Split-plot Experiment Research Articles

Grassland productivity and diversity changes in responses to N and P addition depend primarily on tall clonal and annual species in semiarid Loess Plateau

Ecological benefits and production of grassland on the Loess Plateau are limited by low soil N and P availability. Extraneous N and P fertilization is an efficient management measure to enhance grassland productivity and accelerate grassland restoration. However, biodiversity decline and species loss induced by N and P addition must be noticed. Two grassland communities dominated by tall clonal grass (TCG) and tall clonal forb (TCF) on Loess Plateau were selected. A two-year split-plot experiment (main-plot: 0, 25, 50, and 100 kgN ha−1 yr−1; subplot: 0, 20, 40 and 80 kg P2O5 ha−1 yr−1) was conducted to evaluate the effect of N and P addition on aboveground net primary production (ANPP), light availability, diversity and functional group composition. N and P addition slightly increased ANPP mainly benefiting from clonal species and had few effects on species composition and diversity due to the deficient precipitation during growing season in 2017. However, N or P addition alone resulted in significant ANPP increase, and adding N and P together had larger effects in 2018. The changes in ANPP and diversity after P alone addition were driven by legumes. The ANPP responses to 50 and 100 kg N ha−1 yr−1 combined with P addition in 2018 were mainly driven by pronounced increases in tall clonal or annual species. This large shift of species composition caused diversity decline only in TCF community. The extent of diversity decline was significantly correlated with the degree of light availability reduction. Diversity decline in TCF was a result of strong and uniform light availability reduction induced by increased tall annual forb. Tall clonal and annual species are the key functional groups that drive changes in productivity and diversity in the two communities. The optimum N and P amount to tradeoff productivity improvement and diversity decline were 50 kg N ha−1 yr−1 and 20 kg P2O5 ha−1 yr−1 combination for TCG and 25 kg N ha−1 yr−1 and 20 kg P2O5 ha−1 yr−1 combination for TCF.

Effect of Nitrogen and Variety on Agronomic Performance of Rhodes Grass (Chloris gayana Kunth) in the Sudan

An experiment was conducted in Shambat (2016-2017) in the demonstration farm of the College of Agricultural Studies, Sudan University for Science and Technology, to study the effect of variety and nitrogen fertilization on the agronomic performance of Rhodes grass. Two Rhodess grass varieties (Fine cut and Reclaimer) and 2 nitrogen doses plus control were studied across seven cuts. The treatments were replicated four times in split plot experiment with fertilizer doses assigned to the main plots and the varieties to the sub-plots. The data collected included forage yield, plant height and days to 50% flowering.

Changes in biochemical properties of tomato (cv.240) affected by combination of blue/red optical spectra and Calfomyth spray (Ca and P)

The levels of antioxidant activity and vitamins can change with varying ratios of different wavelengths. This study was conducted as a pot experiment under soilless culture conditions in order to investigate the interactive effects of light supplementation and nutrition (calfomyth solution) on some qualitative traits of tomato fruit. The research was carried out as a split-plot experiment based on a completely randomized design with three light treatments including without supplementary light (control), 60% red light+40% blue light and 90% red light+10% blue light. There were two nutritional treatments including no spraying with calfomyth as commercial fertilizer and foliar application with a concentration of 2 mg/L in three replicates. According to the results, the amounts of vitamin C (16.1 mg/g FW fruit), soluble solids (12.33 mg/g FW fruit), and lycopene (2.95 mg/g FW fruit) were all uppermost by the effect of a higher percentage of red light treatment. Higher percentage of the blue light resulted in the highest leaf chlorophyll content (38.4 mg/g FW leaf), but supplementary light treatments had no significant effects on the titratable acidity. Nutrition (calfomyth foliar application) showed positive impacts on all treatment traits compared to control. Beta-carotene content was affected by none of the treatments with no significant differences. According to this research, it can be expected that the use of complementary light treatments and calfomyth foliar spray may have positive effects on most of the qualitative traits in tomato fruit (cv. 240). Keywords: biochemical properties, tomato, optical spectra, calfomyth, antioxidant, lycopene, phytochrome DOI: 10.25165/j.ijabe.20201305.5797 Citation: Ajdanian L, Aroiee H, Azizi M, Babaei M. Changes in biochemical properties of tomato (cv.240) affected by combination of blue/red optical spectra and Calfomyth spray (Ca and P). Int J Agric & Biol Eng, 2020; 13(5): 79–84.

