Direct and residual effects of nitrogen fertilization, foliar application of potassium and plant growth retardant on Egyptian cotton growth, seed yield, seed viability and seedling vigor

In order to obtain high productivity for a cotton crop, one of the major requirements is to establish an adequate plant population. The use of good-quality seed may ultimately be the best approach to attain this goal problem. The objective of this research was to study the effect of N-fertilization (at rates of 95.2 and 142.8 kg of N ha^?1), foliar application of K (at rates of 0, 0.38, 0.77, 1.15 kg of K₂O ha^?1, applied twice during square initiation and boll development stages) and the plant growth retardant (PGR), mepiquat chloride (applied twice, 75 days after planting at 0.0 [control] and 0.048 kg a.i. ha^?1, and 90 days after planting at 0.0 [control] and 0.024 kg a.i. ha^?1), on seed yield, viability, and seedling vigor of Egyptian cotton (Gossypium barbadense cv. Giza 86). A field experiment was conducted at the Agricultural Research Center, Giza, Egypt in two growing seasons. Growth, mineral uptake, seed yield per plant and per ha, seed weight, seed viability, seedling vigor and cool germination test performance were all found to increase significantly due to the addition of the high N-rate, the foliar application of three potassium concentrations, and the PGR mepiquat chloride. The N and K rates as well as application of mepiquat chloride had no significant effect on the germination rate index in both seasons. Under the conditions of this study, applying N at a rate of 142.8 kg ha^?1 combined with spraying cotton plants with K₂O at 1.15 kg ha^?1 and with mepiquat chloride at 0.048 + 0.024 kg ha^?1 were found to improve seed yield as well as seed viability and seedling vigor in the next season.     

Improving seed germination and seedling growth of Lepidium sativum with different priming methods under arsenic stress

This study was carried out to determine the effects of seven kinds of priming, gibberellic acid (GA), salicylic acid (SA), citric acid (CA), sodium chloride (NaCl), potassium chloride (KCl), zinc (Zn) and iron (Fe) on seed germination and seedling emergence of garden cress (Lepidium sativum) under arsenic stress. Results revealed that germination percentage (GP), seed vigor index (SVI), radicle length (RL), plumule length (PL) and tolerance index (TI) were significantly decreased when arsenic stress was augmented from 0 to 100 mg L^?1. Nevertheless, primed seeds (hormo, nutri and halo-priming) increased seed germination and seedling emergence and tolerance index of L. sativum. Phytotoxicity was also reduced by priming practices. Meanwhile, priming with gibberellic acid (GA) had the most positive effects on measured traits. Generally, the order of the effect of priming treatments tested decreases by the following order: GA > CA > KCl > Fe > Zn > SA > NaCl. The result of this study is coherent with the hypothesis that under heavy metal stress, priming can develop seed germination performance and seedling emergence.     

Beneficial microorganism survival on seed, roots and in rhizosphere soil following application to seed during drum priming

Priming is a technique used to improve seedling establishment of direct-seeded crops such as onion and carrot, resulting in a quick and uniform emergence. This work investigated the application of four selected beneficial microorganisms (Pseudomonas chlororaphis MA342, Pseudomonas fluorescens CHA0, Clonostachys rosea IK726d11 and Trichoderma harzianum T22) to onion and carrot seed during drum priming, and their subsequent survival and establishment in the rhizosphere once the seed was planted. Different application rates of fungi (7 log₁₀ cfu g⁻¹ dry seed) and bacteria (6 log₁₀ cfu g⁻¹ dry seed) were required on onion to achieve the end target of 5 log₁₀ cfu g⁻¹ dry seed, whereas a lower rate (5 log₁₀ cfu g⁻¹ dry seed for both bacteria and fungi) was successful on carrot. Microorganism-treated seed was planted in soil in the glasshouse and root and rhizosphere soil samples were taken at 2, 4 and 8 weeks post-planting. All seed-applied microorganisms were recovered throughout the experiment, although differences in the survival patterns were seen. The bacterial isolates declined in number over time, with P. fluorescens CHA0 showing better overall survival than P. chlororaphis MA342, particularly on the roots and in the rhizosphere soil of carrot. In contrast to the bacteria, the fungal isolate C. rosea IK726d11 showed good survival on both onion and carrot, and increased significantly in number throughout the 8-week period. Trichoderma harzianum T22 remained relatively constant in number throughout the experiment, but showed better survival on carrot than onion roots. Similar results were found in three different soil-types.     

