International Journal of Plant Production
Volume:7 Issue: 3, Jul 2013

In a four-year experiment, five nitrogen rates (0, 60, 120, 180 and 240 kg N ha-1) were tested over irrigated sugar beets grown on clays, underMediterranean conditions, in centralGreece. There, sugar beets are commonly grown under water shortages, high temperatures and high soil Na concentrations. Contrary to previous reports, N rates did not affect significantly population density (as assessed by root number at harvest) and sucrose content in fresh and dry root weight (SC and SCD, respectively). Yield response to N was year dependent and only in one out of four seasons, was there a positive effect of N on sugar yield and white sugar yield. In that case, the estimated optimum N dose was high (220 kg N ha-1). Increasing N rates increased significantly N assimilation (as assessed by petiole NO3-N and root α-amino N) and water content in root (WCR) but decreased biomass partitioning to root (lower harvest index). Selective absorption (SA, the preferential uptake of K over Na in roots) decreased with increasing N rates and it was negatively correlated with sugar beet N nutrition indices (petiole NO3-N and root α-amino N). A negative correlation between SA and petiole NO3-N was also evident when data combined over years, indicating that strong Na exclusion was associated with poor N nutrition, a contradiction to previous reports. The higher the SA, the lower the WCR indicating less dilution of sucrose in root and thus, the higher the SC. Moreover, high SA evoked sucrose accumulation in roots as it was shown by its positive correlation with SCD.

Poorly drained claypan soils can increase the importance of tillage and N management for corn (Zea mays L.) production. Field research in 2008, 2009 and 2010 (high rainfall years) near Novelty, MO (40° 1' N, 92° 11' W) sought to determine the effect of polymer-coated urea (PCU) placement [strip-tillage (ST) deep banded and no-till (NT) broadcast] and application timing (fall, early preplant and preplant) on red clover (Trifolium pratense L.) biomass and corn response compared to non-coated urea (NCU) and anhydrous ammonia (AA) in the presence and absence of nitrapyrin a nitrification inhibitor. Strip-tillage reduced clover dry weights 20% in 2008 and 2009 and early preplant ST reduced dry weights 40 to 45% in 2010 compared to NT. Corn plant population was 8,100 to 8,400 plants ha-1 greater with ST compared to NT. Preplant applications of AA plus nitrapyrin, AA, ST placement of PCU and NCU increased grain yields 1 to 1.2 Mg ha-1 compared to fall applications of these fertilizer sources. Fall and preplant ST placement of PCU increased grain yields 1.2 Mg ha-1 compared to NCU. Strip-till placement of PCU and NCU increased yields 2.1 to 3.2 Mg ha-1 over broadcast applications of these fertilizer sources. Strip-till placement of PCU synergistically increased yield over NCU and broadcast applications of PCU or NCU due to increased stands and possibly due to better plant utilization of the banded N fertilizer utility.

The effect of photoperiod and growing degree days (GDD) on dry matter and dry matter partitioning in Jerusalem artichoke was investigated during 2008-09 and 2009-10. Three Jerusalem artichoke genotypes (CN-52867, JA-89 and HEL-65) were planted in 15 day-intervals between with thirteen different dates (September 20 to March 20) atKhon Kaen University,Thailand. Jerusalem artichoke genotypes responded differently to varying planting dates for harvest index, shoot dry weight, leaf area, number of tubers and tuber size. Two genotypes, CN-52867 and JA-89, were significantly more productive on the planting date of 20 September and they also performed well on planting dates of 5 October to 20 March. Plant grown in long photoperiod with a higher number of GDD produced shoot dry weight rather than greater number of harvestable tubers, while short photoperiod induced high partitioning of assimilates to harvestable tubers. Jerusalem artichoke plants grown during short photoperiod were smaller and produced larger tubers than those grown during long photoperiod. Tuber yield was relatively unchanged across planting dates. SinceJerusalemartichoke during short photoperiod had smaller plants, growing Jerusalem artichoke at higher plant population with optimum density is highly recommended to increase tuber yield. The information obtained in this study is extremely important for Jerusalem artichoke production and breeding in the tropical agro-climatic conditions such asThailand.