Effects of reduced nitrogen and suitable soil moisture on wheat (Triticum aestivum L.) rhizosphere soil microbiological, biochemical properties and yield in the Huanghuai Plain, China

Soil management practices affect rhizosphere microorganisms and enzyme activities, which in turn influence soil ecosystem processes. The objective of this study was to explore the effects of different nitrogen application rates on wheat (Triticum aestivum L.) rhizosphere soil microorganisms and enzyme activities, and their temporal variations in relation to soil fertility under supplemental irrigation conditions in a fluvo-aquic region. For this, we established a split-plot experiment for two consecutive years (2014–2015 and 2015–2016) in the field with three levels of soil moisture: water deficit to no irrigation (W1), medium irrigation to (70±5)% of soil relative moisture after jointing stage (W2), and adequate irrigation to (80±5)% of soil relative moisture after jointing stage (W3); and three levels of nitrogen: 0 kg ha−1 (N1), 195 kg ha−1 (N2) and 270 kg ha−1 (N3). Results showed that irrigation and nitrogen application significantly increased rhizosphere microorganisms and enzyme activities. Soil microbiological properties showed different trends in response to N level; the highest values of bacteria, protease, catalase and phosphatase appeared in N2, while the highest levels of actinobacteria, fungi and urease were observed in N3. In addition, these items performed best under medium irrigation (W2) relative to W1 and W3; particularly the maximum microorganism (bacteria, actinobacteria and fungi) amounts appeared at W2, 5.37×107 and 6.35×107 CFUs g−1 higher than those at W3 in 2014–2015 and 2015–2016, respectively; and these changes were similar in both growing seasons. Microbe-related parameters fluctuated over time but their seasonality did not hamper the irrigation and fertilization-induced effects. Further, the highest grain yields of 13 309.2 and 12 885.7 kg ha−1 were both obtained at W2N2 in 2014–2015 and 2015–2016, respectively. The selected properties, soil microorganisms and enzymes, were significantly correlated with wheat yield and proved to be valuable indicators of soil quality. These results clearly demonstrated that the combined treatment (W2N2) significantly improved soil microbiological properties, soil fertility and wheat yield on the Huanghuai Plain, China.

Effects of Sowing Date and Chitosan on Some Characters of Canola (Brassica napus L.) Genotypes

Changes in the environment that are associated with different sowing dates can be expected to alter canola (Brassica napus L.) growth and development. The objective of this work was to study the effect of sowing date and chitosan on some characters of canola genotypes. Five genotypes (RGS003, Sarigol, Zafar, Dalgan, and Julius) were sown in three sowing dates (October 7, 17, and 27), for two years (2014–2015 and 2015–2016). A factorial split-plot experiment was conducted in a complete randomized blocks design with three replications, where the sowing dates and the two levels of chitosan (0 [control] and 0.2% concentrations) were allotted to main plots and the genotypes were allotted to subplots. The ANOVA revealed that the main effects of sowing date, chitosan and genotype were significant for almost all measured characters. In addition, the interaction effect of sowing date and genotype was significant for plant height, number of silique in shoots, number of seeds per main silique, 1000-seed weight and oil yield. The seed and oil yields in the third sowing date were reduced by 0.46 and 0.49%, respectively, compared to the first sowing date. The results of the present study indicated that early sowing date and chitosan application had positive effects on the measured characters. Cluster analysis divided the cultivars into two groups. Also, the PCA revealed that the three first PC confirmed about 98% of the total variance among the studied genotypes.

Combining the phosphate solubilizing microorganisms with biochar types in order to improve safflower yield and soil enzyme activity

ABSTRACT Soil amendment with biochar could increase soil microbial activity and biomass. This study contributes to an understanding of the synergistic effects of biochar and phosphate solubilizing microorganisms on safflower yield and soil microbial activity enhancement. In the split plot experiments that repeated in two years, the main factor was biochar types included cow manure, wheat straw, wood biochar and control. The sub factors were phosphate solubilizing microorganisms included the mycorrhizal fungi (Glomus etunicatum and G. mosseae), Bacillus lentus, Pseudomonas fluorescence and control. The highest levels of dehydrogenase, urease activity and microbial biomass carbon were obtained from the cow manure biochar. The maximum activity of acid phosphatase was in the plots inoculated by P. fluorescence in all treatments, whether using or not using biochar. The grain yield of plants inoculated with B. lentus and P. fluorescence was in the same statistical group. The highest grain yield equal to 1527 kg/ha was obtained when using cow manure biochar. According to the results, the application of cow manure biochar and phosphate solubilizing microorganisms, especially mycorrhiza species, can be recommended for improving soil biological traits and safflower yield traits.

