Tiller Initiation Research Articles

Responses of phenology, yield attributes, and yield of wheat varieties under different sowing times in Indo-Gangetic Plains.

A field experiment with wheat was conducted at Pusa (25.98°N, 85.67°E, 52m amsl), Bihar (middle Gangetic plains of India), to assess the responses of phenology, yield attributes, and yield to growing season temperature and heat stress. For this purpose, wheat was planted on five dates (viz., 15 November, 25 November, 5 December, 15 December, and 25 December) for three consecutive years (viz., 2014-2015, 2015-2016, and 2016-2017) with three prominent cultivars of the region (viz., RAU-3711, HD-2824, and HD-2733). Five dates of sowing represent different wheat-growing micro-environments as imposed by varying sowing dates encompassing the entire sowing window. The study observed the significant effect of sowing dates on phenophase duration. In general, with progress in the date of sowing, tiller initiation was delayed, while the reverse trend was observed for later growth phases. Sowing environments significantly influenced the number of effective tillers m-2. Average numbers of effective tillers (ET) m-2 for the wheat sown during 15-25 November were almost 11.6% higher than those of the 25 December sown crop. Grain filling duration (GFD) showed a declining trend with the advancement of sowing dates due to increased thermal load on the crop during the reproductive period. 15 November planted crop exhibited the highest GFD (47 days), which was shortened significantly beyond 25 November, signifying agrometeorological non-suitability of wheat sowing beyond this window. Wheat sown on 25 November recorded the highest grain yield (3.21 Mg ha-1), 48.61% higher than the 25 December sown crop due to the congenial thermal regime. In this context, we have identified optimal and sub-optimal conditions to escape heat stress for higher wheat productivity. Moreover, the sum of deviation of temperature from optimum thresholds, computed for sensitive growth phases (50% flowering to physiological maturity), helped us to identify heat stress and its impact on wheat. Genotype-by-environment (GGE) biplot analysis revealed that RAU-3711 was found to be the most stable cultivar. A decrease in the yield of wheat by 4.9% to 12.0%, sown during November, and 33.8% to 42.4%, sown during December, is predicted in 2050-51 and 2080-81, respectively, under RCP 4.5.

Dissecting pleiotropic functions of the wheat Green Revolution gene Rht-B1b in plant morphogenesis and yield formation.

The utilization of reduced plant height genes Rht-B1b and Rht-D1b encoding homeologous DELLA proteins led to the wheat Green Revolution (GR). However, the specific functions of the GR genes in yield determination and the underlying regulatory mechanisms remained unknown. Here we validated that Rht-B1b as a representative of the GR genes affected plant architecture and yield component traits. The up-regulation of Rht-B1b reduced plant height, leaf size and grain weight, but increased tiller number, tiller angle, spike number per unit area (SN), and grain number per spike (GNS). Dynamic investigations showed that Rht-B1b increased SN by improving tillering initiation not outgrowth and enhanced GNS by promoting floret fertility. Rht-B1b reduced plant height by reducing cell size in the internodes, and reduced grain size or weight by decreasing cell number in the pericarp. Transcriptome analyses uncovered that Rht-B1b regulated many homologs of previously reported key genes for given traits and several putative integrators for different traits. These findings specify the pleiotropic functions of Rht-B1b in improving yield and broaden new insights into the regulatory mechanism underlying plant morphogenesis and yield formation.

