Effect of Planting Date on Yield and Yield Components of Grain Sorghum Hybrids

In Kansas, productivity of grain sorghum [Sorghum bicolor (L.) Moench] is affected by weather conditions at planting and during pollination. Planting date management and selection of hybrid maturity group can help to avoid severe environmental stresses during these sensitive stages. The hypothesis of the study was that late May planting improves grain sorghum yield and yield components compared with late June planting. The objectives of this research were to investigate the influence of planting dates yield and yield components of different grain sorghum hybrids, and to determine the optimal planting date and hybrid combination for maximum biomass and grains production. Three sorghum hybrids (early, medium, and late maturing) were planted in late May and late June without irrigation in Kansas at Manhattan/Ashland Bottom Research Station, and Hutchinson in 2010;and at Manhattan/North Farm and Hutchinson in 2011. Data on dry matter production, yield and yield components were collected. Grain yield and yield components were influenced by planting date depending on environmental conditions. At Manhattan (2010), greater grain yield, number of heads per plant, were obtained with late-June planting compared with late May planting, while at Hutchinson (2010) greater yield was obtained with late May planting for all hybrids. The yield component most affected at Hutchinson was the number of kernels∙panicle−1 and plant density. Late-May planting was favorable for late maturing hybrid (P84G62) in all locations. However, the yield of early maturing hybrid (DKS 28-05) and medium maturing hybrid (DKS 37-07) was less affected by delayed planting. The effects of planting dates on yield and yield components of grain sorghum hybrids were found to be variable among hybrid maturity groups and locations.

Relationship Between Canopy Temperature at Flowering Stage and Soil Water Content,Yield Components in Rice

The canopy temperature of rice at the flowering stage and the soil water content were investigated under different soil water treatments （the soil water contents were 24%, 55%, 90% and 175% at the flowering stage）. The canopy temperature was lower than air temperature, and the soil water content significantly influenced the canopy temperature. The lower the soil water content, the higher the canopy temperature, the less the accumulative absolute value of canopy-air temperature difference. Moreover, the maximum difference between treatments and CK in the accumulative absolute value of canopy-air temperature difference appeared at 13：00 μm. in a day, thus, it could be considered as a suitable measuring time. Under the lowest water content treatment, the peak flowering occurred in the first three days （about 70% of panicles flowered）, resulting in shortened and lightened panicle of rice. As to the CK and the high water content treatments, the peak flowering appeared in the middle of flowering duration, with longer panicle length and higher panicle weight. Results indicated the lower the soil water content, the less the filled grain number and grain yield.

Relationship Among Yield Components and Selection Criteria for Yield Improvement in Early Rapeseed (Brassica napus L.)

The objective of this study was to determine the relationship between seed yield and other important agronomic traits of early-maturing rapeseed as a rotation crop in a double-cropping rice area using Pearson＇s correlation coefficient as well as to estimate direct and indirect effects of specific yield component traits on seed yield via path analysis. Nineteen rapeseed genotypes were grown at ten environments in South China during 2008-2009 and 12 characters were evaluated. Analysis of variance showed that environment had a significant impact on all characters. For most characters the genotype by environment interaction was weak and not statistically significant. Simple correlation analysis indicated that the number of primary branches （PB）, number of pods on the main raceme （PR）, and number of seeds per pod made significant contributions to seed yield per plant （SYP）, while 1 000-seed weight was negatively correlated with SYP （r=-0.485, P0.05）. Furthermore, number of pods per plant （PP）, PB, and PR had the greatest direct effects on SYP. In addition, PP and PB were the best indicators to predict seed yield in stepwise regression analysis. Finally, yield component differences between early- and medium-maturity varieties were compared; this showed that to improve the seed yield of early varieties, more emphasis should be given to increase PP, PB, and PR, and reduce plant height and shortening of growth duration in breeding practice.

