FORAGE YEILD AND COMPITITION INDICES OF CEREALS MIXED INTERCROPPING WITH FORAGE LEGUMES IN SULAIMANI REGION

The present study was conducted in Sulaimani region at two different locations, Kanipanka and Qlyasan during winter season of 2019-2020 to estimate the response of forage yield and some competition indices to the effect of crop pure stands and their mixtures of barley and triticale intercropped with narbon vetch and grass pea with some different patterns. The experiment was designed according to Completely Randomized Block Design with three replications. As the average of both location the maximum green forage yield was produced by pure narbon vetch 32.610 ton ha-1, while pure barley produce maximum dry forage yield and dry matter % reached 5.506 ton ha-1 and 8.55% at booting stage respectively, but the crop mixture barley/grass pea at a rate 2:1 produce maximum green and dry forage yield 32.083 and 5.616 ton ha-1 respectively at booting stage. The crop mixture barley/vetch 1:1 gave maximum dry matter% 17.88% at the same stage. The highest value for total LER was 1.401recorded by the mixture of triticale/grass pea at elongation stage, while the highest relative crowding coefficient was 1.285 recorded by the same mixture at a rate 1:1 at the same cutting stage. Maximum competitive ratio for cereals was 3.652 recorded by barley in the mixture barley/grass pea 1:2 at elongation stage, while for legume it was 2.292 for narbon vetch in the mixture triticale/vetch 2:1 at booting stage.

Study of the Physiological Dynamics of Cadmium Accumulation in Two Varieties of Rice with Different Cadmium-Accumulating Properties

This study focused on cadmium (Cd) uptake by two rice varieties, Yuzhenxiang (YZX) and Xiangwanxian 12 (XWX), which differ in their capacity to accumulate Cd, i.e., XWX > YZX. Treatments with three different gradients of soil Cd concentrations showed that with the increase in soil Cd concentration gradient, the Cd content in each rice plant organ also increased, i.e., Cd-3 > Cd-2 > Cd-1. The trend in the Cd content of each organ was such that the farther the organ from the root, the lower its Cd content, i.e., root > stem and sheath > leaf > grain. We observed that for all four growth stages, the booting stage is the key stage in terms of Cd absorption, where the highest levels of accumulation are observed, that is, booting stage > full heading stage > tillering stage > maturity stage. Of the two cultivars, XWX had higher SOD, POD, and CAT activities but lower MDA content. In contaminated soils, SOD, POD, and CAT activities increased gradually with the increase in Cd concentration, while MDA content decreased, which indicated that the low Cd variety XWX had an advantage over the high Cd variety YZX. Through the comparative analysis of photosynthetic physiology, it was found that the low-Cd-accumulating rice variety XWX appeared more tolerant to Cd, while the high-Cd-accumulating rice YZX was more sensitive. Therefore, the low Cd rice variety XWX was more suitable for planting safe rice in Cd-polluted paddy fields.

Hexokinase gene OsHXK1 positively regulates leaf senescence in rice

Background Leaf senescence is a highly complex and meticulous regulatory process, and the disruption of any factor involved in leaf senescence might lead to premature or delayed leaf senescence and thus result in reduced or increased crop yields. Despite sincere efforts by scientists, there remain many unsolved problems related to the regulatory factors and molecular mechanisms of leaf senescence. Results This study successfully revealed that OsHXK1 was highly expressed in senescent leaves of rice. The upregulation of OsHXK1 led to premature senescence of rice leaves, a decreased level of chlorophyll, and damage to the chloroplast structure. The overexpression of OsHXK1 resulted in increases in glucose and ROS levels and produced programmed cell death (PCD) signals earlier at the booting stage. Further analysis showed that expression level of the respiratory burst oxidase homolog (RBOH) genes and OsGLO1 were increased in OsHXK1-overexpressing plants at the booting stage. Conclusions Overall, the outcomes of this study suggested that OsHXK1 could act as a positive regulator of rice leaf senescence by mediating glucose accumulation and inducing an increase in ROS.