Delaying tillering nitrogen topdressing until the midtillering phase improves nitrogen use efficiency and reduces ammonia emission via rice canopy recapture

Tillering nitrogen (N) topdressing is commonly employed to enhance primary-tiller number and achieve a high grain yield for wetland rice. Unfortunately, farmers typically apply N fertiliser shortly at tillering initiation following basal fertilisation, and substantial soil ammonia (NH3) volatilisation occurs due to the low N demand of small plants. Herein, we hypothesised that delaying topdressing N until the midtillering phase could increase canopy recapture of soil NH3 emission and better synchronise N supply with crop N demand, leading to reduced NH3 losses and increased fertiliser N use efficiency. A field experiment was conducted to investigate the effect of conventional tillering N topdressing (CT) at the early tillering stage (2 weeks after basal N application) and delayed tillering N topdressing (DT) until the midtillering phase (∼4 weeks after basal N application) on NH3 emission from soil and the soil-plant system, as well as N uptake, N use efficiency and yield. The 2-year field results showed that DT did not hinder effective tiller production or above-ground dry biomass compared with CT, but improved plant N uptake and total N accumulation after midtillering, leading to 18–27 % higher agronomic efficiency. Correspondingly, 8.9–15 % increases in grain yield were observed for DT compared with CT, mainly attributable to increased panicle number per area and filled grain number per panicle. Following tillering N application, NH3 loss from the soil-plant system under CT accounted for 22 % of top-dressed N, showing only a slight decline compared with that of soil emission. For DT, NH3 loss from the soil-plant system was reduced to 6 %, even though 15 % soil NH3 emission was observed, indicating a more than two-fold increase for in-canopy NH3 recapture. Correspondingly, cumulative net NH3 losses for the entire rice season were decreased by 31% under DT relative to CT. These results provide evidence that delaying tillering N topdressing until the midtillering phase when rice canopy formation is enhanced, can better synchronise fertiliser N supply with crop demand and increase in-canopy NH3 recapture. A large discrepancy remains between NH3 emission from soil and the soil-plant system at midtillering and panicle initiation stages, highlighting the overestimation by the soil dynamic chamber method when quantifying NH3 losses due to overlooking the contribution of canopy recapture of soil-emitted NH3.

Synchronizing Nitrogen Fertilization and Planting Date to Improve Resource Use Efficiency, Productivity, and Profitability of Upland Rice.

Synchronizing nitrogen (N) fertilization with planting date (PD) could enhance resource use efficiency and profitability of upland rice (Oryza sativa L.) production in Thailand. The objective of the study was to assess upland rice responses to four N fertilization rates (NFRs) and three planting dates. Field experiments were conducted during two growing seasons under four NFRs, no N applied (N0), 30 (N30), 60 (N60), and 90 kg N ha−1 (N90), and NFR were applied at the initiation of tillering and panicle emergence stages. The planting dates selected were early (PD1), intermedium (PD2), and late planting (PD3) between September and December of each season. The NFRs and planting dates had a significant influence on N uptake, N use efficiency (NUE), crop water productivity, yield and yield attributes, and profitability of upland rice production. A linear relationship among NFRs, agronomic traits of upland rice, N uptake, and crop water productivity was observed, and a significant seasonal effect was indicated. Fertilization at N90 under PD2 enhanced yields, yield attributes, and grain yields, as well as crop water productivity by 56 and 105% during the second and first seasons, respectively. Grain N, total N, and straw N were increased by 159, 159, and 160%, and by 90, 114, and 153%, during the first and second seasons, respectively. Enhanced N efficiencies, including agronomic efficiency, recovery efficiency, partial factor productivity, and N harvest index, at varying NFRs were observed under PD2 during both seasons. Highly significant (p < 0.001) and positive associations were observed among agronomic attributes, N uptake, NUE, and crop water productivity of upland rice in correlation assessment. Profitability from grain yields was observed with N fertilization and N90 resulted in maximum profit under all the PDs. However, the highest marginal benefit-cost ratio was observed at N60 under PD2 during both seasons. The results suggest that the NFR of 90 kg N ha−1 and planting at the end of September or start of October would enhance resource use efficiency and productivity, and maximize profitability. Furthermore, long–term field investigations with a range of NFRs and adopting forecasting measures to adjust the planting date for upland rice are recommended.

N-Acetylcysteine Priming Alleviates the Transplanting Injury of Machine-Transplanted Rice by Comprehensively Promoting Antioxidant and Photosynthetic Systems.

