轮耕条件下土壤改良及春玉米增产增收效果研究

针对旱作区长期采用单一的土壤耕作方式造成的土壤结构变差及作物生长发育受限等问题,研究由免耕、深松及翻耕组成的不同轮作模式对干旱区春玉米土壤肥力及产量的影响具有重要生产意义。于2014—2016年在兰州市榆中县清水驿乡孟家山村玉米田开展连续免耕(NT)、连续深松(ST)、连续翻耕(PT)、深松、免耕及深松轮耕(ST/NT/ST)、免耕、免耕和深松轮耕(NT/NT/ST)、翻耕、免耕及翻耕轮耕(PT/NT/PT)、翻耕、免耕及深松轮耕(PT/NT/ST)和深松、翻耕及深松轮耕(ST/PT/ST) 8种耕作模式试验,测定8种耕作模式下的土壤孔隙度、土壤养分、干物质和玉米产量,并分析其经济效益。结果表明:在0～60 cm土层,随着土层的增加土壤孔隙度表现为先降后增,以20～40 cm土层的土壤孔隙度最低。5种轮耕措施较耕作前均能增加土壤孔隙度,以ST/PT/ST轮耕模式最优,其次为ST/NT/ST,较PT提高了1.24%、0.25%;土壤养分含量在0～20 cm土层均高于20～40 cm土层,其中,0～20 cm土层免耕与深松进行轮耕下土壤全氮、全磷含量较高,以ST/NT/ST全氮、磷含量最高,20～40 cm土层,对土壤全氮、全磷含量无显著影响,翻耕与深松轮作促进了速效氮、磷、钾的提高,以ST/PT/ST速效氮、磷、钾含量高,免耕土壤有机质含量较其它耕作方式低,其余土壤养分指标为表层富集,下层匮乏;轮耕模式较单一的耕作方式更能促进玉米干物质的累积,其中以ST/NT/ST与PT/NT/PT耕作下玉米干物质高,频繁的翻耕(PT)不利于玉米的生长; 3年产量相比,8种耕作模式中,ST/NT/ST处理下玉米产量显著高于其它处理(ST/NT/STNT/NT/STST/PT/STSTNTPT/NT/ST PT/NT/PT PT)。较单一耕作(NT、ST、PT),ST/NT/ST处理下玉米产量提高了5. 97%、3. 56%、15.75%;且以ST/NT/ST经济效益最高。结论:深松、免耕及深松轮耕有利于改善耕层结构和提高土壤养分,增产增效显著,为旱作区春玉米农田适宜的轮耕模式。     

沙尘对天山积雪消融的影响

积雪是西北干旱区重要的水资源,春季融雪时期,沙尘天气频繁,沙尘沉降会减少积雪表面反射率,增加雪层的太阳辐射吸收,加速积雪的融化,影响干旱区年内的水资源分布。通过融雪期在天山积雪雪崩研究站开展模拟沙尘沉降试验,观测积雪物理特性参数变化,分析沙尘对积雪消融的影响。本研究设置2 g·m^-2、4 g·m^-2、8 g·m^-2、自然雪4个处理,3组重复,从3月4日开始,3月11日结束。结果表明：沙尘沉降对积雪消融具有明显影响。在2 g·m^-2、4 g·m^-2、8 g·m^-2沙尘沉降量下,随着融雪的进行,沙尘沉降量逐渐增大,致使积雪表面粒径增大,积雪反射率降低,雪表层温度差变大,2 g·m^-2、4 g·m^-2、8 g·m^-2导致积雪消融速率比自然状态下的快22.36%、46.05%和76.90%。通过野外试验获得了主要积雪物理参数对沙尘沉降的响应,量化了沙尘沉降对积雪消融的影响,其结果可为西北干旱区水资源管理提供参考。     

