International Journal of Plant Production
Volume:10 Issue: 4, Oct 2016

Field experiments were conducted in 2005-2006 and 2007-2008 and the data were used to calibrate and validate yield and biomass of AquaCrop Model for canola (Brassica napus l.). The model was calibrated with the first year and then was validated with the second year data. Five water stress treatments at different growth stages were performed including fully irrigated during whole growing period (I1), water stress at vegetative stage in spring (I2), water stress at flowering stage (I3), water stress in grain filling stage (I4) and severe water stress conditions during whole growing period with supplemental irrigation in planting and germination stage (I5). AquaCrop model coefficients were calibrated for I1 in 2005-2006 and the calibrated parameters were used for other treatments in both year. In this simulation model was assessed based on measured values of the water content in root zone, evapotranspiration, canopy cover and final yield and dry matter that the latter are the important trait for the farmers The accuracy of the model in calibration was tested using RMSE, NRMSE and d, which were 0.92 t ha , 12.37% and 0.98 for yield and 0.92 t ha-1, 12.37% and 0.98 for biomass, respectively. The RMSE, NRMSE and d values in 2007-2008 (validation year) were obtained as 0.26 t ha-1, 10.01% and 0.92 for yield and 0.84 t ha-1, 14.93% and 0.92 for biomass, respectively. The result of calibration and validation for volumetric water content was acceptable. AquaCrop model estimated the evapotranspiration acceptable in the first year, while the accuracy of model to predict this parameter decreased for validation. Therefore, the model was calibrated effectively for yield and biomass; however, the results were less satisfactory when it came to the simulation of the severe stress (I5).

An assessment of the nitrogen fertilization efficiency should not only include quantitative and qualitative yield changes, but also an analysis of formation some indicators such as: N harvest index (NHI), N use efficiency (NUE), N utilization efficiency (NUtE), N agronomic efficiency (NAE), N physiological efficiency (NPE) and N apparent recovery fraction (NRF). The objective of the study was the evaluation of spring wheat N fertilization efficiency under soil conditions of Luvic Chernozem. Factors of the experiment were: cultivar (Bombona and Tybalt) and level of N fertilization (0, 60, 90, 120 and 150 kg N ha-1). The application of increasing N rates in the wheat crop raised the grain N from 56 to 92 kg N ha-1 and the aboveground biomass N from 70 to 123 kg N ha-1 and it decreased most of the efficiency indicators. The highest NHI value of 84%, PFNUE of 139.5 kg kg-1, NAE of 32.7 kg kg-1, NPE of 72.2 kg kg-1 and an NRF of 47% were observed for the lowest N rate of 60 kg N ha . The NUtE of 92.8 kg kg-1, was at the highest level on the control plot. Every increase on N rate resulted in a significant decrease in the efficiency indicators. The cultivar factor significantly affected the grain and aboveground biomass N and the NAE, NPE and NRF values. Low rainfall depths during the vegetative period favorably affected the NHI, NUtE, NAE and NPE indicators. On the other hand, excessive rainfall depths limited PFNUE, NAE, NPE and NRF.

The effects of nitrogen (N) addition on productive and physiological traits of Triticum dicoccum were assessed under two N levels (0, unfertilized, and 90 kg N ha−1) in field conditions, in two growing seasons. In the study case, the N supply (90 kg N ha−1) was applied in three-split applications (20% at pre-plant stage, 40% at tillering stage, 40% at stem elongation). In unfertilized conditions, the productive and physiological traits were consistently reduced in comparison with fertilized treatments. Indeed, control plots showed lower grain yield, biomass and protein content (about 42, 44 and 19%, respectively) and lower photosynthetic activity at light saturation level (25%) than fertilized plots. The stomatal conductance was 34.2% and 70.8% lower in unfertilized plots than in fertilized those, in the first and second year, respectively. No significant differences for the Ci/Ca ratio were evident between treatments. Emmer physiological and yield performances were affected by N supply, although the crop plasticity to N availability was emphasized.

Tall fescue and meadow fescue are naturally infected with fungal endophytes, Neotyphodium coenophialum and Neotyphodium uncinatum, respectively. Seed traits are an important measure of the effects of the endophytic fungi which has been less addressed. In this study we used endophyte-infected (EI) and endophyte-free (EF) clones of tall and meadow fescue genotypes in the field to investigate the effects of endophytes on seed production traits and subsequently on seed germination and seedling emergence. Endophyte infection increased the plant seed weight, the number of seeds per plant and the number of panicles per plant in both plant species. Seed germination was not affected by endophytes in tall fescue, while it was improved in endophyteinfected plants of meadow fescue. A negative endophyte effect was detectable for seedling emergence percentage and emergence rate of tall fescue, whereas EI plants of meadow fescue were positively affected by the endophyte for these characteristics. The better performance of EI plants for seed production traits may increase their relative fitness in populations and cause them to be more stable in different environmental conditions.

