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1.
Kenji Fujino 《Euphytica》2003,131(1):97-103
Rice is grown in diverse environments at latitudes ranging from 53°N to 40°S. In Japan, Hokkaido is the northernmost rice cultivation region(42–45°N latitude). Only extremely early maturing (heading) varieties that have extremely low photoperiod sensitivity are adapted
to this area. Heading date is the most important trait in adaptation to this particular environment. Also, the efficient manipulation
of heading date is a crucial component of rice improvement. To determine the genetic basis for heading date among cultivars
grown in Hokkaido, the heading behaviour was analyzed. Clear segregations were observed. To estimate the photoperiod sensitivity
of the genes involved, the cultivars and F1 plants from crosses between the cultivars were grown under different daylength conditions. The results indicated that the
genes controlling heading date are photoperiod sensitive, suggesting they play important roles in the northernmost rice cultivation
regions in Japan, to which only cultivars with extremely low photoperiod sensitivity are adapted.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
2.
光、温、水等气候因子是影响水稻产量形成的重要因素。为明确江苏太湖地区不同生育类型水稻产量对不同播期下气候因子变化的响应,以期为该地区不同生育类型品种合理安排播期提供依据,2018—2019年在苏州市农业科学院试验农场内以优质早熟品系苏1785和晚熟品种苏香粳100为材料,采用分期播种方法研究了2种不同生育类型水稻产量及其构成对不同播期气候因子的响应特性。结果表明,不同生育期类型品种随着播期推迟产量降低,晚熟品种产量在播期间和年度间产量变异较早熟品种大,稳产性较差。2个不同生育期类型品种有效穗、每穗总粒数随播期推迟均呈降低趋势,而结实率和千粒重播期间的差异因生育类型不同而异,早播使早熟品种结实率显著下降,迟播则使晚熟品种千粒重显著下降。迟播对早熟品种抽穗前光合势的影响程度高于晚熟品种,对抽穗后干物质积累量和群体生产率的影响则相反,迟播条件下晚熟品种茎鞘物质输出率和运转率下降迅速,不利于茎鞘物质的转运和灌浆物质的积累。相关分析表明,日照时数是影响水稻产量的首要气候因子,日均气温和有效积温对产量的影响因品种生育类型不同存在差异,日均气温和有效积温与早熟品种的产量呈显著正相关关系,而日均气温与晚熟品种的产量相关不显著,气候因子对产量的影响表现为:日照时数>日均气温,有效积温>降雨量。 相似文献
3.
J. S. Sandoval-Islas L. H. M. Broers G. Mora-Aguilera J. E. Parlevliet S. Osada-Kawasoe H. E. Vivar 《Euphytica》2007,153(3):295-308
Sixteen barley cultivars with a susceptible infection type (IT = 7–8) in the seedling stage to an isolate of race 24 of Puccinia striiformis f. sp. hordei were planted at two locations in México. Disease severity (DS) parameters were assessed for the flag leaf and for the upper
three leaves. The cultivars represented at least five levels of quantitative resistance ranging from very susceptible to quite
resistant. “Granado”, “Gloria/Copal” and “Calicuchima-92” represented the most resistant group and had an IT of 7 or 8. The
cultivar × environment interaction variance, although significant, was very small compared with the cultivar variance. The
disease severity parameters were highly correlated. The monocyclic parameter DSm, measured when the most susceptible cultivar had reached its maximum DS, was very highly correlated with the area under the
disease progress curve (AUDPC), r being 0.98.
Components of quantitative resistance were evaluated in two plant stages. In the seedling stage small cultivar effects for
the latency period were observed, which were not correlated with the quantitative resistance measured in the field. In the
adult plant stage the latency period (LP), infection frequency (IF) and colonization rate (CR) were measured in the upper
two leaves. The LP was much longer than in the seedling stage and differed strongly between cultivars. The differences in
IF were too large, those in CR varied much less. The components showed association with one another. The LP and IF were well
correlated with the AUDPC (r = 0.7–0.8).
†Deceased 相似文献
4.
