International Journal of Plant Production
Volume:4 Issue: 3, Jul 2010

The effects of water stress on morphometric characteristics of wild radish seeds as well as the expression of its seed dormancy were investigated in a pot trial at Roseworthy، South Australia in 2005. This experiment was carried out in a completely randomised design with five water regimes (control، S4، S5، S6 and S8) and four replicates. The water stress was exerted by withholding irrigation and placing the pots under a rain shelter at different growth stages starting with the onset of flowering (S4) and ending with the completion of flowering (S8). Wild radish pods from all the treatments were collected fortnightly from November 11 to December 23، 2005 (four collection dates). Seed dormancy was tested with and without pod for all treatments in January and May 2005. All morphometric characteristics of pods including pod wall weight and seed weight were negatively affected by water stress. Pods sampled earlier had thicker pod walls and greater pod segment weight. The germinability of all treatments increased with pod removal. The dormancy level tended to be lower in later collected pods. This Study showed that expression of seed dormancy was influenced by water stress during reproductive development. Therefore، variability in spring rainfall could have a major influence on the level of dormancy in seeds of this weed species produced in different growing seasons

Abstract:The present study aimed to investigate the phenol content and antioxidant activity of a non- conventional Curcuma sp. namely, Curcuma caesia in comparison with another species, Curcuma amada. The total phenol contents of the methanolic rhizome extracts of C. amada and C. caesia were 37.64 and 44.33 mg Tannic acid equivalents (TAE)/g dry material, respectively. The reducing power, and superoxide, ABTS and DPPH radical scavenging activities of C. caesia were higher than C. amada. These results supported that the non-conventional C. caesia could be an economically important plant species due to its antioxidant potential.

Water scarcity and salinity are important limitations for saffron (Crocus sativus L.) production in arid and semi-arid regions. The purpose of this research was to study the interaction effects of water salinity and deficit irrigation on the macroscopic water extraction model for saffron. The effect of salinity and water stress on root-water uptake coefficient was determined by additive and multiplicative functions، and was compared with a recently purposed method. At every irrigation intervals، the root-water uptake coefficient α (h، ho) was reduced as the soil osmotic head (ho) decreased at higher salinity levels. Furthermore، the values of α (h، ho) were reduced at higher irrigation intervals. Root-water uptake coefficient was reduced by decreasing in soil matric head (h) and soil osmotic head at salinity levels greater than control. The results indicated that the additive and multiplicative functions for root-water uptake were not suitable for prediction of root-water uptake coefficient of saffron to show the interaction effect of salinity and deficit irrigation on flower yield prediction. The Mass and Hoffman، and Homaee and Feddes multiplicative equations resulted acceptable estimation of α (h، ho). Furthermore، saffron flower yield was predicted by using Homaee and Feddes α (h، ho) and FAO transpiration reduction coefficient in production function presented by Stewart and his colleagues. Results indicated that the FAO method did not predict the flower yield properly، specially in high irrigation intervals and high salinity levels، but the Homaee and Feddes α (h، ho) resulted in acceptable prediction of the saffron flower yield with a minimum error at salinity and water stress treatments with relative yield of greater than about 40%. Therefore، Homaee and Feddes equation is recommended for estimation of α (h، ho) and flower yield of saffron.

Potassium is a major nutrient which may play an important role in many processes such as ion homeostasis in plant cells and osmotic adjustment of guard cells during stomatal opening and closing. Pathumthani 1 (PT1) rice has been reported as being a salt sensitive cultivar and has been selected as a model plant in this study to investigate the possibility of improving the osmotic potential, pigment stabilization, photosynthetic efficiency and growth characteristics of this plant under salinity stress by potassium nitrate (KNO3) application. Sodium ion accumulation in root and leaves of KNO3 (11.8 mM) treated plants declined as compared to the control plants. In control plants, however, due to decline in potassium ion content, the Na / K ratio increased significantly. A positive relation between Na accumulation and osmotic potential was found. Osmotic potential (Ψs) in the root and leaf tissues of PT1 rice treated with 11.8 mM KNO3 was maintained at low levels, which was accompanied with the stabilization of photosynthetic pigments, high photosynthetic performance and better growth characters under 200 mM NaCl. The photosynthetic ability in plants with KNO3 application was positively related to plant dry weight. Exogenous KNO3 application to rice crops may play a vital role as a short-gun technique for the improvement of salt tolerance.