Genotype and Environment Interactions of Yields and Yield Components of Tea (Camellia sinensis) Cultivars in Kenya

The tea crop provides income and employment to rural populations in many countries. In Kenya, tea, which is the leading export commodity crop, is grown in highlands east and west of the Rift Valley at altitudes ranging from 1300 m to 2700 m above mean sea level. Variable responses of tea genotypes to different environments have been demonstrated. This affects the growth, productivity, and quality of tea. However, most tea husbandry practices are uniform across tea growing regions leading to variations in yields and quality in the different environments. Understanding causes of variations in tea growth parameters and yields to varying environments is vital to optimizing husbandry practices for maximization of productivity. The responses in growth and yield parameters of clonal tea to locations of production and their contribution to yields were compared. A genotype × environment trial was conducted in three sites (Kangaita, Timbilil and Kipkebe). At each site, a trial comprising 20 cultivars was laid in a randomized complete design replicated 3 times. Yields, yield components and climatic data were collected then subjected to analysis of variance and regression analysis. There were significant (p ≤ 0.05) yield variations between clones and locations. Yields ranged from 5162 kg mt/ha on clone TRFK 303/577 at Kipkebe to 935 kg mt/ha/year on clone TRFK 7/3 in Kangaita, surpassing the maximum variation possible postulated in earlier studies. The responses of the tea yield components to weather parameters varied with genotypes and environments. Shoot growth rates in Timbilil (r = 0.476)) and shoot density (Kangaita (r = 0.652) significantly (p ≤ 0.05)) correlated with yields. Yield components and weather parameters contribution to the total yield also varied with locations. The variations demonstrated that not all yield components can be used universally as yield indicators for clonal selection in different locations. For optimal production, selected tea clones should therefore be tested before adoption for commercial planting in other locations.

Influence of Organic and Inorganic Nitrogen on Grain Yield andYield Components of Hybrid Rice in Northwestern Pakistan

Field experiments were conducted to assess the impact of various organic sources, inorganicnitrogen （N） and the different combinations of inorganic N （urea） ＋ organic source on the yieldcomponents （YC） and grain yield （GY） of hybrid rice （Oryza sativa L., Pukhraj） under rice-wheat system.The experiments were conducted at Batkhela （Malakand）, Northwestern Pakistan, in 2011 and 2012.Our results revealed that YC and GY ranked first for the hybrid rice when applied with sole inorganic N（urea）, followed by the application of N in mixture （urea ＋ organic sources）, while the control plots （no Napplied） ranked in the bottom. Among the six organic sources （three animal manures： poultry, sheepand cattle; three crop residues： onion, berseem and wheat）, application of N in the form of poultrymanure was superior in terms of higher YC and GY. When applying 120 kg/hm2 N source, 75% N fromurea ＋ 25% N from organic source resulted in higher YC and GY in 2011, while applying 50% N fromurea ＋ 50% N from organic sources caused higher YC and GY in 2012. Therefore, the combinedapplication of N sources in the form of urea ＋ organic source can produce good performances in termsof higher YC and GY of rice under rice-wheat cropping system.

Quantitative trait loci associated to agronomic traits and yield components in a Sorghum bicolor L.Moench RIL population cultivated under pre-flowering drought and well-watered conditions

The present study aims to identify QTL influencing agronomic traits and yield components under well-watered and pre-flowering drought stress conditions. One hundred F5 recombinant inbred lines (RIL) and the parental lines of a cross between a drought-tolerant and a susceptible line in a field experiment were carried out at Nong Lam University of Ho Chi Minh City, Vietnam. Drought stress was induced by withholding irrigation water from the plants at four weeks after sowing to flowering. Leaf area of the third leaf, stem diameter, plant height, days to heading, anthesis and maturity, panicle length, number of seeds per plant, hundred kernel weight and grain yield were measured. Plants were genotyped with 117 Diversity Arrays Technology (DArT) and eight expressed sequence tag (EST)-derived simple sequence repeat (SSR) markers. Composite interval mapping was carried out on the traits and significant QTL were claimed at a logarithm of the odds (LOD) score >2.5. A total of 50 QTL were detected on nine chromosomes or 13 linkage groups, respectively. Six promising QTL regions with seven QTL for yield and agronomic traits especially related to pre-flowering drought tolerance were identified on chromosomes SBI-01, SBI-03, SBI-04, SBI-05 and SBI-07.

