Impact of climate change on maize yield in China from 1979 to 2016

Climate change severely impacts agricultural production, which jeopardizes food security. China is the second largest maize producer in the world and also the largest consumer of maize. Analyzing the impact of climate change on maize yields can provide effective guidance to national and international economics and politics. Panel models are unable to determine the group-wise heteroscedasticity, cross-sectional correlation and autocorrelation of datasets, therefore we adopted the feasible generalized least square(FGLS) model to evaluate the impact of climate change on maize yields in China from 1979–2016 and got the following results:(1) During the 1979–2016 period, increases in temperature negatively impacted the maize yield of China. For every 1°C increase in temperature, the maize yield was reduced by 5.19 kg 667 m–2(1.7%). Precipitation increased only marginally during this time, and therefore its impact on the maize yield was negligible. For every 1 mm increase in precipitation, the maize yield increased by an insignificant amount of 0.043 kg 667 m–2(0.014%).(2) The impacts of climate change on maize yield differ spatially, with more significant impacts experienced in southern China. In this region, a 1°C increase in temperature resulted in a 7.49 kg 667 m–2 decrease in the maize yield, while the impact of temperature on the maize yield in northern China was insignificant. For every 1 mm increase in precipitation, the maize yield increased by 0.013 kg 667 m–2 in southern China and 0.066 kg 667 m–2 in northern China.(3) The resilience of the maize crop to climate change is strong. The marginal effect of temperature in both southern and northern China during the 1990–2016 period was smaller than that for the 1979–2016 period.     

小麦4B染色体上LOX基因的等位变异及其区域分布

为了解中国不同麦区小麦种质资源籽粒脂肪氧化酶（lipoxygenase,LOX）活性相关基因TaLox-B1的差异和分布,利用小麦4B染色体上的功能标记LOX16和LOX18对7个麦区的436份种质资源进行分子检测。结果表明：在供试材料中共检测到3种TaLox-B1基因等位变异类型,分别为TaLox-B1a（与高LOX活性相关)、TaLox-B1b（与低LOX活性相关）和杂合型,其频率分别为19.0％、70.4％和10.6％。小麦LOX活性基因不同变异类型在各生态区的分布存在明显差异：基因型TaLox-B1a在黄淮冬麦区、北部冬麦区和长江中下游冬麦区分布较多,其比例分别为21.1%、19.8%和17.6%;基因型TaLox-B1b在西南冬麦区和长江中下游冬麦区分布较多,比例分别为87.9%、72.5%;杂合型仅存在于北部冬麦区、黄淮冬麦区与长江中下游冬麦区,比例分别为14.2%、12.4%和9.8%。利用标记LOX16和LOX18对53个自选高代品系进行分子检测,发现自选品系仅有TaLox-B1b与杂合型两种基因型,其中基因型TaLox-B1ab有32个,比例为60.4%。采用分子标记辅助选择,有利于快速鉴定小麦籽粒LOX活性,加速LOX的遗传改良和新品种选育。     

‘哈伯’南天竹组织培养和快速繁殖

为建立‘哈伯’南天竹组织培养和种苗繁育技术体系,以半木质化带芽茎段为外植体材料开展植株再生研究。通过观察对比试验法、L₉(3⁴)正交试验设计完全随机法、极差分析、显著性检验、LSD多重比较,探讨了‘哈伯’南天竹组培的最适培养基配方。试验结果表明：最佳诱导培养基为MS + 6-BA 2.0 mg/L + IBA 0.1 mg/L +蔗糖30 g/L,诱导萌动率71.77%,成活率85.51%;最佳增殖培养基为WPM +6-BA 1.5 mg/L + IBA 0.01 mg/L + 蔗糖30 g/L,增殖系数6.3;最佳生根培养基为1/2 MS+ IBA 0.5 mg/L + NAA 1.0 mg/L + 蔗糖20 g/L + AC 0.2 g/L,生根率97.63%;试管苗移入泥炭土:珍珠岩=3:2(V/V)混合基质中,移栽成活率96.67%。该试验建立了高效稳定的组培快繁技术体系,得到的组培苗后代能够稳定的保持母本优良性状,为工厂化育苗提供了技术支撑。     

马铃薯致病疫霉拮抗细菌研究进展

为了解决马铃薯致病疫霉侵染马铃薯导致其死亡,进而造成马铃薯单位种植产量低的问题。本文从拮抗菌入手,归纳分析细菌类拮抗菌中的主要拮抗菌中芽孢杆菌、假单胞菌和粘细菌对马铃薯致病疫霉的抑制作用。同时,在总结前人研究的基础上,笔者认为在拮抗菌应用方面,可以采用多对一的新型平板对峙筛菌模式来模拟复杂条件下拮抗菌的拮抗作用,以期得到稳定的拮抗菌;并指出应从定植能力和根际微生物影响方面对拮抗菌实际应用的可行性进行研究;此外,提出未来对拮抗菌抑制马铃薯致病疫霉的探究应从表型层面的研究深入到分子层面,以期能成功从源头找寻抑制马铃薯致病疫霉的答案。     

