Dynamic change of mineral nutrient content in different plant organs during the grain filling stage in maize grown under contrasting nitrogen supply

The introduction of new hybrids and integrated crop-soil management has been causing maize grain yield to increase. However, less attention has been paid on the nutrient concentration of the grain; this aspect is of great importance to supplying calories and nutrients in the diets of both humans and animals worldwide. Increasing the retranslocation of nutrients from vegetative organs to grain can effectively increase the nutrient concentration of grain and general nutrient use efficiency. The present study involved monitoring the dynamic change of macro- and micronutrients in different organs of maize during the grain filling stage. In addition, the mobility of different elements and their contribution to grain nutrient content were evaluated in a 2-year experiment under low (LN, no N supplied) and high N (HN, 180 kg N ha⁻¹) supply. Under HN supply, the net remobilization efficiency (RE) of the vegetative organs as a whole (calculated as nutrient remobilization amount divided by nutrient content at silking) of N, P, K, Mn, and Zn were 44%, 60%, 13%, 15%, and 25%, respectively. The other nutrients (Mg, Ca, Fe, Cu, and B) showed a net accumulation in the vegetative organs as a whole during the grain filling stage. Among the different organs, N, P, and Zn were remobilized more from the leaves (RE of 44%, 51% and 43%, respectively) and the stalks (including leaf sheaths and tassels) (RE of 48%, 71% and 43%, respectively). K was mainly remobilized from the leaves with RE of 51%. Mg, Ca, Fe, Mn, and Cu were mostly remobilized from the stalks with the RE of 23%, 9%, 10%, 42%, and 28%, respectively. However, most of the remobilized Mg, Ca, Fe, Mn, Cu, and Zn were translocated to the husk and cob, which seemingly served as the buffer sink for these nutrients. The REs of all the nutrients except for P, K, and Zn were vulnerable to variations in conditions annually and were reduced when the grain yield and harvest index were lower in 2014 compared with 2013. Under LN stress, the RE was reduced in P and Zn in 2013, increased in Cu and unchanged in other nutrients. The concentration of these nutrients in the grain was either unchanged (P, K, Ca, Zn, and B) or decreased (N, Mg, Fe, Mn, and Cu). It is concluded that grain N, P, K, Mn, and Zn, but not Mg, Ca, Fe, Cu, and B concentration, can be improved by increasing their remobilization from vegetative organs. However, enhancing the senescence of maize plant via LN stress seems unable to increase grain mineral nutrient concentration. Genetic improvement aiming to increase nutrient remobilization should take into account the organ-specific remobilization pattern of the target nutrient.     

不同肥力水平下种植密度对浚单29产量性状及产量的影响

[目的]探寻浚单29不同肥力水平地区的适宜种植密度。[方法]研究在高产田与一般田2种肥力水平下浚单29种植密度与产量及其相关产量性状的关系。[结果]2种肥力水平下通过种植密度变化影响穗部性状来影响产量,相同密度,一般田肥力水平下,密度对穗部性状影响大于高产田对穗部性状影响。[结论]在一般田肥力水平下,浚单29最适宜密度为6.75万株/hm2,高产田肥力水平下,浚单29最适宜密度为7.50万株/hm2。     

Achieving legislation requirements with different nitrogen fertilization strategies: Results from a long term experiment

The Nitrates Directive (91/676/EEC, Anonymous, 1991) was developed in Europe to limit environmental threats from intensive livestock farming and N fertilizer applications to crops. It imposed several rules on farmers and public bodies, one of which was nutrient fertilization plan adoption. Here we use results from the Tetto Frati (Northern Italy) Long-Term Experiment to verify the terms and coefficients in the official Italian guidelines and evaluate the limitations imposed to organic fertilization amounts. For this purpose, we mined long-term experimental data of crop yield, N uptake, N use efficiency, and soil organic matter content from miscellanea cropping systems fertilized with farmyard manure (FYM) and bovine slurry (SLU), typical of a dairy farm in Northern Italy. N fertilization efficiency indicators (Removal to Fertilizer ratio, Apparent Recovery and Nitrogen Fertilizer Replacement Value) indicated that in the long run, FYM behaved similarly to urea, and better than SLU. Even N supply rates as high as 250 kg N ha⁻¹ were justified by high rates of crop removal. In fact, among the terms of the mass-balance equation, SOM mineralization was found to be most relevant, followed by meadow rotation residual effects. We conclude that a revised Nitrates Directives application scheme could be more relaxed in its application limit of manure-N, but should be more ambitious in setting efficiency coefficients for manure fertilization.     