Effects of Sowing Date, Cultivar and Chitosan on Quality and Quantity of Rapeseed (Brassica napus L.) Oil

The effects of cultivars and sowing date along with chitosan application on oil yield, yield components and fatty acids of rapeseed (Brassica napus L.), were investigated. Five cultivars (RGS003, Sarigol, Zafar, Dalgan, and Julius) were sown in three sowing dates (October 7, 17, and 27), for two years (2014-2015 and 2015-2016). A factorial split-plot experiment was conducted in a complete randomized blocks design with three replications, where the sowing dates and the two levels of chitosan (0 {control} and 0.2% concentrations) were allotted to main plots and the cultivars were allotted to subplots. ANOVA revealed a significant (P<0.01) effects of the three studied factors on studied characters. Sarigol cultivar had the highest amount of seed yield (4447 kg ha-1), seed oil (45.51%) and biological yield (15672 kg ha-1). These characters had the highest values in the first sowing date. Application of chitosan solution increased the amount of seed yield from 3916 to 4233 (kg ha-1), seed oil from 44.83 to 45.24% and biological yield from 13628 to 14797 (kg ha-1). Delayed sowing dates, increased the linolenic and erucic acids and decreased the palmitic, oleic, and linoleic acids. The results of the present study indicated that early sowing date and chitosan application had positive effects on the quantity and quality of rapeseed oil. Cluster analysis divided the cultivars into two main clusters. The PCA revealed that the three first PC confirmed about 96% of the total variance among the studied cultivars.

Responses of leaf functional traits of dominant plant species in grassland communities to nitrogen and phosphorus addition in loess hilly-gully region.

To analyze plant functional traits of dominant species to nitrogen and phosphorus addition, three species (Bothriochloa ischaemum, Stipa bungeana, and Lespedeza davurica) were selected in the loess hilly-gully region. A split-plot experiment which included three N treatments (0, 50, and 100 kg N·hm-2·a-1) and three P treatments (0, 40, and 80 kg P2O5·hm-2·a-1) was conducted. At the fast-growing stage, leaf length, leaf width, specific leaf area, leaf dry matter content, leaf N content, leaf P content, and leaf N:P were measured. Results showed that under 50 and 100 kg N·hm-2·a-1 treatments, leaf length and width of B. ischaemum increased significantly by 35.3% and 64.4%, respectively, while only the leaf length of S. bungeana and the leaf width of L. davurica increased significantly by 58.8% and 33.9%, respectively. Leaf dry matter content of the three species decreased significantly by 10.7%, 15.3% and 11.2%, respectively. Leaf N content and N:P of B. ischaemum and S. bungeana increased significantly by 23.0% and 99.2%, 45.8% and 96.9%, respectively, compared with unfertilized treatments. Under 40 and 80 kg P2O5·hm-2·a-1 treatments, leaf length, leaf width and specific leaf area of L. davurica increased significantly by 56.9%, 41.4% and 19.6%, respectively, while leaf dry matter content decreased significantly by 14.9%. Leaf P content of three species increased significantly by 96.7%, 110.9% and 238.4%, while the N:P decreased significantly by 45.8%, 42.8% and 53.7%, respectively, compared with those under unfertilized. Under 50 kg N·hm-2·a-1 treatment, compared with no P application, leaf length and leaf width of L. davurica and leaf P content of the three species significantly increased, and leaf N content of B. ischaemum and S. bungeana decreased significantly at 40 and 80 kg P2O5·hm-2·a-1 treatments. Under 100 kg N·hm-2·a-1 treatment, leaf length of B. ischaemum and S. bungeana, leaf width of L. davurica and leaf P content of three species significantly increased, while leaf N content of B. ischaemum decreased significantly after P application. In summary, functional traits of dominant species showed significant responses to short-term nitrogen and phosphorus addition, with the different responses were mainly related to species traits and fertilization levels. Such difference reflected plant adaptation to habitat changes. The divergent responses of different species to nitrogen and phosphorus addition played an important role in maintaining diversity and stability of grassland communities.

