小麦不同种植密度粒重分布特性的研究

对３种种植密度条件下小麦粒重分布特性的研究结果表明：小穗粒重,小穗结实粒数,各粒位粒重和结实数均以中下部小穗为最大,随植株密度的增大,穗粒重和穗粒数呈逐渐减小的趋势,小穗粒重,小穗结实粒数,各粒位的粒重和结实数也呈下降的趋势;不同粒位间的粒重,在结实数大于０．９５的情况下,在其它情况下则表现为第１〉２〉３〉４粒位。     

小麦不同种植密度粒重分布特性的研究

对３种种植密度条件下小麦粒重分布特性的研究结果表明：小穗粒重、小穗结实粒数、各粒位粒重和结实数均以中下部小穗为最大,随植株密度的增大,穗粒重和穗粒数呈逐渐减小的趋势,小穗粒重、小穗结实粒数、各粒位的粒重和结实数也呈下降的趋势;不同粒位间的粒重,在结实数大于０．９５的情况下,表现为第２＞１＞３＞４粒位,在其它情况下则表现为第１＞２＞３＞４粒位     

四种不同穗型小麦的穗部性状分析

为了通过研究不同长相穗型小麦穗部特性,以达到提高产量和挖掘穗部潜力的目的。本文对长方型、棍棒型、椭圆型和纺锤型四种不同长相穗型小麦品种的穗部性状特性进行了分析。结果表明不同穗型小麦在小花数、穗粒数、粒重等方面均表现出先升后降的二次曲线趋势,但不同穗型小麦表现趋势不同,长方型和椭圆型小麦在穗粒数、穗重、各粒位粒重等方面均优于棍棒型和纺锤型小麦,棍棒型小麦由于其特殊的穗型结构,在小穗密度、粒重等方面表现独特,纺锤型小麦在各方面表现均较差。结果表明,在小麦生产用种和品种选育上,穗型的选择至关重要。长方型小麦有提高小麦产量的潜力。     

源库关系改变对小麦灌浆期植株光合速率及~(14)C同化物运转分配的影响

选用千粒重大小不同的小麦品种,研究了去除顶端两个小穗对两类品种（大粒品种和小粒品种）千粒重、穗粒数、穗粒重、籽粒平均灌浆速率、单穗平均增重速率、植株光合速率及１４Ｃ同化物运转分配的影响。试验结果表明,去除顶端两个小穗后,两类品种的千粒重提高,穗粒数降低或基本不受影响,但降低比例明显低于去除小穗数的比例。籽粒平均灌浆速率和单穗平均增重速率（分别表征籽粒库容活性和穗粒库容活性）相应提高。结果,两类品种的穗粒重表现为补偿性增长。两类品种比较,小粒品种的增长幅度大于大粒品种。穗粒库容活性增强使得小粒品种灌浆中后期的植株光合速率提高,使两类品种分配到籽粒中的１４Ｃ同化物比例增加。从而表明,无论是植株光合速率还是同化物的运转分配皆受穗粒库容活性的调控,调控方式和幅度因品种类型而不同。但提高其穗粒重的着眼点都应当是提高穗粒库容活性。     

小麦不同品种光合速率和^14C同化物分配对源库比改变的响应

选用千粒重大小不同的小麦品种,研究了去除顶端两个小穗对两类品种（大粒品种和小粒品种）穗部性状,粒粒平均灌浆速率,单穗平均增重速率,植株光合速率及＾１４Ｃ同位物运输分配的影响。试验结果表明,去除顶端两个小穗后,两类品种的籽粒平均灌浆速率和单穗平均增重速率（分别表征籽粒库容活性和穗粒库容活性）相应提高,穗粒重表现为补偿性增长。两类品种比较,小粒品种的增长幅度大于大粒品种。穗粒库容活性增强使得小粒品种灌     

源库关系改变对小麦灌浆期植株光合速率及^14C同化物运转分配 …

选用千粒重大小不同的小麦品种,研究了去除顶端两个小穗对两类品种千粒穗、穗粒数、穗粒重、籽粒平均灌浆速率、单穗平均增重速率、植株光合速率及＾１４Ｃ同化物运转分配的影响。     

60Co-γ射线诱变连麦2号M3代主要农艺性状的变异及多元分析

用60Co-γ射线诱变小麦连麦2号,对M3代292个穗行进行了主要农艺性状的变异及多元分析.结果表明:各性状的变异幅度是不同的,变异系数从大到小依次为:穗数＞千粒重＞穗长＞小穗数＞株高＞行粒重＞退化小穗数＞穗粒数＞穗粒重;变异率从大到小依次为:穗数＞千粒重＞株高=行粒重＞穗粒数＞穗长＞穗粒重＞小穗数＞退化小穗数.穗数、...     