浅谈阜新蒙古族自治县玉米膜下滴灌农艺措施

以玉米膜下滴灌栽培技术研究成果为依据，总结了辽宁省阜新蒙古族自治县东部地区推广应用该成果的具体措施，并提出相应对策。     

玉米不同自交系幼苗光合对 UV-B 辐射增强的响应

为了探讨玉米不同自交系对UV-B辐射增强的响应，在摸拟光照培养条件下，研究了增强UV-B辐射对玉米不同自交系气体交换参数的影响。结果表明，五叶期UV-B辐射处理6 d后，供试的48个自交系中近一半以上材料的幼苗叶片光合速率、气孔导度和蒸腾速率显著降低10％以上，其材料比例分别为64．6％，47．9％，54．2％；而有62.5％的材料胞间CO2浓度表现为显著增加；相关分析发现，气孔导度与蒸腾速率对UV-B辐射增强的响应值间存在极显著正相关关系；根据气体交换参数对UV-B辐射增强的响应程度将48个材料分成6类，其中对增强UV-B辐射反应比较敏感的材料和能够忍耐UV-B辐射增强的材料均占12．5％。说明玉米不同自交系幼苗叶片气体交换参数对UV-B辐射增强反应敏感程度具有显著的基因型差异，从中能够筛选出对UV-B辐射增强反应敏感和有忍耐能力的材料。     

松花粉破壁方法的比较研究

以松花粉为主要原料,分别采用纤维素酶法、超声波法、发酵法和旋风破碎法对松花粉进行了破壁研究,并从不同角度对几种方法进行了比较。     

玉米果穗发育的生理特性研究

为了探讨玉米优良自交系选育中出现短苞叶品种的原因，从生理角度分析了两玉米自交系品种穗轴与苞叶生长发育变化趋势。结果表明：四个时期中139号苞叶硝酸还原酶活性非常低，对照1号的稍高一些。139号苞叶谷氨酰胺合成酶活性小于1号，且1号的酶活性变化较平缓。139号雌穗轴硝酸还原酶活性变化剧烈，授粉后15d达高峰，明显大于1号。139号雌穗轴谷氨酰胺合成酶活性前三时期始终大于1号，最后一时期二者几乎相等，但1号的酶活性变化平缓。就上述结果从氮代谢方面分析了139号苞叶与穗轴发育失调的原因。     

黎榆A繁殖母本有效穗和结实率与产量的关系

繁殖田母本有效穗和结实率是影响产量的主要因素。通过对10个不同父母本栽插行比的分析结果表明：黎榆A繁殖产量以父母本栽插行比为2：18最高，达292．09kg/667m^2。增加有效穗对于增产的效应要比增加结实率大；有效穗与产量，结实率与产量的偏相关系数均呈正相关，且有效穗与产量的相关达显著水平，多元回归方程为：y-155.6283 4.8660x 0.2342x2.     

对两个玉米雄性不育系的细胞质分类研究

本文从普通遗传学、植物病理学和分子生物学的水平对玉米雄花不育系—元徐cms—小黄和恩二激cms—大黄进行了综合性的分类研究。大田的育性反应表明，这两个不育系的育性恢复受一对显性基因控制。对花粉染色的观察发现F1可育花粉与败育花粉基本上呈1：1分离。用小斑病T小种接种，这两个不育系不表现专化感染。通过mtDNA的分析     

玉米胚挤压膨化系统参数优化试验

研究了用于浸油的玉米胚挤压膨化系统参数(模孔孔径、套筒温度、物料含水率、螺杆转速)对各考察指标(粕的残油率、剪切强度及糊底程度)的影响规律．并对其参数进行了优选。同时对最佳参数的膨化玉米胚与传统浸油的轧胚玉米胚、原始玉米胚的显微结构进行对比分析。研究表明：玉米胚挤压膨化系统参数选择合适，浸出时玉米胚不糊筛底，残油率小于0．5％。