Screening of different Iranian ecotypes of cannabis under water deficit stress

In order to evaluate the tolerance to water deficit stress of 47 different ecotypes of Iranian cannabis (Cannabis sativa L.), a split plot experiment based on a randomized complete block design with two replications was conducted at the Research Station of the University of Tehran in 2015. Ecotypes were considered as the minor factor and water deficit stress was considered as the major factor. There were included 100% (as the control) and 50% evapotranspiration of Etc. Shrubs were harvested after the end of the flowering period of male and female plants. Dry weight was measured. The water use efficiency, yield stability index, stress tolerance index, geometric mean productivity, stress susceptibility index, tolerance index, and mean productivity indices were obtained through dry matter yield under stress and normal conditions. The results showed that, in general, water deficit stress reduced dry matter production. A high correlation was observed between dry matter yield and drought tolerance indices. Geometric mean productivity, stress tolerance index, and mean productivity indices, which had high positive correlations with yield of genotype in stress environments and yield of genotype in non-stress environments, were good indicators of isolating and distinguishing ecotypes in terms of their reaction to water deficit. Qzv-02, Sav-01, Ney-01, Rash-01, and Bsh-01 ecotypes had the highest water use efficiency and the highest yield under water deficit stress.

Can fertilization be a driver of rubber plantation intensification?

Improving the productivity of existing rubber plantations is necessary to cope with the growing demand for natural rubber (NR) while limiting the environmental and social impacts linked to the expansion of rubber cultivation at the expense of natural ecosystems and food crops. The effect of fertilization on NR yield is still unclear and is poorly documented particularly in Thailand, the world leader in NR production. Hence, the main objective of this study was to re-assess the possible effects of fertilization on the yield of intensively managed rubber plantations in Thailand. Our main hypothesis was that the effect of fertilization would be higher with intensive latex harvesting practices (high tapping frequency with ethylene stimulation). To test this hypothesis, we set-up a split-plot experiment with four fertilization doses (T1, no fertilization, T2, T3, T4, respectively low, medium and high doses of NPK fertilizer) and two tapping systems (S/2 d2 with and without ethylene stimulation). Here, we present the results of the first three years on dry rubber yield, latex metabolism assessed with the latex diagnosis method, and latex and rubber properties related to their technological properties. Our results showed a positive effect of fertilization on yield from the first year, but the effect was only statistically significant (p < 0.05) in the third year. The maximum effect of fertilization (+13%) compared to the control treatment (T1) was obtained with the highest dose of fertilizer (T4). Cumulatively over the 3-year period, the increase in yield was +5% with the T2 dose, and +8% with the T3 and T4 dose. Contrary to our main assumption, we observed no interaction between fertilization and ethylene stimulation. Latex diagnosis revealed that the effect of fertilization on yield was linked with a direct effect on latex metabolism mainly through an increase in inorganic phosphorus content (Pi). Finally, we observed no detrimental effect of the fertilizer treatments on latex and rubber quality. We can thus conclude that increasing latex yield through fertilization combined with intensive tapping does not involve any identified risks for the quality of rubber. Taken together, our results demonstrate that fertilization can help increase the yield of rubber plantations where intensive latex harvesting is practised. However, in a context of low NR prices for rubber farmers, the economic return of a +8% increase in yield is questionable. Our trial is continuing to assess the long term effects of the fertilization on yield as well as on the growth and nutritional status of the trees, and the nutrient balance of the plantation.

Strategic timing and rate of sulphur fertilization improves sulphur use efficiency in subirrigated greenhouse-grown chrysanthemums

Industry standards for nutrient delivery to greenhouse-grown ornamentals are typically in excess of the plant’s needs and can be reduced without causing adverse effects. Previous studies have reduced the level of specific nutrients or suite of nutrients over the entire crop cycle or at the onset of reproductive growth. Here, two split-plot experiments (four blocks each) were conducted with subirrigated, potted, disbudded chrysanthemums (Chrysanthemum morifolium Ramat.) grown under greenhouse conditions with sulphate treatment (2.25 mmol L−1 S supplied continuously over the crop cycle in experiment 2 only and 2.25, 1.125, or 0.5625 mmol L−1 S interrupted at inflorescence emergence) as the main plot and cultivar (‘Olympia’ and ‘Covington’) as the sub-plot. Morphological characteristics of plants with fully-expanded inflorescences were unaffected by decreasing S delivery over the crop cycle. Dry mass (DM) yields and S budgets revealed that supply-based S use and S uptake efficiencies increased markedly in both cultivars with decreasing S delivery. Minor amounts of reduced-S, rather than sulphate, were lost from leaves of ‘Covington’ during inflorescence development. High quality chrysanthemums had sufficient leaf-S (0.17%–0.23% DM) at inflorescence emergence even with the lowest S supply, which would deliver an approximate 87.5% reduction in S over the crop cycle compared with industry standards. The primary mechanism to obtain sufficient S for the growth of chrysanthemums in these studies was increased uptake efficiency.

