Evaluation of proline analysis and chlorophyll fluorescence quenching measurements as drought tolerance indicators in durum wheat (Triticum turgidum L. var. durum)

Summary The possibility of using proline accumulation and fluorescence inhibition as predictive tests for drought tolerance in durum wheat has been investigated. The drought susceptibility of 25 genotypes was evaluated by comparing yields and yield components in irrigated and non irrigated conditions in the field. A drought susceptibility index (DSI) was calculated based on yields from irrigated and dry treatments and compared with the results obtained using the two physiological criteria. Proline accumulation and chlorophyll fluorescence inhibition were found to be significantly and negatively correlated with DSI of grain yield, biological yield, and thousand kernel weight, and tiller index. The use of both criteria for breeding durum wheat in Mediterranean dryland is discussed.     

Interactive effects of biochar and micronutrients on faba bean growth,symbiotic performance,and soil properties

Leguminous crops are significantly involved in the global symbiotic biological N₂ Fixation (BNF), an eco‐friendly process in the agriculture system. Biochar is considered as a vital amendment in improving growth and quality of crops and soils. Few investigations have been conducted to determine the combination effect of biochar with microelements on growth of legumes and soil properties. This study was designed to study the effect of soybean straw‐derived biochar (SSDB) with or without microelements on soil microbial and chemical properties, growth, yield, and seed chemical composition of faba bean (Vicia faba L.). Results revealed that dehydrogenase (DHA) and phosphatase (P‐ase) activities were markedly improved with the increase of SSDB rates under addition of microelements and their highest values were recorded after 90 d. Significant increases were noticed in nodulation activities, nodulation numbers (30.1–72.8), concentrations of N (1.62–1.93%), P (0.15–0.21%), and K (0.53–0.67%), and seed chemical constituents due to the addition of SSDB in the presence of microelements. Moreover, the combination of biochar with microelements caused significant changes in microbial counts. Overall, this investigation shows the potential and role of SSDB in enhancing the growth quality of faba bean seeds as well as an improvement of soil characteristics.     

Race specific resistance against Phytophthora infestans in potato is controlled by more genetic factors than only R-genes

Summary For RFLP mapping of R-genes, determining resistance to specific races of Phytophthora infestans in tetraploid potato, it is necessary to develop well segregating populations at the 2x level. During mapping studies, evidence was obtained that more genetic factor(s) are involved in the expression of R-genes than conventionally believed. Two experiments are described in which such an additional genetic factor was suppressing or enhancing the expression of unknown R _nand R _ifactors. R _nand R _iappeared to be present in the investigated plant material, containing R4 and R10, or in one of the susceptible crossing parents. In a third experiment, the expression and the segregation of the well known R1 gene was influenced by an additional genetic factor. In that case there were indications for a dominant suppressor. This was established by the selection of susceptible plants carrying a RFLP allele of probe GP21 closely linked to R1. In three of the four F₁ populations, resulting from crosses between such susceptible plants and susceptible tester plants, resistnat progenies were found. The resistance appeared to be R1-specific. This clearly indicates that in three of the four investigated susceptible plants, the R1 gene was still present but not expressed.     

伊朗北部黄土丘陵区土壤保持耕作措施研究

保持土壤、增加地下水和减少环境污染是伊朗国家科研项目的重要组成部分。Ｇｏｌｅｓｔａｎ省是伊朗北方最重要的农业区之一 ,许多地方水土流失严重。本研究在对这一地区黄土坡区的水土流失情况进行全面评价之后 ,通过两年时间对两个不同的陡坡农场 (在Ｋａｌａｌｅｈ城市附近     

