行距配置对高产冬小麦籽粒灌浆特性及淀粉和蛋白质积累的影响

为研究不同行距配置对小麦籽粒发育及淀粉和蛋白质积累的影响,以4个高产冬小麦品种为材料,在河南浚县农业科学研究所超高产攻关田研究了不同行距配置下小麦籽粒灌浆特性及淀粉、蛋白质的积累动态.结果表明,高产小麦籽粒中可溶性糖含量下降与淀粉含量的增加趋势基本吻合,宽窄行种植模式(S1)籽粒中可溶性糖含量较高,且转化利用较快,促进了籽粒淀粉积累.从行距配置看.周麦22籽粒蛋白质含量以等行距种植模式(S2)较高,偃展4110和矮抗58均以S1较高,而豫麦49-198在两种种植模式下无明显差异.籽粒灌浆速率、千粒重和产量则表现为豫麦49-198、周麦22和矮抗58均以S较高,而偃展4110以S2较高.灌浆模型分析表明,灌浆持续天数和最大灌浆速率出现时间是行距配置影响粒重的主要因素.     

施氮量对两个粒型小麦品种籽粒胚乳细胞增殖及糖含量的影响

为了解小麦胚乳细胞增殖、糖代谢在粒型间的差异及氮营养的调控效应,2009-2010年度以大粒型品种郑育麦9987和小粒型品种郑麦004为材料,研究了施氮量对小麦籽粒胚乳细胞增殖、细胞壁转化酶活性及糖含量的影响。结果表明,郑育麦9987胚乳细胞数(11.92×105)较郑麦004(10.73×105)多11.1%。施氮量影响籽粒胚乳细胞数,其中郑育麦9987低氮处理(150kg·hm-2)的胚乳细胞数目较高氮处理(300kg·hm-2)增加29.1%,而郑麦004则表现为高氮处理较低氮处理增加44.7%。两品种籽粒细胞壁转化酶活性均于花后5~8d达到峰值,花后20d则降到较低水平;籽粒可溶性糖和蔗糖含量均随灌浆进程整体呈先上升后下降趋势,在花后25d有一个小波峰。增施氮肥可增加籽粒细胞壁转化酶活性,提高后期籽粒可溶性糖和蔗糖含量。表明增施氮肥有利于小麦籽粒胚乳细胞增殖、光合产物的积累与运转,从而提高了粒重。     

Insecticidal efficacy of two pirimiphos-methyl formulations for the control of three stored-product beetle species: Effect of commodity

Laboratory bioassays were conducted to evaluate the insecticidal effect of two pirimiphos-methyl formulations, an emulsifiable concentrate (EC) and a capsule suspension (CS) against adults of Sitophilus oryzae, Rhyzopertha dominica and Tribolium confusum in wheat, maize and rice. Pirimiphos-methyl was applied at two dose rates, 2 and 4 ppm, and adult mortality was measured after 2, 7, 14 and 21 days of exposure in the treated commodity. Progeny production was assessed 65 d after the removal of the parental adults. S. oryzae adult survival was significantly higher in rice than in wheat and maize, whereas T. confusum mortality was significantly higher in maize than in the other grains. From the species tested, the most susceptible species was S. oryzae, for which mortality reached 100% after 7 days of exposure in treated wheat and maize, followed by T. confusum and R. dominica. Progeny production was significantly suppressed by pirimiphos-methyl in the case of S. oryzae, but not in the case of R. dominica. In general, only few differences in performance between the EC and the CS formulation were detected. We conclude that the type of grain commodity significantly affects mortality after the application of the two pirimiphos-methyl formulations tested, but this effect is species-dependent.     