The rice (Oryza sativa L.) crop in Arkansas is seeded from late March through early June each year. Farmers need new rice
cultivars that not only produce both high rough rice yields and high head rice across this range of seeding dates but do so
consistently. Thus, a seeding date study was conducted during 1994 and 1995 at Stuttgart, Arkansas, to study seeding date
effects on rough rice yield and head rice and selection for stability. Fourteen rice cultivars were seeded at five dates ranging
from late March through mid-June. Kang's yield-stability statistic was used to select cultivars for both high rough rice yields
and high head rice as well as stability for both traits. Plant stands from March seedings of each year were significantly
lower than for the later seeding dates. Maturity (days to 50 percent heading) was extended at the early seeding dates. Some
rice cultivars, such as ‘LaGrue’, had lower and more variable head rice when seeded early. In the June seeding dates each
year, ‘Kaybonnet’ produced rough rice yields that were more consistent with yields when planted at the earlier planting dates.
‘Bengal’, ‘Cypress’, ‘Kaybonnet’, and ‘Newbonnet’ were cultivars selected by Kang's stability statistic, which was targeted
to select cultivars with stable, high rough rice yields and stable, high head rice. The validity of using Kang's yield-stability
statistic for cultivar selection is also evident empirically by the adaptation and wide use of these four cultivars by southern
U.S. rice producers. These results indicate that seeding date studies and stability analyses would be useful tools for rice
breeders to identify cultivars that will be readily adapted and grown by rice producers.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
5.
Genetic analysis of heading date and other agronomic characters in barley (Hordeum vulgare L.) 总被引：1，自引：0，他引：1
Genetic analyses of heading date, tiller number, plant height, grain yield, kernel weight, and plump and thin kernels were
made in three six-rowed barley crosses (Hordeum vulgare L.) involving four cultivars. Six populations, P1 , P2 , F1 , F2 , BC1 , and BC2 , from each cross were grown and evaluated at Fargo and Prosper, North Dakota, 1982. Parental means within crosses generally
were different except for tiller number. Comparison of generation means suggested that late heading was dominant to early,
high kernel weight was dominant to low, and kernel plumpness was influenced by additive gene action. The relationship between
yield and heading date was not consistent among crosses and positive r values were quite low. It should be possible to select
early maturing, high yielding segregates with plump kernels. Heterosis over the mid-parent was quite similar among crosses
for heading date, but there was no heterosis over the high parent. Inbreeding depression was fairly constant for heading date,
but was less consistent for yield. The lack of uniformity for estimates of inbreeding depression can be related to environmental
variation and to its influence on type of gene action. The ratio of additive to dominance variance was inconsistent among
crosses for heading date and yield. These data suggest selection for these characters should be delayed past the F 2 generation.
Broad sense heritabilities for heading date ranged from 42 to 86%. Values obtained for grain yield were more consistent among
broad sense than narrow sense estimates. Genetic advance estimates were low due to lack of additive variance.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
6.
不同水稻产量形成过程的干物质积累与分配特征 总被引：24，自引：2，他引：22
2003年在福建农林大学教学农场以晚季稻汕优63（三系杂交稻）、两优2186（二系杂交稻）和IR64（常规稻）为材料,研究了3种晚季水稻产量形成过程的干物质积累与分配特征。结果表明,汕优63、两优2186和IR64的干物质积累量在各生育期的变化趋势相似,干物质积累量间亦无显著差异。汕优63、两优2186和IR64的干物质积累量均在黄熟期最高,依次达到2074.13 g/m2、1976.10 g/m2和1924.14 g/m2,完熟期时依次降低到1926.38 g/m2、1933.80 g/m2和1842.30 g/m2,完熟过程中损耗的干物质分别占其干物质积累量的7.12%、2.63%和4.25%,这与呼吸消耗增强,稻株自然衰老有关。汕优63和IR64的群体生长率均以孕穗初期最大,分别为52.13 g/(m2·d)和44.26 g/(m2·d),两优2186的CGR以齐穗期最大（45.15 g/),3种水稻各生育期CGR的大小依次为：孕穗初期（齐穗期）>灌浆期>黄熟期>分蘖盛期>分蘖初期。3种水稻的干物质在各器官中的分配比例均以籽粒的最大,汕优63、两优2186和IR64的干物质分配在籽粒中的比例分别为47.94%,41.14% 和45.69%。灌浆过程中,汕优63、两优2186和IR64总干物质的表观转化率依次为46.87%、24.98%和34.41%。汕优63（三系杂交稻）在物质转化和分配方面比两优2186（二系杂交稻）和IR64 （常规稻）更优。采用三次曲线模型和Logistic模型对3种水稻产量形成过程干物质积累变化进行拟合的结果表明,三次曲线模型拟合的精度均比Logistic模型高,R2均大于0.99。 相似文献
7.