Phosphorus Requirements of Rice Grown in Soils With Different Sodicity

ABSTRACT

Phosphorus (P) fertilization is reported to alleviate the adverse effects of sodicity on survival of the seedlings, growth, and yield of rice. However, it is not known if required levels of Olsen's P to alleviate the adverse sodicity effects varies with increased sodicity stress. The present study, conducted at various pH values (8.0, 9.3, 9.7, and 9.9) with varying levels of P fertilization (P0.0, P0.2, P0.4, P0.6, and P0.8 kg hm^{? 2}), showed that P requirements of rice increased with increases in sodicity stress. At a pH of 8.0, 4.3 mg kg^{? 1} Olsen's P was sufficient for survival of the seedlings, but not for grain weight (6.3 mg kg^{? 1}). Seedlings required 7.0 and 9.5 mg kg^{? 1}Olsen's P to survive at pH 9.7 and 9.9, respectively. Similarly, high P levels were needed for more total and fertile tillers and spikelets numbers. One thousand (1000) grain weight and grain yield responded to 6.3, 7.7, 8.8, and 10.4 mg kg^{? 1} Olsen's P at pH values of 8.0, 9.3, 9.7, and 9.9, respectively. Total chlorophyll in the leaves was significant in P fertilized plants. At a pH of 9.7, plants with 7.9 mg kg^{? 1} Olsen's P had 52% more chlorophyll per 100 ppm sodium (Na) in the leaves compared to those at 6.3 mg kg^{? 1} Olsen's P. This could possibly be due to improved tissue tolerance to Na in P-fertilized plants. Plants fertilized with P had higher P and potassium (K) concentrations in their shoots. Olsen's P levels of 7.7 mg kg^{? 1}, 7.9 mg kg^{? 1}, and 9.5 mg kg^{? 1} were effective in restricting increases of Na (a potentially toxic ion) in shoots at pH 9.3, 9.8, and 9.9, respectively, thus helping plants have better yields.     

Crop sequences and fertilization affect soil vital enzyme activities

This experiment was conducted in split plots based on randomized complete block design with three replications. Three crop sequences: (R1): chickpea, sunflower, wheat, and canola; (R2): green manure, chickpea, green manure, wheat, green manure, and canola; (R3): canola, wheat, and canola were used as main plots. Sub plots consisted of six methods of fertilization: (N1): farmyard manure; (N2): compost; (N3): chemical fertilizers; (N4): farmyard manure + compost; (N5): farmyard manure + compost + chemical fertilizers; and (N6): control. Results showed that the enzyme activities were higher in the N4 treatment. The highest amount of acid phosphatase, protease, dehydrogenase activity, and grain yield was observed in R2 sequence. The highest urease activity (58.6 µg g^?1 h^?1) was obtained in R2N4 treatment. In R2N4 treatment using in-farm inputs, a non chemical fertilizer system can be carried out to improve soil biological activity.     

Morphological variation within a sour cherry collection

Summary Morphological traits of 28 full-sib sour cherry (Prunus cerasus L.) families developed with pollen from European sour cherry selections were evaluated with principal component (PC) analysis. The traits which loaded on the first PC were size characters such as lateral length, leaf area, fruit weight, and trunk diameter increase. These character loading on the first PC could be interpreted as representing gradations between morphologies characteristic of the 2 presumed progenitor species, sweet cherry (P. avium L.) and ground cherry (P. fruticosa Pall.). Mean family differences in trunk diameter increase, lateral length, leaf area, and fruit weight varied approximately 12, 3.7, 2.5, and 2 fold, respectively. These results suggest that it may be possible to select sour cherry hybrids approaching the tree and fruit size of either progenitor species. The results are discussed in reference to germplasm collection and the potential of certain cultivars and hybrids as parents.     

Effects of chromium stress on the subcellular distribution and chemical form of Ca,Mg, Fe,and Zn in two rice genotypes

A hydroponic experiment was carried out to study effects of chromium (Cr) stress on the subcellular distribution and chemical form of Ca, Mg, Fe, and Zn in two rice genotypes differing in Cr accumulation. The results showed that Ca, Mg, Fe, and Zn ions were mainly located in cell walls and vacuoles in roots. However, large amounts of metal ions were transferred from the vacuole to the nucleus and to other functional organelles in shoots. Chromium concentrations in the nutrient solution of 50 μM and above significantly decreased Ca concentrations in the chloroplast/trophoplast, the nucleus, and in mitochondria. It further increased Mg concentrations in the nucleus and in mitochondria, as well as Zn and Fe concentrations in the chloroplast/trophoplast. These Cr‐induced changes in ion concentrations were associated with a significant reduction in plant biomass. It is suggested that Cr stress interferes with the functions of mineral nutrients in rice plants, thus causing a serious inhibition of plant growth. The chemical forms of the four nutrients were determined by successive extraction. Except for Ca, which was mainly chelated with insoluble phosphate and oxalic acid, Mg, Zn, and Fe were extractable by 80% ethanol, d‐H₂O, and 1μM NaCl. The results indicated that these low–molecular weight compounds, such as organic acids and amino acids, may play an important role in deposition and translocation of Mg, Zn, and Fe in the xylem system of rice plants.