[Effects of bundled straw mulching on water consumption characteristics and grain yield of winter wheat in rain-fed semiarid region]. / ç§¸ç§†å¸¦çŠ¶è¦†ç›–å¯¹åŠå¹²æ—±é›¨å »åŒºå†¬å°éº¦è€—æ°´ç‰¹å¾å’Œäº§é‡çš„å½±å“.

To explore a new technique of planting wheat with high yield and efficiency by mulching technology in rain-fed semiarid regions in Northwest China, a two-year fixed-site trail was conducted during 2013-2015. There were five mulching modes: (1) three sowing rows by bundled straw mul-ching with alternating 30-cm-wide mulching belt and planting belt (SM1), (2) four sowing rows by bundled straw mulching with alternating 40-cm-wide mulching belt and planting belt with (SM2), (3) five sowing rows by bundled straw mulching with alternating 50-cm-wide mulching belt and planting belt (SM3), (4) whole plastic film mulching with dibbling (PMF), (5) bare field planting without any mulching (CK). We examined the effects of different mulching modes on water consumption, water use efficiency (WUE), and yield of winter wheat in rain-fed region in Northwest China. The results showed that bundled straw mulching significantly increased soil water storage. Soil water storage with bundled straw mulching was remarkably higher than that with the whole plastic mul-ching with SM1＞SM2＞SM3. Soil water storage at 0-200 cm soil layer in flowering period was increased by 15.4%-20.8%,11.2%-14.7%and 10.1%-14.5% respectively over that in the bare field. Bundled straw mulching significantly increased water consumption during the whole growing period while reduced water consumption from sowing and flowering periods. Further, it increased water consumption from flowering to maturity periods and the ratio of water consumption during this period to the total water consumption during the whole growing periods. The results showed that mulching could increase the consumption ratio of deep water storage from the soil layer below 120 cm. Compared with CK, PMF and SM significantly increased grain yield and water use efficiency by 11.9%-19.5%, 26.9%-27.1%, respectively, and increased water use efficiency by 9.8%-13.9%, 18.4%-22.0% respectively. In all, bundled straw mulching could reduce water consumption ratio in the early growing periods, improve moisture condition, increase grain yield and water use efficiency of winter wheat. Therefore, we concluded that bundled straw mulching is an environment-friendly cultivation technology suitable for the winter wheat in semi-arid region of the Loess Plateau in Northwest China.

[Effect of straw belt-mulching on soil temperature and yield of winter wheat in rain-fed semiarid region.] / ç§¸ç§†å¸¦çŠ¶è¦†ç›–å¯¹åŠå¹²æ—±é›¨å »åŒºå†¬å°éº¦ç”°åœ°æ¸©å’Œäº§é‡çš„å½±å“.

To evaluate the effects of straw belt-covering on soil temperature and yield of winter wheat in rain-fed semiarid region in Northwest China, five mulching modes, including flat field planting without any mulching (CK), whole plastic film mulching (PM), straw mulching by 30 cm covering belt with an interval of 30 cm planting belt with three-row sowing (SM1), straw mulching by 40 cm covering belt with an interval of 40 cm planting belt with four-row sowing (SM2), and straw mulching by 50 cm covering belt with an interval of 50 cm planting belt with five-row sowing (SM3), were set by two-year fixed-site trails in 2013-2015. The results showed that soil temperature significantly varied among different growth stages and soil layers in all treatments. SM1, SM2 and SM3 significantly decreased soil temperature by 1.0-1.3 ℃, 0.7-0.9 ℃ and 0.7-1.1 ℃ in the 0-25 cm soil layer, respectively. The mulching had double effects with increasing and decreasing soil temperatures. The straw mulching significantly increased soil temperature in the duration of seedling to overwintering stage, but greatly decreased soil temperature in the duration of reviving to mature stage. The temperature-increasing effect of film mulching was stronger than that of straw mulching, which was opposite to the temperature-decreasing effect. Straw mulching significantly reduced in the effective accumulated temperature and the daily temperature variations during the whole growth stages. The effective accumulated temperature under straw mulching decreased by 3.4-33.5 ℃·d, and the soil temperature difference decreased by 0.6-2.0 ℃. During over-wintering stage, the straw mulching showed a higher average soil temperature (0.2-0.3 ℃) and negative accumulated temperature (0.4-17.0 ℃·d) than those under the CK. The straw mulching significantly increased grain yield by 11.9%-19.5%. The variations of spikes per unit area were the main factor responsible for yield difference. The findings indicated that that straw mulching method is suitable for winter wheat production in rain-fed region of Northwest China.