江苏不同熟期粳稻品种的齐穗期和安全播期预测 总被引：1，自引：0，他引：1
为明确当前江苏各地不同熟期粳稻品种的安全播期,以江苏的4个熟期类型的5个常规粳稻品种为材料,在江苏连云港(34°83′N)、淮安(33°34′N)、扬州(32°25′N)和苏州(31°18′N)等4地,进行自5月10日起每10天1期,共8个播期的播种试验,得出各播期的相应齐穗期。以齐穗期温光预测模型y=a＋b1x1＋b2x2拟合其实得的播期与齐穗期资料。用该模型拟合4个试验点、5个供试品种计20组数据,得出20个预测式,其拟合度R2在0.9927~0.9998之间,均达极显著水平。用各试点所在地近25年各年粳稻品种安全齐穗期及逐日平均温度,依齐穗期光温模型预测式经多次迭代推得各年的安全播期,进而求得90%保证率的安全播期并作各地生产应用分析。在江苏淮北的北部,麦稻两熟田水稻的可播栽始期为6月15日,中熟中粳的安全播期为6月21日,此类品种可用于该地直播;其他各熟期类型品种安全播期均早于当地可播栽始期,故不能用于直播。在淮北南部稻麦两熟田的可播栽始期为6月12日左右,中熟中粳和迟熟中粳的安全播期分别在7月4日和6月22日,此两类品种可用于该地麦茬直播;早熟晚粳安全播期在6月17日、18日,在大面积生产中因接茬时间过紧应慎用于麦茬直播;中熟晚粳的安全播期为6月8日,不可用于直播。在苏中南部,水稻可播栽始期为6月8至11日,中熟中粳、迟熟中粳、早熟晚粳类型两品种的安全播期分别在7月12日、3日、6月25日和28日,可用于该地直播;中熟晚粳的安全播期为6月11日,用于直播接茬时间太紧,不可应用。在苏南,水稻的可播栽始期为6月5日,供试4熟期类型品种的安全播期分别为7月18日、13日、9日至10日和7月3日,仅考虑安全齐穗各熟期类型品种均可用于麦茬直播,但因中粳类型品种直播稻生育期过短、产量不高,不宜应用。 相似文献
8.
Relationship between cold resistance,heading traits and ear primordia development of wheat cultivars
Summary For breeding early heading wheat cultivars with resistance to frost damage which are well adapted to dry areas of West Asia and North Africa, the relationships between winter hardiness, ear primordia development and heading traits, i.e. veernalization requirement, photoperiodic response and narrow-sense earliness, were assessed using a total of 30 genotypes of wheat (Triticum aestivum L.) grown in an experiment in Syria. The results of artificial freezing tests indicated that cultivars with good winter hardiness were to be found only in the winter wheat cultivars which required 50 or more days of vernalization treatment. These winter wheat cultivars did not initiate internode elongation without vernalization even at 95 days after planting. Thus their ear primordia were still underground and were protected from frost injury at this stage. Photoperiodic response and narrow-sense earliness were not associated with winter hardiness and earliness of internode elongation, but were related to the number of days to heading after planting. This indicated the possibility for breeding early heading cultivars with winter hardiness and tiller frost avoidance by combining high vernalization requirement, short narrow-sense earliness and neutral response to photoperiod. 相似文献
9.
Kulbhushan Saxena Arbind K. Choudhary Rakesh K. Srivastava Abhishek Bohra Rachit K. Saxena Rajeev K. Varshney 《Plant Breeding》2019,138(3):243-251
Pigeonpea breeding activities started about a century ago and for decades only late maturing cultivars dominated the global cultivation. Historically, no early maturing cultivar was available for a very long time and breeding of such varieties started in the third quarter of 20th century but at a low key. From these efforts, some pigeonpea varieties maturing in 90–150 days were bred. Information gathered from various sources revealed that the first few early maturing genotypes originated through spontaneous mutations in the late maturing field‐grown landraces. In other cases, transgressive segregation and induced mutations also produced early maturing varieties. At present, the high yielding early maturing cultivars are contributing significantly towards widening the adaption barriers and in the diversification of some age‐old cropping systems. In this paper, the authors, besides discussing the importance of early maturing cultivars in present agricultural systems, also summarize information related to the origin of primary sources of earliness. 相似文献
10.