The stress of transplanting injury adversely affects rice growth and productivity worldwide. N-acetylcysteine (NAC), the precursor of glutathione, is a potent ROS scavenger with powerful antioxidant activity. Previous studies on the application of NAC in plants mainly focused on alleviating the stress of heavy metals, UV-B, herbicides, etc. However, the role of NAC in alleviating transplanting injury is still not clear. A barrel experiment was carried out to explain the mechanism of NAC regulating the transplanting injury to machine-transplanted rice during the recovery stage. The results showed that NAC priming shortened the time of initiation of tillering and increased the tiller numbers within 3 weeks after transplanting. In addition, NAC priming increased the chlorophyll content, net photosynthetic rate, and sucrose content, thereby improving the dry weight at the recovery stage, especially root dry weight. At the same time, NAC priming significantly increased the activity of ascorbate peroxidase (APX), glutathione reductase (GR), catalase (CAT), and superoxide dismutase (SOD). In addition, it also regulated flavonoids and total phenols contents to reduce hydrogen peroxide (H2O2) and malondialdehyde (MDA) contents, especially at the initial days after transplanting. These results suggest that NAC priming improves the tolerance of rice seedlings against transplanting injury by enhancing photosynthesis and antioxidant systems at initial days after transplanting, thereby promoting the accumulation of dry matter and tillering for higher yield returns.

Effects of drought stress on some phytochemical characteristics of rice cultivars under different chemical and organic nutritional sources

To study the phytochemical properties of rice cultivars using different nutrients (chemical and organic) under drought stress, a split-plot factorial experiment with randomized complete block design with three replications at Dasht-e-Naz field in Sari city, in the crop years 2016 and 2017 were repeated. The drought stresses were fully performed in three levels; stress on the time of tillering initiation (15 days after transplanting), in remobilization stage (the end of flowering and the beginning of grain filling stage), and no stress (control) as the main factors in terms of elimination of irrigation and re-irrigation after the appearance of hairy cleavage. The type of nutrition system was considered as the sub-factors in the factorial pattern in terms of four levels of vermicomposting and Azolla compost, in the quantities of 6 and 8 tons per hectare respectively, humic acid (4.5 per one thousand), the conventional chemical fertilizers (Nitrogen, Phosphor, and Potassium), and two cultivars (Shirodi and the local Tarom). The highest proline, CAT, POX, APX, and enzymes ABA were also carried out under drought stress conditions in the remobilization stage using conventional fertilizer (Nitrogen, Phosphor, and Potassium) in the local Tarom cultivar. Therefore, according to this experiment’s results, the local Tarom cultivar, due to increased activity of enzymes under stress conditions, is a tolerant cultivar. One can also consider humic acid’s role in increasing drought tolerance of rice cultivars by reducing the oxidative damage caused by active oxygen species created under drought stress and protecting plants’ physiological processes.

A proteomic analysis of grain yield-related traits in wheat.

Grain yield, which is mainly contributed by tillering capacity as well as kernel number and weight, is the most important trait to plant breeders and agronomists. Label-free quantitative proteomics was used to analyse yield-contributing organs in wheat. These were leaf sample, tiller initiation, spike initiation, ovary and three successive kernel development stages at 5, 10 and 15 days after anthesis (DAA). We identified 3182 proteins across all samples. The largest number was obtained for spike initiation (1673), while the smallest was kernel sample at 15 DAA (709). Of the 3182 proteins, 296 of them were common to all seven organs. Organ-specific proteins ranged from 148 in ovary to 561 in spike initiation. When relative protein abundances were compared to that of leaf sample, 347 and 519 proteins were identified as differentially abundant in tiller initiation and spike initiation, respectively. When compared with ovary, 81, 35 and 96 proteins were identified as differentially abundant in kernels sampled at 5, 10 and 15 DAA, respectively. Our study indicated that two Argonaute proteins were solely expressed in spike initiation. Of the four expansin proteins detected, three of them were mainly expressed during the first 10 days of kernel development after anthesis. We also detected cell wall invertases and sucrose and starch synthases mainly during the kernel development period. The manipulation of these proteins could lead to increases in tillers, kernels per spike or final grain weight, and is worth exploring in future studies.

