Genotypic variation in nitrogen use efficiency in medium- and long-duration rice

A field experiment was conducted in the dry season at Los Baños, Philippines, to assess the differences in grain yield and N utilization of 10 medium-duration (119±4 days after seeding [DAS]) genotypes and 10 long-duration (130±4 DAS) ones with varying acquisition and usage of soil and fertilizer N. Significant differences among genotypes were observed in grain yield and N uptake, efficiency and partitioning parameters (physiological N use efficiency [PNUE], agronomic N use efficiency [ANUE], apparent recovery [AR], partial factor productivity of applied N [PFP_N], N productivity index [NPI], and N harvest index [NHI]). The N-efficient genotypes that produced high grain yield at both low and high levels of N were IR54790-B-B-38, BG380-2, BG90-2 (medium-duration), and IR3932-182-2-3-3-2, IR54853-B-B-318, and IR29723-88-2-3-3 (long-duration). Inefficient genotypes that produced low yields at low N levels but responded well to N application were IR58125-B-B-42, IR49457-33-1-2-2-2, and BG34-8 (medium-duration), and IR8192-200-3-3-1-1, IR21848-65-3-2-2, and PR106 (long-duration). IR20 (medium) and Palawan (long-duration) were N-inferior genotypes giving low yields at both low and high N levels. Increase in grain yield was highly correlated with N uptake (r²=0.75**). The grain yield-N uptake relationship for individual genotypes indicated significant differences in slope and in the yield obtained with soil N (GY₀). Differences in GY₀ were due to genotypic variation in N uptake and efficiency of use. NHI was related to both N uptake and use efficiency. NPI, which integrated both GY₀ and PNUE, provided a better ranking of genotypes. The performance of efficient and inefficient genotypes over a range of soil and fertilizer N supply was consistent over three seasons of trials.     

Relationships among twelve genotypes of roselle (Hibiscus sabdariffa L.) cultivated in western Mexico

The aim of this study was to characterize agromorphological and molecular relationships between twelve genotypes of roselle (Hibiscus sabdariffa L.) grown in western Mexico. Variables related to crop yield and management at two localities were used for agromorphological characterization. Data were analyzed using principal component analysis. The first four components explained 75.77% of the variation between genotypes. Molecular characterization was conducted using the inverse sequence-tagged repeat marker, which separated the 12 genotypes into two main groups. Three of the genotypes that grouped together at the molecular level had a similar leaf phenotypic characteristic (the number of lobes), which differed from that of the other genotypes. Variation between genotypes was evident in respect of molecular variables, which were used as genetic markers to distinguish between genotypes. Grouping of genotypes according to agromorphological variables, which reflect the response of a genotype to the environment, yielded similar results to molecular grouping. Genetic structure analysis indicated that the China, Fresa, Diamante, and Gigante genotypes probably share a common origin.     

Estimation of paddy water productivity (WP) using hydrological model: an experimental study

Water productivity (WP) expresses the value or benefit derived from the use of water. A profound water productivity analysis was carried out at experimental field at Field laboratory, Centre for Water Resources, Anna University, India, for rice crop under different water regimes such as flooded (FL), alternative wet and dry (AWD) and saturated soil culture (SSC). The hydrological model soil-water-atmospheric-plant (SWAP), including detailed crop growth, i.e, WOFOST (World Food Studies) model was used to determine the required hydrological variables such as transpiration, evapotranspiration and percolation, and bio-physical variables such as dry matter and grain yield. The observed values of crop growth from the experiment were used for the calibration of crop growth model WOFOST. The water productivity values are determined using SWAP and SWAP–WOFOST. The four water productivity indicators using grain yield were determined, such as water productivity of transpiration (WP_T), evapotranspiration (WP_ET), percolation plus evapotranspiration (WP_ET+Q) and irrigation plus effective rainfall (WP_I+ER). The highest value of water productivity was observed from the flooded treatment and lowest value from the saturated soil culture in WP_T and WP_ET. This study, reveals that deep groundwater level and high temperature reduces the crop yield and water productivity significantly in the AWD and SSC treatment. This study reveals that in paddy fields 66% inflow water is recharging the groundwater. There is good agreement between SWAP and SWAP–WOFOST water productivity indicators.     