超级早、晚稻品种的源库协调性 总被引：4，自引：0，他引：4
为了探讨超级早、晚稻品种的高产机理,对其源库特性进行了研究。与非超级稻品种(对照)相比,超级早、晚稻品种的总库容量、粒叶比、粒束比均较大,且与产量显著正相关;在整个灌浆结实期的源库增量比略大,但早稻在灌浆中后期(抽穗后10~25 d)和晚稻在灌浆前期(抽穗后0~10 d)均明显大;起始灌浆速率和平均灌浆速率均大,结实率与起始灌浆速率显著正相关,产量与平均灌浆速率极显著(早稻)或显著(晚稻)正相关;生育后期的根系活力衰退值较小,而剑叶的气-叶温差除早稻的株两优819和晚稻的淦鑫688外,其它均大。根系活力衰退值与产量显著负相关,剑叶的气叶温差与产量显著正相关。研究表明,较大的库容量且源库协调性较好是超级早、晚稻品种超高产的重要机理。 相似文献
11.
Wheat (Triticum aestivum L.) cultivars for the warm regions of South Asia must produce high yields and possess resistance to spot blotch (Cochliobolus sativus), early maturity and high kernel weight. A study was conducted to determine the effectiveness of selecting for high grain yield based on a selection index for spot blotch resistance, maturity and kernel weight in four wheat crosses involving a susceptible cultivar and resistant genotypes. Initial selection of 40 progeny lines in each cross had been made using a selection index based on disease severity, days to heading and kernel weight as reported by Sharma and Duveiller [{Crop Sci 43 (2003) 2031}]. The five highest grain-yielding progeny lines from among the 40 lines in each cross, their parents and five popular commercial cultivars were evaluated in field trials at two sites in Nepal in the 2002 and 2003 wheat seasons. Multiple spot blotch assessments were made to determine the area under disease progress curve (AUDPC). Grain yield, thousand-kernel weight (TKW), days to heading and plant height were examined. The wheat genotypes in the farmer's field were also ranked on the basis of cultivar preference criteria by the local farmers. The 20 progeny lines always showed a higher (+11 to +125%) grain yield and heavier (+10 to +44%) kernels than their parents and a lower (−83 to −89%) AUDPC than the susceptible parent. The progeny lines showed 98–100% grain yield, 97–100% TKW and 66–78% AUDPC compared to the highest grain-yielding commercial cultivar. Based on the farmers' preference criteria for a desirable wheat genotype, the best progeny lines ranked from 3rd to 5th, whereas the two commercial cultivars ranked 1st (Gautam) and 2nd (BL 1473). Results indicated that selection was effective in combining adaptation genes present in a local cultivar with some level of tolerance to spot blotch and resistance genes from exotic genotypes, which translated into improved agronomic performance and disease resistance. The selection index and farmer participatory approach used in this study could serve as a guideline in breeding efforts targeted for high yielding genotypes for wheat-growing conditions in South Asia where spot blotch is a serious biotic constraint to yield. 相似文献
12.
硒肥对香稻香气和糙米硒含量以及产量的影响 总被引：3，自引：0，他引：3
为了探明齐穗期喷施亚硒酸钠(Na_2SeO_3)对香稻香气、糙米硒含量和产量的影响,为富硒香稻栽培提供理论依据。设置了4个Na_2SeO_3浓度水平,依次为0(Se0),10(Se1),20(Se2),30 mg/kg(Se3),以常规香稻品种美香占和农香18为试材进行盆栽试验,研究了不同硒肥水平对糙米香气含量、茎鞘香气含量、叶片香气含量、籽粒香气含量、糙米硒含量和产量及其构成因素的影响。结果表明:2个供试品种在Se1、Se2水平下,其糙米香气2-AP含量维持在较高水平,这主要得益于在Se1、Se2普遍提高了香稻茎鞘、籽粒以及叶片齐穗后7 d和齐穗后14 d的香气含量。其中晚季美香占Se2显著提高了糙米香气含量,达到了35.73 ng/g,比Se0提高了85.03%,晚季农香18的Se2糙米香气最高,但差异未达到显著水平,早季美香占Se1的糙米香气含量显著高于其他处理,早季农香18的Se1、Se2、Se3糙米香气显著高于Se0。齐穗期喷施Na_2SeO_3能显著提高糙米硒含量。早季农香18的Se3实际产量显著低于其他处理,原因在于较高的硒浓度降低了结实率和千粒质量。齐穗期喷施适当浓度的亚硒酸钠,结实率可以得到提高或保持。在本试验条件下,兼顾2种香稻品种对硒肥的反应,齐穗期喷施Na2SeO_3最适宜浓度为10~20 mg/kg。 相似文献
13.