The Effects of Different Levels of Nitrogen on Yield and Yield Components of Rainfed Wheat in Two Regions of North Khorasan

To study the effects of different levels of nitrogen fertilizer on yield and yield components of cultivars of rainfed wheat a study was done in the crop year 2012-2013 as factorial in a randomized complete block design with 3 replications, in 2 research stations of Kohne Kand city in Bojnord and Shirvan dryland research station. The treatments of study contain cultivars of wheat in 4 levels (Rasad, Sabalan, Cross Sabalan and Azar 2) and 4 levels of nitrogen fertilizer (75, 50, 25 and 0 kilograms nitrogen per hectare). The results showed that the yield in Shirvan was significantly higher than that in Bojnoord. Moreover, the impact of cultivar and nitrogen on yield and yield components was significant in both regions and among different cultivars Azar 2 has the highest yield in both regions and the lowest yield was for cross Sabalsn in Shirvan and Sabalan in Bojnoord. Furthermore, yield increased by increasing the nitrogen in both regions but there was no significant difference between levels 50 and 75 kilograms per hectare. Among yield components except the number of spikes per square meter, others had a high correlation with yield.

Effects of Nitrogen Fertilizer on Seed Yields and Yield Components of Zoysia japonica Established by Seeding and Transplant

The study was conducted to determine the optimum fertilizer-N application rate formaximum seed yields of Zoysiagrass stands from seeding and transplant respectively, atJiaozhou, Shandong Province, China from 2001 to 2003. In the third year after establishment,seed yields and yield components for both stands showed a similar response to fertilizer-N. Maximum fertile tiller numbers (3342 heads m-2 and 2941 heads m-2 from stands seeded inrows and transplanted, respectively) and the highest seed yields (844.50kgha-1 and 874.65kg ha-1 from stands seeded in rows and transplanted, respectively) were obtained at a Nfertilizer rate of 20kgha-1 in autumn and 10kgha-1 in spring (30kgha-1 N in total). Thefertile tillers and seed yields decreased with further increasing of N fertilizer rate.Fertilizer-N application could increase the length of spike, spikelets per fertiletiller, seed number per spike, setting percentage and thousand seed weight. The 1000-seed weight and the length of spike from transplant plots were higher than that fromseeding plots. The optimal harvest time of zoysiagrass at Jiaozhou was on the 36th dayafter peak anthesis, near June 15th, when the seed moisture content was 26-28%.

Root morphological traits and their relations with yield components of dry-raised mid-season indica rice

Research on root morphological traits of dry-raised seedlings (D-RS) at different growth stages of rice have so far attracted less attention. In this study, using mid-season indica hy-

Winter wheat yield improvement by genetic gain across different provinces in China

The replacement of winter wheat varieties has contributed significantly to yield improvement worldwide,with remarkable progress in China.Drawing on two sets of data,production yield from the National Bureau of Statistics of China and experimental yield from literature,this study aims to(1)illustrate the increasing patterns of production yield among different provinces from 1978 to 2018 in China,(2)explore the genetic gain in yield and yield relevant traits through the variety replacement based on experimental yield from 1937 to 2016 in China,and(3)compare the yield gap between experimental yield and production yield.The results show that both the production and experimental yields significantly increased along with the variety replacement.The national annual yield increase ratio for the production yield was 1.67%from 1978 to 2018,varying from 0.96%in Sichuan Province to 2.78%in Hebei Province;such ratio for the experimental yield was 1.13%from 1937 to 2016.The yield gap between experimental and production yields decreased from the 1970s to the 2010s.This study reveals significant increases in some yield components consequent to variety replacement,including thousand-grain weight,kernel number per spike,and grain number per square meter;however,no change is shown in spike number per square meter.The biomass and harvest index consistently and significantly increased,whereas the plant height decreased significantly.

Influence of potassium fertilization and foliar application of zinc and phosphorus on growth,yield components,yield and fiber properties of Egyptian cotton(Gossypium barbadense L.)