Indiahas the largest area under onion (Allium cepa) crop but its average productivity (14.21 t ha-1) is considerably lower than the world’s average of 19.4 t ha-1. Besides low productivity, irrigation efficiencies are also very low i.e. 30-35% in India. Managing onion crop with less than adequate irrigation water availability is a challenge in several parts of the country. Options of i) deficit irrigation (DI) i.e. 20% or 40% less water application at one of the growth stages of the crop and ii) controlled deficit of 20% or 40% on all growth stages i.e. regulated deficit irrigation (RDI) were explored for maximizing IWUE of onion under deficit water application through subsurface drip irrigation. A field experiment was conducted on onion (var. Agrifound light red) for three years from October to May in 2007-08, 2008-09 and 2009-10 to study the effect of DI and RDI on onion yield and its quality under subsurface drip irrigation. In DI treatments, the crop was provided the irrigation with 60% and 80% of ETc creating water stress of 40 and 20%, respectively at developmental (2nd), bulb formation (3rd) and bulb maturity (4th) crop growth stages. In case of RDI treatments, 20% and 40% water stress was created throughout the crop season by applying the irrigation water at 80% and 60% ETc. The maximum yield (44.7 t ha-1) was obtained in the full-irrigation treatment (T1). In RDI, 20 and 40% deficit water application saved 19.2 and 41.7% water and resulted in 20 and 32% reduction in yield, respectively. In DI, 20% water deficit in the growth stages of 2nd, 3rd and 4th saved 2.1, 13.2 and 4.6% of water with 19.8, 18.3 and 11.2% reduction in yield, respectively in comparison to full irrigation water application. This suggests that RDI is better option of water saving than DI. Saving of water through RDI may be used to irrigate additional cropped area. Strategy suggested for productions of onion crop can be adopted in large scale to offset high cost of onion, which is cause of concern for all stake holders.

alt stress is one of the major constraints for wheat cultivation inIranand leads to a considerable loss in crop yield each year. In high salinity soils, the reduced osmotic potential of soil solutes may cause physiological drought. In this study the salt tolerance of different drought-tolerant bread wheat genotypes were studied by examining various agronomic and physiological traits, including Na+ and K+ concentrations, the Na+/K+ ratio in leaf and spike, shoot dry weight, leaf greenness, stomatal conductance, leaf area, osmotic potential, relative water content (RWC) and grain yield. Two pot experiments were conducted using a completely randomized design with three replications. Wheat genotypes were grown in pots and irrigated either with tap water (EC=0.5 dSm-1) or saline water (EC≈18 dsm-1) as control and salt stress treatments, respectively. Significant differences were observed in all measured traits between control and stress treatments except for the spike potassium concentration. Differences between genotypes were significant for all traits except for RWC and osmotic potential. Among the different genotypes, one drought-tolerant genotype appeared salt tolerant, three were semi-salt-tolerant, one drought-sensitive genotype appeared semi-salt-sensitive, and two drought-tolerant genotypes appeared salt-sensitive and semi-salt-sensitive. This study shows that drought tolerance does not necessarily lead to salt tolerance. Some physiological traits including Na+ content, leaf area, SPAD number, stomatal conductance and shoot dry weight, which are significantly correlated with grain yield and show remarkable variations among wheat genotypes, may be useful parameters for measuring the responses of other wheat genotypes to high-salinity soils in the field.

Vertisols occur extensively in centralIndiaand have high production potentials. Because of the high clay content (40-60% or more), high bulk density (1.5-1.8 Mg m-3) and related properties, these soils have high moisture storage capacity. Conversely, these soils become very hard when dry and very sticky when wet. Since last two decades, scientists, farmers and also the policy makers have been striving to manage these soils through harnessing the beneficial attributes as well as overcoming the production constraints. Some of the potential options are efficient surface land configuration and crop diversification. Field experiments were conducted at the Research Farm atBhopalto evaluate the land surface configuration and crop diversification. Results of our experiment on vertisols showed a considerable reduction in run off of water and also soil loss from broadbed and furrow (BBF) compared to flat-on-grade (FOG) during rainy season and at the same time crop productivity was significantly improved in BBF. It enhanced yield of soybean (Glycine max (L.) Merr.), maize (Zea mays L.), pigeonpea (Cajanus cajan (L.) Millsp.) as sole and as well as intercropping and sole chickpea (Cicer arietinum L.) by about 12.7-20.0% over FOG. The yield of crops (soybean, maize and pigeonpea), expressed as soybean equivalent yield, was compared and it showed an improvement in yield from different intercropping systems on BBF. The residual effect of rainy season crops on succeeding chickpea was not significant; however, its yield in two irrigation (one pre-sowing plus one post-sowing) was significantly greater than pre-sowing irrigation only in both land configurations. Water use efficiency (WUE) of chickpea was more under BBF than FOG. The study elucidates the constraints and potentials of vertisol for crop production especially with reference to centralIndiaand effective ways to improve crop productivity through land surface modification and crop diversification.