Increased interests in low-input agriculture in recent years has seen the growing development in the use of commercial biological inoculants to increase the mobilization of key nutrients such as nitrogen (N), phosphorus (P) and potassium (K) to enhance their availability to crop plants. The objectives of this field experiment with tobacco were to determine i) reduced rates of inorganic fertilizer coupled with microbial inoculants that produce plant growth, ii) yield and nutrient acquisition levels equivalent to those with full rates of fertilizers and iii) the minimum level to which fertilizer could be reduced with the use of bioinoculants. The microbial inoculants used were plant growth promoting bacteria viz., Azospirillum, Azotobacter, Bacillus subtilis and Frateuria aurantia alone or a mixture of them in combination with 75% chemical fertilizer. Results showed that supplementing 75% of the chemical fertilizer rate with inoculants produced plant growth, yield and nutrient (N, P and K) acquisition that were statistically equivalent to the full fertilizer rate without inoculants. When inoculants were used in single, double or triple with 75% RDF the beneficial effects were usually not consistent. However, inoculation with the mixture of PGPR (N, P and K mobilizers) at 75% RDF produced significantly superior yield better than the full fertilizer dose without inoculants. Without inoculants use of fertilizer rates lower than the recommended resulted in significantly less plant growth, yield and nutrient uptake. The results suggest PGPR based inoculants can be used and should be further evaluated as components of integrated nutrient management strategies.

The use of efficient and effective nodulating Bradyrhizobia strains considered as an ecologically and environmentally sound management strategy for soybean production. A -yr (2009 and 2010) field experiment was conducted to evaluate the effects of seven indigenous Bradyrhizobium strains, one exotic TAL-102 and three N fertilizer rates, i.e., 25, 50 and 100 kg N ha-1 on the productivity and N2 fixation of rainfed soybean [Glycine max (L.) Merr.] grown in the Himalayan region of Rawalakot Azad Jammu and Kashmir (AJK), Pakistan. The experiment was conducted in a randomized complete block design with three replications. Bradyrhizobium inoculation accelerated plant growth by increasing shoot length (26 47%), root length (45-73%) and shoot dry weight (58-104%). Seed yield in the control was 861 kg ha-1 that significantly increased to 1450–2072 kg ha-1 with Bradyrhizobium strains. Seed yields under indigenous NR20 and NR22 strains was 24 and 28% higher than that recorded from the exotic TAL-102. Number of nodules, nodules dry weight and acetylene reduction assay with Bradyrhizobium strains were 55–123%, 94–178% and 38–103%, (respectively) higher than the non-inoculated control. The higher N rate (N100) depressed nodulation and N2 fixation. A significant variation in the symbiotic effectiveness and yield potential showed that inoculation response was site/strain specific. Two indigenous strains NR20 and NR22 were found highly efficient and displayed superiority over the exotic strain TAL-102. Multi-locational trials are required to check the suitability of these isolated isolates for other agro-climatic conditions before using as inoculants or bio-fertilizers.

To identify countermeasures to the effects of climate warming on crop production, we must understand the changes in crop phenology and the relationships between phenology and climate change and cultivar. We used summer maize phenological and climate data in the North China Plain, collected from 1981 to 2010. This study analyzed the spatiotemporal trends in phenological data and lengths of different growing phases, mean temperatures and rainfall. The analyses showed that sowing, jointing and anthesis occurred relatively early at 13 48.1%), 11 (40.7%) and 13 (48.1%) stations, respectively. Maturity dates were delayed significantly at 10 (37.0%) stations. The lengths of the vegetative growing phases, vegetative and reproductive growing phase at most stations showed a negative trend. The lengths of the reproductive growing phase increased at 25 (92.6%) stations, respectively. Furthermore, at most stations, the correlations between T means and lengths of the various growing phases were negative, whereas the correlations between rainfall and lengths of various growing phases were positive. Furthermore, a field experiment, including four summer maize cultivars which were introduced during the 1950s, 1970s, 1990s and 2000s, was carried out during 2012 to 2014. The analyses showed that the durations of the various growing phases increased significantly. These results indicated that climate warming accelerates summer maize growth and shortens the growing periods of maize growth, whereas cultivars shift might prolong the maize growing season. Therefore, the maize cultivars with more longer whole growing period should be adopt in the North China Plain under the trend of global warming and the adaptation strategy of maize production under climate change should include crop phenology in response to climate change. The findings presented here could guide the development of options to adapt maize production to climate change in the North China Plain and other areas with similar ecologies.