Chilling temperature stimulates growth, gene over-expression and podophyllotoxin biosynthesis in Podophyllum hexandrum Royle.

Podophyllotoxin (PPT) and its derivatives, isolated from the rhizome of Podophyllum hexandrum Royle (P. hexandrum), are typically used in clinical settings for anti-cancer and anti-virus treatments. Empirical studies have verified that P. hexandrum had stronger tolerance to chilling, due to involving PPT accumulation in rhizome induced by cold stress. However, the cold-adaptive mechanism and its association with PPT accumulation at a molecular level in P. hexandrum are still limited. In this study, the morpho-physiological traits related to plant growth, PPT accumulation and key gene expressions controlling PPT biosynthesis were assessed by exposing P. hexandrum seedlings to different temperatures (4 °C and 10 °C as chilling stress and 22 °C as the control). The results showed that chilling significantly increased chlorophyll content, net photosynthetic rate, stomatal conductance, and plant biomass, whereas it greatly decreased transpiration rates and intercellular CO2 concentration. Compared to the control, the chilling treatments under 4 °C and 10 °C conditions induced a 5.00- and 3.33-fold increase in PPT contents, respectively. The mRNA expressions of six key genes were also up-regulated by chilling stresses. The findings are useful in understanding the molecular basis of P. hexandrum response to chilling.

[Genetic analysis of accumulation and remobilization of water soluble carbohydrates regulated by drought in wheat RIL stem at grain-filling stage].

Recombinant inbred lines (RIL, Longjian 19 x Q9086, F8) and their parents were undertaken to study characteristics of quantitative genetics of water soluble carbohydrates (WSC) accumulation, remobilization and its contribution to grain mass in different main stem internodes at the grain-filling stage as well as the correlations among the target traits under the rainfed (DS) or well-watered (WW) condition. All of the target traits of RIL had wide variations under both water conditions. The variation coefficient ranged from 2.7% to 62.1% under the DS, and from 1.9% to 52.1% under the WW. The diversity index varied from 0.61 to 0.90 under the DS, and from 0.64 to 0.89 under the WW. All tested traits were significantly affected by the genotype, water condition, internode and growth stage. The growth stage exerted strong impacts on the WSC content. The water condition and internode greatly influenced the WSC remobilization rate. But, the WSC contribution rate to grain was jointly controlled by the genotype, water condition and internode. There were significantly positive correlations between the WSC contents at the early flowering and grain-filling stages, the WSC remobilization rate and its contribution rate to grain at pre-anthesis stage, with the higher correlation coefficients under the DS than under the WW. All traits showed low heri- tability under both water conditions (hB2 = 0.31-0.56 under the DS, 0.44-0.67 under the WW). The numbers of gene pairs controlling all traits ranged from 6 to 29 under the DS, and from 3 to 19 under the WW. It indicated that alleles responsible for all the target traits of RIL showed substantially transgressive segregation and greatlysignificant sensitivity to the water condition, confirming the characteristics of quantitative traits.

[Effects of source-sink regulation on water soluble carbohydrates of vegetative organs and thousand-grain mass of wheat under different water conditions].

