含量品种的平均垩白度和垩白粒率均显著低于中高直链淀粉含量品种,而其胶稠度和长宽比则高于中高直链淀粉含量品种;降低直链淀粉含量有利于改良垩白和胶稠度,适当增加籼稻的长宽比有利于降低垩白。     

不同籼型三系保持系的稻米品质相关性状分析

对16个籼型三系保持系稻米品质进行研究,考察了子粒的长宽比、千粒重、垩白粒率、垩白度、直链淀粉含量等指标及指标间的相关性．品质评价结果表明．现有水稻品系G763B和新育品系422B的外观品质等级为1级．吉香B的外观品质等级为2级。相关性分析表明长宽比与垩白度、垩白粒率呈极显著的负相关：直链淀粉含量与垩白度呈极显著的正相关;粒宽与垩白度、垩白粒率呈正相关。     

栽培模式对稻米品质特性的影响

以超级稻组合88S/1128和常规优质稻品种湘晚籼17号为材料,探讨了不同栽培模式(旱作覆膜、水作覆膜、旱作不覆膜、常规栽培等)对稻米品质的影响。结果表明,2个品种一致表现为旱作覆膜栽培的糙米率、精米率最高,水作覆膜栽培的整精米率最高;同一品种不同栽培模式的粒长和长宽比无显著差异,但覆膜栽培的垩白粒率、垩白大小更高。88S/1128旱作覆膜与常规栽培相比,直链淀粉含量降低、胶稠度变小、糊化温度升高;而湘晚籼17号旱作覆膜与常规栽培相比,直链淀粉含量降低、胶稠度变大、糊化温度降低。2个品种蛋白质含量表现一致,均为旱作不覆膜常规栽培旱作覆膜水作覆膜。稻米品质性状变异度最大的为外观品质,其次为蒸煮食味品质,碾米品质变异度相对较小。     

实地氮肥管理对稻米品质的影响

在大田试验条件下,观察了实地氮肥管理对水稻产量和稻米品质的影响。与农民习惯施肥法相比,实地氮肥管理在水稻产量持平或略有提高的情况下明显降低了施氮量。实地氮肥管理提高了稻米的加工品质,降低了垩白米率、垩白面积和垩白度,提高了稻米的透明度,改善了外观品质;实地氮肥管理还明显降低了直链淀粉含量,提高了胶稠度,降低了糊化温度和蛋白质含量。此外,实地氮肥管理明显提高了米粉的最高黏度、崩解值,降低了消减值,改善了稻米的食味品质。农户示范也取得了类似的结果。对实地氮肥管理改善稻米品质的原因进行了讨论。     

灌溉对杂交水稻产量及稻米品质的影响

在不同灌溉方式条件下,土壤含水量出现差异,造成对稻株水分供应的不同影响。试验结果表明,在亏水较重、时间较长的情况下,杂交水稻产量明显减少,稻米品质下降。减产的原因主要是每穗谷粒数少。米质主要是加工品质、蛋白质含量降低及胶糊化变劣。长期湿润灌溉由于使土壤沉降收缩,造成含水量长期偏低,对杂交水稻产量及品质不利。     

Effects of semidry flour milling on the quality attributes of rice flour and rice noodles in China

To investigate the effects of semidry-milling on the quality attributes of rice flour and rice noodles, the properties of rice flours and cooking properties of rice noodles prepared with wet-, dry- and semidry-milled rice flours were characterized. The level of starch damage of semidry-milled rice flour at 30% moisture was significantly decreased to the level of wet-milled rice flour (P < 0.05); the whiteness of dry-milled rice flour was decreased compared with wet-milled rice flour (P < 0.05), while that of semidry-milled rice flour was not; the wet- and semidry-milled rice flours showed similar morphology and water hydration properties; the dry milling method reduced significantly the hardness, chewiness, and resilience of rice noodles (P < 0.05) compared with wet-milling, but semidry-milling did not; the cooking qualities of rice noodles produced by semidry-milling were comparable to wet-milling. It indicated the semidry-milling at 30% moisture may provide the protective effects on the characteristics of rice flours, which could be used to produce similar qualities of rice noodles to the wet-milling.     