Aims Supplying optimal quantities of mineral nutrients to growing crop plants is one way to improve crop yields.Nutrients need to be used rationally in order to avoid a negative ecological impact and undesirable effects on the sustainability of agricultural production systems.Excessive application of nutrients also affects the farmer’s economy.In order to calculate the amount of fertilizer to be applied to crops,it is necessary to develop recommendation programmers that adjust nutrient rates to crop requirements.Methods Experiments in two successive seasons were conducted to investigate the effect of K fertilization and foliar application of Zn and P on yield and fiber properties of cotton cv.Giza 86.Potassium(0.0 and 47.4 kg of K ha^(-1))was soil applied,while chelated zinc(0.0 and 57.6 g of Zn ha^(-1),applied twice at 70 and 85 days after sowing‘DAS’)and phosphorus(0.0,576,1152 and 1728 g of P ha^(-1),applied twice at 80 and 95 DAS)were applied to the foliage.Important findings Dry matter yield,total chlorophyll concentration,K,Zn and P uptake per plant,number of opened bolls per plant,boll weight,seed index,lint index,seed cotton yield per plant,seed cotton and lint yield ha^(-1) and earliness of harvest increased with the application of K,Zn and P.Treatments generally had no significant effect on lint percentage and fiber properties,with exceptions,for micronaire reading and flat bundle strength,and uniformity ratio,where the mean values of these characters were significantly increased over the untreated control by applying K,and for the micronaire reading in the first season,when applying P at 1728 g ha^(-1),and uniformity ratio in the second season,when applying Pat 1152 and 1728 g ha^(-1),where the mean values of these characters were significantly increased over the untreated control by applying P.Under the conditions of this study,applying K fertilization at 47.4 kg ha^(-1) combined with spraying cotton plants with zinc at 57.6 g ha^(-1) and also with P at 1728 g ha^(-1) improved growth and yield of Egyptian cotton.

Genetic Analysis of Yield and Its Components of B.napus Hybrids Using Resynthesized Rapeseed Lines

Resynthesized rapeseeds obtained by crossing the diploid parents Brassica rapa and Brassica oleracea have significant potential in hybrid breeding because of their higher genetic basis compared with Brassica napus cultivars. In this study, an 8 × 8 complete diallel experiment using four B. napus cultivars （BN） and four resynthesized rapeseed lines （RS） as parents was designed to study heterosis and genetic inheritance for yield components. The results showed that heterosis for yield per plant, the number of pods per plant and number of seeds per pod were high, with means 32.77, 24.49 and 15.71%, respectively. Diallel analysis showed that both additive and dominant effects were significant for yield and yield components. All traits, except for 1 000-seed weight, were significant for bl mean squares and exhibited directional dominance. Dominant genes had positive effects on yield per plant, pods per plant and 1000-seed weight, and negative effects on seeds per pod （r=-0.86, -0.62, -0.41, and 0.47, respectively）. Narrow-sense heritability for yield per plant, pods per plant, and 1 000-seed weight and seeds per pod were 66, 31, 46 and 78% for the four traits, respectively. The Fl hybrids showed considerable yields compared to B. napus cultivars when B. napus cultivars and resynthesized rapeseeds were used as parents （NR hybrids）, with many more pods per plant and lower seeds per pod compared with the rapeseed cultivars, indicating that the resynthesized rapeseed may be applicable in current hybrid breeding programs.

Genetic Dissection of Net Effects Between Yield and Its Components in Sea Island Cotton (Gossypium barbadense L.)

The number of bolls, individual boll weight, and lint percentage are three important yield components of lint yield of cotton. In the present study, nine parents, twenty F1, and twenty F2 crosses of intraspecific hybrids of sea island cotton （Gossypium barbadense L.） were grown at Tarim University, Alar, Xinjiang, China, in 2000 and 2001. Lint yield and its three component traits were measured and analyzed by an extended conditional mixed linear model approach. Lint percentage made the largest contribution to additive, additive x environment, and dominance x environment variations for lint yield. The contribution ratios of number of bolls, individual boll weight, and combined contribution of these two traits to additive x environment and dominance x environment variations for lint yield were not statistically significant. Lint yield of different parents could be affected differently by lint percentage. Lint yield of some parents was closely correlated with lint percentage, whereas for other parents, the behavior of individual boll weight and number of bolls played much more important roles on lint yield than that of lint percentage. It was shown by the conditional and conventional predicted additive x environment interaction effects of parents that the environment condition could influence different parents with varied effects.

