采用旱棚盆栽试验,以郑单958为材料设置3个水分水平（正常水分W3、轻度水分胁迫W2、重度水分胁迫W1）和高氮N3（施纯氮315 kg hm–2）、中氮N2（施纯氮210 kg hm–2）、低氮N1（施纯氮105 kg hm–2）、不施氮N0四个控释尿素施氮水平,探讨控释尿素水氮耦合对夏玉米产量和光合特性的影响。结果表明,控释尿素水氮耦合对夏玉米产量和光合特性具有显著影响。相同水分条件下,夏玉米产量随施氮量增加而增加,W1条件下增产13.17%~20.96%,W2条件下增产13.93%~32.48%,W3条件下增产14.37%~21.83%。相同施氮水平下,产量也随水分增加而增加,W2N3、W3N2和W3N3的产量在所有处理中较高。水氮耦合对夏玉米穗位叶净光合速率的影响显著,W1条件下N3、N2和N1处理间差异不显著,均显著高于N0,W2、W3各施氮处理的净光合速率随施氮量增加而增加,W3各处理的平均净光合速率高于其他2个水分处理,W2N3比W3N3和W3N2前期略低,后期无显著差异。水氮耦合效应能有效减缓穗位叶的实际光化学效率ΦPSII、叶片光化学猝灭系数qP以及PSII反应中心的最大光能转换效率的下降速率,提高光能利用率。控释尿素水氮耦合能有效提高夏玉米花后穗位叶净光合速率,保证籽粒对营养物质的需求,提高穗位叶实际和最大光化学效率,从而提高夏玉米的产量,产量构成因素中增加千粒重和穗粒数的优势较大。综合产量与光合特性、荧光特性的表现,在田间持水量为75%±5%的土壤条件下,控释尿素施氮量以纯氮210 kg hm–2为最佳;在田间持水量为55%±5%的土壤条件下,控释尿素施氮量以纯氮315 kg hm–2为宜。
Drought stress is one of the most important factors limiting maize production. Rab17 is an ABA-responsive gene and associated with drought tolerance. In order to identify haplotypic structure and mine allelic variants at rab17 locus, nucleotide diversity and linkage disequilibrium (LD) structure of rab17 were evaluated among a mini core set of Chinese diversified maize inbred lines. Totally, 19 SNP and 18 insertion/deletions (InDels) were identified, among which 81% were in non-coding regions and 19% in coding regions. The results showed that a high level of diversity appeared within 1 kb upstream of the rab17 locus, and declined quickly downstream of the gene region. Rapid decay of linkage disequilibrium of rab17 region with distance within 1 kb was detected. Functional markers which can be developed based on haplotype 14 are expected to have contribution to molecular breeding for drought tolerance.