Improvement of growth,under field conditions,of wheat inoculated with <Emphasis Type="Italic">Pseudomonas chlororaphis</Emphasis> subsp.<Emphasis Type="Italic"> aurantiaca</Emphasis> SR1

Effects of inoculation of wheat (Triticum aestivum L.) with the rhizobacterium Pseudomonas chlororaphis subsp. aurantiaca strain SR1 (termed SR1) were studied at an experimental field site in Río Cuarto, Argentina. Treatments involved SR1 inoculation with or without nitrogen/phosphorus fertilization. Inoculation produced a significant increase in plant height and root length in early growth stages. Inoculation plus fertilization with 40 kg ha⁻¹ urea/30 kg ha⁻¹ diamonic phosphate (“50% dose”) gave a yield increase of 636 kg ha⁻¹ relative to control, and an increase of 472 kg ha⁻¹ relative to fertilization with 80 kg ha⁻¹ urea/60 kg ha⁻¹ phosphate without inoculation. SR1 inoculation without fertilization, compared to control, produced increases of 6% in weight of 1,000 grains, 13% in number of spikes per plant, and 30% in number of grains per spike. Inoculation plus 50% dose fertilization also improved these parameters. Results of the study indicate that inoculation of wheat with SR1 improves various growth and yield parameters, and allows reduced dosage of nitrogen/phosphorus fertilizers in the field.     

Mepiquat chloride seed treatment and germination temperature effects on cotton growth, nutrient partitioning, and water use efficiency

Cotton seed (Gossypium hirsutum L. cv. Stoneville 825), treated with 0, 0.2, 1.0, and 2.0 g active ingredient (a.i.) mepiquat chloride (MC) kg^–1, was evaluated for the effect of MC on early plant growth. Emergence rate and total emergence of MC-treated seed and control were similar regardless of germination temperature. However, the number of leaves and squares and the dry weight of leaves, stems, and roots for hydroponically grown cotton plants were significantly lower at lower germination temperatures (15°C for 3 day/30°C for 1 day and 15°C for 4 days) than at higher germination temperatures (30°C for 4 days and 30°C for 3 days/15°C for 1 day). All MC treatments significantly decreased the number of nodes, leaves, and squares, as well as dry weight of leaves, stems, and roots, as compared to control plants at 28 days after emergence. MC seed treatments also significantly reduced plant height and total leaf area compared to controls. Water-use efficiency (WUE) was significantly lower for the 1.0 g a.i. MC treatment than for control plants. In general, the highest rate of MC seed treatment resulted in greater concentrations of calcium, phosphorus, and nitrogen in plant leaves and stems and also in greater concentrations of magnesium, phosphorus, and nitrogen in roots than in controls.     

Revegetation and reclamation of soils using wild leguminous shrubs in cold semiarid Mediterranean conditions: Litterfall and carbon and nitrogen returns under two aridity regimes