Yong-Feng Yan Doug-Hwan Choi Do-Soon Kim Byun-Woo Lee 《Journal of Crop Science and Biotechnology》2010,13(2):69-73
Cadmium (Cd) is absorbed by rice root and transferred into the other rice organs including grain. A solution-culture experiment
was conducted to investigate the absorption and distribution of Cd supplied at different growth stages of rice. Two rice cultivars,
a japonica ‘Chucheong’ and a tongil-type ‘Milyang23’ that exhibit high and low ability of Cd absorption by root and accumulation
in grain were grown in culture solution and subjected to 2 ppm CdCl2 treatment for 2 weeks at four different growth stages:
before panicle initiation stage (BPI), after panicle initiation stage (API), early ripening stage (ER), and mid-ripening stage
(MR). Cd concentration and accumulation in rice organs were measured at harvest. The two rice cultivars accumulated two to
three times greater amounts of Cd in grain in the two Cd treatments before heading (BPI and API treatments) than in the Cd
treatment after heading (ER and MR treatment). The higher grain Cd accumulation in BPI and API treatments was not attributed
to the higher Cd uptake but to the higher translocation from root to shoot and the higher redistribution from shoot to grain
than ER and MR treatments These results imply that the remobilization of Cd through phloem during leaf senescence is the major
process for Cd accumulation in rice grain rather than direct transport of absorbed Cd through the xylem-phloem transfer to
grain. ‘Milyang23’ absorbed significantly smaller amount of Cd than ‘Chucheong’. However, ‘Milyang23’ accumulated more than
a three times larger amount of Cd in grain compared to ‘Chucheong’ as the former exhibited the higher root-shoot translocation
and shoot-grain remobilization as well. It indicates that the greater Cd translocation from root to shoot and subsequent higher
Cd remobilization from shoot to grain, not the higher absorption ability, have led to the higher Cd accumulation and concentration
in grain of ‘Milyang23’. 相似文献
14.
Differences in DNA methylation patterns might lead to differences in fruit maturation time in the citrus Satsuma, but the underlying mechanism is unclear. Here, we explored the differences in methylation patterns during fruit ripening in Satsuma among 20 early‐ and late‐maturing Satsuma varieties and compared DNA methylation patterns in two Satsuma cultivars (Ooita wase and Aoshima unshiu) at different developmental stages using methylation‐sensitive fragment length polymorphism (MSAP) analysis. We cloned and sequenced DNA from different bands to identify differentially methylated genes involved in fruit ripening. The internal methylation of CCGG sequences occurred more frequently in the early‐maturing Satsuma cultivars (8.47%) than the late‐maturing cultivars (6.74%), whereas the external methylation of CCGG sequences occurred less frequently in the early‐maturing cultivars (24.98%) compared to the late‐maturing types (27.27%). Genes encoding the G protein α subunit and zinc‐binding protein of the histidine triad (HIT) family and two unknown genes homologous to expressed sequence tag (EST) sequences (CX052976.1 and CX071135.1) were found to be modified by methylation during the fruit ripening process. These findings suggest that DNA methylation might play important roles in regulating fruit ripening in Satsuma. Our results lay the foundation for analysing the molecular mechanism underlying fruit ripening in this important citrus crop. 相似文献
15.
Heat tolerance in spring wheat. I. Estimating cellular thermotolerance and its heritability 总被引：1，自引：0，他引：1
High temperature is a major environmental stress factor limiting wheat (Triticum aestivum L.) productivity. Improvement of
heat tolerance in wheat is an important breeding objective. Genetic variation in cellular thermotolerance among 56 spring
wheat cultivars was evaluated at the seedling stage of growth by cell membrane thermostability (CMS) and triphenyl tetrazolium
chloride (TTC) assays. A subset of eight lines was also evaluated at the flowering stage using the same assays. With both
assays Average thermotolerance tended to decrease from the seedling to the flowering stages. However, thermotolerance was
well correlated between growth stages among the eight cultivars for both CMS (r = 0.92; p = 0.004) and TTC (r = 0.84; p =
0.050). The correlation between TTC and CMS among the eight cultivars tested at the seedling and the flowering growth stages
was significant (r = 0.74; p = 0.031 and r = 0.75; p = 0.029, respectively). The same correlation was less strong, though
still significant (r = 0.32; p = 0.014) across 56 cultivars at the seedling stage. In a study of the cross V747 (tolerant)/Barkaee
(susceptible), broad sense heritability was estimated at 89% for TTC. Most of the genetic variance was additive. CMS in seedlings
of 16 cultivars was positively and significantly (p ≤ 0.05) correlated with yields of these cultivars in each of four hot
environments in Mexico, Sudan, India, and Brazil. The same correlations for TTC were positive but nonsignificant.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
16.