小麦不同品种光合速率和14 C同化物分配对源库比改变的影响

 选用千粒重大小不同的小麦品种,研究了去除顶端两个小穗对两类品种(大粒品种和小粒品种)穗部性状、籽粒平均灌浆速率、单穗平均增重速率、植株光合速率及14C同化物运输分配的影响。试验结果表明,去除顶端两个小穗后,两类品种的籽粒平均灌浆速率和单穗平均增重速率(分别表征籽粒库容活性和穗粒库容活性)相应提高,穗粒重表现为补偿性增长。两类品种比较,小粒品种的增长幅度大于大粒品种。穗粒库容活性增强使得小粒品种灌浆中后期的植株光合速率提高,使两类品种分配到籽粒中的14C同化物比例增加。从而表明,无论是植株光合速率还是同化物的运转分配皆受库容活性的调控,调控方式和幅度因品种类型而不同。     

小麦不同品种光合速率和~(14)C同化物分配对源库比改变的响应

选用千粒重大小不同的小麦品种,研究了去除顶端两个小穗对两类品种（大粒品种和小粒品种）穗部性状、籽粒平均灌浆速率、单穗平均增重速率、植株光合速率及１４Ｃ同化物运输分配的影响。试验结果表明,去除顶端两个小穗后,两类品种的籽粒平均灌浆速率和单穗平均增重速率（分别表征籽粒库容活性和穗粒库容活性）相应提高,穗粒重表现为补偿性增长。两类品种比较,小粒品种的增长幅度大于大粒品种。穗粒库容活性增强使得小粒品种灌浆中后期的植株光合速率提高,使两类品种分配到籽粒中的１４Ｃ同化物比例增加。从而表明,无论是植株光合速率还是同化物的运转分配皆受库容活性的调控,调控方式和幅度因品种类型而不同。     

激光—^60Co—γ辐射诱变小麦生物学效应初步研究

研究小麦品种“绵阳21号”和“汉源小麦”及其~(60)Co—γ一代(γ_1)等四个材料,经N_2和He—Ne激光辐照的20种处理(包括对照)的辐射生物学效应。试验结果表明,激光一代(L_1)植株高度,单株分蘖数,单株有效分蘖数,穗长,小穗数,不实小穗数,退化小穗数,小穗密度,主穗粒数,主穗粒重,分蘖穗粒重,单株粒重,抽穗期,叶面积,穗下轴长,倒一节间长,倒一节间粗等17种性状,都表现出不同处理所引起的生物效应差异。同株高,单株分蘖数、单株有效穗数、主穗长度、不实小穗数,主穗粒数、主穗粒重,单株粒重等8个性关变异系数的比较看出:He—Ne激光(照射10分钟)辐照干种子,“汉源小麦—γ_1”比“汉源小麦”产生的变异大,比对照(未照射)的变异更大。同时,发现不同品种所引起的抽穗期、株高、穗长等14种性状的变异分别达显著或极显著,由剂量不同引起抽穗期、主穗粒重和不实小穗数等三种性状的变异显著。     

Effects of decreasing the number of grains in ears of cvs Hobbit and Maris Huntsman winter wheat

At 6 days after anthesis, grain numbers in ears of Maris Huntsman and Hobbit winter wheat growing in the field were decreased either by removing the two lower grains in each spikelet (degraining) or by removing the top half of the ear (halving). At maturity, degraining increased the dry weight of the third grains in each spikelet of Maris Huntsman by 11% and of Hobbit by 40%, compared with third grains in intact ears. Halving increased the mean dry weight of all the grains in the lower six spikelets of the ear slightly less; it increased the number of grains in Hobbit but not in Maris Huntsman. The responses to halving in Hobbit were greater with additional nitrogen fertiliser. At 28 days after anthesis in both varieties, degraining increased grain dry weight and the amount of water, reducing sugar, amino acids and total nitrogen in third grains. Effects of halving on these properties of the two lower grains of each spikelet were much less or nil. The increases in nitrogen content of grains at 28 days and at maturity caused by degraining or halving were relatively greater than the increases in dry weight and were similar in the two varieties.     