Better irrigation management and more efficient management of crop production require modeling of plant growth and crop yield. More applicable models are usually simple and requires less and accessible inputs. The objective of this study was to develop a model for growth and yield prediction of saffron under various irrigation regimes. In this modeling soil water budget and other simple relationships for evapotranspiration partitioning, leaf area index determination and leaf dry mattertranspiration function, corm-transpiration function and saffron-corm function were used. The developed model was calibrated based on available data of basin irrigation experiment under different irrigation regimes and verified based on independent data under different climatic conditions. In calibration, the comparison between predicted and measured values of different crop parameters did not show any significant difference (P=0.05) and model was able to estimate LAI (with NRMSE=0.16), crop evapotranspiration (NRMSE=0.19), surface evaporation (NRMSE=0.22), leaf dry matter (NRMSE=0.33) and corm yield (NRMSE=0.19) and saffron yield (NRMSE=0.16) properly. In validation, the statistical results of comparison between predicted and measured values of various crop parameters were different and model was able to estimate corm and saffron yield with acceptable accuracy. Furthermore, this model might be used only for saffron crop because the incorporated crop functions are developed for saffron.

The study was conducted with the application of the model MoDrY (Model-Dry periods-Yield) for the estimation of the level of potato yields on the basis of dry periods occurring during the particular periods between the phenological phases of the crop plant. A characteristic feature of this model, unlike most existing weatheryield models, is that the principle of its operation is based only on information on the occurrence of precipitation. In the study the authors used research material from the years 1971-1983 and 1985-1996 (25 years) and diurnal sums of atmospheric precipitation from the same periods. Five interphase periods were adopted for the analyses: planting-emergence, emergence-lateral shoots, lateral shoots-start of blooming, start of blooming-haulm drying, haulm drying-harvest. The authors also used a model of changes in the resources of water available for plants during dry periods. Six measures were adopted to characterise the error of approximation: coefficient of correlation, coefficient of determination, mean relative error, RRMSE, EF and CRM. The coefficient of correlation obtained was at the level of 0.92 and the mean relative error at the level of 9.27%. Validation was performed by means of the Cross Validation test (CV), version LOO.

Low soil fertility and high weed infestation are the main culprits for the declining maize production inWestern Kenya. Technology packages to address these constraints exist, but their effectiveness is likely to be influenced by variability in soil types and farm management practices in the region. Trials were conducted during the 2008/2009 cropping seasons to investigate the nutrient use efficiency and yield response of maize to some recommended management options for smallholder farmers on three dominant soil types ofWestern Kenyanamely Acrisol, Nitisol and Ferralsol. Irrespective of seasons, average maize yields were highest on Nitisol (3.6 t ha-1) and lowest on Ferralsol (2.1 t ha-1). Maize yield gaps (difference between potentially achievable and actual yields) differed by season and soils with 4-5 t ha-1 on Nitisol and about 6 t grain ha-1 on Acrisol and Ferralsol. On Nitisol, the largest share of this yield gap (80%) was closed by the addition of mineral fertilizer, while on Ferralsol, reduced tillage could close 25-60% of the yield gap. The highest agronomic (13-39 kg grain kg-1 N) and physiological (50-160%) N use efficiencies were obtained with mineral fertilizers, while the addition of organic amendments resulted in the highest P use efficiency (15-154 kg grain kg-1 P), irrespective of soil type and season. As soil types and management options differentially affect yields and nutrient use efficiency of maize, there is a need for field-specific targeting of technologies to address maize production constraints inWestern Kenya.

Genotype × environment (G×E) interaction complicates the identification of superior genotypes. An understanding its causes is needed for a more effective breeding strategy. The objective of this study was to determine the plant traits that cause genotype × location (G×L) interaction for pod yield in peanut using a modeling approach. The CSM-CROPGRO-Peanut model was used to simulate pod yield for 17 peanut genotypes for 14 locations representative of all peanut production areas in Thailandusing 30 years of historical weather data. Sensitivity analysis was used to determine the effects of individual and combinations of plant traits on pod yield and yield response to environments by varying the value of one or more cultivar coefficients and then evaluating their effects. The results showed that the cultivar coefficients that showed major effects were the duration from first seed to physiological maturity (SDPM), maximum leaf photosynthesis rate (LFMAX), the maximum fraction of daily growth that is partitioned to seed and shell (XFRT), single seed filling duration (SFDUR) and the duration of pod addition (PODUR). Those having minor effects were the duration from emergence to first flower (EMFL), maximum leaf size (SIZLF) and maximum seed weight (WTPSD). The cultivar coefficients that caused the differences in both mean yield and yield response to locations between peanut genotypes in different pairs included LFMAX, XFRT, SDPM, SFDUR and PODUR, but the causal characters differed among pairs of genotypes. It was concluded that changing the degree of genotypic response to environments is possible through selection for a combination of some of these traits, and that model simulation could be used to identify those traits.