This study was designed to evaluate the litter produced by Mediterranean shrub legumes subjected to two conditions of aridity. Seasonal litterfall patterns and litter chemistry showed no significant variation with soil aridity. The effects of aridity on the amount of litter produced were related to the plant species. A higher availability of water led to a 110% increase in litter production by Colutea arborescens (3191 vs. 1516 kg ha^–1) and to a 24% increase for Medicago strasseri (5288 vs. 4258 kg ha^–1). The litter provided by Colutea cilicica failed to significantly increase (1651 vs. 1825 kg ha^–1) in less arid conditions. In our experimental conditions, Dorycnium hirsutum showed high mortality and scarce persistence. In general, the litter supplied by these shrub legumes was low in lignin and showed high levels of easily degradable organic-C. Its N content, in the range 18 to 26.5 g kg^–1, was similar to that described by others for multipurpose tropical legumes. Under the semi-arid conditions of central Spain, C. arborescens and C. cilicica gave rise to potential yearly returns of 662 and 693 kg ha^–1 organic-C, and 35 and 44 kg ha^–1 N, respectively. M. strasseri provided a yearly organic-C return (1742 kg ha^–1) similar to that of a mature Mediterranean wood, and to a potential N return (78 kg ha^–1) that substantially exceeded this reference. Compared to the sclerophyllous species typical of the Mediterranean environment, shrub legumes show a much greater potential for enhancing N and organic-C levels, and consequently, for improving the biological activity of degraded soils. This feature is thought to be associated with the rapid and constant renewal of their leaves and their ability to provide the soil with other easily degraded materials.     

Vegetation is the main factor in nutrient retention in a constructed wetland buffer

Wetland buffers may play an important role in the retention of nitrogen (N) and phosphorus (P) that can be released in large quantities from forestry operations. In this study, we investigated the retention capacity of N and P of wetland vegetation comparing the control area with two experimental areas within one site before and after N and P pulse (45 kg N and 15 kg P) lasting one growing season (ca. 150 d). N and P pulse caused a significant increase in the plant biomass and N and P content in the upper experimental area, which received most of the added nutrients. Added N and P was mainly retained in the above and below ground parts of E. vaginatum, especially in storage organs and roots which form a long-term sink for nutrients. Total N retention in the plant biomass during the first year after N and P treatment ranged from 25.3 kg (equals to 126.7 kg N ha^–1) in the upper experimental area to 6.1 kg (20.4 kg N ha^–1) in the lower experimental area and 4.7 kg (15.7 kg N ha^–1) in the control area. P retention ranged from 2.6 kg (13.1 kg P ha^–1) in the upper experimental area to 1.0 kg (3.4 kg P ha^–1) in the lower experimental area and 0.5 kg (1.8 kg P ha^–1) in the control area. The retained proportions of N and P in the plant biomass in the two experimental areas were approximately 70% of the added N (45 kg N y^–1) and approximately 25% of the added P (15 kg P y^–1) during the first year after N and P addition in 1999. Our study shows that vigorously colonising and growing vegetation is the main factor in the retention of N, a significant factor in the retention of P in a constructed wetland buffer, and thus an important contributor to the prevention of detrimental effects of N and P leaching on watercourses.     

Impact of nitrogen cycling on stream water quality in a basin associated with forest, grassland, and animal husbandry, Hokkaido, Japan