Agronomic performance of late-season rice in South China

Improving rice yields is critical for global food security. China is a major rice-producing country having two rice cropping systems, i.e. single-season rice cropping system and a double-season system with both early- and late-season rice. There have been reports on the sink-source traits contributing to high grain yield for single- and early-season rice, but such information is limited for late-season rice. In this study, field experiments were conducted at the research farm of Guangxi University, Nanning, Guangxi Province, China in the late rice-growing season. Grain yield and sink-source traits were compared among five cultivars (Guiliangyou 2, Teyou 838, Y-liangyou 087, Teyou 582, and Yuxiangyouzhan) in 2012 and then three cultivars (Guiliangyou 2, Teyou 838, and Y-liangyou 087) in 2013. Y-liangyou 087 produced 6–26% higher grain yield than did the other cultivars. This higher grain yield was driven by improvements in sink-source capacity. Sink capacity was 8–31% higher in Y-liangyou 087 than in the other cultivars. Well-balanced relations between spikelets m^?2 and grain weight was responsible for the higher sink capacity in Y-liangyou 087. The result was that Y-liangyou 087 produced 11–17% greater biomass (source capacity) than did the other cultivars. The greater source capacity in Y-liangyou 087 was mainly attributed to higher radiation use efficiency (RUE). Our study suggests that enhancing sink capacity through balanced relations between number of spikelets per unit land area and grain size, while improving source capacity through increasing RUE is a feasible way to achieve higher grain yield of late-season rice in South China.     

区域性冬小麦籽粒蛋白含量遥感监测技术研究

小麦籽粒的品质越来越受到农学家或是食品加工厂的高度重视。目前,很多国家从农 民手中收购小麦时,筛选质量优、蛋白质含量高的小麦,并对其农户给予一定奖励。实现实时监 控和掌握小麦籽粒品质信息,从而更好地指导生产,减少检测化验时间,降低生产成本,有效提 升工作效率。     

华北地区玉米机收籽粒与机收果穗性能及效益初析

华北地区玉米机收籽粒普及率非常低,人们对机收籽粒的认知水平不足。对玉米机收籽粒和机收果穗两种不同收获方式,从收获成本、时间、损失率、籽粒质量等多方面进行比较,结果表明,机收籽粒比机收果穗收获成本可以节省5.7%,时间可以节省50%以上,机收籽粒虽然破损率稍高(比机收果穗高6%),有待进一步改善,但是综合效果好,适合华北地区推广。     

籼稻C84和粳稻春江16B重组自交系遗传图谱构建及籽粒性状QTL定位与验证

【目的】本研究旨在挖掘水稻粒型新基因、探索其分子机理,解析籽粒发育调控遗传网络奠定基础,并为通过分子标记聚合有利基因开展超级稻分子设计育种提供理论依据。【方法】以植株和籽粒形态差异较大的晚粳稻品种春江16B(CJ16B）和广亲和中籼稻背景恢复系C84为亲本构建含有188个家系的重组自交系为作图群体,利用158对在双亲中存在多态性差异的分子标记,构建了遗传连锁图谱,总遗传距离为1428.40cM,平均标记间距为9.04cM。在构建遗传图谱的基础上,完成RIL188个株系籽粒的粒长、粒宽、粒厚、长宽比和千粒重等5个性状考查并进行QTL定位。【结果】在海南陵水和浙江杭州两地共检测到籽粒相关主效QTL30个,包括籽粒QTL新座位18个,解释遗传变异3.51%~17.25%。其中粒长、粒宽、粒厚和长宽比QTL位点分别为9个、5个、5个和6个,千粒重QTL位点5个。经基因座位比对,发现有5个QTL区间与已克隆的调控籽粒形态相关基因座位相近,我们通过对双亲目标基因的测序并根据差异位点设计dCAPs分子标记进行验证。【结论】该RIL群体及其遗传图谱可用于水稻重要农艺性状主效QTL基因的定位和克隆,新定位的18个粒型QTL可以为水稻籽粒发育调控网络提供补充和资料积累。     

半干旱区玉米行距调整增密对群体冠层结构及产量的影响

为增加玉米种植密度,构建不同的群体冠层结构,以玉米不同行距配置为基础,研究乳熟期玉米群体的光能利用情况,分析不同行距配置对冠层结构及产量、产量构成因素的影响。结果表明,玉米产量与群体消光系数达到显著相关,且为负相关。在吉林省半干旱区玉米宽窄行行距70-30 cm和宽窄行行距80-30 cm配置下玉米群体对光能资源的利用达到最佳,且有效提高玉米群体产量,增产分别达到8.06%和22.82%。     