Impact of amylose content on starch retrogradation and texture of cooked milled rice during storage

Milled rice from 11 varieties, with amylose levels from 1.2 to 35.6% dry base, were collected to study the impacts of amylose content on starch retrogradation and textural properties of cooked rice during storage. The relationship between amylose content and different properties was determined using Pearson correlation. Starch retrogradation enthalpy (ΔH_r) of cooked rice was determined by differential scanning calorimetry. ΔH_r values were found to be positively correlated with amylose content (0.603 ≤ r ≤ 0.822, P < 0.01) during storage. Textural properties were determined by a Texture Analyser. The hardness of cooked rice showed a positive correlation with amylose content (0.706 ≤ r ≤ 0.866, P < 0.01) and a positive correlation with ΔH_r of cooked rice (r = 0.650, P < 0.01) during storage. The adhesiveness showed a negative correlation with amylose content (−0.929 ≤ r ≤ −0.678, P < 0.01) and a negative correlation with ΔH_r of cooked rice (r = −0.833, P < 0.01) during storage. Hardness showed a negative correlation with adhesiveness (r = −0.820, P < 0.01). These results indicated that amylose content has significant effects on starch retrogradation and textural properties of cooked rice. The cooked rice with high amylose content is easy to retrograde, the cooked rice with low amylose content retrograded slowly. Sarch retrogradation contributes to the changes of textural properties of cooked rice during storage.     

"920"处理对水稻eA系种子耐贮藏性研究

用不同尝试的“920”对含euil基因的水稻长穗颈不育系（eA系）与不含该基因的不育系（A系）进行处理,收获种子储藏6个月、9个月和12个月后分别测试发芽率的发芽势。结果表明,无论eA系和A系,其种子储藏时间不超过9个月时,发芽率、发芽势不发生显著变化;储藏时间达1a(12个月）时,个别浓度处理间或材料间开始出现显著差异。但喷施“920”不会eA系种子发芽率和发芽势,个别浓度处理还有提高发芽率和发芽势的趋势。     

香米品质与微量元素含量特征关系的研究

采用“江永香稻”与、香稻80－66”两个香稻品种，在香稻产地与非产地同时进行大田试验，对其稻米、灌溉水与土壤中的11种微量元素含量与稻米品质各项指标进行了分析。结果表明：不同产地同一品种稻米品质与不同品种稻米品质存在明显差异；江永香米的Zn,Mn,Cr含量均比普通稻米及香稻80－66的含量高，香稻80－66香米中Zn含量也较普通稻米高。香米产地香米香味长期不退化，可能与灌溉水中Zn元素含量较高有关。     

辽宁省水稻品质性状分析

采取聚类分析和表型主成分分析法,对2004年辽宁省区试的27个水稻新品种的9个品质性状进行了分析,结果表明,垩白粒率和垩白度的品种间差异较大,是今后水稻品质育种的重点。在选出的7个影响稻米品质的主因子中,垩白、精米率、糙米率、胶稠度以及直链淀粉为影响水稻品种品质的主要因子,水稻品质育种首先应注意垩白和碾米品质的选择。     

QTL mapping of grain quality traits in rice

Grain quality improvement is one of the most important goals in a rice breeding program. An indica variety with small grain size was crossed to a japonica variety with large grain size to construct a set of recombinant inbred lines (RILs) which was used to identify quantitative trait loci (QTLs) controlling eight grain quality traits. Based on a linkage map of 185 SSR markers, a total of 16 QTLs were mapped on six chromosomes. A pleiotropic main effect QTL (M-QTL) flanked by RM3204 and RM16 on chromosome 3 influences the grain length (GL), length width ratio (LWR) and head rice ratio (HRR), explaining the phenotypic variation of 46.0, 36.1 and 29.7%, respectively. A total of 18 epistatic QTLs were identified for all the traits except MRR, distributed on all the chromosomes except chromosome 10. Two M-QTLs for GL and one M-QTL for GW were involved in epistatic QTL. No significant interaction between M-QTL or epistatic QTL and environment was detected except AC having significant M-QTL by environment interaction with minor effect. GL and LWR have a significant negative relation with HRR which might make it difficult to develop long grain with higher HRR in the rice breeding practice.     