Development and Floret Survival in Wheat Ears With Supernumerary Spikelets

In the supernumerary spikelet wheat, AUS159I0, the supernumeraryspikelet primordia appeared just after the ear reached the terminalspikelet stage. Appearance of the primordia of the multiplesessile spikelets preceded that of indeterminate rachilla spikelets.Supernumerary spikelets had a lower number of potentially fertileflorets per spikelet than normal (non-supernumerary) spikeletsin the ear and thus a smaller number of grains per spikelet.Mean weight per grain in the supernumerary spikelet wheat waslower than in the cultivar, Meering, without supernumerary spikelets.Total grain number in the supernumerary spikelet ear was greaterthan in the normal ear despite the lower spikelet fertilityin the former. Within the supernumerary spikelet ear the multiplesessile spikelets had a higher number of grains per spikeletand mean weight per grain than the indeterminate rachilla spikelets.It appears possible to improve the productivity of the supernumeraryspikelet ear by breeding for reduced expression of the indeterminaterachilla spikelets. Wheat, ear development, floret survival, supernumerary spikelets, grain number     

The Effect of Speckled Leaf Blotch on Apical Development and Yield in Winter Wheat in New Zealand

Speckled leaf blotch (Mycosphaerella graminicola) reduced yieldin a winter wheat trial by 18 per cent. Detailed analyses ofthe effects of disease on yield components showed that diseasereduced both grain number per ear and grain weight. The reductionin grain number per ear was due to a decrease in grain numberper spikelet, and this occurred for both main stem and tillers,and occurred equally at each spikelet position on the ear. The effect of disease on grain number was traced back to anearlier reduction in floret primordium number per ear, especiallyfloret number per spikelet. It was suggested that floret primordiumproduction was affected by the reduced assimilate supply tothe developing apex. The effects of disease on yield could therefore be attributedto effects on plant development both before and after anthesis.The disease effects on yield were not necessarily associatedwith the time of maximum disease severity. Plots with the early phase of disease epidemic only showed asignificant reduction in yield, but there was some evidenceof compensation for early reductions to yield potential in thelater-determined yield components. We suggest, therefore, thatan effective disease-control programme must take into accountthe possible early effects of disease on yield potential. Mycosphaerella graminicola, speckled leaf blotch, winter wheat, yield loss, apical development     

Impact of brown stink bug (Heteroptera: Pentatomidae) feeding on corn grain yield components and quality

Brown stink bug, Euschistus servus (Say) (Heteroptera: Pentatomidae), damage on developing corn, Zea mays L., ears was examined in 2005 and 2006 by using eight parameters related to its yield and kernel quality. Stink bug infestations were initiated when the corn plants were at tasseling (VT), mid-silking (R1), and blister (R2) stages by using zero, three, and six in 2005 or zero, one, two, and four bugs per ear in 2006, and maintained for 9 d. The percentage of discolored kernels was affected by stink bug number in both years, but not always affected by plant growth stage. The growth stage effect on the percentage of discolored kernels was significant in 2006, but not in 2005. The percentage of aborted kernels was affected by both stink bug number and plant growth stage in 2005 but not in 2006. Kernel weight was significantly reduced when three E. sercus adults were confined on a corn ear at stage VT or R1 for 9 d in 2005, whereas one or two adults per ear resulted in no kernel weight loss, but four E. servus adults did cause significant kernel weight loss at stage VT in 2006. Stink bug feeding injury at stage R2 did not affect kernel damage, ear weight or grain weight in either year. The infestation duration (9 or 18 d) was positively correlated to the percentage of discolored kernels but did not affect kernel or ear weight. Based on the regression equations between the kernel weight and stink bug number, the gain threshold or economic injury level should be 0.5 bugs per ear for 9 d at stage VT and less for stage R1. This information will be useful in developing management guidelines for stink bugs in field corn during ear formation and early grain filling stages.     

不同生态区小麦品种的穗发芽抗性评价

本研究对来自不同生态区的137个小麦品种进行穗发芽抗性鉴定,计算相对发芽指数,并分析这些品种穗部籽粒性状、品质指标、吸胀萌发后0～72 h α-淀粉酶活性及其基因表达量与穗发芽抗性之间的关系。结果表明: 长江中下游麦区小麦的平均发芽指数最低,抗穗发芽品种最多,其次是长江上游麦区,黄淮麦区抗穗发芽品种相对较少。红粒品种小麦的相对发芽指数低于白粒品种,相对发芽指数与籽粒长度、宽度呈极显著正相关,与小穗数呈显著正相关,与穗型、穗色、穗长、小穗密度、穗粒数、千粒重无显著相关性。相对发芽指数与容重呈极显著负相关,与面团形成时间和出粉率呈显著负相关,与蛋白质含量、湿面筋含量、吸水率、稳定时间、沉降值、拉伸面积、延展性、最大阻力无显著相关性。不同品种的α-淀粉酶活性随吸胀萌发时间的延长呈上升趋势,萌发24～72 h的相对发芽指数与α-淀粉酶活性呈极显著正相关,穗发芽中抗以上品种萌发48 h后α-淀粉酶活性聚类分析结果与穗发芽鉴定结果一致。萌发后各时段α-淀粉酶基因表达量与相对发芽指数呈极显著正相关。     