Fruit and Juice Metric Characteristics of Two Yellow Passion Fruit (Passiflora edulis Degener) Genotypes Grown in Southeastern Nigeria

An investigation was undertaken to determine the fruit and juice metric traits of fresh fruits obtained from two yellow passion fruit genotypes grown in south-eastern Nigeria in two seasons. The passion fruit genotypes (Conventional and KPF-4) received 0, 10, 20, 30, 40 t ha-1 poultry manure (PM) rates in 2014 and 0, 10, 20 t ha-1 PM, 5 t ha-1 PM + 200 kg ha-1 NPK 15:15:15, 10 t ha-1 PM + 200 kg ha-1 NPK and 400 kg ha-1 NPK in 2016. Ten ripe and freshly dropped fruits in 2015 and 2017 were picked and taken to the laboratory. Fruit and juice metric traits (such as fruit length, circumference, pulp weight, juice volume and weight) were measured. Data collected were subjected to analysis of variance following the procedure for split-plot experiment in completely randomized design. KPF-4 significantly (p&lt;0.05) produced longer, wider and heavier fruits than the Conventional in 2015 whereas in 2017 all the fruit metric traits did not significantly (p&gt;0.05) differ between the genotypes. Juice volume (682 ml) and pulp fresh weight (942 g) in 2015 were significantly highest in the Conventional when they received 20 or 40 t ha-1 PM. Application of 10 t ha-1 PM + 200 kg ha-1 NPK in 2016 enhanced the production of highest juice volume (723 ml) and pulp fresh weight (770 g) in the Conventional. Juice percentage and fruit metric traits of yellow passion fruit could be enhanced with the application 20 t ha-1 PM, considering lesser cost of PM procurement, or combined application of 10 t ha-1 PM + 200 kg ha-1 NPK.

Nitrogen applications made close to silking: Implications for yield formation in maize

Given the growing interest in late N applications made at vegetative stages just prior to silking (R1), there is a need to characterize how yield formation in maize responds when a small amount of N is applied early in the season, and the bulk of N fertilizer is delayed to vegetative stages close to R1. To understand how the development of kernel number (KN) and weight (KW) are affected by this shift in fertilizer N availability, a two-year split-plot experiment was conducted. The main plot factor consisted of five pre-plant N rates (in kg N ha−1: 0, 80, 140, 200, 260) and a split-plot factor consisted of an N application at V13, 9 or 11 days before R1. Split-plots either received no in-season N or a non-limiting N rate such that the total N applied equaled 260 kg N ha−1. At 0 kg N ha−1 pre-plant, N stress significantly reduced radiation use efficiency and crop growth rate during the critical period around R1, which in turn reduced potential kernel number (pKN) and potential kernel sink capacity (pKW) by the start of the linear phase of grain-fill. When 80 or 140 kg N ha-1 was applied pre-plant, N stress was not detected at or prior to the start of the linear phase of grain-fill, but reductions in KN and/or KW occurred later, within 30–40 days of R1. The V13 N application increased grain yield at the lower pre-plant N rates by either: i) preventing reductions in pKN and pKW at the start of the linear grain-fill period or by ii) better maintaining KN and KW during the linear phase of grain-fill. At maturity grain yield in the split-N treatments receiving 260 kg N ha−1 at V13 was statistically similar to 260 kg N ha−1 applied pre-plant, but maize N uptake increased in response to the V13 N application only once the crop became N deficient. Overall, these results provide a physiological understanding of the impact of late N applications on yield formation in maize and can assist in the further development of N management strategies that better synchronize fertilizer N supply with crop N demand.