Salinity and water stress reduces the ability of plant to take up water and decrease growth rate, photosynthesis rate (An) and stomatal conductance (gs) of plants. In this study, effects of deficit irrigation with different salinity levels and planting method (in-furrow and on-ridge) as strategies for coping with water and salinity stress on physiologic properties of rapeseed was investigated in a two years experiment. Irrigation treatments consisted of full irrigation (FI) and 0.75FI and 0.50FI in first year and 0.65FI and 0.35FI in second year and salinity treatments of irrigation water were 0.6 (well water), 4.0, 7.0 m and 10.0 dS-1 in first year and 0.6, 4.0, 8.0 and 12.0 dSm-1 in second year. Planting in-furrow increased seasonal dry matter by 8.4 and 9.6%, respectively at first and second year (with frost occurrence in dormant period in second year) relative to on-ridge planting. In-furrow planting increased maximum leaf area index compared with on-ridge planting by 12.8% for second year. Deficit irrigation and salinity decreased dry matter, leaf area index and had no significant effect on crop growth rate (CGR) and relative growth rate (RGR). Decrease in applied water resulted in lower stomatal conductance (gs) and photosynthesis rate (An) and salinity had no significant effect on these traits. Ratio of photosynthesis rate to transpiration rate (leaf scale transpiration efficiency, An/T) decreased when leaf vapor pressure deficit (VPD) increased and in water and salinity stress conditions, transpiration efficiency of rapeseed decreased. A linear function between An/T and VPD with negative slope indicated that in higher VPD, An/T decreased, therefore in water stress condition or in arid and semi-arid region in comparison with humid region An/T of rapeseed decreased. There was no significant difference between the effects of water salinity levels (up to 12 dS m-1) and planting method on slopes of the relationships between An and gs and VPD. As forage plant, rapeseed can be cultivated in soils with salinity of 3.4 dS m-1 and 11.7% deficit irrigation can be imposed without dry matter reduction and in-furrow planting method was proposed in salinity and water stress conditions in comparison with on-ridge planting.

Safflower (Carthamustinctorius L.) is an oilseed crop adapted to drought prone arid and semi-arid environments. This study was conducted to evaluate the effects of water deficit stress on antioxidant activity, membrane stability index (MSI), leaf chlorophyll content, leaf area index (LAI) and their relationship with seed yield using 64 safflower genotypes grown under normal and water deficit stress field condition. Plants were grown under normal irrigation until branching growth stage when water deficit stress was applied to the plants. Analysis of variance showed the significant effects of genotype, water deficit and their interactions on the physiological traits that examined. Water deficit stress significantly decreased leaf area index, leaf chlorophyll content and the membrane stability index means over all 64 genotypes whereas it caused significant increase in antioxidant compounds (APX and POX). The results also revealed the positive and significant correlations between antioxidant enzyme activities with seed yield under water deficit conditions. The stress susceptibility index (SSI) identified water-deficit tolerant genotypes (Kordestan 3 and C411) that did have outstanding yield performance per se in stress environments.

Eight spring wheat cultivars were evaluated under three heat stress conditions (early, late and very late) in order to identify suitable cultivars to develop heattolerant genotypes resistant to future global warming. Results from the study indicate that stress did not negatively affect flag leaf area in ‘Prodip’ and ‘Sufi’, flag leaf dry matter partitioning in ‘Prodip’, ‘BARI Gom-26’ and ‘Shatabdi’, above-ground dry matter partitioning in ‘Shatabdi’ and ‘BARI Gom-26’, seedling emergence in ‘Sufi’ and ‘BARI Gom-26’, or tiller production in ‘Sufi’ and ‘BARI Gom-26’. With respect to lower yield reduction, relative performance and heat susceptibility index (HSI), ‘Sufi’ was highly heat stress-tolerant, followed by ‘BARI Gom-26’ and ‘Shatabdi’. On the basis of HSI values in early heat stress and extremely late heat stress (corresponding to early and extremely late sowing), ‘BARI Gom-26’ (HSI=0.10, 0.65) and ‘Shatabdi’ (0.22, 0.62) were highly tolerant to early heat stress and moderately tolerant to extremely late heat stress while ‘Sufi’ was highly tolerant (0.35) to extremely late heat stress and moderately tolerant (0.51) to early heat stress. All other genotypes were susceptible to heat stress, among which ‘Gourab’ (2.19, 1.46) was the most susceptible followed by ‘Sourav’ (1.19, 1.42), ‘Prodip’ (1.03, 1.23), ‘BARIGom-25’ (1.61, 0.89) and ‘Bijoy’ (1.04, 1.28). Thus, ‘BARIGom ’, ‘Shatabdi’ and ‘Sufi’ have the greatest potential to be used as high-yielding wheat genotypes under warm to hot environments and could be used in a breeding programme to develop heat-tolerant wheat.