玉米机械收获子粒破碎率与含水率关系的品种间差异

基于2012～2017年在北疆大田机械粒收条件下获取的收获质量评价数据,分析当地主栽的9个品种机械粒收过程中子粒破碎率和含水率的关系。调查范围内,不同品种收获期子粒含水率平均值分布范围为19.6%(KX9384,KWS1568)～28.2%(联创808),破碎率平均值分布范围为2.8%(新引M753)～8.5%(KWS2564),收获时品种间子粒含水率和破碎率均存在显著差异。分析显示,虽然131个样本子粒含水率(y)与破碎率(x)之间呈极显著正相关(r=0.302**),符合二次曲线(y=ax~2+bx+c)关系,但不同品种破碎率对子粒含水率的响应程度具有一定差异。在相同含水率条件下不同品种耐破碎性能存在较大差异,相应满足国标破碎率≤5%和≤8%要求适宜收获的子粒含水率范围也不同。筛选出新引M751、新引M753、KX9384、登海618和先玉335等耐破碎性能较好的品种。     

Relationships among the chalkiness,kernel size and endosperm cell morphology of rice kernels at different spikelet positions within a panicle

The occurrence of chalky kernels in rice is causally related to kernel size and endosperm morphology. This study aimed to investigate the occurrence of chalky kernels by analyzing kernel size, and the number and area of endosperm cells. Spikelets were sampled from upper and middle primary branches and lower secondary branches in a panicle, and divided into four categories: upper, middle, and lower perfect (PF) kernels and lower milky-white (MW) kernels. On the lower secondary branches, there was a higher percentage of chalky kernels, with smaller kernel lengths, widths and thicknesses, than the kernels on the upper and middle primary branches. MW kernels were smaller in size than PF kernels even on the same lower secondary branches. Regardless of grain appearance quality traits, the total areas of endosperm cross sections in lower kernels were significantly smaller than in upper kernels owing to the decreased cell area, and there was a significant negative correlation between the number of cells and average cell area. When the numbers and the areas of cells were analyzed using angular 30° intervals from the line connecting the center point and the dorsal vascular bundle, the MW kernels had significantly less cells than PF kernels near the ventral side at 120–180°. Thus, the decrease in the number of cells near the ventral side was a main causal factor in the decrease in MW kernel widths compared with PF kernel widths, and this suggested that cell division in MW kernels was inhibited at the early grain-filling stage.     

Harvest index is a critical factor influencing the grain yield of diverse wheat species under rain-fed conditions in the Mediterranean zone of southeastern Turkey and northern Syria

Environmental and plant factors critical to the grain yields of bread (Triticum aestivum L.), durum (T. durum L.) and emmer (T. dicoccum L.) wheat cultivars were investigated at two Mediterranean rain-fed field sites: Adana in southeastern Turkey (2009 and 2010) and Aleppo in northern Syria (2009). The grain yield (GY) and biological yield (BY) of most cultivars were higher in Adana than in Aleppo, and the lower GY in Aleppo resulted from lower harvest index (HI) and lower BY due to higher temperatures and lower rainfall. The variations in the HI among cultivars were greater in Adana than in Aleppo. The GY was closely related to the HI but not the BY across cultivars at each site, and a higher GY was accompanied by a superior conversion-efficiency of incident radiation during the grain filling period for grain yield [GY/Ra, where Ra is the cumulative radiation for 30 days after heading (D₃₀)] across all observations. The GY/Ra correlated negatively with the average temperature for D₃₀, and higher HI values resulted in higher GY/Ra. In Adana, the time from anthesis to physiological-maturity decreased as the average temperature for D₃₀ increased, resulting in a lower HI. Cultivars exhibiting the early heading trait can effectively escape the negative impacts of terminal high-temperature and water-shortage conditions on the HI. The results suggested that the HI is a critical factor for GY across diverse wheat cultivars under terminal high-temperatures and water-shortages in Mediterranean areas, and the BY is also an important factor under severe water-limitation conditions.