Two winter wheat cultivars with different drought tolerance were selected to investigate the effects of source-sink regulation on the vegetative organs water soluble carbohydrates (WSC) content and 1000-grain mass (TGM) of wheat under drought stress (DS) and well watered (WW) conditions. Sink-cutting increased the WSC content of different vegetative organs significantly, and promoted the relative transportation of the WSC positively; while source-cutting caused opposite responses. The effects of source-sink regulation on the WSC content and its relative transportation amount (TA) and transportation rate (TR) were significantly higher under DS and sink-cutting than under WW and source-cutting, for drought-resistant cultivar (Longjian 19) than for drought-sensitive Q9086, and for peduncle internode and PedI than for penultimate internode and PenI. Under source-cutting, the superior organs of Longjian 19 in the TR of total WSC were sheath, PedI, and PenI, which also contributed to the fructan TR of the two cultivars, while those of Q9086 were the PenI and the third internode from top (ThiI). Source-cutting decreased the TGM of Longjian 19 and Q9086 significantly, with the decrement being 27.3% and 31.7% under DS and 25.3% and 12.1% under WW, respectively. The correlation coefficients of the WSC content and its TA and TR and the TGM were significantly higher under sink-cutting than under source-cutting, and also, under DS than under WW. There existed a higher correlation coefficient (r2 > 0.900) of the TGM and the total WSC and fructan contents in different vegetative organs. The vegetative organs with closer correlation between their WSC content and its TA and TR and the TGM were mainly sheath and PedI. Under DS, the traits associated with the total WSC content had a higher correlation with TGM; under WW, the traits associated with sucrose and glucan contents generally showed a higher correlation with TGM. It was suggested that the effects of source-sink regulation on the WSC content of vegetative organs and the TGM were significantly affected by soil water environment, wheat genotype, and vegetative organs location.

Relationship between podophyllotoxin accumulation and soil nutrients and the influence of Fe2+ and Mn2+ on podophyllotoxin biosynthesis in Podophyllum hexandrum tissue culture.

Podophyllotoxin (PDT) and its derivatives, which are isolated from the Podophyllum species, are widely used in the clinical setting. The present study was designed to analyze the correlation between PDT levels in the rhizomes of Podophyllum hexandrum (P. hexandrum) and Dysosma versipellis (D. versipellis) and the nutrients in soil. We also aimed to investigate the influence of Fe(2+) and Mn(2+) on the enzyme activity of phenylalanine ammonia lyase (PAL), cinnamyl alcohol-dehydrogenase (CAD), and deoxypodophyllotoxin 6-hydroylase (DOP6H) and PDT accumulation via P. hexandrum tissue culture. The results showed that PDT accumulation was positively correlated with the NO3(-), PO4(3-), Na(+), Fe, and Mn levels and was negatively correlated with the SO4(2-) and K(+) levels, while the correlation with the Mg(2+), Ca(2+), Cu and Zn levels was not significant. The Fe(2+) and Mn(2+) levels were associated with the increased activity of PAL and CAD at 3-18 days; Fe(2+) enhanced the activity levels by 2.66- and 1.76-fold, respectively, and Mn(2+) was associated with a 1.68- and 1.10-fold increase in activity levels, respectively, compared with the control (CK) at 18 days. DOP6H activity was enhanced by Mn(2+), but it was not significantly affected by Fe(2+). Finally, PDT production was enhanced approximately 60% and 34% by Fe(2+) and Mn(2+), respectively, compared with CK at 16 days. These observations may be useful for the generation of PDT and related lignans via commercial cultivation as well as cell and tissue culture of P. hexandrum and other related plant resources.

[Experiment precision and comprehensive environmental evaluation of regional wheat trials in rainfed regions of China].

Based on the grain yield data of regional trials with 233 winter- and spring wheat cultivars (lines) in rainfed farmlands at 82 locations in four subregions of China in 2003-2009, this paper studied the experiment precision (EP), variety comparison precision (VCP), and testing-site discrimination ability and representativeness of national regional trials, and comprehensively evaluated the trial environment. The results showed that in one-location-one-year experiments, the average coefficient of variation (CV) and the relative least significant difference (RLSD) were 6.1% and 10.5%, respectively, and in multi-location-one-year experiments, the CV was all within 8.2%, and the CV and RLSD were mostly well controlled, indicating that the trials had a high precision. The testing-site discrimination ability was the highest in the northwest spring wheat subregion, but showed less difference in the other subregions. The testing-site representativeness was the best in the northeast spring wheat subregion, and the worst in the northwest spring wheat subregion. On the basis of the comprehensive consideration of the testing-site discrimination ability and representativeness, and by using the parameters of the environmental comprehensive assessment (r(g)h) of GGE model, it was shown that the proportion of the ideal trial locations for wheat in our rainfed farmlands was only 32.4%. Among the wheat production regions, the proportions of the ideal trial locations were in the order of northwest spring wheat subregion (40.9%) > northeast spring wheat subregion (33.3%) > Huang-Huai winter wheat subregion (30.4%) > north winter wheat subregion

[Genetic characteristics associated with drought tolerance of plant height and thousand-grain mass of recombinant inbred lines of wheat].

