拔节期阶段性干旱对小麦茎蘖成穗与结实的影响

Effects of Drought Stress During Jointing Stage on Spike Formation and Seed Setting of Main Stem and Tillers of Winter Wheat

【目的】针对黄淮海地区自然降水季节分布不均、阶段性干旱频发导致小麦产量和水分利用效率低的问题,探索拔节期阶段性干旱对冬小麦主茎和分蘖成穗与结实的影响,可为该地区冬小麦节水栽培提供理论和技术支持。【方法】于2017—2019年冬小麦生长季,在室外遮雨条件下进行盆栽试验。以小麦品种山农29和衡0628为试验材料,在拔节后0—10 d期间设置5个水分处理:充分供水(CK,保持土壤相对含水量75%—80%,土壤有效含水量为42.2—46.7 mm);拔节后0—5 d轻度干旱(T1,保持土壤相对含水量为65%—70%,土壤有效含水量为33.4—37.8 mm)、重度干旱(T2,保持土壤相对含水量为45%—50%,土壤有效含水量为15.6—20.1 mm);拔节后0—10 d轻度干旱(T3,保持土壤相对含水量为65%—70%,土壤有效含水量为33.4—37.83 mm)、重度干旱(T4,保持土壤相对含水量为45%—50%,土壤有效含水量为15.6—20.1mm),测定了茎蘖幼穗发育进程及茎蘖成穗和结实性状等指标。【结果】在拔节后0—10 d期间不同程度干旱对小麦主茎成穗无明显影响,但是随着干旱时间的延长和干旱程度的加大,低位蘖(Ⅲ和Ⅰp)成穗率迅速下降,而高位蘖(Ⅱp和Ⅰ1)成穗率呈先升高后下降趋势。拔节后0—5 d轻度或重度干旱,高位蘖成穗率均较高,单位面积成穗数与CK无显著差异;拔节后0—10 d轻度干旱,高位蘖成穗率虽与CK相近,但由于低位蘖(Ⅲ、Ⅰp)成穗率下降幅度较大,导致单位面积成穗数显著降低,山农29和衡0628单位面积穗数下降幅度分别为4.94%—5.06%和6.77%—8.33%;拔节后0—10 d重度干旱,Ⅱ蘖以上分蘖成穗率均下降,山农29和衡0628单位面积成穗数下降幅度分别为10.97%—11.52%和15.00%—15.55%。拔节后0—5 d轻度干旱,2个品种主茎和各蘖位分蘖的结实性、单穗产量和单位面积产量均与CK无显著差异。拔节后0—5 d重度干旱,2个品种各中位蘖的结实小穗数和穗粒数均显著减少,主茎和高位蘖受影响不明显;山农29各茎蘖单粒重不受影响而单穗产量显著降低;衡0628各茎蘖单粒重和单穗产量显著降低;山农29和衡0628单位面积籽粒产量均显著降低,分别比CK减少5.14%—5.46%和5.45%—6.24%。拔节后0—10 d轻度和重度干旱,2个品种茎蘖的总小穗数、结实小穗数、穗粒数、单粒重、单穗产量和单位面积籽粒产量均显著降低,且以中位蘖下降幅度较大;重度干旱处理各茎蘖的穗粒数和单穗产量及单位面积籽粒产量显著低于轻度干旱处理。山农29和衡0628单位面积籽粒产量在T3处理下分别比CK减少12.87%—13.30%和15.52%—16.59%;在T4处理下分别比CK减少23.18%—25.92%和26.05%—31.22%。【结论】拔节后短时间轻度干旱(拔节后0—5 d保持土壤相对含水量65%—70%,土壤有效水含量33.4—37.8 mm)对小麦成穗和结实无显著影响;干旱时间过长、程度过大则会大幅度降低低位蘖(Ⅲ和Ⅰp)成穗率、总小穗数、结实小穗数、穗粒数、单粒重和单穗产量,导致单位面积籽粒产量显著下降。在拔节后5 d干旱或拔节后10 d轻度干旱条件下,高位蘖(Ⅱp和Ⅰ1)成穗率有所提高,在一定程度上可弥补干旱造成的损失,这可能与低位分蘖受旱后成穗率降低,群体变小,动摇分蘖分配的营养增多、生存空间增大有关,为生产中通过合理措施调控,实现小麦稳产提供了理论依据。山农29对拔节期阶段性干旱的抗性高于衡0628。