NILs of Cold Tolerant Japonica Cultivar Exhibited New QTLs for Mineral Elements in Rice

Chilling stress at booting stage can cause floret deterioration and sterility by limiting the supply of food chain and the accumulation of essential mineral elements resulting in reduction of yield and grain quality attributes in rice. Genomic selection of chilling tolerant rice with reference to the accumulation of mineral elements will have great potential to cope with malnutrition and food security in times of climate change. Therefore, a study was conducted to explore the genomic determinants of cold tolerance and mineral elements content in near-isogenic lines (NILs) of japonica rice subjected to chilling stress at flowering stage. Detailed morphological analysis followed by quantitative analysis of 17 mineral elements revealed that the content of phosphorus (P, 3,253 mg/kg) and potassium (K, 2,485 mg/kg) were highest while strontium (Sr, 0.26 mg/kg) and boron (B, 0.34 mg/kg) were lowest among the mineral elements. The correlation analysis revealed extremely positive correlation of phosphorus (P) and copper (Cu) with most of the cold tolerance traits. Among all the effective ear and the second leaf length correlation was significant with half of the mineral elements. As a result of comparative analysis, some QTLs (qBRCC-1, qBRCIC-2, qBRZC-6, qBRCHC-6, qBRMC-6, qBRCIC-6a, qBRCIC-6b, qBRCHC-6, and qBRMC-6) identified for calcium (Ca), zinc (Zn), chromium (Cr) and magnesium (Mg) on chromosome number 1, 2, and 6 while, a novel QTL (qBCPC-1) was identified on chromosome number 1 for P element only. These findings provided bases for the identification of candidate genes involved in mineral accumulation and cold tolerance in rice at booting stage.

Quantitative Research on Drought Loss Sensitivity of Summer Maize Based on AquaCrop Model

In this study, the growth periods of summer maize was divided into seedling, booting and flowering-grain stage. Based on the simulation results of AquaCrop model, the drought loss sensitivity of summer maize in different growth periods was analyzed. The sensitivity curves fitting using the soil moisture content of the effective root zone and the fixed soil layer both indicated that the booting stage was the most sensitive to water stress, which was the critical period for irrigation, followed by the seedling stage. Compared with the curve parameters fitted by the soil water content of the effective root zone, the maximum Biomass Loss Rate fitted by the fixed soil layer water content was higher and the Drought Hazard Index corresponding to the disaster-causing point and the turning point in the seedling stage moved backward. Accordingly, the best irrigation opportunity may be missed and resulting in a large reduction in production if an irrigation scheme is formulated at the seedling stage based on the sensitivity curve of summer maize fitted by the water content of a fixed soil layer. This study also adapted the Jensen model to calculate the normalized moisture sensitivity coefficient and studied the response of final crop yield to water deficit in different growth periods. The results showed that the normalized moisture sensitivity coefficients at the seedling stage, booting stage, and flowering-grain stage were 0.251, 0.524, 0.224 respectively, which verified the rationality and feasibility of using the cumulative loss of biomass to measure the final yield loss.

Inluence of Different Levels of Cowdung on Mitigation of Water Deficit Effect on Wheat

The experiment was conducted in pot at the net house of the department of Agronomy, Sher-e-Bangla Agricultural University, Dhaka during the period from November, 2018 to March, 2019to find out the optimum dose(s) cowdung to mitigate the water deficit effect on wheat. The experiment comprised of two factors viz. factor A: Five levels of cowdung, i) C0= Control (No cowdung), C1= 25% less cowdung of recommended dose, C2 = Recommended dose of cowdung, C3 = 25% higher cowdung of recommended dose and C4 = 50% higher cowdung of recommended dose, and factor B: four levels of water deficit at, i) D0 = Control (No water deficit), D1= Crown root initiation stage (20-19 DAS), D2 = Booting stage (45-54 DAS) and D3= An thesis stage (55-64 DAS). The experiment was laid out in a Factorial R and omized Complete Block Design with three replications. The test crop variety was BARI Gom28. The result reveled that cowdung level had positive impact on yield of wheat under water deficit condition, and 50% higher cowdung of recommended dose (C4) gave the highest grain yield (5.12g plant-1). The particular treatment also produced the highest number of effective tillers plant-1 (5.25), spike length (10.39 cm), spikelet spike-1 (15.72), grains spike-1 (32.56), grains spikelet-1 (2.07) and 1000-grain weight (47.32 g) of wheat. The treatment C3 (25% higher cowdung of recommended dose) also gave statistically similar yield with C4 treatment. In respect of water deficit imposition treatments, grain yield was found the highest in control treatment which was statistically similar with water deficit imposition at booting stage treatment (D2). These two treatments also showed the higher and similar number of effective tillers plant-1 (4.86 and 4.58), spike length (10.53cm and 10.11cm), spikelets spike-1(15.50 and 15.19), grains spike-1 (34.10 and 30.17), grains spikelet-1 (2.20 and 1.98) and 1000-grain weight (45.42g and 45.36g, respectively). Regarding the interaction of levels of cowdung and water deficit imposition at different stages of plant growth, C4D0 and C3D0 were highest yielder which was attributed to higher 1000-seed weight, number of effective tillers plant-1, spikelets spike-1 and grains spike-1. Contrary, 25% higher cowdung than recommended dose (as it saved 25% cowdung) seems promising to overcome yield loss due to water deficit imposition at booting stage of wheat (D2). However, application of cowdung (12.5 t ha-1) was found effective to combat water deficit at booting stage (D2) of wheat compared to other growth stages. Bangladesh Agron. J. 2021, 24(1): 93-100

