不同降雨年型下水分处理对大穗型小麦品种籽粒灌浆及产量的影响

在大田条件下，探讨了不同降水年型不同水分处理条件下大穗型小麦品种籽粒灌浆及产量的变化。结果表明：通过用不同方程对籽粒生长动态进行拟合，Cubic方程最精确。2000～2001干早年型W和Ws与两个灌浆持续期参数(Se、S)相关性显著．2001～2002丰雨年型W和Ws与3个灌浆速率参数(V、Vs、Vmax)间相关性达显著水平。两年度相比，2000～2001年度籽粒灌浆持续期短，灌浆速率小，导致粒重降低。灌水对灌浆参数的效应年际间存在差异，2000～2001年度随灌水次数增多，S和Se延长，灌浆速率降低；而2001～2002年度随灌水次数增多，S和Se缩短，灌浆速率以灌—水处理最小．灌两水处理最高。灌水对产量的影响，2000～2001年度显著增产，2001～2002年度处理间无显著差异，灌三水处理较灌两水处理反而减产。     

小麦氮素营养与籽粒灌浆期氮素转移的研究进展

对小麦氮素营养与籽粒灌浆期氮素转移研究进展进行了综述。过去进行的大量研究结果表明,小麦籽粒最终累积的氮素有相当一部分来自于灌浆期间营养器官中氮素的再转移,来自营养器官氮(内源氮)与土壤中新吸收氮(外源氮)的比例基本上是1:2。因此,花后营养器官氮素营养水平是决定小麦籽粒产量、籽粒中氮素累积量和蛋白质含量的一个重要因素。灌浆期间营养器官氮素向籽粒发生转移的同时,常常伴随着叶片光合性能的下降和叶片的衰老。不同基因型品种在灌浆期的氮素转移程度不同,表现为随品种演替,旗叶、茎秆和叶鞘中氮素的输出率增加,而转移氮对籽粒氮的贡献率却下降。氮收获指数(NHI)可以描述植物向籽粒分配氮的能力,是衡量作物对氮利用效率的指标。氮收获指数存在显著的基因型差异,虽然现代小麦品种吸氮量高于古老品种,但氮收获指数在现代和古老小麦品种间的差异因不同研究者而异,有的认为现代品种高于古老品种,但也有人认为与年代无关;小麦氮收获指数一般在0.55～0.80之间,很少超过0.8。过去对小麦籽粒灌浆期间的氮素转移虽然进行了大量研究工作,取得了许多重要进展,但仍有许多问题需要进一步深入研究,如根冠关系和灌浆过程中氮素转移的相互关系,田间个体和群体调控及不同高产栽培模式下灌浆过程中氮素转移的     

小区谷物联合收获机气吹式割台设计与试验

为解决现有小区谷物联合收获机割台中有残留、不易清机等问题,设计了一种采用正面气流将禾吹弯再切割的气吹式割台。根据力学原理建立了均匀气流吹禾模型,以小麦顺利进入割台而不掉落为要求,计算得气流支管出口风速为47.35 m/s。以能产生均匀气流为目标,通过理论计算得到气流管道的主要结构参数为:气流总管锥度1∶14.29,气流支管排列间距100 mm。对影响割台残留量和损失率的3个关键工作参数:气流支管出口与割刀的垂直和水平距离、气流支管出口与水平夹角进行了单因素试验和正交试验。单因素试验表明:气流支管出口与割刀的垂直和水平距离在15~27 cm内对割台损失率的影响呈现先降后升的趋势,气流支管与水平夹角对割台损失率和残留量的影响先缓慢减小,后增加较快。正交试验表明:最优组合为气流支管出口与割刀的水平距离21 cm、气流支管出口与割刀的垂直距离21 cm、气流支管出口与水平的夹角10°,此时总损失率为0.88%,割台残留量为1.21 g。气吹式割台残留量少,总损失率低,达到了小区小麦种子收获技术要求。     

磷化氢熏杀其抗性害虫实仓试验

用磷化铝片对储藏在房式仓（仓容５１６ｍ３）中的４００ｔ散装小麦进行熏蒸。储 不小麦水分为１１．５％,储藏平均温度为２９．３℃,小麦用ＰＶＣ（厚度０．１２５ｍｍ）复盖。熏 蒸期间用磷化氢检测管测定ＰＨ3浓度。采用１．０３ｋｇ磷化铝片（可释放０．３４ｋｇ磷化氢） 分成小包进行熏蒸,磷化氢最高值为 １． ０ｍｇ／Ｌ。熏蒸 １６天的 ＣＴ值为 ２１３ｍｇ· ｈ／Ｌ。用 敏感和抗性品系的米象和谷蠹进行生物试验表明．熏蒸１个月后所有的成虫都死亡;熏 蒸４２天所有中度抗性的谷蠹没有发现Ｆ１代成虫出现．米象的印和蛹不能发育为成虫。     

High Risk of the Formation of Milky White Rice Kernels in Cultivars with Higher Potential Grain Growth Rate under Elevated Temperatures

Abstract

Our objective was to clarify whether rice cultivars with a higher grain dry-matter increase rate (GIR) under elevated temperature condition show a higher percentage of milky white rice kernels (MWK). The rate of MWK judged using a rice-quality selector significantly varied with the cultivar and experimental year. The spikes of the cultivars detached 5–7 days after heading were solution-cultured with an adequate nutrient supply for one week at 25, 28 and 33ºC. GIR was overall the highest at 28ºC, and GIR at this temperature was considered to reflect the potential GIR in all the grains tested. There was a close correlation between the rate of MWK and the GIR at 28ºC under field conditions when temperatures during the grain-filling period were approximately over 25ºC. It was suggested that cultivars with a higher potential GIR under elevated temperature conditions have a higher risk of the formation of MWK.     