【Objective】To address the problem of low wheat yield and water efficiency caused by irregular distribution of natural precipitation season and the frequent rate of staged drought in the Huang-Huai-Hai Plain of China, this paper provided theoretical as well as technical provisions for water-saving cultivation of winter wheat in this area by exploring the effects of water insufficiency on the main stem and tiller spikes formation and panicles traits during jointing stage.【Method】A 2-year pot experiment under external rain conditions was carried out from 2017 to 2019 in winter wheat growth season, and the two winter wheat varieties of Shannong 29 and Heng 0628 were used as experimental materials. The total five water treatments were set up during 0-10 d after jointing, including full irrigation treatment during whole growing season as control(CK, maintaining soil relative water content of 75%-80%, the effective soil water content of 42.2-46.7 mm), 0-5 d light drought stress after jointing(T1, maintaining soil relative water content of 65%-70%, soil availability water content of 33.4-37.8 mm), 0-5 d severe drought(T2, maintaining soil relative water content of 45%-50%, available soil water capacity is 15.6-20.1 mm), 0-10 d light drought stress after jointing(T3, maintaining soil relative water content is 65%-70%, soil availability water content of 33.4-37.8 mm), and 0-10 d severe drought stress(T4, maintaining the soil relative water content 45%-50%, availability water content of 15.6-20.1 mm).【Result】The results revealed that different degrees of drought stress had no significant effect on the main stem of wheat during 0-10 d after jointing, the effective spike rate of low tiller(Ⅲ, Ⅰp) decreased rapidly with the increasing the drought level and extension of drought time, while the effective spike rate of high tiller(Ⅱp and Ⅰ1) increased first and then decreased. Light or severe drought at 0-5 d after jointing stage, Ⅱp and Ⅰ1 were higher in effective spike rate, and there was no significant difference in spike number per unit area from CK. Although the effective spike rate of Ⅰ1 and Ⅱp was similar to that of CK in 0-10 d light drought after jointing stage, the percentage of spikes per unit area decreased significantly due to the decrease of Ⅲ, Ⅰp and Ⅳ. The number of spike per unit area of Shannong 29 and Heng 0628 was decreased by 4.94%-5.06% and 6.77%-8.33%, respectively. For 0-10 d light drought after jointing, the effective rate of tiller of Ⅱ and more was decreased of severe drought. The number of spikes per unit area of Shannong 29 and Heng 0628 was decreased by 10.97%-11.52% and 15.00%-15.55%, respectively. The treatment of light drought at 0-5 d after jointing stage, the panicle characteristics, single stem grain yield and grain yield per unit area of the two cultivars were not significantly different from CK. The treatment of severe drought from 0 to 5 days after jointing, the fertile spikelets number and the grain number in the two cultivars were significantly reduced, and the main stem and later occurring tillers were not affected. The single grain weight of Shannong 29 was not affected, but the yield of single stem grain yield was significantly reduced, the single grain weight and single stem grain yield of Heng 0628 was significantly reduced, the grain yield per unit area of Shannong 29 and Heng 0628 decreased significantly, which was 5.14%-5.46% and 5.45%-6.24% lower than CK, respectively. For the light and severe drought from 0 to 10 days after jointing, the spikelets number, the fertile spikelets number, grain number, single grain weight, single stem grain yield and grain yield per unit area of the two cultivars were significantly reduced;The median tillers had substantial reduction;The number of grains per ear and the yield of single-stem grain and the grain yield per unit area of severely drought-treated stems were significantly lower than those of light drought treatment. Under the T3 condition, the grain yield per unit area of Shannong 29 and Heng 0628 was decreased by 12.87%-13.30% and15.52%-16.59%, respectively. Under the T4 condition, the grain yield per unit area of Shannong 29 and Heng 0628 decreased by 23.18%-25.92% and 26.05%-31.22%, respectively.【Conclusion】The above results indicated that short-term light drought after jointing(0-5 days after jointing, maintaining soil relative water content of 65%-70% and soil effective water content of 33.4-37.8 mm) had no significant effects on wheat earing and fruiting;The percent of tillers to panicle, the spikelets number, the fertile spikelets number, grain number, single grain weight and single stem grain yield of the low tillers(Ⅲ, Ⅰp) would be greatly reduced, and the grain yield per unit area was significantly reduced increased drought stress and time. However, the effective spike rate of high tillers(Ⅱp and Ⅰ1) in two degrees of 0-5 d after jointing and light drought training of 0-10 d after jointing was increased to some extent, which could make up for the loss caused by drought, which might be related to the decrease of the effective spike rate of low tillers, the decrease of population size, and the increase of nutrition and living space for high tillers. Shannong 29 had the stronger potential to adapt drought stress at jointing stage than Heng 0628.