Comparative transcriptome analyses reveal different mechanism of high- and low-tillering genotypes controlling tiller growth in orchardgrass (Dactylis glomerata L.)

BackgroundTillering is an important agronomic trait underlying the yields and reproduction of orchardgrass (Dactylis glomerata), an important perennial forage grass. Although some genes affecting tiller initiation have been identified, the tillering regulatory network is still largely unknown, especially in perennial forage grasses. Thus, unraveling the regulatory mechanisms of tillering in orchardgrass could be helpful in developing selective strategies for high-yield perennial grasses. In this study, we generated high-throughput RNA-sequencing data from multiple tissues of tillering stage plants to identify differentially expressed genes (DEGs) between high- and low-tillering orchardgrass genotypes. Gene Ontology and pathway enrichment analyses connecting the DEGs to tillering number diversity were conducted.ResultsIn the present study, approximately 26,282 DEGs were identified between two orchardgrass genotypes, AKZ-NRGR667 (a high-tillering genotype) and D20170203 (a low-tillering genotype), which significantly differed in tiller number. Pathway enrichment analysis indicated that DEGs related to the biosynthesis of three classes of phytohormones, i.e., strigolactones (SLs), abscisic acid (ABA), and gibberellic acid (GA), as well as nitrogen metabolism dominated such differences between the high- and low-tillering genotypes. We also confirmed that under phosphorus deficiency, the expression level of the major SL biosynthesis genes encoding DWARF27 (D27), 9-cis-beta-carotene 9′,10′-cleaving dioxygenase (CCD7), carlactone synthase (CCD8), and more axillary branching1 (MAX1) proteins in the high-tillering orchardgrass genotype increased more slowly relative to the low-tillering genotype.ConclusionsHere, we used transcriptomic data to study the tillering mechanism of perennial forage grasses. We demonstrated that differential expression patterns of genes involved in SL, ABA, and GA biosynthesis may differentiate high- and low-tillering orchardgrass genotypes at the tillering stage. Furthermore, the core SL biosynthesis-associated genes in high-tillering orchardgrass were more insensitive than the low-tillering genotype to phosphorus deficiency which can lead to increases in SL biosynthesis, raising the possibility that there may be distinct SL biosynthesis way in tillering regulation in orchardgrass. Our research has revealed some candidate genes involved in the regulation of tillering in perennial grasses that is available for establishment of new breeding resources for high-yield perennial grasses and will serve as a new resource for future studies into molecular mechanism of tillering regulation in orchardgrass.

A Rice Variety (BRRI dhan29) Yield Performance as Influenced by Foliar Application of Salicylic Acid in Bangladesh

Objective of this study was to examine and evaluate the role of different rates of salicylic acid (SA) as foliar spray on growth and yield performance of BRRI dhan29. The experiment was conducted at Sher-e-Bangla Agricultural University, Bangladesh from November, 2016 to May, 2017 following a randomized complete block design with five rates of SA in six replications. The results showed that the lower rate of SA (upto 0.75 mM) has a positive effect on rice biomass production including effective tiller per hill, filled grain per panicle, grain yield and straw yield. The highest dry matter production at both maximum tillering and panicle initiation stages was found at SA spray rate of 0.5 mM. The highest number of effective tillers per hill (14.7) as well as the highest filled grain (120.4) and grain yield (8.1 t/ha) were found at SA rate of 0.75 mM. However, the maximum biomass production was obtained at SA rate of 0.25 mM. The minimum grain yield (7.0 t/ha) was observed in the control treatment.