Wheat Cultivar Susceptibility to Grain Damage by the New Zealand Wheat Bug,Nysius huttoni,and Cultivar Susceptibility to the Effects of Bug Proteinase on Baking Quality

Immature wheat grain in New Zealand is attacked sporadically by the native insect (bug),Nysius huttoni.This ‘bug-damaged wheat’ contains a bug salivary proteinase, and bread made from this wheat has a characteristically poor loaf volume and texture. Historical baking data suggest variations in wheat cultivar susceptibility to bug damage. This suggestion was tested in two trials (1992/1993 and 1993/1994) on immature wheat using nine or seven New Zealand cultivars and breeding lines enclosed together in nylon mesh cages with and withoutN. huttoni.Visible damage, bug-proteinase levels, electrophoretic protein patterns, and baking properties of the grain were analysed. Both trials showed that susceptibility to bug damage was significantly different amongst cultivars and breeding lines. The ranking of cultivar susceptibility was the same for the two trials, except for cv. Arawa, which was one of the most susceptible cultivars in the first trial, but one of the least susceptible in the second trial. Cultivars Domino and Oroua consistently showed less susceptibility to bug attack. The breeding line WW378 and the cultivar Otane were the most susceptible to bug attack. The high quality bread wheats (Otane, Oroua, Domino and Batten) were less susceptible to the effects of bug proteinase in baking than the poor baking quality wheats (Karamu, WW378, ASPS9927 and ASPS9928). Batten was significantly less susceptible than any other cultivar in test baking. There was no relationship between bug-damage susceptibility and grain characters such as colour, hardness and texture, or head characters such as shape, awns and waxiness.     

Uptake and use efficiency of N, P, K, Ca and Al by Al-sensitive and Al-tolerant cultivars of wheat under a wide range of soil Al concentrations

The impacts of acidic soils and Al toxicity on wheat nutrient economy have been scarcely researched under field conditions even though these soils are widely spread in wheat production areas around the world. The main objective of this study was to quantitatively evaluate the element (N, P, K, Ca and Al) economy of an Al-sensitive and an Al-tolerant wheat cultivar growing under different soil Al concentrations at field conditions. To reach this objective, two field experiments were conducted in an Andisol in Valdivia (39°47′18″S, 73°14′05″W), Chile. Treatments were a factorial arrangement of: (i) two spring wheat cultivars (Al-sensitive, Domo.INIA and Al-tolerant, Dalcahue.INIA) and (ii) five exchangeable Al levels (0-2.7 cmol₍₊₎ kg⁻¹) with three replicates. At harvest, plant biomass was sampled and divided into 5 organ categories: ears, grains, blade leaves, stems plus sheath leaves and roots. The element content (N, P, K, Ca and Al) in each organ was measured to quantify element uptake and concentration, nutrient uptake efficiency (UPE) and nutrient utilization efficiency (UTE). Element uptake (N, P, K, Ca, and Al) was negatively affected by the increased soil Al concentration in above-ground and root biomass in both cultivars (R² = 0.61-0.98, p < 0.01), although clear differences were found between cultivars. On the contrary, the impact of soil exchangeable Al on the plant element concentration was minor, showing weak associations with soil Al levels. However, the Al concentration in above-ground tissues of the Al-sensitive cultivar was an exception because it increased exponentially with the Al soil concentration (R² = 0.96-0.99, p < 0.001). Nutrient uptake efficiencies, UPEs (N, P, K and Ca), were negatively affected by soil Al concentrations and were well described by linear equations in both cultivars (R² = 0.58-0.98, p < 0.05), with notable differences between them. Both nutrient uptake (capture) and UPE were the traits that best explained above-ground biomass production (R² = 0.82-0.99, p < 0.001, n = 20). Nutrient utilization efficiency, UTEs (N, P, K and Ca) responded more conservatively to the soil Al concentration, except for the Al sensitive cultivar under very high soil Al levels.     

Effects of genetic improvements on grain yield and agronomic traits of winter wheat in the Yangtze River Basin of China

