籼型水稻两用核不育系2136S的选育

在低纬度、高海拔的贵阳自然低温条件下,按照广适应性籼型水稻两用核不育系选育的光温指标进行严格鉴选,成功地选育出了具有起点温度低(23.5℃),稳定不育期长和可育期自交结实率高的籼型水稻两用核不育系2136S。本文报道了2136S的选育过程及其主要特性。     

Phosphate-rich soils in the European Union: estimating total plant-available phosphorus

The estimation of plant-available phosphorus (P) has become important for farmers and environmental agencies, because it can help them: (i) use existing soil P reserves more efficiently, and (ii) establish criteria for reducing or stopping application of P fertilizers, which can cause water eutrophication. In this study, total plant-available P (TPAP) in 12 P-rich soils from major agricultural areas of the European Union was estimated by successive cropping in pots, and compared to the amount of P extracted by different methods. Plant desorption curves generally conformed to a Temkin equation (P uptake = A+B log(P concentration in soil solution)). P uptake was also linearly related to the change in Olsen P of soil. Of the various laboratory methods used to estimate TPAP, extraction by goethite (viz., a ‘near-infinite’ Fe oxide sink) proved the most efficient, followed by repeated extraction with an anion-exchange resin in chloride form. Isotopically exchangeable P (IEP) was found to be useless for estimating TPAP, particularly in acid soils. However, IEP at 14 days, combined with the P concentration in the soil solution, provided a good estimate for TPAP. In practice, TPAP can also be predicted from Olsen P, provided the varying efficiency of bicarbonate in extracting P from soils in different pH ranges is considered.     

地温与玉米品种出苗关系的研究

利用5个春玉米品种自然条件下分期播种出苗情况以及地温气象资料,对地温与玉米出苗的关系进行了研究和分析。结果表明:出苗率随着播种后的时间推移呈逻辑斯蒂曲线,土温与出苗时间呈指数曲线变化,土壤平均温度与地积温呈二次曲线T=816.61-57.26t+1.17t2,根据方程得出了玉米出苗最适宜温度是24.37℃。并利用积温模型得出5个品种的发育起点温度是5.12~8.40℃,不同品种其发育起点温度不同。     

番茄临界氮浓度模型的建立及氮素营养诊断

为构建鲜食番茄临界氮浓度稀释曲线模型,在此模型基础上建立氮素吸收模型和氮营养指数模型,对鲜食番茄氮营养状况进行诊断。试验分别于2016 年、2017 年以鲜食番茄‘苏粉14 号’为试验材料,设置了5 个施氮水平,研究鲜食番茄地上部生物量与氮浓度的动态变化。结果表明,鲜食番茄地上部生物量随氮肥施用量的增加而增加,氮质量分数随着生长发育时间而降低;鲜食番茄临界氮浓度与地上部生物量之间符合幂函数的关系,%Nc=3.7574DW-0.155,相关系数R2=0.8505。氮素吸收模型与氮营养指数模型可对鲜食番茄的适宜施氮量与氮素丰缺状况进行诊断,本试验条件下番茄适宜施氮量为270.92~281.79 kg/hm2。     

浅谈农林高校哲学教育创新

当前农林高校的哲学教育存在很多困难。解决问题的出路是进行哲学教育创新。哲学教育创新包括哲学教育功能创新、哲学教育理念创新、哲学教育师生关系创新、哲学教育教学方式创新、哲学教育实践环节创新和哲学教育考核策略创新六个方面。     

膜下滴灌棉花关键生育期不同灌水量、灌水次数对其生长、产量及水分利用效率的影响

通过2004年棉花生长季田间试验,我们研究了膜下滴灌棉花关键生育期不同灌水量和灌水次数对其生长、产量及水分利用效率（WUE）的影响,旨在建立河北南部棉区滴灌条件下的优化灌溉模式,提高作物水分利用效率,达到节水增产目的。试验结果表明：不同灌水方式对棉花产量和水分利用效率的影响具有显著差异,棉花需水关键期花铃期分2次少量灌水处理,每次灌水量10．42mm,明显优于两次多量灌水和集中一次灌溉等其他处理,产量和WUE最高,分别高达4929．0kg／hm^2和0．98kg／m^3,具有明显的节水增产效益。     

Comparing Copper Requirements of Faba Bean,Chickpea, and Lentil with Spring Wheat