Effect of the Application of Foliar Selenium on Canola Cultivars as Influenced by Different Irrigation Regimes

Selenium (Se) is an essential micro-nutrient element for animals and human, which also has some beneficial roles in many plant species. This study aimed to evaluate the application of foliar Se on canola cultivars under different irrigation regimes. The study was carried out in two consecutive years, in the form of a factorial split plot experiment, based on an RCB design with three replications. Sodium selenate solution was sprayed on the leaves of 6 winter canola exposed to 3 different irrigation regimes. The results revealed that most of the studied traits were affected by foliar selenium, especially seed yield, seed oil yield, leaf proline content and leaf chlorophyll a content. Under drought stress conditions, foliar selenium caused a significant increase in seed yield, seed oil yield, and the relative water content of leaves. According to partial regression analysis, foliar selenium changed the nature of relationships governing the traits, especially under drought stress conditions. The results showed that, selenium reduced the effects of drought stress through improving the relative water content of the leaves. Therefore, foliar selenium can be a useful strategy to achieve sustainable agriculture, especially under water deficit conditions.

Bio-removal of Zn from contaminated water by using green algae isolates

Abstract Wastewater is one of the main sources of the heavy metals. These hazardous compounds find their way through water resources and consequently threaten human being’s life and other living organisms. Several solutions have been proposed to address this issue. Nowadays, using algae to eliminate these elements is the most effective method in terms of cost and time in comparison with other biological and chemical methods. This research was carried out to evaluate the capability of native algae species in Zn removal from industrial sewage. A split plot (in time) experiment which consists of one main factor (time) and three subsidiary factors including basic solution at two levels, algae isolates at three levels and Zn concentration at three levels of 0 (blank solution), 10, and 100 mg/L from ZnSO4.7H2O) was conducted. Firstly, the dominant and fast growing algae isolates were separated from the depth of 20 cm, in Botanical Garden of Tabriz University and Khalatpoushan Research Station, Tabriz, Iran. Then, three efficient isolates were selected for the second phase of the experiment. After sufficient growth of the superior selected algae isolates on minimal medium, algal suspension was prepared and the population adjusted to 3×104 cell per mL, and then the suspension was transferred to the Erlenmeyer flasks (100 mL) including Tabriz wastewater and basic solution. OD, pH and Zn concentration was measured in intervals of 3, 6, 9, 15 and 20 days. Based on the results, the highest Zn absorption by two algae isolates was recorded in the minimum medium with the blank solution and in the municipal wastewater with the concentrations of 10 and 100 mg/L which can be concluded that both isolates were capable of eliminating contamination effectively in the natural environment compared to the laboratory condition. At the concentrations of 0 and 10 mg/L, almost all Zn was removed from both medium and at the concentrations of 100 mg/L, approximately 90% of Zn was removed from both culture mediums. Accordingly, it can be concluded that both algal isolates can be considered as a suitable bio-remover for removing Zn form polluted waters.

Bio-fertilizer Improves Physio-biochemical Characteristics and Grain Yield of Safflower (Carthamus tinctorius L.) under Drought Stress

Water shortage can affect growth and productivity of safflower. Application of beneficial soil microorganisms as an alternative for chemical fertilizers is effective approach to improve environment health and soil productivity as well as plant growth and development. This study was conducted as a split plot experiment (using RCB design) in field conditions to evaluate the effect of plant growth promoting rhizobacteria (PGPR) on some physiological and biochemical traits of safflower under water stress in 2016. Results indicated that some enzyme activities such as SOD, CAT, GPX and MDA were induced under water stress conditions. Moreover, dityrosine, proline and ABA contents were also enhanced under water deficit condition. In contrast, water stress negatively affected the LWC, Fv/Fm, plant biomass, grain yield, oil and protein percentage and grain yield. However, application of biological fertilizers especially Azotobacter + Azospirillum positively improved those traits.

Influence of sowing dates and zinc levels on yield and yield components of wheat (Triticum aestivum)

In order to evaluate the influence of sowing dates and zinc levels on yield and yield components of wheat (Triticumaestivum L.) in Ahwaz, a split-plot experiment including three sowing dates (29 Nov, 14 and 30 Dec) in main plots and five zinc levels (0 (control), 10, 20, 30 and 40 kg/ha) in sub plots were implemented with three replicates in research farm of Agricultural Sciences and Natural Resources University of Khuzestan, Ahwaz, Iran. The mean comparison of sowing dates showed that the maximum grain yield was related to sowing date of 29 Nov and the minimum was obtained from 30 Dec. The mean comparison of zinc levels showed that the highest grain yield was in 30 kg/ha zinc and the lowest was in 0 kg/ha zinc. The mean comparison of interaction effect showed that the maximum grain yield was produced from 29 Nov and 30 kg/ha zinc and the minimum amount was related to 30 Dec and 0 kg/ha zinc. In general, in all sowing dates, zinc application increased grain yield of wheat.

