Evolving gene pools in crop plants

Summary The three gene pool system can be applied usefully to the whole range of crop plants. The primary gene pool (GP1) show varying degrees of fragmentation. No morphological discontinuity is apparent between wild and cultivated Lathyrus sativus but clear discontinuities have developed between conspecific wild and cultivated Phaseolus and Vigna species. Further discontinuities can develop in cultigens where disruptive selection has been practiced, as in Beta vulgaris, Linum usitatissimum and Brassica oleracea where more than one distinct crop has evolved within a single biological species. Each such crop has developed its own distinctive gene pool.     

Variation in progenies of an Arachis hypogaea x diploid wild species hybrid

Summary Derivatives of a cross between cultivated peanuts, Arachis hypogaea L. (2n=40), and the wild species collection GKP 10017 (2n=20) were compared morphologically, for leafspot resistance and for yield. The objective of the study was to determine the effects of wild species germplasm on the A. hypogaea genome. The sterile F₁ hybrid which resulted from crossing the two species was treated with colchicine to restore fertility at the 6x ploidy level. The resulting hexaploid was cytologically unstable and progeny lost chromosomes until stability was regained at the 2n=40 chromosome level. Forty-seven characters were used to analyze the variation among plants in the tetraploid interspecific hybrid population. The plants were compared to four cultivated lines plus GKP 10017. Many hybrids were intermediate to the two parents in morphology. Individual traits such as growth habit, pod and seed size, elongation of the constricted area between pods, nodulation and leaflet size were altered by the presence of GKP 10017 germplasm in many of the hybrid plants. Cercospora arachidicola Hori and Cercosporidium personatum (Berk. & Curt.) Deighton resistances were evaluated for all plants. Several hybrids had few lesions due to either leafspot pathogen. In addition, 24 largeseeded interspecific hybrid selections were compared to the cultivated variety NC 5 for yield. Five selections were superior to both parents at p=0.01. Morphology, disease resistance and yields appeared to be greatly influenced by the wild species GKP 10017 germplasm in plants of the interspecific hybrid population. The potentials of using wild species for improvement of the cultivated peanut are discussed.Paper number 5948 of the journal series of the North Carolina Agricultural Research Service, Raleigh, NC 27650. The investigation was supported in part by ICRISAT and SEA-CR grant no. 701-15-51.     

Agronomic performance and genetic shifts of genotype mixtures in peanut

Summary Little information is available on the genetic shifts that may take place when seed mixtures of peanut are grown over time. Five peanut lines with distinct seed coat colors, but similar plant types, pod yields, and maturities, were grown in pure stands for four years. A mixture with equal numbers of seed from each of the five lines was grown each year. All mixtures were subsampled and grown in subsequent years without reconstitution. Yield, 100-seed weight, and total sound mature kernel proportions from the mixtures were higher than the pure stand average of the five lines, but yield and total sound mature kernel proportions were lower than the average adjusted for individual line production. The best component line was significantly better than the mixture for pod yield, 100-seed weight, and proportion of sound mature kernels. Intergenotypic competition shifted the mixture composition to increase the proportion of one of the high yielding lines after only two years, while other high yielding lines in the test either maintained or decreased their original proportion. The two lowest yielding lines in pure stand also decreased in proportion over time.Contribution of the Florida Agricultural Experiment Station. Journal Series No. R-00550.     

Application of Mitscherlich–Bray Equation for Fertilizer Use on Groundnut

Field experiments were conducted at two locations in order to formulate phosphorus and potassium fertilizer recommendations of groundnut (Arachis hypogea) based on Mitscherlich–Bray equation. The treatments comprised four levels of phosphorus (0, 30, 60, and 90 kg phosphorus pentoxide (P₂O₅) ha^?1) and three levels of potassium (0, 30, and 60 kg potassium oxide (K₂O) ha^?1) in all possible combinations. Theoretical maximum yield of groundnut was calculated by plotting log y (pod yield) versus 1/x (amount of nutrients applied). Fertilizer recommendation for various soil fertility levels and yield target were developed, and their validities were tested by conducting two field verification trials on the same soil. The results showed that although general recommended fertilizer dose resulted in highest yield of groundnut at both the locations, but value cost ratio and rate of increase in income were lowest with this fertilizer treatment, and 90% of maximum yield treatment was superior in terms of economics of fertilizer and risk factor.     