Wheat is an important food crop worldwide. Genetic improvements have contributed much to wheat production since the 1960s. Verifying the evolution of agronomic traits and the physiological basis of grain yield will facilitate breeders and agronomists in developing new wheat cultivars, with the aim of stable and high yields. Thirty-five wheat cultivars, bred or widely planted in the Yangtze River Basin from 1950 to 2005, were grown in field experiments under three N rates (0, 112.5, and 225 kg N ha⁻¹) from 2006 to 2009 in Nanjing, China. Wheat grain yield, kernels per spike, 1000-kernel weight (TKW), and harvest index (HI) increased linearly with cultivar development from the 1950s to the 2000s, whereas spikes per unit land decreased significantly with cultivar development during the same period, and stabilized with further genetic improvements in cultivars. Grain yield, kernels per spike, and TKW differed with N rate and with cultivar. Grain yield, spikes per unit land, and kernels per spike increased significantly with increasing N fertilizer, but TKW and HI decreased. Cultivar height decreased with cultivar development from the 1950s to the 1980s, and remained relatively stable in subsequent cultivars. The proportion of the length of the top internode to total plant height increased with cultivar development from the 1950s to the 1980s and thereafter fell, while the length of the basal internode (BI) maintained a shortening trend. Leaf area per culm, leaf area index (LAI), net photosynthetic rate (Pn), and photosynthetic activity duration (PAD) of the flag leaf increased with cultivar development. Leaf area, LAI, and Pn increased significantly with increasing N fertilizer, while PAD did not. Single spike yield increased linearly with genetic development in cultivars, and these increases mainly resulted from increasing kernel number and weight, which were closely related to source size and cultivar. Grain yield was positively correlated to leaf area, LAI, Pn_Max, PAD, and single spike yield; single spike yield was positively correlated to leaf area, LAI, Pn_Max, and PAD, suggesting that grain yield improvements were mainly associated with improvements in the source (leaf area, LAI, Pn, PAD, etc.) and sink (single spike yield). Sink-source ratios increased with genetic development of cultivars, suggesting that productivity per leaf improved and that sink-source relationships have reached close to optimum in the Yangtze River Basin. Furthermore, breeding for high yield should be related to improvement in kernels per spike and TKW per unit land and increased sink-source ratios with a feasible LAI, and N fertilizer management should be considered during breeding for higher yields.     

Benzoxazinoid and alkylresorcinol content,and their antioxidant potential,in a grain of spring and winter wheat cultivated under different production systems

The health-promoting properties of the grains of common wheat (Triticum aestivum L.) are associated with the presence of unique phytochemicals. This study determines the profile of alkylresorcinols (ARs) and benzoxazinoids (BXs) in T. aestivum spring and winter cultivars grown in Poland under the two different production systems: conventional and organic. Wheat grain extracts were subjected to qualitative and quantitative UPLC-UV-MS/MS analyses. The ARs profile consisted of five 5-n-alkylresorcinol derivatives, among which 5-n-heneicosylresorcinol (C21:0) and 5-n-nonadecanylresorcinol (C19:0) predominated; while six different BXs were determined in hydrothermally treated grains. Our research shows significant differences in the contents of ARs and BXs among wheat cultivars, as well as the two production systems used. Organically grown varieties had their total contents of ARs and BXs significantly higher than those grown conventionally. Another aim of the study was to determine the antioxidant capacity of alkylresorcinol extracts from tested wheat cultivars. The quantitative TLC-DPPH• method for determining the antiradical capacity of wheat ARs extracts was developed. We observed a positive relationship between the free radical scavenging activity of extracts and the total amount of ARs. The biological activity research is important for developing value-added wheat cultivars, having an improved profile and composition of nutritional substances.     

增铵营养对专用型小麦可溶性糖转运及淀粉积累的影响

为给小麦氮肥管理提供理论依据,选用强筋小麦品种郑麦9023和弱筋小麦品种郑麦004为材料,在大田试验条件下研究了增铵营养对不同专用型小麦旗叶、籽粒可溶性糖含量与籽粒中淀粉及其组分含量的影响。结果表明,增铵营养条件下,两种小麦旗叶、籽粒中可溶性糖含量与籽粒淀粉及其组分含量在灌浆期间的变化趋势基本一致,但在灌浆中后期差别较大,与郑麦9023相比,郑麦004对增铵营养的响应更为显著。在NO3-∶NH4+为50∶50时小麦旗叶、籽粒可溶性糖含量变化及淀粉积累增加最显著。在此处理下,花后24d郑麦9023和郑麦004旗叶可溶性糖含量分别增加了7%和21%;增铵营养对两个小麦品种淀粉组分支/直比例影响不一,与对照相比,增铵营养导致郑麦9023下降了3.2%,使郑麦004增长了1.1%。增铵营养可能主要通过增加小麦旗叶中可溶性糖含量促进籽粒淀粉积累,与强筋小麦品种郑麦9023相比,弱筋小麦品种郑麦004的各项指标表现更为优异。     