Reduced Growth and Nitrogen Uptake During Waterlogging at Tillering Permanently Affect Yield Components in Late Sown Oats.

In Mediterranean Europe, winter cereals can experience soil waterlogging starting from crop establishment up to stem elongation and, in late sowings, this stress is combined with temperatures favorable to plant metabolism. Oats response to waterlogging has been rarely investigated, but these species seems to recover better than other cereals. In a 2-year experiment, Avena sativa and Avena byzantina were sown at the end of winter in pots placed outdoors. At the two-tiller stage, plants were exposed to waterlogging for periods ranging from 0 to 35 days. The dry weight and the N-concentration of shoots and roots were determined on waterlogged plants and drained controls at the start and the end of each waterlogging period, and at maturity. At maturity, the grain yield and its components were determined. To relate oat response to its specific morphological and developmental traits, results were compared to the published results in wheat and barley. Both oat species suffered severe damage during waterlogging: the uptake of nitrogen and the N-concentration of shoots were reduced after 7 days, tiller initiation and root growth after 14 days, and shoot growth after 21 days. All plants survived waterlogging, and the relative growth rates of roots and shoots and the net uptake rate of nitrogen were resumed during recovery. Nevertheless, at maturity, the straw and root biomass were markedly lower with all waterlogging durations, and grain yield decreased by 42% up to approximately 81% following an asymptotic equation. The most affected yield components were the number of panicles per plant and the number of kernels per panicle, but their relative sensitivity changed according to waterlogging duration. The slight increase in tiller fertility in response to short waterlogging and the small and irregular decrease in the number of kernels per spikelet suggest that the two oats could recover the initiation and size of inflorescences better than other winter cereals. Despite this, waterlogging in spring was highly detrimental to these oats because of severe damage under waterlogging and because of the inability to initiate new tillers and adequately resume root growth during recovery, once plants had achieved the phase of stem elongation.

Nutrient uptake, partitioning, and removal in two modern high-yielding Colombian rice genotypes

The objective of this research was to determine the difference on growth between a rice cultivar with Clearfield® technology (Only Rice 228) and a hybrid (Benja 1); to characterize nutrient uptake, distribution, accumulation and removal between these two commercial genotypes. Tests under shade house and field conditions were performed to estimate macro and micronutrient uptake patterns. Plants were sampled at nine growth stages (emergence, initiation of tillering, active tillering, initiation of panicle primordia, booting, flowering, milky, soft dough and mature grain) and divided into different organs for nutrient determination. The results showed that “Benja 1” plants (92 d) had a shorter cycle than “Only Rice 228” (OR 228) plants (118 d). “OR 228” exhibited a greater biomass production (16.575 kg ha−1 vs. 12.621 kg ha−1) in field. The nutrient acquisition was faster in the hybrid Benja 1 between tillering initiation and the milky grain stage in which the N, K, Ca, Mg, Mn, B, and Cu uptake was more evenly and highly distributed throughout these stages in both conditions. “Benja 1” showed a higher nutrient harvest index (HI). HI values above 50% (P (62%), N (61%), Cu (67%), S (55%), and Mg (52%)) were found in Benja 1 under field conditions. The results also highlight Si removal in both rice genotypes, in which Benja 1 stands out. These results provide information on the nutrient uptake and partitioning of modern rice genotypes, and give the knowledge to optimize fertilizer programs and timing recommendations for rice biomass and grain production in Colombia.