The direct discharge of wastes from agricultural fields and livestock feedlots increases the concentration of nitrogen (N) in streams. This study was conducted to determine the impact of farm N budgets on stream water quality. In 1999–2000, we investigated an experimental livestock farm of 457 ha in the Kepau River watershed in Shizunai, Southern Hokkaido, Japan, where grasslands and maize fields account for 33% of the farm's total area. Annual N flow was calculated on the basis of the farm's land management records. Livestock was supplied with 15.2 t N yr⁻¹ from agricultural lands, which made the farm 81% self-sufficient. Livestock excreta produced 17.2 t N yr⁻¹, of which 4 t N yr⁻¹ was lost, probably by ammonia volatilization during decomposition. Apart from manure, the major N inputs were 9.1 t N yr⁻¹ of chemical fertilizers, 6.4 t N yr⁻¹ of atmospheric deposition, and 12.6 t N yr⁻¹ biological N fixation. The major outputs were uptake by forest vegetation of 11.0 t N yr⁻¹, denitrification of 1.5 t N yr⁻¹, and livestock feed production. Consequently, the annual surplus N on the whole farm was estimated to be 12.7 t N yr⁻¹, which corresponds to 28 kg N ha⁻¹ of agricultural land.The annual N load from the farm to the Kepau River was measured at 14.4 t N yr⁻¹. Ninety percent of this load, however, occurred during rainfall and spring snowmelt. Within one 2-week snowmelt period, 5.0 t N was discharged, which corresponds to 35% of the annual load. Although the average N concentration of stream water below the farm was 2.8 mg N L⁻¹, the maximum concentration recorded during the snowmelt season was 13.5 mg N L⁻¹. The N concentration of the stream water increased and the silica (Si) concentration decreased as the stream flow rate increased. Consequently, the molar ratio of Si/N frequently dropped below 2.7, the critical level for the occurrence of eutrophication. The large N load during rainfall and snowmelt could be ascribed to open ditches, which collect tile drainage and surface runoff from the fields, discharging it directly to the river, bypassing the forested riparian zone.     

A comparison of soil carbon pools and profiles in wetlands in Costa Rica and Ohio

Wetlands are large carbon pools and play important roles in global carbon cycles as natural carbon sinks. This study analyzes the variation of total soil carbon with depth in two temperate (Ohio) and three tropical (humid and dry) wetlands in Costa Rica and compares their total soil C pool to determine C accumulation in wetland soils. The temperate wetlands had significantly greater (P < 0.01) C pools (17.6 kg C m⁻²) than did the wetlands located in tropical climates (9.7 kg C m⁻²) in the top 24 cm of soil. Carbon profiles showed a rapid decrease of concentrations with soil depth in the tropical sites, whereas in the temperate wetlands they tended to increase with depth, up to a maximum at 18–24 cm, after which they started decreasing. The two wetlands in Ohio had about ten times the mean total C concentration of adjacent upland soils (e.g., 161 g C kg⁻¹ were measured in a central Ohio isolated forested wetland, and 17 g C kg⁻¹ in an adjacent upland site), and their soil C pools were significantly higher (P < 0.01). Among the five wetland study sites, three main wetland types were identified – isolated forested, riverine flow-through, and slow-flow slough. In the top 24 cm of soil, isolated forested wetlands had the greatest pool (10.8 kg C m⁻²), significantly higher (P < 0.05) than the other two types (7.9 kg C m⁻² in the riverine flow-though wetlands and 8.0 kg C m⁻² in a slowly flowing slough), indicating that the type of organic matter entering into the system and the type of wetland may be key factors in defining its soil C pool. A riverine flow-through wetland in Ohio showed a significantly higher C pool (P < 0.05) in the permanently flooded location (18.5 kg C m⁻²) than in the edge location with fluctuating hydrology, where the soil is intermittently flooded (14.6 kg C m⁻²).     

Regulation of Nitrogen Metabolism,Photosynthetic Activity,and Yield Attributes of Spring Wheat by Nitrogen Fertilizer in the Semi-arid Loess Plateau Region

It is critical for spring wheat (Triticum aestivum L.) production in the semi-arid Loess Plateau to understand the impact of nitrogen (N) fertilizer on changes in N metabolism, photosynthetic parameters, and their relationship with grain yield and quality. The photosynthetic capacity of flag leaves, dry matter accumulation, and N metabolite enzyme activities from anthesis to maturity were studied on a long-term fertilization trial under different N rates [0 kg ha^?1(N1), 52.5 kg ha^?1 (N2), 105 kg ha^?1 (N3), 157.5 kg ha^?1 (N4), and 210 kg ha^?1 (N5)]. It was observed that N3 produced optimum total dry matter (5407 kg ha^?1), 1000 grain weight (39.7 g), grain yield (2.64 t ha^?1), and protein content (13.97%). Our results showed that N fertilization significantly increased photosynthetic parameters and N metabolite enzymes at all growth stages. Nitrogen harvest index, partial productivity factor, agronomic recovery efficiency, and nitrogen agronomic efficiency were decreased with increased N. Higher N rates (N3–N5) maintained higher photosynthetic capacity and dry matter accumulation and lower intercellular CO₂ content. The N supply influenced NUE by improving photosynthetic properties. The N3 produced highest chlorophyll content, photosynthetic rate, stomatal conductance and transpiration rate, grain yield, grain protein, dry matter, grains weight, and N metabolite enzyme activities compared to the other rates (N1, N2, N4, and N5). Therefore, increasing N rates beyond the optimum quantity only promotes vegetative development and results in lower yields.