Plant characteristics associated with weed competitiveness of rice under upland and lowland conditions in West Africa

Weeds are a major constraint to rice (Oryza spp.) production in West Africa. Superior weed competitive rice genotypes may reduce weed pressure and improve rice productivity. Two upland and two lowland experiments were conducted in southern Benin to examine genotypic variations in weed-suppressive ability and grain yield under weedy conditions, and to identify plant characteristics that could be used as selection criteria for improved weed competitiveness. A total of 19 genotypes, including Oryza sativa and Oryza glaberrima genotypes and interspecific hybrids developed from crossing O. sativa and O. glaberrima, were grown under weed-free and weedy conditions in an upland with supplemental irrigation and in a flooded lowland. In weedy plots, hand weeding was done once or not at all. Mean relative yield loss across all genotypes due to weed competition ranged from almost 0% to 61%. Large genotypic variations in weed biomass and grain yield under weedy conditions were found. Visual growth vigor at 42 and 63 days after sowing (DAS) under weed-free conditions significantly correlated with weed biomass at maturity in both upland and lowland experiments (R² = 0.26–0.48). Where weed pressure was low to moderate, with mean relative yield loss less than 23%, the multiple regression models using grain yield and plant height at maturity or only grain yield measured under weed-free conditions as independent variables could explain 66–88% of the genotypic variation in grain yield under weedy conditions. At higher weed pressure (mean relative yield loss: 61%), as observed in one of the upland experiments, biomass accumulation of rice at 42 days after sowing was associated with higher grain yield under weedy conditions. Biomass accumulation also significantly correlated with visual growth vigor at the same sampling dates. Therefore, we conclude that grain yield, plant height at maturity and visual growth vigor at 42–63 DAS under weed-free conditions appear to be useful selection criteria for developing superior weed competitive rice genotypes.     

Yield response of rice (Oryza sativa L.) genotypes to drought under rainfed lowland: 3. Plant factors contributing to drought resistance

A series of experiments were conducted in drought-prone northeast Thailand to examine the magnitude of yield responses of diverse genotypes to drought stress environments and to identify traits that may confer drought resistance to rainfed lowland rice. One hundred and twenty eight genotypes were grown under non-stress and four different types of drought stress conditions.Under severe drought conditions, the maintenance of PWP of genotypes played a significant role in determining final grain yield. Because of their smaller plant size (lower total dry matter at anthesis) genotypes that extracted less soil water during the early stages of the drought period, tended to maintain higher PWP and had a higher fertile panicle percentage, filled grain percentage and final grain yield than other genotypes. PWP was correlated with delay in flowering (r=−0.387) indicating that the latter could be used as a measure of water potential under stress. Genotypes with well-developed root systems extracted water too rapidly and experienced severe water stress at flowering. RPR which showed smaller coefficient of variation was more useful than root mass density in identifying genotypes with large root system.Under less severe and prolonged drought conditions, genotypes that could achieve higher plant dry matter at anthesis were desirable. They had less delay in flowering, higher grain yield and higher drought response index, indicating the importance of ability to grow during the prolonged stress period.Other shoot characters (osmotic potential, leaf temperature, leaf rolling, leaf death) had little effect on grain yield under different drought conditions. This was associated with a lack of genetic variation and difficulty in estimating trait values precisely.Under mild stress conditions (yield loss less than 50%), there was no significant relationship between the measured drought characters and grain yield. Under these mild drought conditions, yield is determined more by yield potential and phenotype than by drought resistant mechanisms per se.     