Abstract

The copper (Cu) requirement of four crop species was measured in a glasshouse experiment using yield of dried shoots and Cu content (Cu concentration multiplied by yield of dried shoots) of 62 day old plants grown in two different alkaline soils. The species compared were faba bean (Vicia faba L. cv. Fiord), chickpea (Cicer arietinum L. cv. Tyson), lentil (Lens culinaris Medik cv. Digger), and spring wheat (Triticum aestivum L. cv. Stretton). The comparative Cu requirement of the species was determined from yields of dried shoots when no Cu fertilizer was applied, the amount of applied Cu required to produce the same percentage of the maximum (relative) yield of dried shoots, and the Cu content of dried shoots. The concentration of Cu in youngest tissue and in dried shoots was used to determine critical concentrations of Cu in tissue associated with 90% of the maximum yield. Faba bean used indigenous soil Cu more effectively than wheat, followed by chickpea and then lentil. As measured using both shoot yield and Cu content in shoots, the Cu requirement was lowest for faba bean, and increased in the order faba bean < wheat < chickpea < lentil. Copper concentration in dried youngest tissue and in dried shoots increased with an increase in the amount of added Cu. The critical Cu concentration in the youngest tissue was (mg Cu/kg): 4.6 for lentil, 2.6 for chickpea, 1.5 for wheat, and 2.8 for faba bean; corresponding values for dried shoots (mg Cu/kg) were 6.3 for lentil, 3.3 for chickpea, 2.8 for wheat, and 3.0 for faba bean.     

Soybean Growth on Calcareous Soil as Affected by Three Iron Sources

Abstract

Iron (Fe) chlorosis is a common symptom in many soybean (Glycine max L. Merr.) producing areas throughout the United States. On the Blackland soils found in northeast Texas, Fe chlorosis occasionally appears during vegetative growth, but often abates by the time plants flower. However, it is not clear whether preplant additions of Fe will enhance soybean growth or yield on this soil or whether different sources of Fe give different responses. In a greenhouse study, soil from a pH 8.4 Houston Black clay (fine, smectitic, thermic Udic Haplusterts), with a DTPA‐extractable concentration of 11.7 mg Fe kg^?1, was treated with FeSO₄ (0, 3, 10, 30, and 100 ppm Fe), sodium ferric diethylenetriamine pentaacetate (FeDTPA) (0, 0.3, 1.0, 3, and 10 ppm Fe) or sodium ferric ethylenediamine‐di (o‐hydroxyphenylacetate) (FeEDDHA) (0, 0.3, 1.0, 3, and 10 ppm Fe). Pot size was 19 L and soil dry mass was 10 kg. Soybean (cv. Hutcheson) seed were planted in November 2000 and seedlings were thinned to three per pot at the first true leaf stage. The third uppermost fully expanded leaf of each plant was harvested at growth stage R3 for nutrient analysis. Between 20 and 100 days after planting, six nondestructive leaf chlorophyll readings were obtained from the third uppermost fully expanded leaf. Entire plants were harvested at R6 (mid podfill) for nutrient and biomass yield determination. Leaf blade Fe concentration ranged from 79 to 87 mg kg^?1 in the untreated check plants to a high of 109 mg kg^?1 for the 10 ppm FeDTPA‐Fe treatment, all of which were greater than the acknowledged critical level of 60 mg kg^?1. No visible Fe‐deficiency symptoms appeared during the study. Chlorophyll (SPAD 502) values during the R3 to R5 growth stages were greater for all of the FeSO₄ treatments than for the 0 ppm treatment. The 10 ppm FeDTPA‐Fe treatment and the 3 ppm FeEDDHA‐Fe treatment exhibited higher leaf chlorophyll readings than the untreated checks during the R3 to R5 growth stage. The average seed yield from the 12 Fe fertilized treatments at growth stage R6 was only 12% greater (not significant) than the untreated check. Total biomass (root plus shoot) was not affected by the treatments. There was no evidence that the higher rates of Fe caused reduced growth. Overall, our results do not suggest that soil‐applied Fe will consistently stimulate soybean growth or yield on this soil, at least when DTPA‐extractable soil Fe is at 12 mg kg^?1 or higher. However, because of the trends for increased seed yield in some of the Fe treatments, field studies using soil‐ and/or foliar‐applied Fe are warranted.     

The use of alum to decrease phosphorus loss from dairy farm laneways in southern New Zealand

Dairy farm laneways are sources of enriched P loss. Aluminium sulphate (alum) has been shown to decrease P loss when applied to land; our hypothesis was that alum may serve as a cost‐effective strategy to mitigate P loss from laneways connected to streams. A 4‐month field study, over the milking period when cows regularly used the laneway, showed that alum (25 and 50 kg/Al/ha) initially lowered FRP losses for four events, over 60 days, following application. If connected to a stream, the cost‐effectiveness of alum use on dairy farm laneways (51–75 USD per kg P retained) was high compared to other strategies on a grazed dairy farm.     

地震折射层析法在红壤关键带地层划分中的应用研究

地球关键带结构的识别对于理解关键带系统中发生的地球物理化学过程有重要意义,以往基于钻井和剖面来研究关键带地下结构的方法不足以充分反映关键带地下构造全貌,近些年地震折射层析方法在浅层地表勘探中兴起.为探究关键带地下结构的空间变异特征,本研究以红砂岩基岩的鹰潭孙家流域和板岩基岩的长沙沿江阶地为研究区,通过高精度地震折射层析...