不同杀青方式龙井茶自动化连续生产线加工工艺探讨

文章剖析了不同杀青方式龙井茶自动化连续生产线的设备配置和工艺流程,对生产线的龙井茶品质进行感官评价,为龙井茶生产线推广应用提供借鉴。     

特早熟抗病棉花品种辽棉35选育及栽培技术

本文主要介绍辽棉35的选育过程、生物学特性、产量、纤维品质、抗病性及栽培技术要点。     

不利气象条件对果业生产的影响及果园管理建议

针对近年来不利气象条件频发情况,分析了不利气象条件对果业生产的影响,提出减轻不利气象条件对果树影响的建议和不利气象发生后果园的管理要点。     

Screening and Verification of Low Nitrogen Tolerant and Nitrogen Sensitive Cotton Germplasm

[Objective] The aim of this study is to evaluate nitrogen efficient cotton germplasms and improve nitrogen use efficiency. [Method] Eighty cotton germplasms were selected and evaluated in the hydroponic experiment under low (0.25 mmol·L^－1) and high (5 mmol·L^－1) nitrogen concentration. Different traits for screening were identified and nitrogen use efficiency types were classified. Field experiments were also performed for comparison and confirmation of the identified germplasms. [Result] The results showed that there were significant differences in the total plant dry matter, shoot nitrogen accumulation and nitrogen absorption efficiency in cotton germplasms at the two nitrogen levels. Based on coefficient of variation, principal component analysis and correlation, six traits including total plant dry matter, shoot dry matter, root dry matter, total nitrogen accumulation, shoot nitrogen accumulation and nitrogen absorption efficiency were used as screening indicators. According to the Heatmap clustering analysis and the nitrogen efficiency comprehensive index, two germplasms (Lu05R59 and CCRI 69) were identified as low nitrogen tolerant and nitrogen efficient, and two germplasms (Coker 201 and Xinluzhong 30) as low nitrogen sensitive and nitrogen inefficient. The results of field experiment were consistent with the results of the hydroponic culture at the seedling stage. [Conclusion] It was finally determined that Lu05R59 and CCRI 69 were the low nitrogen tolerant and nitrogen efficient germplasms, and Coker 201 and Xinluzhong 30 were low nitrogen sensitive and nitrogen inefficient germplasms. The results of these studies provide the possibility for screening and rapid identification of nitrogen use efficiency in cotton at the seedling stage, and provide the ideal materials and theoretical basis for further study of cotton nitrogen efficient.     

Regulatory role of l-proline in fetal pig growth and intestinal epithelial cell proliferation

l-proline (Pro) is a precursor of ornithine, which is converted into polyamines via ornithine decarboxylase (ODC). Polyamines plays a key role in the proliferation of intestinal epithelial cells. The study investigated the effect of Pro on polyamine metabolism and cell proliferation on porcine enterocytes in vivo and in vitro. Twenty-four Huanjiang mini-pigs were randomly assigned into 1 of 3 groups and fed a basal diet that contained 0.77% alanine (Ala, iso-nitrogenous control), 1% Pro or 1% Pro + 0.0167% α-difluoromethylornithine (DFMO) from d 15 to 70 of gestation. The fetal body weight and number of fetuses per litter were determined, and the small and large intestines were obtained on d 70 ± 1.78 of gestation. The in vitro study was performed in intestinal porcine epithelial (IPEC-J2) cells cultured in Dulbecco''s modified Eagle medium-high glucose (DMEM-H) containing 0 μmol/L Pro, 400 μmol/L Pro, or 400 μmol/L Pro + 10 mmol/L DFMO for 4 d. The results showed that maternal dietary supplementation with 1% Pro increased fetal weight; the protein and DNA concentrations of the fetal small intestine; and mRNA levels for potassium voltage-gated channel, shaker-related subfamily, member 1 (Kv1.1) in the fetal small and large intestines (P < 0.05). Supplementing Pro to either gilts or IPEC-J2 cells increased ODC protein abundances and polyamine concentrations in the fetal intestines and IPEC-J2 cells (P < 0.05). In comparison with the Pro group, the combined administration of Pro and DFMO reduced the expression of ODC protein and spermine concentration in the fetal intestine, as well as the concentrations of putrescine, spermidine and spermine in IPEC-J2 cells (P < 0.05). Meanwhile, the percentage of cells in the S-phase and the mRNA levels of proto-oncogenes c-fos and c-myc were increased in response to Pro supplementation, whereas depletion of cellular polyamines with DFMO increased tumor protein p53 (p53) mRNA levels (P < 0.05). Taken together, dietary supplementation with Pro improved fetal pig growth and intestinal epithelial cell proliferation via enhancing polyamine synthesis.