     

Regeneration of Cyperaceae, with particular reference to seed ecology and seed banks

Cyperaceae (sedges) are an important component of many ecosystems. To understand better their regeneration, we examined seed ecology, including dispersal, seed characteristics, and germination behavior that relate to seed bank development and persistence. We also evaluated sedge seed banks from 104 studies, representing a wide array of habitats. Sedge seed bank development and persistence were associated with germination and dormancy traits, namely: dormancy level, seasonal dormancy patterns, and requirement for light, alternating temperatures, and aerobic conditions. Interplay of traits appears to have resulted in low-risk germination strategies adapted to exploit infrequent occurrence of gaps and facilitate formation of persistent seed banks. A variety of dispersal modes and morphological adaptations occurred, but many species had no apparent specialized structures. The main dispersal vectors were water and then animals. About 216 species, in 21 genera, were recorded in the seed bank survey. High densities (>50,000 m⁻²) occurred occasionally in wet habitats, but generally values were low (<500 m⁻² in 70% of entries). Species richness was also generally low (mean 4.8 species study⁻¹), but ranged from 10 to 33 species in certain wetlands. Our studies showed varied reproductive strategies within habitats, persistence, and ability of many species to colonize disturbed habitats. Overall, seed banks tended to be persistent (>1 year). Maximum longevity ranged between 10 and 295 years, but for certain species viability was lost in <3 years. Seeds of many sedges occurred in deeper soil layers to depths >1 m. Seed production, low in rhizomatous species, ranged between 0 and 345,000 seeds m⁻² year⁻¹. Amphicarpy or pseudo-viviparous plantlets occurred in limited numbers of species. The relation between seed production, seed rain, and seed bank is largely obscure and awaits further investigation. For successful restoration and species conservation projects, seed banks (or a source of seeds) are necessary, combined with suitable germination and establishment conditions. Future seed bank studies are considered.     

Effects of Mechanized,Deep Application of Slow-Release Fertilizer on Yield and Nitrogen,Phosphorus, and Potassium Utilization of Direct-Seeded Rice

Compared with the standard method of manual fertilizer broadcasting (MFB), mechanized hill-drilling direct-seeding with deep application of slow-release nitrogen fertilizer (MHDDF) is an efficient method to integrate both fertilization and seeding. However, there are few studies that combine the use of slow-release fertilizer with MHDDF. We sought to explore the combined effect of MHDDF with slow-release fertilizer on rice yield and nitrogen, phosphorus, and potassium utilization, compared to MFB. We compared three different MHDDF methods (D30: 450 kg ha^?1, D40: 600 kg ha^?1, D50: 750 kg ha^?1), with one MFB method (B50: 750 kg ha^?1), and one control (CK: 0 kg ha^?1). We found that the yield of all MHDDF method was higher than that of both the MFB method. Yield was the highest in the D50 treatment and was 14.14–46.03% higher than that in B50 treatment. Biomass accumulation, nutrient accumulation, and nutrient use efficiency were similarly higher in MHDDF method than both MFB and CK. Compared to B50, the D50 treatment increased nitrogen recovery efficiency by 170.53–231.50%, phosphorus recovery efficiency by 480.00–724.25%, and potassium recovery efficiency by 201.55–169.59%. Overall, we found that combining MHDDF with slow-release fertilizer was an effective method to increase rice yield and nutrient use efficiency compared with MFB.