The Effects of Short-Term Exposure to Low Temperatures During the Booting Stage on Starch Synthesis and Yields in Wheat Grain

Low temperatures (LT) in spring can have a major impact on the yields of wheat in winter. Wheat varieties with different cold sensitivities (the cold-tolerant Yannong 19 variety and the cold-sensitive Yangmai 18 variety) were used to study the responses of the wheat grain starch synthesis and dry material accumulation to short-term LT during the booting stage. The effects of short-term LT on the activities of key wheat grain starch synthesis enzymes, starch content and grain dry-matter accumulation were determined by exposing the wheat to simulated LT of from −2 to 2°C. Short-term LT stress caused a decrease in the fullness of the wheat grains along with decreased activities of adenosine diphosphate glucose pyrophosphorylase (AGPase, EC2.7.7.27), soluble starch synthase (SSS, EC2.4.1.21), granule-bound starch synthase (GBSS, EC2.4.1.21), and starch branching enzyme (SBE, EC2.4.1.18) at different spike positions during the filling stage. The rate of grain starch accumulation and starch content decreased with decreasing temperatures. Also, the duration of grain filling increased, the mean and the maximum filling rates were reduced and the quality of the grain dry-matter decreased. The number of grains per spike and the thousand-grain weight of the mature grains also decreased. Our data showed that short-term LT stress at the booting stage caused a decrease in the activities of key starch synthesis enzymes at the grain-filling stage. These changes reduced the accumulation of starch, decreased the filling rate, and lowered the accumulation of grain dry matter to ultimately decrease grain yields.

Identification and characterization of heat-responsive microRNAs at the booting stage in two rice varieties 9311 and Nagina 22

MicroRNAs (miRNAs) are small, non-coding, regulatory RNAs that play important roles in abiotic stress responses in plants. but their regulatory roles in the adaptive response to heat stress at the booting stage in two rice varieties 9311 and Nagina 22, remain largely unknown. In this study, 464 known miRNAs and 123 potential novel miRNAs were identified. Of these miRNAs, a total of 90 differential expressed miRNAs were obtained with 9311 libraries as control group, of which 54 upregulated and 36 downregulated miRNAs. To gain insight into functional significance, 2773 potential target genes of these 90 differentially expressed miRNAs were predicted. GO enrichment showed that the predicted target genes of differentially expressed miRNAs including NACs, LACs, CSD, and Hsp40. KEGG pathway analysis showed that target genes of these differentially expressed miRNAs were significantly enriched in plant hormone signal transduction pathway. The expression levels of ten differentially expressed miRNAs and their target genes obtained by qRT-PCR were largely consistent with the sequencing results. This study lays a foundation for the elucidation of the miRNA-mediated regulatory mechanism in rice at elevated temperatures. Key words: rice, heat-responsive, microRNA, target gene, booting stage, high-throughput sequencing

Morpho-physiological responses in wheat (Triticum aestivum L) influenced by normal and water stress conditions

Drought is a disaster around the world accumulating salt and ero-sion in lands. Presently, a research was conducted to determine the morpho-physiological response in bread wheat under normal and stress irrigations. This experiment was conducted at the experimental field of Sindh Agriculture University, Tandojam, Hy-derabad, Pakistan, for two consecutive years during the Rabi season of the year 2011-12 and 2012-13. Stress was imposed by withhold-ing irrigations at three different growth stages of the plant, i.e. T1: normal irrigations applied, T2: stress at tillering stage, and T3: stress at the booting stage. The progenies Sarsabz x Khirman and Sarsabz x TD-1 contributed the highest heritability% (81.0% and 85.5%) for osmotic potential (-MPa) at stress at booting stage. For grain yield spike-1(g), the progeny Kiran-95 x Khirman showed maximum her-itability as 84.37 in T3. However, the progeny TD-1 x Imdad proved to be the best combiner progeny indicating highest heritability per-centage (91.0%) among the progenies for grain yield at booting stress.