Yield performance and grain lipid composition of standard and oleic sunflower as affected by water supply

Sunflower has potential in Mediterranean farming systems because of the modest auxiliary input requirement, appreciable productivity and quality of raw material. These aspects are affected by the interactions among genetic, environmental and agronomic factors, which have not been fully explored. Therefore, the effects of four water regimes as proportion of crop evapotranspiration (0%, 33%, 67%, 100%) on grain yield and its components, oil yield and grain lipid constituents, i.e. fatty acids (FAs), unsaponifiable matter (UM), phytosterol (Phy), policosanol (PC) and tocopherol (Toc) fractions of a standard and an oleic sunflower hybrids were assessed in a 2-year field experiment. The relationships between crop productive traits and oil quality features were also analysed.     

Tolerance of 42 bread wheat genotypes to drought stress after anthesis

The present research characterized yield and yield components of 42 wheat genotypes after terminal drought stress. The experiment was in twice replicated simple rectangular lattice design, conducted at irrigated and terminal stress conditions during 2006-2007. These study genotypes had significant differences for grain yield at level of 1%. Genotypes 4057, Viking/5/Gds/4.., Sabalan and 5041 respectively with 6.313, 6.159, 5.793 and 5.774 t ha(-1) had the highest yield and Gascogen has the lowest yield with 2.561 t ha(-1). Mean of total grain yield for under study genotypes was 5.628 t ha(-1) in non-stress and 3.305 t ha(-1) in drought stress conditions. Drought stress decreased amount of grain yield 2.323 t ha(-1) that was noticeable. Interaction of Genotype x environmental conditions was significant at probability level of 1% for grain yield. Yield of all genotypes in drought condition was lower than non-stress condition. Genotypes Viking/5/Gds/4/Anza/3/Pi.., Sabalan, 4061,4057 and 4041 had more yield in non-stress condition and MV17/Zrn, Sabalan, Saysonz and 4032 in stress condition. Stress intensity pay attention to total grain yield was 42%. Genotypes Viking/5/Gds/4/.. and Sabalan had high grain yield and was better than other genotypes and controls (Toos and Crosse Shahi), according to GMP, STI and MSTI. And had the most amount of stress tolerance index as compared with other genotypes confirms this subject. Correlation of yield with other traits was not significant in non-stress condition. In drought condition, correlation of grain yield with 1000 grain weight and total number of tillers per plant was positively significant. ANOVA showed significant differences between osmotic pressures for coleoptile length, between genotypes for mean and maximum coleoptile length and between interactions of genotypes x osmotic pressures for mean and maximum coleoptile length. Mean comparisons showed the highest total, mean and maximum coleoptile length in -7 bar PEG+I ml L(-1) potassium humate treatments. Genotypes Sardari and Sabalan had the highest amounts of total, mean and maximum coleoptile length. With due attention to interaction genotype x osmotic pressures, genotypes Sardari, Sabalan and 4057 in -7 bar PEG+1 ml L(-1) potassium humate had the most amounts of noted characters than others. In conditions of this experiment, potassium humate caused increase in tolerance rate of genotypes against drought stress.     

Simultaneous selection for seed and forage production in cocksfoot (Dactylis glomerata): application of drought tolerance and susceptibility indices

An experiment was conducted to estimate drought tolerance of some cocksfoot genotypes based on seed and forage yield and related indices (including tolerance index, mean productivity, geometric mean productivity, reduction percentage index, stress tolerance index and stress susceptibility index) and to identify relationships between measured traits. Twenty‐five genotypes were evaluated in the field under control and drought‐stress environments over 2 years. The results revealed a high variation for seed yield and forage yield and the measured indices under both moisture conditions. No correlation was observed between seed yield and forage yield under the control treatment, but this correlation was positively significant under the water‐stress treatment. Drought‐tolerant and susceptible genotypes were identified based on seed and forage yield performance. Genotypes 2, 4 and 7 had high seed yield, while genotypes 7 and 10 had high forage yield under both stressed and non‐stressed conditions and were identified as the most tolerant genotypes in each category. The results also revealed that genotypes 1, 2, 4, 6, 7, 8 and 24 had relatively high seed and forage yield in both control and drought‐stressed conditions. These genotypes can be used for further studies to improve both seed and forage yields concurrently.     

