施氮量对马铃薯干物质积累特性和产量的影响

以辽宁省主推马铃薯品种辽薯6号为试验材料,采取膜下滴灌种植模式,在底施氮磷钾(15∶15∶15)复合肥750 kg/hm^2的基础上,设置5个追施氮水平(N 1:0 kg/hm^2;N 2:60 kg/hm^2;N 3:105 kg/hm^2;N 4:180 kg/hm^2;N 5:225 kg/hm^2),以滴施方式追施,研究施氮量对马铃薯干物质积累特性及产量的影响。结果表明,马铃薯叶、茎的干物质积累量和分配比例均随着施氮量的增加而增加,以N 5处理最高。块茎的干物质积累量和分配比例随着施氮量的增加先增加后降低,以N 3处理最高。马铃薯的干物质转运量、转移率、平均薯块质量、单株薯块质量、产量均以N 3处理最高,显著高于其他处理,其中产量为46.5 t/hm^2,分别较N 1、N 2、N 4、N 5处理提高92.9%、78.2%、9.7%、18.6%。相关分析表明,马铃薯的干物质积累量、积累速率、转运量、转移率与平均薯块质量、单株薯块质量和产量均呈极显著正相关。说明N 3处理通过对马铃薯叶、茎及块茎干物质积累量及分配比例的调控,提高了叶和茎干物质向块茎的转运量和转移率,进而增加了平均薯块质量、单株结薯质量和产量。综上,追施氮量以105 kg/hm^2最佳。

控施氮肥对马铃薯根际土壤微生物及酶活性的影响

为了研究控施氮肥对马铃薯根际土壤微生物及酶活性的影响,采用随机区组试验,底肥施用氮磷钾(15∶15∶15)复合肥750 kg/hm^(2),设置5个滴施氮肥量:0 kg/hm^(2)(N1)、60 kg/hm^(2)(N2)、105 kg/hm^(2)(N3)、180 kg/hm^(2)(N4),225 kg/hm^(2)(N5)。结果表明,马铃薯根际土壤微生物和酶活性对氮肥用量的响应存在显著差异,根际土壤细菌和放线菌数量以N3处理最高,真菌数量以N4处理最高。根际土壤脲酶、蔗糖酶、磷酸酶和过氧化氢酶活性以N3处理最高,且不同生长阶段对氮肥用量的响应存在显著差异。施氮量为105 kg/hm^(2)时有利于增加马铃薯根际土壤细菌和放线菌数量,抑制真菌数量,提高了土壤脲酶、蔗糖酶、磷酸酶和过氧化氢酶的活性,优化了马铃薯根际土壤的生态环境。

Abscisic Acid Transport and Homeostasis in the Context of Stomatal Regulation

The discovery of cytosolic ABA receptors is an important breakthrough in stomatal research; signaling via these receptors is involved in determining the basal stomatal conductance and stomatal responsiveness. However, the source of ABA in guard cells is still not fully understood. The level of ABA increases in guard cells by de novo synthesis, recycling from inactive conjugates via β-glucosidases BG1 and BG2 and by import, whereas it decreases by hydroxylation, conjugation, and export. ABA importers include the NRT1/PTR family protein AIT1, ATP-binding cassette protein ABCG40, and possibly ABCG22, whereas the DTX family member DTX50 and ABCG25 function as ABA exporters. Here, we review the proteins involved in ABA transport and homeostasis and their physiological role in stomatal regulation. Recent experiments suggest that functional redundancy probably exists among ABA transporters between vascu- lature and guard cells and ABA recycling proteins, as stomatal functioning remained intact in abcg22, abcg25, abcg40, aitl, and bglbg2 mutants. Only the initial response to reduced air humidity was significantly delayed in abcg22. Considering the reports showing autonomous ABA synthesis in guard cells, we discuss that rapid stomatal responses to atmospheric factors might depend primarily on guard cellsynthesized ABA, whereas in the case of long-term soil water deficit, ABA synthesized in the vasculature might have a significant role.