Baking quality of emmer-derived durum wheat breeding lines

Durum wheat (Triticum turgidum L. var. durum) is used predominantly for pasta products, but there is increasing interest in using durum for bread-making. The goal of this study was to assess the bread-making potential of 97Emmer19, an Emmer wheat (Triticum turgidum L. var. dicoccum) and in breeding lines derived from crosses of 97Emmer19 with adapted durum wheat cultivars. 97Emmer19 and its progeny were evaluated in 2005 and 2006 along with five durum wheat cultivars. Three bread wheat (Triticum aestivum L.) cultivars were included as checks to provide a baseline of bread making quality observed in high quality bread wheat cultivars. 97Emmer19 exhibited higher LV than all the durum wheat checks and approached the LV achieved with the bread wheat cultivar ‘AC Superb’. Breeding lines derived from 97Emmer19 had higher LV than those of the durum wheat checks, confirming that this trait was heritable. In general, durum wheat cultivars with elevated gluten strength and/or increased dough extensibility were noted to have higher LV. Dough extensibility appeared to be a more critical factor as gluten strength increased. These results indicate that there is potential to select for genotypes with improved baking quality in durum breeding programs.     

氮肥施用对稻茬小麦冠层结构及产量、品质的影响

为给安徽省沿淮稻茬小麦高产栽培的氮肥合理运筹提供理论依据,通过大田试验,选用当地小麦主栽品种济麦22（半冬性中筋品种）和烟农19（半冬性强筋品种）为材料,设置0、90、180、270和360 kg·hm^-2 5个施氮水平,分析施氮量对两种基因型小麦冠层结构、产量及品质的影响。结果表明,在0~180 kg·hm^-2 施氮范围内,随着施氮量的增加,小麦株高、叶面积指数和叶片SPAD值显著上升,群体截获更多光能,冠层截获光合有效辐射显著增加,群体透光率显著降低,冠层光谱反射率在400～725 nm波段逐渐下降,在725～1 000 nm逐渐上升;随着施氮量的进一步增加,360 kg·hm^-2 施氮处理的各冠层指标与270 kg·hm^-2 施氮处理之间差异未达到0.05显著水平。籽粒产量随施氮量增加呈先升后降趋势,2个小麦品种产量均以270 kg·hm^-2 施氮处理最高。穗数、穗粒数均随施氮量增加而显著提高,都以360 kg·hm^-2 施氮处理最大,但180、270和360 kg·hm^-2 施氮处理间差异较小或不显著;千粒重则表现为先升后降的趋势,以90 kg·hm^-2 施氮处理最高。小麦籽粒蛋白质含量、湿面筋含量、沉降值均随施氮量增加而逐渐提高,除2014-2015年270和360 kg·hm^-2 两个施氮处理间差异不显著外,两年不同施氮处理间均差异显著。综合高产、优质、低环境风险的选择条件,沿淮稻茬麦区小麦季氮素在180~270 kg·hm^-2 范围内偏下限施用较为适宜,强筋品种烟农19可适当提高施氮量。     

Influence of competition,irrigation levels and nitrogen fertilization on protein content and protein yield of three spring wheat (Triticum aestivum L.) cultivars

Protein content and protein yield of three spring wheat cultivars differing in morphological and physiological growth characters were found to be influenced by intercultivar competition, irrigation levels and nitrogen fertilization. The protein content of the tall cultivar C 306 and the protein yield of the dwarf cultivar HD 2160 were more than the other cultivars. Binary mixed stands were not superior to the better component cultivar. Intercultivar competition increased the protein content of dwarf and semi-dwarf cultivars, but decreased the protein content of tall cultivar. On the other hand, protein yield of the dwarf cultivar decreased and that of tall cultivar increased when grown in mixed stands. Protein yield of semi-dwarf cultivar increased when grown with dwarf cultivar, but decreased when grown with tall cultivar. Two or three irrigations increased the protein content and protein yield of all the three cultivars and their mixed stands over one irrigation. Protein content and protein yield of the cultivars and their mixed stands were higher when 150 kg N/ha was applied than when 80 kg N/ha was applied.     