Three sowing date trials, each planted with one cultivar, were performed to measure the natural incidence of the Maize rayado
fino virus (MRFV). The lowest incidences (1–6%) were obtained at the sowing dates normally practised in the tested regions.
Earlier or later sowing dates had higher to much higher incidences (up to 18 and 32%). Two cultivar trials, one with four
cultivars and one with eight cultivars, showed significant differences in incidence, ranging from 14.0% in ‘Iniap-160’ to
2.0% in ‘Cadet-2’. In one trial with plots of 1000 m2, the cultivar Iniap-122 was sown at three sowing dates. In each plot, plants that developed MRFV symptoms at the 8–10 leaf
stage, at the 12–14 leaf stage and at the emergence of tassels were marked. Marked MRFV-affected plants were compared with
non-MRFV-affected plants in their neighbourhood to estimate yield loss due to MRFV. The yield losses at the three sowing dates
were 2.5, 1.6 and 4.8%, respectively. It was concluded that the yield loss due to MRFV is quite small provided sowing is restricted
to the normal sowing period. 相似文献
17.
18.
不同氮素利用效率基因型水稻氮素积累与转移的特性 总被引：24，自引：5，他引：19
选用氮素利用高效型和低效型具有代表性的12个粳稻基因型, 研究水稻氮素积累、转移特性的差异及其与氮素利用效率的相互关系。结果表明, 有效分蘖临界叶龄(N-n)、抽穗和成熟期, 氮高效类型水稻的氮素积累量极显著高于氮低效类型, 而拔节期差异不明显。水稻氮素的阶段性积累量, 除(N-n)至拔节阶段, 氮高效类型水稻极显著低于氮低效类型外, 其余各阶段氮高效类型水稻的氮积累量均极显著高于氮低效类型。水稻氮素的阶段性积累率, 移栽至(N-n)和(N-n)至拔节阶段氮低效类型水稻显著大于氮高效类型, 而在拔节至抽穗和抽穗至成熟阶段则表现出相反的趋势。抽穗前的氮素转移量和转移率, 氮高效类型水稻显著或极显著大于氮低效类型, 而抽穗前氮对籽粒的贡献率, 氮高效类型极显著低于氮低效类型。氮高效类型水稻具有在(N-n)前氮素适度积累, (N-n)后至抽穗阶段, 氮素的有效积累高而无效积累弱的特点。因此至抽穗期, 氮高效类型水稻的氮素积累量大于氮低效类型, 具有较高的氮素转移量和转移率。但由于氮高效类型水稻在抽穗以后仍具有较强的氮素积累能力, 因此其抽穗前氮对籽粒的贡献率相对低于氮低效类型。 相似文献
19.
为防止盲目拓展播期,通过大田分期播种试验、热量分布及利弊分析,结合发育期及生物要素研究。结果表明,尽管早播早稻一度获得最高分蘖倍率,但收获时以适期播种最终得到最高的有效茎倍数。早播的获得最大总生物量,适期播种获得理想的产量。早播早稻无效分蘖较多;适期播种在产量结构方面表现出优势;晚播早稻在成穗数、单穗结实粒数上不理想;早播早稻管理成本高,遭遇苗期低温、花期暴雨概率大。晚播早稻抽穗灌浆期遭遇高温热害情况多,对叶绿素、光合、稻米品质有不利影响。拓展播期需综合考虑气候变化与反复性带来的风险,以及热量分布对生物总量与产量的不同影响。 相似文献
20.
小麦慢叶锈品种具有侵染率低、潜伏期长、孢子堆小、产孢量少、严重度低、病害进展曲线下面积小和病害虽流行但产量损失不显著等特点.潜伏期和扬花期平均病害严重度与产量损失的关系最密切,因此测定某一小麦品种的潜伏期(x_1)和平均病害严重度(x_2)(田间感病对照品种发病达50%或95%时),可以作为衡量该品种慢(快)叶锈性的两个指标和选种的依据.用y=94.67-3.10x_1+0.51x_2估测由叶锈造成的小区产量损失(y)有一定可靠性(R=0.96).用聚类分析法把供试品种分为慢锈、中慢、中快和快锈品种类型.苗期和成株期慢叶锈性有一定的吻合性. 相似文献