春小麦籽粒灌浆期蛋白质含量动态变化规律的定量分析

以3个不同品质类型春小麦为材料,在设定不同肥力和气象条件等环境因子影响试验的基础上建立灌浆期籽粒蛋白质含量动态变化的曲线拟合方程,以定量揭示籽粒蛋白质含量的动态变化过程与规律。结果表明,籽粒蛋白质含量随时间动态变化规律符合三次多项式曲线,即蛋白质含量变化呈现自开花始先降低而后增加的凹性曲线变化。方程的各特征量具有相应的籽粒蛋白质含量动态变化的生物学意义;基因型与环境因素对籽粒蛋白质含量动态变化的影响通过方程的系数和特征量而体现。灌浆期籽粒蛋白质含量的动态变化过程中,不同基因型具有不同特点,且基因型间的关系也随之发生动态变化。     

Yield response of rice (Oryza sativa L.) genotypes to drought under rainfed lowlands: 2. Selection of drought resistant genotypes

Drought frequently reduces grain yield of rainfed lowland rice. A series of experiments were conducted in drought-prone northeast Thailand to study the magnitude and consistency of yield responses of diverse, rainfed lowland rice genotypes to drought stress environments and to examine ways to identify genotypes that confer drought resistance. One hundred and twenty-eight genotypes were grown under non-stress and four different types of drought stress conditions. The relationship of genotypic variation in yield under drought conditions to genetic yield potential, flowering time and flowering delay, and to a drought response index (DRI) that removed the effect of potential yield and flowering time on yield under stress was examined.Drought stress that developed prior to flowering generally delayed the time of flowering of genotypes, and the delay in flowering was negatively associated with grain yield, fertile panicle percentage and filled grain percentage. Genotypes with a longer delay in flowering time had extracted more water during the early drought period, and as a consequence, had higher water deficits. They were consistently associated with a larger yield reduction under drought and in one experiment with a smaller DRI. Genotypes, however, responded differently to the different drought stress conditions and there was no consistency in the DRI estimates for the different genotypes across the drought stress experiments. The results indicate that with the use of irrigated-control and drought test environments, genotypes with drought resistance can be identified by using DRI or delay in flowering. However, selections will differ depending on the type of drought condition. The inconsistency of the estimates in DRI and flowering delay across different drought conditions reflects the nature of the large genotype-by-environment interactions observed for grain yield under various types of drought in rainfed lowland conditions.     

喷施铁肥对不同基因型小麦产量和铁吸收的影响

为研究小麦的最佳喷施铁肥时期并筛选高铁基因型小麦,采用盆栽方法,以14个不同基因型小麦为材料,通过不同时期喷施铁肥,比较其对小麦产量和铁吸收的影响。结果表明,小麦拔节期叶面喷施铁肥可以增加籽粒产量、籽粒铁含量、籽粒铁累积量及占植株总铁积累量的比例。拔节期喷施铁肥提高了小麦根系的铁含量、累积量及根系铁占植株总铁累积量的比例。不同基因型小麦喷施铁肥时茎中的铁含量、铁累积量及占植株总铁累积量的比例均显著降低。小麦体内的铁主要储存在根系中,地上部的铁主要分布在叶片等营养器官中。与低铁基因型相比,高铁基因型小麦具有较低的籽粒产量和生物量,但籽粒产量占全株总生物量的比例却高于低铁基因型。无论是否喷施铁肥,高铁基因型小麦籽粒铁含量、铁累积量及占植株总铁累积量的比例均显著高于低铁基因型小麦。无论是否喷施铁肥,高铁基因型的根系生物量显著低于低铁基因型,但根系铁含量则显著高于低铁基因型,铁累积量则没有显著差异。拔节期喷施铁肥是促进不同基因型小麦生长、改善小麦铁营养状况的有效途径。     