Tiller Initiation and its Effects on Yield and Yield Components in Winter Wheat

Core Ideas A marking technique was used to monitor leaf and tiller development. The earlier a tiller is formed the more kernels it produces. Seeding rate influences tiller initiation and productivity. ABSTRACTVegetative growth in the form of tillers is crucial to final yield in winter wheat (Triticum aestivum L.). To understand the impact management practices have on tiller initiation, a study was conducted using two seeding rates (1.9 × 106 vs. 6.8 × 106 ha−1) and two N timing applications (single vs. split). Tillers initiated in the fall made up the majority of spikes compared to tillers initiated from 1 January to the start of jointing (GS 30). Tillers initiated in March at either seeding rate produced very few kernels spike–1, low kernel weight, and contributed little to yield. At the high seeding rate, tillers initiated prior to 1 January were responsible for more than 87% of the grain yield. Tillers produced in January– February produced 5 to 11% of the final yield, while tillers produced in March contributed less than 2%. In contrast, at the low seeding rate tillers produced in January–February made up 20 to almost 60% of the final yield. Overall, this study shows the timing and rate of leaf initiation impacts yield and yield components. Earlier tillers have an advantage in that they have shorter periods of leaf development that result in more leaf area which in turn supports more kernel spike–1 and heavier kernels, thus more grain weight per spike. Timing of N (single vs. split) application resulted in no significant impact on tiller development, spike number, kernel number, kernel weight, or grain yield.

Dynamics of dry matter and nitrogen distribution in transplanted rice on mollisols

We studied the dynamics of dry matter (DM) and nitrogen (N) distribution in different plant parts (leaf, stem, and panicle) and grain yield of transplanted rice due to N management practices through neem coated urea (NCU). The results indicated that application of NCU at 125% recommended dose of N (RDN) with 50:25:25 split schedule at basal (B), active tillering (AT), and panicle initiation (PI) stages resulted in higher DM and N distribution to leaf, stem, and panicle at 60 and 90 days after transplanting and harvest than the application of prilled urea at 100% RDN with the same split schedule (existing practice). Further, the increment in grain yield was 10.95% than the existing practice. Hence, we suggest the application of NCU at 125% RDN with 50:25:25 split schedule at B, AT, and PI stages for achieving higher DM and grain yield on Mollisols.

Measuring Tiller Development and Mortality in Winter Wheat under Field Conditions

Core Ideas Seeding rate is important for measuring phyllochron interval and maximum number leaf. As seeding rate increases, phyllochron interval increases; as seeding rate increases, maximum leaf number decreases. High seeding rate led to an increase in tiller production per m2 compared with low seeding rate. Neither seeding rate nor N application timing increased tiller viability. Vegetative growth in the form of tillers is crucial in development of wheat (Triticum aestivum L). To better understand wheat development and tiller initiation, a study was conducted using two seeding rates (193 vs. 676 m−2) and two N application timings (single vs. split). Using a detailed marking technique to track leaf and tiller growth, tillers plant−1, rate of leaf appearance tiller−1, phyllochron interval (PI), accumulated heat units, and maximum leaf number (MLN) were measured. Although the timing of tiller initiation did not differ among the two seeding rates, results showed that at the low seeding rate (LSR) the frequency of leaf appearance on each tiller was increased, resulting in tillers having more leaves at decimal growth stage (DGS) 30. At the high seeding rate (HSR), leaf appearance among tillers was reduced, resulting in only fall tillers having enough leaf area to sustain growth from DGS 30 to harvest. The MLN was significantly greater at the LSR compared with the HSR. The MLN for the main stem was greater than those found on Tiller 1, and MLN for Tiller 1 was greater than those found on Tiller 2. There were no significant interactions or main effects involving the timing of N. It is difficult to determine the role that N application timing has on tiller and leaf development since there was not a consistent effect of N timing on PI and no effects of N timing on MLN.

Clonality-dependent dynamic change of plant community in temperate grasslands under nitrogen enrichment.

