不同耐密性玉米品种地上部与根系性状的协同效应

【目的】阐明不同玉米品种在增密种植条件下地上部性状和根系构型的协同响应，为耐密性玉米的遗传改良提供理论支撑。【方法】以我国18个主栽玉米品种为试材，设置2个种植密度(6万株/hm²和7.5万株/hm²)，分别在吐丝期和成熟期测定14个地上部农艺性状和8个根系构型性状，利用方差分析与回归分析等统计方法解析耐密高产品种的地上地下协同关系。【结果】随着种植密度的增加，玉米单株地上部和根系生物量及籽粒产量等指标下降，群体地上部生物量和籽粒产量显著提高。根据两个种植密度下的群体产量，受试品种中6个被划分为高低密度下均高产的双高型(DH);3个品种为仅高密度下高产的高密高产型(HH);7个品种为高低密度下均低产的双低型(DL);2个品种为仅低密度下高产的低密高产型(HL)，供试品种主要为双高型(DH)和双低型(DL)。在高密度下，DH品种比DL品种具有更多的吐丝前干物质累积量和更高的收获指数，DH品种在减少根系干重、节根数和根系宽度的同时，保持了较高的根系表面积与总根长。综合两个种植密度下地上部与根系性状对产量的贡献，发现吐丝期茎秆干物质、成熟期籽粒干物...

Coordination of shoot and root traits of maize cultivar types with different density tolerance

  【Objectives】  We investigated the changes in shoot and root traits of maize under different plant densities for better understanding of the mechanism underlying maize adaptation to high-density tolerance.  【Methods】  A field experiment was carried out with 18 maize hybrid cultivars commonly used in China, under high (75000 plants/hm2) and low (60000 plants/hm2) plant densities. A total of 14 shoot traits and 8 root architecture traits were measured at silking and maturity stages. The shoot and root cooperative responses to varying densities were assessed by regression and correlation of the traits.  【Results】  Compared to low plant density, high plant density decreased shoot and root biomass and yield per plant, but significantly increased population shoot biomass and grain yield. Based on the population yield under the two plant densities, 6 cultivars were rated as high yield type under the two densities (DH), 3 as high yield type under high density only (HH), 7 cultivars as low yield type under the two densities (DL), and 2 cultivars as high yield under low density (HL). Under high plant density, DH type cultivars had higher dry matter accumulation than the DL type cultivars at silking and maturity stages. DH cultivars had higher root area and total root length with decreasing root dry weight, number of nodes and root width. Under the two plant densities, stem dry matter at the silking stage, grain dry matter and harvest index at the maturity stage positively contributed to yield, while the number of root nodes negatively contributed to yield.  【Conclusions】  DH cultivars coordinate the relationship between shoot and root well and allocated the limited carbon resources more reasonably irrespective of the plant density treatments. By reducing the number of node root, and increasing the root length and root absorption surface area, DH cultivars efficiently improved nutrient absorption of root system and the shoot growth of maize. Moreover, DH cultivars coordinated the source-sink relationship by increasing dry matter accumulation before silking and dry matter distribution to grains after silking, thereby increasing yield.