Decrease in sorghum grain yield due to the dw3 dwarfing gene is caused by reduction in shoot biomass

Positive correlations between plant height and grain yield have been reported for sorghum. The introduction of stay-green in sorghum, and the associated reduction in lodging, has opened the possibility to exploit this positive association. The aim of this study was to analyse the direct effects of the dwarfing gene dw3 (and therefore plant height) on shoot biomass, grain yield, and yield components in pairs of 3-dwarf genotypes and their isogenic 2-dwarf tall mutants. Isogenic pairs with different genetic backgrounds were grown in three field experiments under nutrient and water non-limiting conditions. Tall mutants were significantly taller and produced more shoot and stem biomass than their shorter counterparts. Generally, tall types yielded more grain than short types, but significant interactions between experiment, genetic background and stature affected the consistency of the results. dw3 only affected grain size and not grain number. Increased grain mass of tall types was associated with significantly greater stem mass per grain at anthesis and greater shoot biomass per grain accumulated between anthesis and maturity. The increased biomass of tall plants was therefore important for increased grain yield under optimum conditions. Potential implications of increased biomass production for drought adaptation are discussed.     

播期对春玉米生长发育、产量及水分利用的影响

以郑单958和鲁单984为材料,研究了两个播期条件下春玉米的生长发育、产量形成和水分利用情况。结果表明：播期对春玉米生长发育和产量影响显著,且品种间表现趋势一致。晚播春玉米生育期缩短,在各时期叶面积指数和干物质积累均显著高于早播春玉米。晚播春玉米产量(干重)提高,粒重在播期间、品种间差异均不显著。晚播春玉米穗粒数显著提高,品种间差异不显著。推迟播期后总耗水量增加,但增加幅度小于产量增加的幅度,水分利用效率略高于早播春玉米。在本试验条件下,晚播春玉米具有较优叶面积指数,有利于干物质积累并向子粒转移,增加穗粒数。因此,在春玉米播期的选择上不应单纯考虑生育期的延长,应重视早播春玉米前期营养生长受限对产量的影响。     

Critical period for grain number establishment of near isogenic lines of two- and six-rowed barley

In barley no studies have attempted to pinpoint the critical period for grain number determination, and it is frequently stated that the critical period is similar to that of wheat. However, there are important differences between the species and among barley genotypes (i.e. two- and six-rowed types) suggesting that this assumption requires testing. The objectives of this paper were (i) to determine the critical period for grain number determination in two- and six-rowed barleys, and (ii) to identify which yield components were more sensitive to changes in incident radiation during that period.

Two field experiments were conducted using two pairs of near isogenic lines differing only in the spike type. Shading was imposed at different periods throughout the crop cycle (from 60 days before heading to 15 days after) to reduce incident solar radiation approximately 70%.

The critical period for grain number determination tended to be slightly earlier in two- (ca. between 40 and 10 days before heading) than in six-rowed barleys (ca. between 30 days before heading until that stage). In terms of the external phenology, the beginning of the critical period for setting grains was 10 days after the beginning of stem elongation, and 10 days before flag leaf appearance in two- and six-rowed lines, respectively. Changes in the number of grains per unit area were correlated with crop growth rate during the critical period for yield determination.     