Over 40% of 450 registered wheat cultivars (Triticum aestivum) worldwide are composed of multiple biotypes

Many of 450 common wheat cultivars bred and registered during the twentieth century in 12 countries were proved, due to seed-by-seed analysis, to be composed of two or more biotypes differing in their alleles at the gliadin (Gli) loci. These multiple biotypes may be regarded as authentic progeny of the respective parent lines, as evidenced by the gliadin composition of the respective parents. Therefore, the official claim for each cultivar to be uniform is commonly not maintained in practice. The most frequent was a non-uniform cultivar composed of two biotypes differing at one Gli locus, but there were cultivars represented by a large set of related genotypes differing at several Gli loci. The proportion of the multi-biotype cultivars was never less than 15% for a country collection, exceeding 50% in other countries. This proportion differed significantly between neighbouring countries. In Australia, all multi-biotype cultivars were found in eastern states; in the state of Victoria, their frequency was statistically higher than in the rest of the country. The proportion of multi-biotype cultivars among newly-released cultivars decreased with time in Australia and the UK. Thus, the non-uniformity of registered cultivars represents a general and important phenomenon of common wheat as a crop.     

Fungicide and cultivar effects on the development and temporal progress of wheat blast under field conditions

The epidemiology of wheat blast, caused by the Triticum pathotype of Pyricularia oryzae, is poorly understood, making it very difficult to manage. We reported on the individual and combined effect of host resistance and fungicide application for managing wheat blast disease on spikes. Two field experiments (Exp. 1 and Exp. 2) were conducted in a region of Brazil where blast is not known to be endemic to evaluate its development as influenced by fungicide and host resistance. Plots of wheat cultivars BR-18 (partially resistant) and Guamirim (susceptible) were either treated with the fungicide epoxiconazole + pyraclostrobin or left non-treated, and then inoculated with a spore suspension of P. oryzae at mid-anthesis. Spike blast incidence and severity, quantified at regular intervals after inoculation, increased over time, and fungicide and cultivar had statistically significant effects (P < 0.005) on both measures of disease and their temporal rates of progress. Relative to Guamirim-non-treated, BR-18-non-treated (resistance alone) led to 44 and 64% control of final incidence and severity, respectively, in Exp. 1, and 3 and 49% control, respectively, in Exp. 2. Guamirim-treated (fungicide alone) led to 65% control of incidence and 77% control of severity in Exp. 1, and 64% control of incidence and 95% control of severity in Exp. 2. For both incidence and severity, fungicide and resistance alone also reduced the temporal rate of progress relative to the susceptible non-treated. However, the greatest overall efficacy was observed when resistance and fungicide were combined, with over 70 and 90% control of final incidence and severity, respectively, and over 75% reduction in the temporal rate of spike blast progress. Based on percent control, the integrated effect of resistance and fungicide was additive for incidence, severity, and their temporal rates of progress, demonstrating the value of combining the two strategies to manage spike blast.     

Effects of Fusarium culmorum and water stress on durum wheat in Tunisia

The effects of water stress on Fusarium foot and root rot in durum wheat were investigated in growth chamber, greenhouse and field tests in Tunisia. In the seedling stage, emergence of six durum wheat cultivars in the growth chamber was significantly reduced by inoculation with Fusarium culmorum and water stress (P<0.0001), with more disease under drier conditions. Additionally, the tiller number per mature plant, the 1000 grain weight and disease severity in mature stage were reduced by inoculation in greenhouse studies. In a field test, inoculation with F. culmorum significantly reduced the yield (P<0.001), by more than 17% for Om Rabiaa and 38% for Karim, the two cultivars tested. Yield was also significantly affected by precipitation and irrigation levels. The severity of the disease, estimated by the percentage of white heads, was separately affected by the cultivar (P<0.001) and inoculation (P = 0.0004). Percentage of white heads was 1.5 and 2 × higher in inoculated plants than non-inoculated for Om Rabiaa and Karim cultivars, respectively. Disease severity was highest in treatments with the greatest water stress. This is the first detailed study of water stress and F. culmorum on durum wheat in Tunisia, and indicates that cultivar resistance and irrigation management may be important in the management of Fusarium foot rot.     