Nutrient deficiency limits population development,yield formation,and nutrient uptake of direct sown winter oilseed rape

Direct-sowing establishment method has great significance in improving winter oilseed rape（Brassica napus L.） production and guaranteeing edible oil security in China. However, nutrient responses on direct sown winter oilseed rape（DOR） performance and population development dynamic are still not well understood. Therefore, five on-farm experiments were conducted in the reaches of the Yangtze River（RYR） to determine the effects of nitrogen（N）, phosphorus（P）, and potassium（K） deficiencies on population density, dry matter production, nutrient uptake, seed yield, and yield components of DOR plants. Four fertilization treatments included the balanced NPK application treatment（NPK, 180 kg N, 39.3 kg P, 100 kg K, and 1.8 kg borax ha–1） and three nutrient deficiency treatments based on the NPK treatment, i.e., –N, –P, and –K. The results indicated that DOR population density declined gradually throughout the growing season, especially at over-wintering and pod-development stages. Nutrient deficiency decreased nutrient concentration in DOR plants, limited dry matter production and nutrient uptake, and thereby exacerbated density reduction during plants growth. The poor individual growth and reduced population density together decreased seed yield in the nutrient deficiency treatment. Averaged across all the experiments, seed yield reduced 61% by N deficiency, 38.3% by P deficiency, and 14.4% by K deficiency. The negative effects of nutrient deficiency on DOR performances followed the order of –N–P–K, and the effects were various among different nutrient deficiencies. Although N deficiency improved DOR emergence, but it seriously limited dry matter production and nutrient uptake, which in turn led to substantial plants death and therefore resulted in a very low harvested density. The P deficiency significantly reduced initial density, limited plants growth, and exacerbated density reduction. The K deficiency mainly decreased individual growth and yield, but did not affect density dynamic. Our results highlighted the importance of balanced NPK application in DOR production, suggesting that management strategy of these nutrients should be comprehensively considered with an aim to build an appropriate population structure with balanced plant density and individual growth.

Effects of deficit irrigation with saline water on spring wheat growth and yield in arid Northwest China

Field experiments were conducted in 2008 and 2009 to study the effects of deficit irrigation with saline water on spring wheat growth and yield in an arid region of Northwest China. Nine treatments included three salinity levels sl, s2 and s3 （0.65, 3.2, and 6.1 dS/m） in combination with three water levels wl, w2 and w3 （375, 300, and 225 mm）. In 2008, for most treatments, deficit irrigation showed adverse effects on wheat growth; meanwhile, the effect of saline irrigation was not apparent. In 2009, growth parameters of wl treatments were not always optimal under saline irrigation. At 3.2 and 6.1 dS/m in 2008, the highest yield was obtained by wl treatments, however, in 2009, the weight of 1,000 grains and wheat yield both followed the order w2 〉 wl 〉 w3. In this study, spring wheat was sensitive to water deficit, especially at the booting to grain-filling stages, but was not significantly affected by saline irrigation and the combination of the two factors. The results demonstrated that 300-mm irrigation water with a salinity of less than 3.2 dS/m is suitable for wheat fields in the study area.

Influence of water potential and soil type on conventional japonica super rice yield and soil enzyme activities

We carried out a pool culture experiment to determine the optimal water treatment depth in loam and clay soils during the late growth stage of super rice. Three controlled water depth treatments of 0-5, 0-10 and 0-15 cm below the soil surface were established using alternate wetting and drying irrigation, and the soil water potential （0 to -25 kPa） was measured at 5, 10 and 15 cm. A 2-cm water layer was used as the control. We measured soil enzyme activities, root antioxidant enzyme activities, chlorophyll fluorescence parameters, and rice yield. The results showed that the 0-5-cm water depth treatment significantly increased root antioxidant enzyme activities in loam soil compared with the control, whereas soil enzyme activities, chlorophyll fluorescence parameters and yield did not differ from those of the control. The 0-10- and 0-15-cm water depth treatments also increased root antioxidant enzyme activities, whereas soil enzyme activities, chlorophyll fluorescence parameters and yield decreased. In clay soil, the soil enzyme activities, root antioxidant enzyme activities, chlorophyll fluorescence parameters, and yield did not change with the 0-5-cm water treatment, whereas the 0-10- and 0-15-cm water treatments improved these parameters. Therefore,the appropriate depths for soil water during the late growth period of rice with a 0 to -25 kPa water potential were 5 cm in loam and 15 cm in clay soil.