Drought is a feature of climate that can occur in virtually all climates. Therefore, it is an inevitable global but site-specific phenomenon which requires tools to predict and strategies and options to cope with it. In this research, the ability and effectiveness of the Bayesian Decision Networks (BDNs) approach in decision-making and evaluating drought management options for rainfed wheat production in the eastern region of Golestan Province, Iran are demonstrated. The results revealed that during drought conditions, the Koohdasht cultivar had higher yield than other cultivars of wheat. Two management scenarios have been specified for the forecasted period on the basis of wheat cultivars adopted in the region. The results of scenario analysis with a BDN model indicate that the probability of low, medium and high yield levels in scenario 2 (Koohdasht 70%, Zagros 20% and the other cultivars 10%) has a better status compared with scenario 1 (current condition). The paired t- test indicates that there is a significant difference between the two scenarios for wheat yield in low and medium states (P

UV-B radiation affects crop plants. Growing interest has been shown in studying the effects of UV-B radiation exclusion on crops since 1993. This article summarized the general consequences of UV-B radiation exclusion on crop plants from the aspacts of plant morphology, growth and development. UV-B exlusion has promoting effects on plant height, internode and leaf size. UV-B exclusion increases root biomass and stimulates nodulation of legume crops with increased number and size of nodules and enhances the leghemoglobin. Higher levels of α-tocopherol is found in UV-B plants, which plays an important role in translocating photoassimilates from the leaves to the roots. UV-B exclusion could be a useful tool for physiologists and molecular biologists to further address mechanisms involved in UV-B radiation damage in crop plants.

The measurement of carbon isotope discrimination (∆) provides an integrated insight into the response of plants to environmental change. To investigate the potential use of ∆ for identifying shade tolerance in rice, five rice varieties were selected and artificially shaded (53% light reduction) during the grain-filling period in 2010 and 2011, in Sichuan, China. Shading treatment had a significant influence on the ∆ of rice organs, resulting in clear increases in the ∆ of stems plus sheaths (∆Sm), rice grains (∆Gm) and rice flour (∆Fm) at maturity, but a reduction in the ∆ of leaves (∆Lg) at the grain-filling stage. The relationships between ∆ and leaf photosynthetic and chlorophyll fluorescence characteristics and grain yield showed a close dependence on plant organs and light regimes. Under shading treatment, photosynthetic rate was negatively associated with ∆Gm and the ∆ of stems plus sheaths at the grain-filling stage (∆Sg), whereas ∆Sm was significantly (PPSII (PSII), photochemical quenching (qP) and non-photochemical quenching (NPQ). Moreover, grain filling and grain weight under shading treatment were positively correlated with ∆S g, but negatively related to ∆Sm in 2011. In contrast, a significantly (Passociation between grain weight and ∆Lg was observed in 2010. It was found that lower values of ∆L g, ∆Sm and ∆Gm in rice indicated better light-harvesting and light-use capability and also higher grain filling and grain weight of rice.

Organic agriculture is an ecological production management system aimed at sustainable production of safe food, environmental protection and maintenance of soil health. The objective of this study was to evaluate, in a period of organic transition, the effects of different organic fertilizers on wheat yield, grain quality and soil characteristics. The research was performed in an experimental farm of Southern Italy (Foggia), over a three year period. An organic commercial fertilizer and compost, obtained from municipal wastes, with and without a commercial bioactivator, were compared in a randomized block design. Grain yield and quality and soil total organic carbon content (TOC) were measured. The Henin-Dupuis model was also tested to simulate soil organic C dynamics after organic fertilizer application. Among the years, significant differences were observed in grain yield and quality, indicating that wheat crop response was influenced by the weather conditions. The grain and straw yield was not significantly affected by the organic fertilizer used, though the compost resulted in significantly lower grain quality compared with the organic commercial fertilizer. In any case, at the end of the experimentation, the compost resulted in significantly higher TOC (%) compared to the organic commercial fertilizer. The results showed that the compost may be used as an alternative to sustain wheat productivity, feasible also from an economic point of view and to conserve soil fertility. Finally, under the local Mediterranean conditions, the soil organic C dynamics could be defined by the Henin-Dupuis model, also considering the C supply of annual root residues.

Wheat (Triticum aestivum L.) is widely cultivated in the Mediterranean zone where plants generally suffer from water stress during heading and reproductive stages. This research was carried out at the experimental farm of the faculty of agriculture, Kafrelsheikh University using two water treatments (water stress and well-watered), four N levels (0, 80, 160 and 24 kg ha-1) and two ascorbic acid levels (0 and 200 mg l-1). Water stress substantially reduced yield and related-traits compared with well-watered crop; however, AA application improved yield productivity and chlorophyll content was associated with the maintenance of leaf water status under water stress. Catalase (CAT) and peroxidase (POX) activity showed significant increases in plants treated with ascorbic acid (AA) under water stress. Among different nitrogen levels, the highest N level (240 kg N ha-1) performed better during 2012/2013 and 2013/2014 seasons. Under water stress condition the higher N level (240 kg ha-1), despite determining an increase in grain N content, did not imply an increase in NUE, due to a decrease in grain yield which positively related to N uptake. Exogenous application of ascorbic acid (AA) has been found very effective in mitigating the adverse effects of water stress, which might be attributed by activities of antioxidant enzymes (CAT and POX). In addition, inducing a stimulatory effect on all the yield-related traits. Maximum productivity and related traits were recorded under well watered condition treated by 240 kg N ha-1. Nonetheless, exogenously applied ascorbic acid has better able to produce appropriate productivity under water stress.