Clonal plants with diverse growth forms are dominant in plant community of temperate grasslands and sensitive to enhanced atmospheric nitrogen (N) deposition. However, whether and how clonal plants with different growth forms differ in their responses to N deposition remains unclear. We investigated the long-term (14-year) and short-term (4-year) effects of N addition on clonal plants of three growth forms (clumper, stoloniferous and rhizomatous clonal plants) in temperate grasslands of northern China by monitoring the clonal traits and belowground meristems. We found that, for the first time, the effects of N addition on clonal plants were dependent on N-addition duration and growth forms of clonal plants. Short-term N addition enhanced growth of clumper clonal plants, while long-term N addition favored growth of rhizomatous clonal plants and suppressed growth of stoloniferous clonal plants. We further revealed that clumper clonal plants can preempt space by tillering rapidly, thus conferring their dominance in the community and suppressing vegetative reproduction of stoloniferous clonal plants upon exposure to short-term N enhancement. In contrast, long-term N addition depressed initiation of buds and tillering of clumper clonal plants. Moreover, long-term N addition shortened rhizome internode and enhanced vegetative reproduction of rhizomatous clonal plants, leading to their ultimate dominance in the steppe community. Our results highlight the important roles of belowground meristems and clonal traits in control of dynamic changes of plant community in response to N enrichment. These findings provide a new perspective to understand N-induced changes in plant community of temperate grasslands.

Growth parameters of autumn rice under various irrigation schedules and nutrient management

A field experiment was conducted at Instructional-cum-Research (ICR) Farm, Assam Agricultural University, Jorhat-13 during autumn season of 2015 to study the nutrient management of direct seeded autumn rice under various irrigation schedules. The experiment consisted of four irrigation schedules viz., I1(No irrigation), I2(Irrigation at tiller initiation (TI) + boot leaf stage (BL)), I3(Irrigation at TI + panicle initiation (PI) + BL), I4 (Irrigation at TI + PI + Grain filling stage(GF)) and three nutrient management practices viz.,F1(100 % RDF +2t/ha FYM), F2(50 % RDF +1.5 t/ha enriched compost), F3(50 % RDF + 1.5 t/ha Vermicompost). The trial was laid out in split plot design with three replications. The soil was sandy loam. Inglongkiri rice variety was used in the experiment. Results revealed that irrigation schedule I3(Irrigation at TI + PI + BL) recorded significantly the highest growth characters of rice in terms of plant height, number of leaves per plant, and dry matter accumulation. Different nutrient management practices brought about significant differences in plant population per and dry matter accumulation. The highest of these parameters were recorded under application of 50% RDF along with 1.5 t/ha enriched compost and this was statically at par with F1 (100% RDF +2 t/ha FYM).

Effect of fertilizer levels and supplementary irrigation on late maturing transplanted paddy under rainfed medium land situations

A field experiment was conducted at the Research Farm of Indian Institute of Water Management (IIWM), Bhubaneswar in the kharif season for two years (2012 and 2013) to study the effect of supplementary irrigation and fertilizer levels on long duration paddy variety ‘Swarna ’grown in a medium land having dyke height of 20 cm around the plots. Dry spells of 18 to 21 days duration occurred at panicle initiation and flowering stage in the first year, and at active tillering and panicle initiation stage in the second year. The results revealed that as compared to the rainfed situation, two supplementary irrigations (5 cm each using flexi pipe) during the dry spells (at active tillering, panicle initiation and flowering stages) improved rice grain and straw yield by 15.7% and 10.3%, respectively. Recommended fertilizer dose (80 kg N, 40 kg P 2O5 and 40 kg K2O ha−1) increased rice grain and straw yields by 18.2% and 16.1%, respectively, as compared to the 60% of the recommended dose.