Bioassays with diatomaceous earth formulations: Effect of species co-occurrence,size of vials and application technique

Two series of laboratory bioassays were carried out in order to evaluate the effect of the simultaneous presence of two insect species inside the experimental vials and the effect of different sizes (50, 65, 90, 145 mm in diameter) of experimental vials on the efficacy of diatomaceous earth (DE) formulations as wheat (Triticum durum Desf.) protectants. Three DE formulations were tested; Insecto, SilicoSec and one DE enhanced with pyrethrum, PyriSec. In a third series of bioassays the influence of application technique of DE formulations in wheat and maize (Zea mays L.) on their insecticidal efficacy was also evaluated in the laboratory. Two DE formulations were tested; SilicoSec and Protect-It. The application technique was based on the duration of admixing (0.5 or 3 min) and surface treatment (without admixing) of DE formulations in grain. In all series of bioassays three species were tested; Sitophilus oryzae (L.) (Coleoptera: Curculionidae), Rhyzopertha dominica (F.) (Coleoptera: Bostrychidae) and Tribolium confusum Jacquelin du Val (Coleoptera: Tenebrionidae). Significant differences were noted in mortality levels of the tested species among the three DE formulations and among doses for the simultaneous presence of two insect species in all combinations and the different size of vials. In contrast, no significant differences were found in the mortality levels among the adult densities of any of the insects tested. The progeny production was low for all tested species. The increase of diameter of vials used in the bioassays decreased the mortality of S. oryzae and T. confusum adults significantly whereas no significant differences were noted for R. dominica adults. The increase of dose and exposure interval reduced differences of R. dominica adult mortality in admixture durations in the case of wheat. For S. oryzae, no significant differences in adult mortality in maize were found among admixture durations while significant differences were detected in wheat.     

春季不同时期低温对小麦光合特性和粒重形成的影响

为探讨春季低温导致小麦粒重下降的生理机制,以春性品种扬麦16和半冬性品种徐麦30为材料,分别于倒二叶出生期、孕穗期和开花期对小麦进行人工气候室低温处理,研究不同时期低温对小麦光合生理特性、干物质积累和转运及强、弱势粒粒重形成的影响。结果表明,不同时期低温对叶片SPAD值的影响均表现为低温处理开始至结束后3 d持续下降,结束后6～9 d逐渐回升,两品种在低温处理结束当天和处理后3 d均以孕穗期低温处理下SPAD值降幅最大。不同时期低温处理显著降低叶片净光合速率和气孔导度,并影响花前干物质转运和花后干物质积累。与孕穗期、开花期低温处理相比,倒二叶出生期低温处理显著降低小麦花前干物质转运量,但提高花后干物质积累及其对籽粒产量的贡献率,千粒重降幅最小,扬麦16和徐麦30分别仅为4.49%和4.20%。不同时期低温处理下小麦强势粒粒重的降幅均小于弱势粒,倒二叶出生期低温处理下弱势粒粒重降幅显著低于孕穗期和开花期低温处理。相关性分析表明,低温胁迫下小麦平均千粒重和强势粒粒重相关性不显著(r=0.319,P>0.05),但与弱势粒粒重显著相关(r=0.691,P<0.05)。综上,春季低温胁迫主要通过影响小麦开花前后的光合作用和同化物向籽粒的转运,限制弱势粒的灌浆充实,最终导致粒重下降。     

