A Dynamic Model for Water and Nitrogen Limited Growth in Spring Wheat to Predict Yield and Quality

Annual variation of bread wheat ( Triticum aestivum L.) yield and quality has caused problems for agronomic policy in northern regions. Yield prediction methods based on visual assessment of crop may be inaccurate as they are not based on quantitative data. The aim of this study was to develop a simple dynamic model, based on daily climatological data, enabling prediction of crop growth, and changes in crop yield, and grain protein concentration and starch quality. The model was built using field data collected in 1972–88. Spring wheat cultivars included in the study were Kadett and Ruso. The calibration of growth and Hagberg falling number (used as a measure of starch quality) sub-models resulted in a highly significant positive correlation between measured and calculated values. The calibration of nitrogen sub-models failed, however, with poor correlation between measured and calculated values. The model was tested against independent field data collected during 1989–90, and results correlated with calibration results. The yield predictions based on independent field data were accurate, and the same as or similar to field trial results. However, the independent Hata revealed flaws in soil-water and Hagberg falling number sub-models.     

蜀柏毒蛾种群抽样技术的研究

根据蜀柏毒蛾的空间格局参数及株内分布规律,参照Morris(1960)的标准和Iwao(1971)的模型,对蜀柏毒蛾种群样本单元进行选择,确定以株为样本单元,并选择平行线式,Z字形式、棋盘式取样方法,列出了允许误差D=0.05,0.10,0.20,0.50时和不同虫口密度下的理论抽样数表。依照Kuno(1969)模型建立了序贯抽样表。     

狭翅雏蝗蝗蝻抽样技术的研究

本文在空间格局研究的基础上,对狭翅雏蝗蝗蝻在不同密度下的理论抽样数及序贯抽样技术进行了研究。结果表明：狭翅雏蝗蝗蝻的理论抽样数可据ｎ＝（１／Ｄ２）（１２７５６／ｍ＋０３６１８）确定,序贯抽样可依Ｉｗａｏ法确定的两条截止线Ｔｏ（ｎ）＝８０７５ｎ±１１４１０５ｎ和据Ｋｕｎｏ确定的最大抽样数Ｔｎ＝１２７５６／（Ｄ２－０３６１８／ｎ）结合起来使用。     

极早熟水稻新品系“新90-3”的适宜育插秧期及栽培技术研究

通过对水稻极早熟新品系“新90-3”缸栽试验结果分析,确定了5月10日到5月20日为最佳播期,在适当晚育、晚插的情况下,穴苗数不低于7棵,主茎叶片数平均为14片叶,伸长节间数5个,有效分蘖临界叶龄期为9片叶。     

基质及含水量不同对猕猴桃扦插生根的影响

以‘徐香’猕猴桃为试材,采用嫩枝扦插法进行繁殖,研究基质及含水量不同对猕猴桃扦插生根的影响。结果表明：不同配比基质含水量不同对猕猴桃扦插生根有影响。基质相对含水量为70%时,蛭石和珍珠岩按1∶1的扦插生根效果最好,生根率为66.50%,平均生根数量为4.50条,平均根长为5.83 cm。以期对‘徐香’猕猴桃扦插技术应用推广具有重要意义。     

不同栽培深度对张良姜生长及产量的影响

通过研究不同栽培深度对张良姜出苗、生长、产量及品质的影响,以期为生产中科学栽培提供理论依据。试验在露地条件下进行,通过深度试验(5 cm、10 cm、20 cm、高垄)研究了张良姜在不同栽培深度、不同时期在株高、茎粗、叶片数、子姜级数、单株重等方面的差异。结果表明,栽培深度10 cm最利于张良姜的出苗;栽培深度20 cm利于张良姜前期地上部生长;面对降水较多的异常天气,高垄栽培张良姜品质最优、产量最高。     

Effect of candidate gene polymorphisms on reproductive traits in a Large White pig population