The Effects of Floret Sterilization on Grain Number and Grain Weight in Wheat Ears

This paper describes the effects of sterilizing certain floretson the development of others within the ears of wheat, cultivarMaris Ranger. Sterilization of all the florets in spikelets2, 4, 6, and 8 (numbered from the base of the ear upwards) ledto more grain setting and greater grain growth in the untreatedspikelets. These compensatory increases were insufficient toprevent a depression in the yield of grain per ear. Sterilizationof more than one of the basal florets of spikelet 8 led to amore frequent setting of the grain in the distal florets onthat spikelet and to the centrally positioned grain becomingheavier. The physiological basis for the inhibitory influences of theolder and developing grain on the unfertilized florets and youngergrain is discussed.     

中国骨干玉米自交系抗旱性分析与评价

在新疆典型干旱、半干旱地区,通过玉米自交系的14个主要产量性状对干旱胁迫的响应特征进行分析,用主成分分析法筛选其抗旱性的主要鉴定指标,并采用抗旱系数和抗旱指数对自交系的抗旱性进行聚类分析,综合评价47份自交系的抗旱性。结果显示:(1)干旱导致玉米自交系株高、穗位高、叶绿素含量降低,果穗短小,秃尖增大,穗行数和行粒数减小,千粒重和穗粒重降低,最终造成产量下降。(2)各自交系抗旱性强弱与干旱条件下的穗粒重、穗粗、行粒数、千粒重、株高、穗位高、穗长、秃尖长、穗行数、叶绿素含量等性状具有较密切的关系,其中抗旱性表现较好的自交系是掖52106、英64、478等,其次是Mo17Ht、Mo17、丹340、郑58、X178、C103等。研究表明,在育种实践中,田间自交系抗旱性筛选应以穗粒重、穗粗、行粒数、千粒重、株高、穗位高、穗长、秃尖长、穗行数、叶绿素含量等为主要指标,并结合产量抗旱系数、抗旱指数对自交系抗旱性进行综合评价。     

Some treatments affecting growth substances in developing wheat ears

Cytokinin, auxin and gibberellin-like substances were bio-assayed in extracts from developing ears of wheat plants grown in various conditions. Changes in cytokinin activity along the ears may be related to the earlier flowering in the middle of the ear. Ears on the main stems of plants from which all the tillers had been removed contained less cytokinin than the main-stem ears of normal tillered plants. When grain development was stopped by preventing fertilization of the ovules the ear contained more cytokinin than normal ears. With de-tillered plants, removing flag leaves before anthesis increased cytokinin, gibberellin and auxin in the ears; later removal of flag leaves did not affect cytokinin but decreased gibberellin in the ears. Conversely, removing ears before anthesis did not affect cytokinin or auxin in the flag leaves, but their gibberellin was less than that of flag leaves on intact plants. Treatment of wheat ears with zeatin did not affect grain weight or number per ear which supports the conclusion that the growth substances in the ear may be adequate for normal grain growth.     

Phenotypic and genetic analysis of spike and kernel characteristics in wheat reveals long-term genetic trends of grain yield components

Key message

Phenotypic and genetic analysis of six spike and kernel characteristics in wheat revealed geographic patterns as well as long-term trends arising from breeding progress, particularly in regard to spikelet fertility, i.e. the number of kernels per spikelet, a grain yield component that appears to underlie the increase in the number of kernels per spike.

Abstract

Wheat is a staple crop of global relevance that faces continuous demands for improved grain yield. In this study, we evaluated a panel of 407 winter wheat cultivars for six characteristics of spike and kernel development. All traits showed a large genotypic variation and had high heritabilities. We observed geographic patterns for some traits in addition to long-term trends showing a continuous increase in the number of kernels per spike. This breeding progress is likely due to the increase in spikelet fertility, i.e. the number of kernels per spikelet. While the number of kernels per spike and spikelet fertility were significantly positively correlated, both traits showed a significant negative correlation with thousand-kernel weight. Genome-wide association mapping identified only small- and moderate-effect QTL and an effect of the phenology loci Rht-D1 and Ppd-D1 on some of the traits. The allele frequencies of some QTL matched the observed geographic patterns. The quantitative inheritance of all traits with contributions of additional small-effect QTL was substantiated by genomic prediction. Taken together, our results suggest that some of the examined traits were already the basis of grain yield progress in wheat in the past decades. A more targeted exploitation of the available variation, potentially coupled with genomic approaches, may assist wheat breeding in continuing to increase yield levels globally.