A total of 120 recombinant inbred lines (RIL) derived from Chinese winter wheat cultivars Longjian 19xQ9086 and the two parents were taken as test materials to study the quantitative genetics characteristics of their plant height at different development stages, thousand-grain mass, as well as the correlations between the two traits under rainfed (drought stress) and well-watered conditions, and evaluate the genetic variation of the RIL. Under the two water conditions, the target traits of the RIL showed substantial transgressive segregation and great sensitivity to water condition. The drought stress coefficient of the plant height was higher at jointing stage, being up to 0.851. There was a significant positive correlation between the plant height at different development stages and the thousand-grain mass, and comparing with that at other growth stages, the plant height at jointing stage had a higher correlation coefficient with the thousand-grain mass (R2DS = 0.32, R2WW = 0.28). The plant height at both jointing and flowering stages had significant positive and direct effect but negative and indirect gross effect on the thousand-grain mass, while the plant height at heading and maturing stages was in adverse. The target traits showed a lower heritability ranged from 0.27 to 0.60. The numbers of the gene pairs controlling the thousand-grain mass were 10 under rainfed and 13 under well-watered conditions, while those of the gene pairs controlling the plant height at different development stages were 3-7 under rainfed and 4-14 under well-watered conditions, respectively. According to the clustering of the drought stress coefficient of plant height, the RIL could be classified into five subgroups, showing the abundant variation of the RIL in their phe- notypes and in the sensitivity to water condition. It was considered that the test RIL were appropriate for the study of the quantitative genetics of wheat drought resistance.

[Variation analysis on the grain yield and main agronomic traits of spring wheat in rainfed regions of China].

Based on the grain yield data of spring wheat from the 2002-2005 regional trials with 13 cultivars (lines) on the rainfed farmlands at 18 locations of China, and by using variance analysis and GGE (genotype main effect plus genotype-by-environment interaction) biplot, this paper studied the effects of genotype, environment, and genotype x environment interaction (GEI) on the yield variation of spring wheat and the yield stability of different cultivars (lines). Comparing with genotype and GEI, the environment had much more contribution on the yield variation, accounting for 87.5%-92.0% of the total. In the GEI items, genotype x location had the greatest effect, whereas genotype x year had the smallest one. The average yield of modern spring wheat genotypes across years and locations in China was 2550 kg x hm(-2). Among the three yield components, thousand kernel weight (TKW) had the least variation under environmental change. The main environment factors affecting the yield variation were annual accumulated temperature ( > or =10 degrees C), precipitation in growth season, mean air temperature, altitude, annual precipitation, and frost-free period. The grain yield had significant positive correlations with spike number per unit area (SPU) (r = 0.675**), TKW (r = 0.456**), and kernels per spike (KPS) (r = 0.581**), and the SPU, KPS and TKW also had positive correlations (r = 0.244-0.480**) with each other, implying that these three yield components might be increased or improved synchronously.

Identification of quantitative trait loci and environmental interactions for accumulation and remobilization of water-soluble carbohydrates in wheat (Triticum aestivum L.) stems.

Genetic analyses of nine traits associated with stem water-soluble carbohydrate (SWSC) accumulation and remobilization at grain-filling period under drought stress (DS) and well-watered (WW) conditions were undertaken using doubled haploid lines (DHLs) derived from two Chinese common wheat cultivars. Some significantly and very significantly positive correlation was observed among nine traits associated with SWSC. Higher phenotypic values for most traits were detected under DS. Broad sense heritabilities (h(B)(2)) of the traits showed wide fluctuations between two water treatments. A total of 48 additive and 62 pairs of epistatic QTL for nine traits were identified as distributing on all 21 chromosomes. A majority of QTL involved significant additive and epistatic effects with interactions of QTL and environments (QEIs). Two additive and two pairs of epistatic loci involved only QEIs without corresponding significant additive or epistatic effects. The contributions of the additive QEIs were two- to fourfolds higher than those of their corresponding additive QTL. Most of the additive QEIs for traits associated with SWSC interacted with DS. In addition, some QTL for the grain-filling efficiencies and thousand-grain weight were colocated in the same or adjacent chromosome intervals with QTL for accumulation and remobilization efficiency of SWSC before 14 days after flowering.