The objective of this study was to test for association of candidate single nucleotide polymorphisms (SNPs) with sow prolificacy reproductive traits, such as litter size, ovulation rate and lifetime performance, in gilts of a Large White pig population. Preliminary research on 25 animals selected from the high‐ and low‐performance groups of 347 animals with case‐control studies indicated that seven genes were associated with total number of piglets born (TNB). Six of the seven genes were associated with reproductive traits, including TNB, number of piglets born alive (NBA) and average weight of piglet weaning (AWW). A MBL2 SNP was significantly associated with TNB and NBA in first parity. A CFB SNP was associated with TNB in first parity. An ACE SNP was associated with TNB in first and second parities. An EGF polymorphism was associated with TNB, NBA and AWW in second parity. A KCNC2 polymorphism was significantly associated with TNB and NBA in second parity. A SLC22A5 SNP was associated with TNB and NBA in second parity. Six candidate SNPs were associated with TNB; the only exception was a PRKAG3 polymorphism. A candidate gene approach enables some of these polymorphisms to be used in genetic improvement programs based on marker‐assisted selection.     

Estimation of genetic parameters for farrowing traits in purebred Landrace and Large White pigs

Genetic parameters were estimated for six reproductive traits related to farrowing events in Landrace and Large White pigs; total number born (TNB), number born alive (NBA), number stillborn (NSB), total litter weight at birth (LWB), mean litter weight at birth (MWB), and gestation length (GL). We analyzed 62,534 farrowing records for 10,637 Landrace dams and 49,817 farrowing records for 8,649 Large White dams. Estimated heritabilities of TNB, NBA, NSB, LWB, MWB, and GL by single‐trait repeatability model analyses were 0.12, 0.12, 0.08, 0.18, 0.19, and 0.29, respectively, in Landrace, and 0.12, 0.10, 0.08, 0.18, 0.16, and 0.34, respectively, in Large White. Genetic correlation between NBA and NSB was unfavorable: 0.20 in Landrace and 0.33 in Large White. Genetic correlations of GL with the other five traits were weak: from ?0.18 with NSB to ?0.03 with NBA in Landrace, and from ?0.22 with NSB to ?0.07 with NBA in Large White. LWB had a highly favorable genetic correlation with NBA (0.74 in both breeds), indicating the possibility of using LWB for the genetic improvement of NBA.     

An efficient empirical Bayes method for genomewide association studies

Linear mixed model (LMM) is one of the most popular methods for genomewide association studies (GWAS). Numerous forms of LMM have been developed; however, there are two major issues in GWAS that have not been fully addressed before. The two issues are (i) the genomic background noise and (ii) low statistical power after Bonferroni correction. We proposed an empirical Bayes (EB) method by assigning each marker effect a normal prior distribution, resulting in shrinkage estimates of marker effects. We found that such a shrinkage approach can selectively shrink marker effects and reduce the noise level to zero for majority of non‐associated markers. In the meantime, the EB method allows us to use an ‘effective number of tests’ to perform Bonferroni correction for multiple tests. Simulation studies for both human and pig data showed that EB method can significantly increase statistical power compared with the widely used exact GWAS methods, such as GEMMA and FaST‐LMM‐Select. Real data analyses in human breast cancer identified improved detection signals for markers previously known to be associated with breast cancer. We therefore believe that EB method is a valuable tool for identifying the genetic basis of complex traits.     

广西冬蕉留把数对产量和果实性状的影响

针对广西地区冬蕉‘威廉斯B6’的留把数开展研究，结果发现，留有8把和留有9把香蕉植株产量分别为30.77和27.29 kg。两处理总果指分别为155.53和168.67只，留有8把的处理每把把重范围为2.40～6.80 kg，比留有9把的处理每把高出0.50～2.00 kg，且留有8把的香蕉果指长和果指粗高于留有9把处理，商品果率高12.2%。综合比较，在广西地区冬蕉建议留有8把，可以提高香蕉产量和商品率。