Effect of foliar application of plant growth regulators on nitrous oxide (N2O) emission and grain yield in wheat

Agricultural soils are the major source of global nitrous oxide (N2O) emission, and more than two thirds of N2O emission originate from soil. Recent studies have identified that green plants contribute to transport of N2O to the atmosphere. We investigated the effects of foliar application of plant growth regulators (PGRs) and growth stimulating chemicals on N2O emission and wheat grain yield for 2years. The PGRs' abscisic acid (ABA) and cytozyme (20mgL-1), kinetin (10 and 20mg L-1) and wet tea extract (1:20 w/w) along with distilled water as control were sprayed on wheat canopy at the tillering and panicle initiation stages. Our results showed that cytozyme and tea extract enhanced the plant dry biomass over control. Kinetin (10 and 20mgL-1) and cytozyme increased the plant photosynthetic rate and photosynthate partitioning towards the developing grain. ABA (20mgL-1) and kinetin (10 and 20mgL-1) reduced the N2O emission over control primarily through regulation of leaf growth, stomatal density and xylem vessel size. Leaf area, stomatal density and xylem vessel size were found to be associated with N2O transport and emission. We concluded that use of ABA and kinetin can reduce N2O emissions without any impact on wheat grain yield.

Pseudomonas fluorescens strains selectively suppress annual bluegrass (Poa annua L.)

Annual bluegrass (Poa annua L., ABG) is a cool-season annual grass that is a major weed species in turf, turfgrass-seed and sod production, and golf courses of the western United States. The life cycles of ABG and TG are very similar, but ABG is typically more competitive. Because these plants are so similar, selective control using conventional methods is limited. Pseudomonas fluorescens biovar B strain XJ3, biovar B strain XS18, and biovar A strain LRS12 are naturally-occurring soil bacteria that suppress ABG growth. These bacterial strains do not inhibit the growth of desirable turf species, other crops, or native plants. When applied to the soil and/or seeds in the fall, the bacteria establish in the soil community and increase in numbers during the cool temperatures of fall and spring, coinciding with the early root growth of ABG. These bacteria grow along roots and deliver a compound that inhibits root formation, root growth, and tiller initiation of ABG. The bacteria can also be used in combination with herbicides to inhibit the growth and seed production of standing ABG. Bacteria that selectively suppress ABG can be used to reduce the weed-seed bank in golf courses, lawns, turf, and turf-seed production. These bacteria add a formidable tool in the toolbox to fight invasive grass weeds, while limiting the need for tillage and herbicides for weed control.

Switchgrass SBP-box transcription factors PvSPL1 and 2 function redundantly to initiate side tillers and affect biomass yield of energy crop.

BackgroundSwitchgrass (Panicum virgatum L.) is a dedicated lignocellulosic feedstock for bioenergy production. The SQUAMOSA PROMOTER-BINDING PROTEIN (SBP-box)-LIKE transcription factors (SPLs) change plant architecture and vegetative-to-reproductive phase transition significantly, and as such, they are promising candidates for genetic improvement of switchgrass biomass yield. However, the genome-wide identification and functional characterization of SPL genes have yet to be investigated in herbaceous energy crops.ResultsWe identified 35 full-length SPL genes in the switchgrass genome. The phylogenetic relationship and expression pattern of PvSPLs provided baseline information for their function characterization. Based on the global overview of PvSPLs, we explored the biological function of miR156-targeted PvSPL1 and PvSPL2, which are closely related members of SPL family in switchgrass. Our results showed that PvSPL1 and PvSPL2 acted redundantly to modulate side tiller initiation, whereas they did not affect phase transition and internode initiation. Consistently, overexpression of the miR156-resistant rPvSPL2 in the miR156-overexpressing transgenic plants greatly reduced tiller initiation, but did not rescue the delayed flowering and increased internode numbers. Furthermore, suppression of PvSPL2 activity in switchgrass increased biomass yield and reduced lignin accumulation, which thereby elevated the total amount of solubilized sugars.ConclusionsOur results indicate that different miR156-targeted PvSPL subfamily genes function predominantly in certain biological processes in switchgrass. We suggest that PvSPL2 and its paralogs can be utilized as the valuable targets in molecular breeding of energy crops for developing novel germplasms with high biofuel production.Electronic supplementary materialThe online version of this article (doi:10.1186/s13068-016-0516-z) contains supplementary material, which is available to authorized users.