Effects of Soil Salinity and Alkalinity on Grain Quality of Tolerant,Semi-Tolerant and Sensitive Rice Genotypes

Soil salinity and alkalinity adversely affects the productivity and grain quality of rice.The grain quality of 19 rice genotypes characterized as salt tolerant (T),semi-tolerant (ST) and sensitive (S) was assessed in lysimeters containing saline and highly alkaline soils.Head rice recovery was reduced by salinity stress whereas it was not affected by alkalinity stress.The ratio of length to width (grain dimensions) was significantly reduced in the T genotype even at low electrical conductivity (EC,4 mS/cm) and alkalinity (pH 9.5),whereas in the ST genotype,it was significantly reduced at high salinity (EC 8 mS/cm).There was no significant effect of any levels of salinity or alkalinity on grain dimensions in the S genotype.Amylose content was significantly reduced in T and ST groups even at low EC (4 mS/cm) and alkalinity (pH 9.5) and the effect in the S genotype was only at high salinity.Starch content showed significant reduction at high salinity and alkalinity (EC 8 mS/cm and pH 9.8) in the T and ST genotypes and no significant effect was observed in the S genotype.The effect of both levels of salinity (EC 4 and 8 mS/cm) and high alkalinity (pH 9.8) on gel consistency was observed only in the S genotype.The tolerant genotypes IR36 under high salinity,and CSR10 and CSR11 under alkali stress showed less reduction in amylose content.The T genotype BR4-10,and ST genotypes CSR30,CSR29 and CSR13 showed better gel consistency under saline and alkali stress.Amylose content was affected even at low salinity stress and thus important to be considered in breeding rice for salt tolerance.Overall,the grain quality of T and ST genotypes was less affected by saline and alkali stress compared to S ones.     

Characterization of sorghum genotypes for traits related to drought tolerance

Grain sorghum (Sorghum bicolor L. Moench) is a genetically diverse cereal crop grown in many semiarid regions of the world. Improving drought tolerance in sorghum is of prime importance. An association panel of about 300 sorghum genotypes from different races, representative of sorghum globally, was assembled for genetic studies. The objectives of this research were to (i) quantify the performance of the association panel under field conditions in Kansas, (ii) characterize the association panel for phenological, physiological and yield traits that might be associated with tolerance to limited moisture (drought), and (iii) identify genotypes with higher yield potential and stability under different environments that may be used in the sorghum breeding program. Results show large diversity for physiological and yield traits such as chlorophyll content, leaf temperature, grain numbers and grain weight per panicle, harvest index and yield. Significant differences were found for plant height, grain weight and numbers per panicle, harvest index, and grain yield among and within races. The US elite lines had the highest number of grains and grain weight per panicle while the guinea and bicolor races recorded the lowest. Harvest index and yield was highest for the US elite lines and the caudatum genotypes. Overall, there was a negative correlation between plant height and grain weight, grain numbers and yield. Harvest index and grain numbers were negatively affected by moisture limitation for all the races. Among the races, the caudatum genotypes were more stable in grain yield across the different environments. Overall, there was a wide variability within the association panel for physiological and yield traits that may prove to be useful for improving drought tolerance in sorghum.     

Path analysis for selection of drought tolerant sugarcane genotypes through physiological components

Water deficit is among the main environmental factors limiting agricultural productivity of sugarcane in Northeast Brazil by affecting virtually every aspect of plant growth, with consequent reduction of the agro-industrial productivity of this crop. This study aimed to use path analysis to evaluate the physiological components of sugarcane under two water conditions, with photosynthesis as the basic variable, in order to obtain subsidies that can help the genetic breeding of this crop by selection of superior clones with drought tolerance. The experiment was carried out in a greenhouse with a completely randomized experimental design, 4 × 2 factorial arrangements (four sugarcane genotypes × two soil moisture regimes: control, with 80-100% available water and stressed, with 0-20% water available) and with four replications. Each plot consisted of one pot with 12 kg of substrate containing one plant. Treatments were maintained at a humidity close to field capacity with daily replacement of the evapotranspired water with a water supply for 66 days of cultivation for treatments under stress. Evaluations were conducted on the fourth day after severe water stress at 70 days of cultivation. Data from nine physiological variables were considered, with six of these being used in the model after exclusion of those that were contributing to multicollinearity. Variables used in path analysis were enough to explain the variation found in photosynthesis under both water conditions. Stomatal conductance, transpiration and the SPAD index should be considered as a priority in breeding programs for sugarcane aiming to get more productive and tolerant genotypes to water stress, and selection indexes should be used with due consideration of these variables to promote gains in photosynthesis.     