Salinity is considered as one of important physical factors influencing rice (Oryza sativa L.) production. Knowledge of salinity effects on rice seedling growth and yield components would improve management practices in fields and increase our understanding of salt tolerance mechanisms in rice. This study was designed to assess the role of Saltol QTL in regards to effects of salinity on plant growth and yield components of different genotypes of rice at different growth stages. A greenhouse study was conducted to evaluate the response of 30 rice genotypes to three levels of salt stresses (0, 60, 100 mM NaCl) at reproductive stage. The seedling stage response of these genotypes to salinity with electrical conductivity at 12 dSm-1 also investigated. Pollen viability, number of unfilled and filled grain and grain yield per plant were evaluated. The rice genotypes differed significantly for salt tolerance at seedling stage. The genotypes were also significantly varied for the traits measured at the reproductive stage. The interactions of genotypes × salinity treatments were significant for pollen viability, number of unfilled grain and grain yield. Grain yield reduction due to salinity was more sever for control to 60mM than for 60mM to 100mM. Pollen viability was found to be a robust criterion to screen the genotypes for salt tolerance at the reproductive stage. Pokkali cultivar possessing a major quantitative trait locus (QTL) for salt tolerance at seedling stage (Saltol) mapped on chromosome 1 was used as reference for haplotyping. Thirty rice genotypes divided into 16 different haplotypes based on Saltol QTL. RM8094 and RM10745 microsatelite markers found to be the most effective markers for discriminating the salinity tolerant genotypes.

Valerian (Valeriana officinalis L.) is an important medicinal plant that is widely exploited for its roots and rhizomes which contain valepotriates and valerenic acids (with putative pharmacological activities). Thus root proliferation of valerian is very important. The aim of this study was to establish a practical tissue culture method for rapid and large-scale induction of V. officinalis L. roots with high capacity for production of valerian phytomedicine. Explants derived from leaves, petioles, and root segments (both basal and apical) of four months aged plantlets were cultured on MS basal medium supplemented with different concentrations (0.625-5 µM) of auxin and cytokinin hormones. Then accumulation of valerenic acids and valepotriates in developed root cultures was studied to find the best yielding conditions. Maximum valerenic acids (0.84%) and valepotriates contents (7.41%) were quantified in roots developed on petiole explants and in roots formed on root basal segments in medium supplemented with 1.25 μM and 0.625 μM indole-3-acetic acid, respectively. These values were significantly (P<0.05) higher than those in roots from basal and apical root segments without plant growth regulators as control. The highest average number (29.00) of directly formed roots developed on leaf explants in media supplemented with 5 μM α- naphthalene acetic acid. Also maximum number of indirectly developed roots (30.05) was observed on root apical segments in media containing 2.5 μM α- naphthalene acetic acid. These results suggest that besides the applied plant growth regulators, the type of primary explant is also relevant for biosynthetic capacity of these metabolites in root cultures.

The adaptive responses of crop genotypes and patterns of genotype x location (G x L) interaction are important to crop improvement as they are the basis for selection for specific adaptation and for elucidation of the causes of G x L interaction. Their legitimate assessment، however، requires yield data for the test genotypes for a large number of sites and over multiple years. Such data are seldom available from actual trials but could be provided by a crop simulation model. The objectives of this study were to assess the adaptive responses of a set of diverse peanut genotypes and to determine the various patterns of G x L interaction between pairs of these genotypes using a modeling approach. Pod yield of 17 peanut lines was simulated for 112 locations covering all peanut production areas in Thailand over three seasons and 30 years with the Cropping System Model (CSM) CROPGRO-Peanut. The data were analyzed for the adaptive response to locations of each peanut genotype with linear regression. Patterns of G x L interaction for the individual pairs of genotypes were determined. The results showed that the test genotypes could be classified into five groups based on mean yield and adaptive response، i. e. ، average yield with a low (<1. 00) regression coefficient (Entries 5، 6، 8) ، above average yield with an average (=1. 00) regression coefficient (Entries 3، 7، 10، 11، 12) ، above average yield with a high (>1. 00) regression coefficient (Entries 13، 15، 17) ، below average yield with a low regression coefficient (Entry 1) ، and below average yield with an average regression coefficient (Entries 2، 4، 9، 14، 16). These characteristics are the basis for selection for either broad or specific adaptation. All three patterns of G x L interaction، i. e. ، no interaction، non-crossover interaction and crossover interaction، were also identified. Further analysis of these interaction patterns is recommended to elucidate the crop characters and environmental factors that are the causes of G x L interaction. The results indicate the potential of using crop simulation models as a tool to analyze adaptation of crop genotypes and to determine the pattern of G x L interaction for the individual genotype pairs.

Olive trees have been traditionally cultivated in dry conditions as it is a crop very well adapted to Mediterranean dry lands. Foliar fertilization is a widespread application method used by olive growers to correct frequent deficient levels of potassium in olive trees under rainfed conditions. Monopotassium Phosphate (MKP) is an economic and easily available fertilizer and a fast source of P and K when it is applied as a foliar spray. The influence of environmental and formulation factors on the efficiency of MKP foliar application has never been evaluated. In this study the different responses of five MKP foliar treatments (control-untreated، MKP3% at dayligh، MKP3% overnight، MKP3% plus urea and MKP3% plus surfactant) on olive trees under field conditions were evaluated during three different application times (April، July، and November). In all cases، MKP3% plus urea and MKP3% plus surfactant increased P contents with July being the most effective treatment month. All treatments، except MKP3% at dayligh، improved the K nutritional state of olive in July، but not in November or April. In general، the addition of urea and surfactant to the MKP3% solution and its application in July improved its efficiency on olive trees، most likely due to the higher proportion of young leaves present during this period.