Molecular Mapping of QTLs for Yield and Yield-Related Traits in Oryza sativa cv Swarna × O. nivara (IRGC81848) Backcross Population

Advanced backcross QTL analysis was used to identify QTLs for seven yield and yield-related traits in a BC2F2 population from the cross between a popular Oryza sativa cv Swarna and O. nivara IRGC81848. Transgressive segregants with more than 15% increased effect over Swarna were observed for all the traits except days to heading and days to 50% flowering. Thirty QTLs were detected for seven yield and yield-related traits using interval and composite interval mapping. Enhancing alleles at 13 (45%) of these QTLs were derived from O. nivara, and enhancing alleles at all the QTLs for stem diameter and rachis diameter were derived from O. nivara. Three stem diameter QTLs, two rachis diameter QTLs and one number of secondary branches QTL identified by both Interval and composite interval mapping contributed more than 15% of the total phenotypic variance. The QTL epistasis was significant for stem diameter and plot yield. The most significant QTLs qSD7.2, qSD8.1 and qSD9.1 for stem diameter, qRD9.1 for rachis diameter and qNSB1.1 for number of secondary branches are good targets to evaluate their use in marker-assisted selection. O. nivara is a good source of novel alleles for yield related traits and reveals major effect QTLs suitable for marker-assisted selection.

Effects of UV-B Radiation and Water Stress on Soybean Yield

Soybean Dongnong 47 was subjected to the experiments of increasing UV-B radiation and water stress on soybean yield components in different growth periods. The results showed that 100-seed weight greatly increased during the early stage of pod filling in the treatment of weak UV-B radiation, seed number per plant as well as seed weight per plant and Dongnong47 yield also increased, while the yield and yield components of Dongnong47 during the blossom to mature period were negatively affected in the treatment of intensive UV-B radiation. 100-seed weight of Dongnong47 all increased in the double factor treatments of UV-B radiation and water stress, with the drought intensified, seed number per plant, seed weight per plant and yield of Dongnong47 decreased, the change of 100-seed weight were various and the antagonistic action of UV-B radiation and water stress were related with their intensity.

Effect of Reaction-Finished Solution of Hydrochar(HRFS)Application on Rice Grain Yield and Nitrogen Use Efficiency in Saline Soil

We conducted a pot experiment to examine the feasibility of applying a reaction-finished solution of hydrochar(HRFS)to enhance rice production in a saline soil.With this purpose,HRFS was applied(0,10,20,40,60,80 and 100 mL/pot)and rice yield and nitrogen(N)use efficiency(NUE)were determined.HRFS application significantly(P<0.05)increased rice grain yield by 19.6%-30.0%compared to the control treatment(CKU,with N but without HRFS addition).Moreover,HRFS application promoted plant height and straw biomass of rice.Increases of rice yield were mainly achieved by increases in the number of panicles and grains per panicle.Compared with the CKU treatment,the NUE of HRFS amendments significantly(P<0.05)increased by 56.3%-71.7%.This indicated that the improvement of NUE was one of the mechanisms to improve rice grain yield with HRFS amendment.The results of regression analysis showed that there was a positive relationship(R^(2)=0.8332)between rice yield and HRFS application rate within an appropriate range.The highest rice yield was recorded with the HRFS application of 40 mL/pot,but a further increase in HRFS application rate appeared to reduce rice yield.Based on the results of this pot study,HRFS application can increase rice yield in a saline soil by regulating its yield components and enhancing NUE.However,impact of HRFS on these variables showed a“dose effect”.

Perspective on oil flax yield and dry biomass with reduced nitrogen supply

Field experiment was arranged in a randomized complete block design to determine effects of nitrogen(N)application levels(J0:150 kg/hm^2,J1:120 kg/hm^2,J2:90 kg/hm^2,J3:60 kg/hm^2)on regulating dry biomass accumulation,allocation and translocation,and grain yield of oil flax during 2018 cropping season.Significant promotion was observed in dry matter during accumulation stage of oil flax,when N rate was reduced by 40%(from 150 to 90 kg/hm^2).Under J2 treatment,translocation of dry matter from vegetative organs to pod increased by 38.46%and 61.54%respectively,when compared with J1 and J0 treatment Dry matter distribution proportion of pod at maturity increased 4.47%-7.61%,contribution rate of leaf to grain upgraded 5.09%-8.77%,and number of effective pods and grains per pod increased by 27.16%-45.38%and 6.49%-26.59%respectively compared to other treatments.As a result,seed yield of oil flax under J2 treatment was 2.23%-18.21%higher than those of other treatments.Our study recommended 90 kg/hm^2 as the best N fertilizer level to improve seed yield of oil flax.