Impact of Abiotic Stress on Quality Traits of Maize Forage at Two Growth Stages

Maize (Zeamays L.) forage quality traits are reported to show varying responses to abiotic stress. Four trials were conducted in Sudan (Africa) during the summer and winter seasons (2013 – 2014) at two locations: Shambat (normal soils) and Soba (salt affected soils) to investigate the effects of abiotic stress on the nutritive value of maize forage. In each trial nine maize genotypes were studied under two watering regimes arranged in split plot experiment in randomized complete block design. The compound effect of salt, water and heat stresses created by the combination of locations, seasons and watering regimes were used to investigate the effect of abiotic stress on forage quality at silk initiation and dough growth stages. Character associations under stressed and none stressed conditions were studied. NDF, ADF, CP, forage yield and related traits were measured. Abiotic stress significantly lowered the nutritive value in terms of crude protein, digestibility and intake potential. Digestibility under stressed condition was slightly improved as growth stage advanced from silk initiation to dough stage. Correlations under non stress conditions between forage yield and quality traits were either favorable with NDF and weak or insignificant with ADF and CP. Under stress conditions, similar trend generally exists apart from the unfavorable correlation of CP with each of yield and ADF, in addition to earliness with NDF. The compound effect of salt, water and heat stresses have adverse impact on the nutritive value of maize forage. Varieties combining high performance in quality and forage yield could be developed under non-stressed or stressed conditions.

Prediction of Seasonal Frost Heave Behavior in Unsaturated Soil in Northeastern China Using Interactive Factor Analysis with Split-Plot Experiments and GRNN

Few studies of frost heave mechanisms have considered multifactor interactions, particularly in unsaturated saline soils typical of northeastern China. We collected soil samples in western Jijin Province and assessed their potential frost heave behavior with reference to four controllable factors: soluble salt content (CSS), compactness (C), temperature (T), and water content (WC) using a two-level split-plot experiment. The resulting frost heave ratio was between −0.6% and 2.1%. Analysis of variance showed that water content, compactness, and temperature had significant effects on frost heave behavior, with water content having the strongest correlation (factor coefficient of 0.82), while content of soluble salt (CSS) had no significant effect. The interaction factors (products of single factors) CSS × WC and C × WC had significant effects on frost heave behavior. A correlation analysis using these interaction factors with experimental data drawn from previous research showed results consistent with the improved frost heave experiment as the significant effects of single factors on frost heave behavior ranked from WC &gt; C &gt; T and the interaction factors CSS × WC and C × WC gain had significant effects. We then established two generalized regression neural network (GRNN) models based on the single and interaction factors in order to predict frost heave behavior, showing that adding the latter to the input dataset improved the model accuracy. Thus, future research on predicting frost heave behavior in unsaturated saline soils should consider multiple interacting factor for greater accuracy.

Evaluation of drought tolerance of triticale (xTriticosecale Wittm. ex A. Camus) genotypes along with bread wheat and barley genotypes

The effects of drought stress on morphological and yield traits of six different genotypes of triticale along with wheat and barley were studied. The experiment was conducted in agricultural college of Sarayan, University of Birjand in 2016-2017 growing season. Experiment was a split-plot experiment based on randomized complete block design with drought stress in main plots and eight mentioned genotypes in subplots in three replications. Results of analysis of variance and means comparison analysis showed significant and negative effect of drought stress on grain yield and biological yield of all investigated genotypes. There was significant difference among investigated genotypes of triticale, wheat, and barley for grain yield under drought stress at 1 % probability level. Pazh genotype of triticale was found as the most drought tolerance genotype, among all investigated genotypes, based on almost all drought tolerance indexes. The highest significant correlation with grain yield was related to biological yield, harvest index, spike/shoot ratio, height and straw yield. GGE biplot analysis of genotypes based on their Yp and Ys showed that Pazh, Jualino, and Sanabad genotypes of triticale had more trends to Ys principal component than ET-89-11 line, wheat, and barley genotypes, therefore show more tolerance to drought stress.