Frequency of occurrence of various drought types and its impact on performance of photoperiod-sensitive and insensitive rice genotypes in rainfed lowland conditions in Cambodia

Lowland rice production in the Mekong region is generally low because crops are cultivated under rainfed conditions and often exposed to drought. To examine how field water availability affects productivity of different genotypes in rainfed lowland rice, the field experiments were carried out for six years at eight locations in Cambodia. We classified 34 genotypes used in the experiments into photoperiod-insensitive [short (IS) and medium (IM) maturity] and sensitive [medium (SM) and long-duration (SL) maturity] genotype groups. Mean days-to-flower from sowing was 87 in IS, 112 in IM, 112 in SM and 132 in SL and mean grain yield was 2.0, 2.8, 2.5 and 2.4 t ha⁻¹, respectively. Drought environment was quantified for each experiment by determining whether free water level was observed to be less than the soil surface during three growth stages: GS1 (maximum tillering), GS2 (panicle development) and GS3 (grain filling). The drought frequency estimated from 44 field experiments was 18% in all IM, SM and SL at GS1, 23%, 25% and 32% in IM, SM and SL, respectively at GS2, and 43%, 45% and 57% at GS3. Thus, the drought occurred more frequently after flowering, particularly in the SL group. Based on the results, the IM genotypes may be grown to escape from drought during the GS2 and GS3 periods by sowing early (June) in the drought environment. When sown late (August), the SM genotypes are exposed to less drought risk because they flower earlier than the IM genotypes. Compared with the SM genotypes, the SL genotypes are highly exposed to water stress during the GS3 period, resulting in yield reduction. SM and IM had similar occurrence of drought environment, but yield reduction due to drought was less in SM than in IM. Thus, photoperiod-sensitive cultivars with medium maturity are preferred in drought-prone lowland fields, particularly when sowing is delayed. In the favourable water environment, the SM genotypes can be better than the IM genotypes when sown early in the season, while the IM genotypes performs better than the SM genotypes with late sowing. This suggests that for lowland fields without drought photoperiod-insensitive cultivars are recommended and photoperiod-sensitive cultivars can be preferred if sown early.     

吉林省春玉米土壤中、微量元素“潜缺乏”初探

在吉林省中、西部玉米主产区进行高产条件下硫、镁、锌、锰、硼施用效果试验。结果表明,增施中、微量元素可以有效促进植株对营养元素的吸收、子粒的形成以及干物质的累积,不同中、微量元素响应程度区域性差异较大。中部地区以硫效果最好,产量增幅10.4%～12.0%,氮、磷、钾养分累积量分别增幅12.0%～12.8%、12.9%～21.7%、0～11.5%,其次是硼、镁;西部地区以锌效果最好,产量增幅18.7%～35.0%,氮、磷、钾养分累积量分别增幅40.8%～62.4%、39.4%～59.5%、9.4%～70.5%,其次是硼、锰、硫。依据区域特点,有针对性地补充中、微量元素可有效提高作物生产力,增产增收。     

Variability in Grain Quality Characters of Upland Rice of Assam,India

The grain quality of 100 upland/ahu rice genotypes from Assam,India was assessed.The characteristics measured were grain length,grain width,cooked grain length,cooked grain width,grain elongation ratio after cooking,grain widening ratio after cooking,alkali spreading value,gel consistency,as well as starch,amylose,amylopectin and total soluble sugar contents.Considerable genetic variability among the 100 rice genotypes was observed for the characteristics under study.Analysis of variance revealed highly sig...