湖北省花生平衡施肥技术研究Ⅴ.花生养分积累分配规律

分析了花生的养分积累及分配变化规律。结果表明,花生总干物质量、养分积累量除钙、镁在荚果膨大期最大外其余均随生育进程而增加,至收获期达到最大。每生产100 kg荚果,花生带走氮3.63 kg,磷0.47kg,钾1.45 kg,钙0.90 kg,镁1.00 kg,铁1.38 kg,铜0.02 kg,锌0.26 kg,硼0.05 kg。开花下针期是花生养分积累的关键时期。开花下针期后,花生除钙、镁外的营养元素主要从叶片和茎向荚果逐渐转移,根系分配变化较小。     

花生的分类及种质资源

花生属（Arachis L.）有80多个种，原产地均在南美洲，大部分种质具有抗性强、耐践踏、耐牧、持久性强等一种或几种特性且能生产数量可观的绿色饲料。通过介绍国外对花生的分类和花生种质资源的研究以及国内少量的引种表现认为，花生属的种质资源较为丰富，且其中优良者居多，因此，开展广泛的引种研究工作，解决热带亚热带豆科牧草（尤其是混播草地）的持久性问题，在生产上具有重要的意义。     

低温胁迫下磷酸二氢钾对蔓花生的生理影响研究

施用KH2PO4后,蔓花生（Arachis dura nensis）植株的超氧化物歧化酶（SOD）活性和过氧化物酶（POD）活性高于对照。质膜相对透性（RPP）低于对照。说明KH2PO4可以提高蔓花生植株保护酶系活性,降低RPP,在一定程度上提高了蔓花生植株的抗寒能力。     

温室快速鉴定花生根结线虫病抗性新方法

为了通过对花生抗线虫鉴定方法的比较,确定更加快速有效的抗性鉴定技术,作者于2002～2003年在佐治亚大学的Tifton试验站进行了温室盆栽试验。结果表明,侵染期幼虫与虫卵均可用于花生抗线性鉴定的温室接种,但与使用虫卵接种相比,以侵染期幼虫作为接种体需要多花3～5d的时间收集幼虫;接种后14d,可以依据0～5级的虫瘿分级标准将供试的4份花生种质区分开来;接种后6～10周依据卵块数量或每克根中的虫卵数可以进一步确认花生的抗性水平。虫瘿级数、虫瘿数量、卵块数量及每克根中的卵量之间存在着极显著(P<0.01)的正相关关系。根据研究结果提出了温室中花生抗线虫鉴定的程序方法:以8000粒卵/株为适宜接种量,接种后14d依据0～5级的虫瘿分级标准进行初筛,对初筛入选的材料再在接种后6周根据卵块数量或卵量验证其抗性。     

花生油酸/亚油酸比值(O/L)遗传研究

研究采用三个不同的杂交组合,"青苗豆×泉州麻壳"、"富川大花生×隆安宝湾花生"和"汕油162×Sunoleic95R",分别对其F2代油酸/亚油酸比值(O/L)进行柱形图分析.结果表明,不同的亲本其后代呈现出不同的图形分布,一个杂交组合后代呈现多峰,另外两个是偏离正态分布的单峰,根据图形分布可以判断出O/L是由主基因控...     

花生种子受黄曲霉菌侵染后若干生化成份的变化及其与抗性的关系

花生种子人工接种黄曲霉菌（Aspergillus flavus Link)侵染的生化测试结果表明，接种前后花生种子的过氧化物酶（POX），多酚氧化酶（PPO）和苯丙氨酸解氨酶（PAL）活性以及木质素含量等均发生显著变化。接种前POX活性与侵染率呈极显著负相关，接种后POX活性随感染天数增加而增加，感病品种比抗病品种POX活性增幅大。接种后1－3d抗病品种PPO和PAL活性达峰值，而感病品种3－6d达峰值，接种后第7d木质素含量与感染率呈显著负相关（r=-0.7406），木质素含量的变化与POX活性变化呈显著正相关。