Effects of broad-leaf crops and their sowing time on subsequent wheat production

Lupin, field pea, lentil, chickpea, canola, linseed, and barley were sown at different times (late April-early July) to study their effects on subsequent wheat production on a red earth at Wagga Wagga, New South Wales. The cultivars of field pea (Pisum sativum) included Dunn, Derrimut, Maitland and Dinkum; narrow-leaf lupin (Lupinus angustifolius) cultivars were Danja, Geebung and Gungurru, and either the L. angustifolius line 75A/330 (1989–1990) or the broad-leaf lupin L. albus cv. Ultra (1991–1992). Only one cultivar of the other crops was grown in any year and after 1989 lentil (Lens culinaris cv. Aldinga) was replaced by chickpea (Cicer arietinum cv. Amethyst). The canola (cv. Shiralee (1989–1991), cv. Barossa (1992)) and linseed (cv. Glenelg) rotations received annual applications of 40–50 kg N/ha as urea.Compared to barley and the oilseeds, grain legumes increased soil mineral N supply to the following wheat crop. Over 4 years the mean wheat grain yield response to a broad-leaf crop, relative to barley, was 115% for lupin, 84% for field pea, 88% for linseed and 86% for canola. However, the effects of the various crops on subsequent wheat grain yields and grain protein varied markedly with season. The main advantage of lupin over field pea occurred in years when disease reduced growth of field pea crops. In high rainfall years, wheat yields following lentil and chickpea were lower than those following lupin. The narrow-leaf cultivars of lupin promoted greater wheat yields than either the reduced branching line 75A/330 or the broad-leaf albus cultivar Ultra. Delayed sowing of lupin reduced yield and grain protein of wheat, except when low rainfall curtailed growth of either crop in the rotation. There was little effect of field pea sowing date on wheat grain yield but sowing in late June combined with a dry spring, reduced mineral N supply and grain protein. Late sowing of oilseeds had no consistent effect on wheat grain yield but increased grain protein in most years. Late sowing of barley typically increased wheat grain yield but had little effect on grain protein. The effects of sowing time were mainly attributed to effects on soil N supply and for barley on disease incidence in the subsequent wheat.     

Effect of planting date,fungicide timing and cultivar susceptibility on severity of narrow brown leaf spot and yield of rice

Narrow brown leaf spot (NBLS) of rice (Oryza sativa L.) is caused by Cercospora janseana (Racib). O. Const. (Synonyms: Cercospora oryzae Miyake, Passalora janseana Racib. U.). Experimental studies were conducted at Rice Research Station, Louisiana State University, and Agricultural Center, Crowley, to manage NBLS by fungicide application of propiconazole at different growth stages of rice cultivars having different susceptibility levels to NBLS in different planting dates. Results of these studies revealed that April (early) had less NBLS severity as compared to May (late) planting. Very susceptible cultivars, CL131 and Cheniere, had the highest and resistant cultivars, Della and Presidio, had the lowest NBLS severity at both the planting dates. Propiconazole application significantly reduced the NBLS severity in comparison to untreated. Fungicide application at panicle initiation was the most effective time to manage NBLS on the very susceptible and susceptible cultivars at both planting dates. NBLS on moderately susceptible cultivars was best managed by applying fungicide either at panicle initiation or early boot stage in early planting but panicle initiation was the best time to apply fungicide in late planting. Resistant cultivars did not need fungicide in April planting but did need in May planting. Rice yield was determined to be higher in April than May planting. Fungicide application at early boot stage protected the yield by 9.4% in April planting and 34.2% when applied at panicle initiation in May. Susceptible cultivar, Cheniere, exhibited the greatest yield and resistant cultivars had lowest yield in both the planting dates regardless of its susceptibility level to NBLS. Yield of very susceptible to susceptible cultivars was reduced in late planting but no effect was observed on yield of moderately susceptible and resistant cultivars.     

Ascorbate Oxidase levels in Wheat and their Relationship to Baking Quality

Flour samples from 127 samples of wheat of 13 different cultivars grown throughout New Zealand during two seasons were extracted with 1mNa₂SO₄(pH 8·3) and assayed for ascorbate oxidase (AOX) at pH 6·2 by a continuous spectrophotometric method. The mean AOX activity of the cultivar with the greatest activity, Domino, was more than three times that of the cultivar with the lowest activity, Brock. The differences in AOX activity amongst cultivars were maintained for two seasons. The range of AOX activities of different wheat samples within each cultivar was about two-fold for most cultivars. A sample of cv. Domino with the highest activity was 14 times more active than the lowest activity sample of cv. Brock. There was a significant correlation between low AOX activity and bake score of cultivars or individual wheat samples. There was also a correlation between log AOX and protein content, and protein content was also correlated with bake score. Flour stored for 300 days at 20°C and wheat stored for two or more years had reduced AOX activities and bake scores. However, flour containing low endogenous AOX activity produced the same bake scores with ascorbic acid plus squash AOX as with ascorbic acid alone. It was concluded that the level of AOX in wheat was not critical to the ascorbic acid improver effect, provided sufficient oxygen was mixed into the dough by high-speed mixers.