     

Activity and efficacy of Bacillus subtilis strain NJ-18 against rice sheath blight and Sclerotinia stem rot of rape

A strain of Bacillus subtilis (NJ-18) with broad antimicrobial activity was screened in the laboratory and in the field. NJ-18 inhibited the in vitro radial extension of hyphae of the phytopathogenic fungi Rhizoctonia solani and Sclerotinia sclerotiorum. The bacterium apparently produced antifungal metabolites that diffused through the agar and caused abnormal swelling of hyphae. The in vitro data and observations indicated that one of the mechanisms of inhibition by NJ-18 is antibiosis. In field experiments for control of sheath blight of rice, fermentation of NJ-18 at 5.0 × 10⁷ cfu ml⁻¹ significantly reduced disease incidence and severity; NJ-18 alone or combined with 50% kresoxim-methyl treatment at 225 g ai ha⁻¹ provided better control than 50% kresoxim-methyl at 225 g ai ha⁻¹ or Jinggangmycin at 120 g ai ha⁻¹, and control by NJ-18 alone was as high as 100.0%. In field experiments for control of Sclerotinia stem rot of rape, fermentation of NJ-18 at 1.0 × 10⁷ cfu ml⁻¹ again significantly reduced disease incidence and severity; control by NJ-18 was as high as 77.1% and was comparable with control by 46% dimethachlon and better than control by 50% carbendazim at 750 g ai ha⁻¹. We conclude that strain NJ-18 of B. subtilis is a promising biological control agent and should be further studied and tested for control of sheath blight of rice, Sclerotinia stem rot of rape, and other diseases.     

Improving the performance of transplanted rice by seed priming

Transplanting is the major method of rice cultivation in the world, in which seedlings are raised in nursery and then transplanted into well puddle and prepared fields. The traditional nursery sowing method is tedious and produces week seedlings that reduce the final yield due to high mortality. The potential of seed priming to improve the nursery seedlings and thus the transplanted rice was evaluated in the present study. The experiment was conducted in the rice growing area (31.45° N, 73.26° E, and 193 m) of Pakistan, during 2004–2005. Seed priming tools employed during the investigation included traditional soaking, hydropriming for 48 h, osmohardening with KCl or CaCl₂ (Ψ_s −1.25 MPa) for 24 h (one cycle), 10 ppm ascorbate for 48 h or seed hardening for 24 h. Priming improved the initial seedling vigor and resulted in improved growth, yield and quality of transplanted fine rice while traditional soaking behaved similar to that of untreated control. Osmohardening with CaCl₂ resulted in the best performance, followed by hardening, ascorbate priming and osmohardening with KCl. Osmohardening with CaCl₂ produced 3.75 t ha⁻¹ (control: 2.87 t ha⁻¹) kernel yield, 11.40 t ha⁻¹ (control: 10.03 t ha⁻¹) straw yield and 24.57% (control: 22.27%) harvest index. The improved yield was attributed due to increase in the number of fertile tillers. Significant positive correlation was found between mean emergence time of nursery seedlings and kernel yield, nursery seedling dry weight and kernel yield, fertile tillers and kernel yield, and leaf area duration and kernel yield.     

Hot-water treatment of seed as a method for decreasing the incidence of certain cotton and flax seedling diseases

Improved pathogen-free seed germination and better seedling growth were obtained by hot-water treatments at 60 °C for 10 min of seed of the cotton varieties Karnak and Ashmouni, and at 45 °C for 5 min of seed of the flax varieties Giza 4 and Baladi. These treatments also reduced pre- and post-emergence losses due to Rhizoctonia solani and Fusarium oxysporum f.sp. vasinfectum in cotton, and to F. oxysporum f.sp. lini in flax, and resulted in better growth of the surviving plants.     