Genetic control of acquired high temperature tolerance in winter wheat

Summary The development of high temperature-tolerant wheat (Triticum aestivum L.) germplasm is necessary to improve plant productivity under high-temperature stress environments. The quantification of high temperature tolerance and the characterization of its genetic control are necessary for germplasm enhancement efforts. This study was conducted to determine the genetic control of acquired high temperature tolerance in common bread wheat cultivars. Reduction of 2,3,5-triphenyltetrazolium chloride (TTC) by heat-stressed seedling leaves was used as a quantitative measure to characterize acquired high temperature tolerance. Eleven-day-old seedlings of 20 F₁ progeny produced through a complete 5×5 (Payne, Siouxland, Sturdy, TAM W-101, and TAM 108) diallel mating design were acclimated at 37° C for 24 hours, followed by a 2-hour incubation at 50° C. Under these test conditions, acquired high temperature tolerance ranged from a high of 75.7% for the genotype TAM W-101 × TAM 108, to a low of 37.3% for the genotype Payne × Siouxland. Partitioning of genotypic variance revealed that only the general combining ability component effect was statistically highly significant, accounting for 67% of the total genotypic variation. These results suggest that enhancing the level of high temperature tolerance in wheat germplasm is feasible utilizing existing levels of genetic variability and exploiting additive genetic effects associated with high temperature tolerance.Contribution of the Texas Tech College of Agric. Sci. Journal no T-4-386. This work was supported by USDA specific agreement No. 58-7MNI-6-114 from the Plant Stress and Water Conservation Laboratory, USDA-ARS, Lubbock, Texas, USA     

Crossability percentages of bread wheat landraces from Sichuan Province,China with rye

Summary The crossabilities of 177 landraces of wheat (Triticum aestivum L.) from Sichuan Basin and its adjacent mountain ranges with rye (Secale cereale L.) have been tested. 16 landraces possess a higher crossability than Chinese Spring, 34 landraces have a similar and 127 landraces have a lower crossability than Chinese Spring or are non-crossable with rye. Most landraces with high crossability occur in Qinling Mountain and Dabashan Mountain Ranges in north of Sichuan and the valleys of Minjiang River, Fujiang River and Jialinjiang River in Sichuan Basin.     

The potential of integrated marketing in increasing adoption of land rehabilitation practices in northwest New South Wales,Australia

Land degradation is a major threat to the productivity of agricultural land in Australia, and on the soils used for growing wheat (Triticum aestivum) soil erosion and fertility decline are serious problems. A study financed jointly by NSW Agriculture, Grains Research and Development Corporation (GRDC) and agribusiness looked at the effectiveness of using integrated marketing to increase adoption of dryland lucerne (Medicago sativa) in rotations in northwestern NSW as a means to rehabilitate degraded wheat soils. At the time of the study, average wheat and protein yields were declining. Integrated marketing, with heavy reliance on television advertising, was run during Summer 1992 and Autumn 1993. Approximately 750 wheat growers, located around Moree in NSW comprised the target group. A similar number of comparable farmers from around Dalby in southern Queensland, who were not exposed to the promotional campaign, formed the control group. Farmers were surveyed by mail just before and 18 months after the campaign. While the results were compounded by severe drought during the study time, as well as by other constraints, the data suggest none the less the value of this approach in getting farmers to change their practices. One in six wheat growers in the target area were aware of the free information kit available via the advertised 1800 number or freepost mail coupon; one in twelve obtained the kit. Television was the most influential media in eliciting a response, followed by the Australian Grain Magazine. The results suggested that the campaign did in fact engender the desired change. The study highlights the possible role integrated marketing may play in rural Australia, whether the subject dealt with is agricultural, environmental or other, not because of any novelty value, but because of the technique itself. © 1998 John Wiley & Sons, Ltd.     

Effect of Foliar Application of Phosphorus on Winter Wheat Grain Yield,Phosphorus Uptake,and Use Efficiency

ABSTRACT

One would expect foliar applied phosphorus (P) to have higher use efficiencies than when applied to the soil, but limited information is available concerning this. Experiments were conducted in 2002, 2003, and 2004 to determine the effect of foliar applications of P on winter wheat grain yields, P uptake, and use efficiency. Twelve treatments containing varying foliar P rates (0, 1, 2, and 4 kg ha^{? 1} in 2002 and 2003 and additional 8, 12, 16, and 20 kg ha^{? 1} in 2004) with and without pre-plant rates of 30 kg ha^{? 1} were evaluated. Foliar applications of P at Feekes 7 generally increased grain yields and P uptake versus no foliar P. Use efficiency was higher when P was applied at Feekes 10.54. Results from this study suggested that low rates of foliar applied P might correct mid-season P deficiency in winter wheat, and that might result in higher P use efficiencies.