Rapid prediction of head rice yield and grain shape for genome-wide association study in indica rice

Rice milling and appearance qualities are the main determinants of market price of the milled rice, so great breeding efforts have been directed to improve the milling and appearance quality. The success of breeding efforts depends on the accurate and rapid phenotyping of the quality traits in early generations. This study was conducted to first validate the effectiveness of the PaddyCheck to measure head rice yield (HRY) and paddy grain length of 40 indica rice cultivars. The results indicated that the PaddyCheck data had positively correlated with the lab methods of HRY (r = 0.81**) and grain length (r = 0.97**). An association panel including 281 indica rice accessions was phenotyped with the PaddyCheck and the data were used for genome-wide association study (GWAS) to identify quantitative trait locus (QTL) for milling and appearance quality. A total of nine QTLs were identified, among which the major genes GS3 and qSW5 were identified for grain length and width, respectively. Furthermore, a novel QTL on short arm of chromosome 6 was identified for HRY. Our study indicated that PaddyCheck measurement was accurate and effective, and could be applied in rice breeding for improvement of grain shape and milling quality. The nine QTLs identified in indica rice could be used in marker assisted selection in rice breeding programs.     

Iron and phosphorus utilization in rats fed soaked and dehulled bambara groundnut supplemented with sorghum or crayfish

Thirty-six adult Wistar albino male rats (75–128 g) of age 8 weeks were used to study the effect of dehulled and soaked bambara groundnut combined with sorghum or crayfish on iron and phosphorus balances of rats fed for 10 days. Three out of the ten days were for adjustment and the rest for the balance period. Six diets were formulated and fed to the rats. The mixed protein diets provided 10% protein daily for the entire study period. Casein(CA) served as a reference protein. Rats fed the CA diet had significant decreases (p < 0.05) in food intake, maintenance body weight, phosphorus intake and phosphorus balance when compared with those of the test groups. As judged by iron nutriture, dehulled brown bambara groundnut (DBGB) appeared to be superior to the white variety. Soaking seriously affected iron utilization in brown variety. Dehulling produced significant increases (p < 0.05) in phosphorus balance in animals fed the white variety of bambara groundnut compared with the brown variety. On the other hand, soaking produced positive phosphorus balance in rats consuming the brown variety. Addition of crayfish produced a slight nonsignificant decrease (p > 0.05) in rodents eating the brown variety. These results suggested that varietal difference and treatment affected iron and phosphorus utilization in rats fed bambara groundnut in conjunction with sorghum and/or crayfish.     

栽培因素对北方粳稻米质的影响(Ⅲ)--移栽密度对米质的影响

水稻移栽密度的研究表明在密植、稀植和超稀植处理中,产量随密度减小而增加,外观品质变好,但加工品质和食味品质下降.移栽密度相同,移栽方式不同时,方形移栽方式有增产的趋势,但不利于提高米质;双行移栽方式有利于提高米质;长方形移栽方式米质趋于中间.     

Direct measurement of rice bran lipase activity for inactivation kinetics and storage stability prediction

Rice bran is a rich source of valuable nutrients and has potential for high-value applications. Endogenous lipases catalyze the hydrolysis of rice bran oil to free fatty acids, which initiates lipid oxidation. The evaluation of the success of rice bran stabilization processes in terms of the degree of lipid oxidation and shelf-life has so far relied on the measurement of free fatty acid content over a storage period of 3–6 months. In the present study, a photometric and a titrimetric pH-stat method for direct lipase activity measurement immediately after debranning were adapted to rice bran. The photometric method was further applied to determine rice bran lipase/esterase inactivation kinetics, which are useful to optimize stabilization treatments in order to prevent overprocessing and retain maximum level of nutrients. Rice bran was heat-treated in a specialized, hermetically sealable reactor at controlled holding times (5–40 min), temperatures (70–145 °C) and moisture contents (10–20%). Temperature dependency of the lipase/esterase inactivation rate could be described by the Arrhenius equation. Empirical findings on the importance of moisture content for effective rice bran stabilization could be quantified. Furthermore, the results demonstrate the great potential of the method to predict the shelf-life of stabilized rice bran without time-consuming storage tests.