Application of zeolite improves water and nitrogen use efficiency while increasing essential oil yield and quality of Salvia officinalis under water-deficit stress

Soil moisture and nitrogen (N) are two of the most important factors affecting the production of medicinal plants. So, the management strategy of these factors is critical and to be identified. In order to study the application of zeolite (Z) (0 and 10 ton ha^?1) in S. officinalis culture medium under different irrigation regimes (30 % depletion of available soil water (ASW)) and 60 % depletion of ASW) and N (0, 75 and 150 kg N ha^?1) a split-factorial experiment was carried out with three replicates in 2018. The highest fresh and dry weight were achieved at irrigation after 30 % depletion of ASW while using 150 kg N ha^?1 and 10 ton Z ha^?1. Maximum water use efficiency (WUE) (22.10 g.L^-1) was obtained after 60 % depletion of ASW and 150 kg N ha^?1 and 10 ton Z ha^?1. Besides, the maximum nitrogen use efficiency (NUE) was obtained after 60 % depletion of ASW and 75 kg N ha^?1 and 10 ton Z ha^?1 (14.25 kg.kg^-1N). Maximum essential oil (EO) content (1.06%) and cis-Thujone were obtained from plants subjected to 60 % depletion of ASW and, application of 75 kg N ha^?1 and 10 ton Z ha^?1. Applying Z with N, in different irrigation regimes did improve soil conditions for achieving higher, WUE and NUE, increased the EO content and yield while decreasing the negative effects from water-deficit stress and has provided a direction towards a stable system.     

Soil seed banks in church forests of northern Ethiopia: Implications for the conservation of woody plants

Church forests are sanctuaries for different organisms, ranging from microbes to large animals, which have almost disappeared in most parts of northern Ethiopia. Despite the actual and potential significance of these forests, studies and documented information on their bio-physical features and socio-economic setting are either scanty or totally lacking. A study was, therefore, carried out in seven of these church forests, namely Hiruy, Zahara, Gibtsawit, Gelawdiwos, Dengolt, Debresena and Ascha with the objective of assessing the composition, densities and spatial heterogeneity of soil seed banks. The number of viable seeds in the soil samples, from both germination and sieving, corresponded to a seed bank density down to 9 cm in the soil of 7594 seeds m⁻² at Ascha, 2064 seeds m⁻² at Debresena, 4208 seeds m⁻² at Dengolt, 3158 seeds m⁻² at Gelawdiwos, 2754 seeds m⁻² at Gibtsawit, 2759 seeds m⁻² at Hiruy, and 1909 seeds m⁻² at Zahra. The total number of species recorded was 50, representing at least 22 plant families, in the seven church forests, of which 13 were recorded from Ascha, 29 from Debresena, 26 from Dengolt, 19 from Gibtsawit, 22 from Gelawdiwos, 20 from Hiruy and 21 from Zahra. There was a significant difference in seed densities and number of species recovered from the soil seed banks of the seven church forests. Ascha had a significantly higher seed bank density than all other church forests. Dengolt exhibited a significantly higher number of species compared with other church forests. Of the identified species recorded from the seven church forests, 83% were herbs, 11% trees and 6% shrubs. Our results revealed that church forests accumulate large quantities of persistent seeds of herbaceous species in the soil while only five (6%) of the 91 woody species recorded in the standing vegetation of the seven church forests were represented in the soil seed banks. The fact that most of the dominant tree species do not accumulate seeds in the soil suggests that their regeneration from seeds would be prevented by removal of mature individuals in the standing vegetation. The results also provided further evidences that consolidate the conclusions of previous studies, i.e. the future existence of the woody flora characteristic of dry Afromontane areas in Ethiopia depends on the conservation and sustainable utilization of the few remnant natural forests.     

Kaolin and Jasmonic acid improved cotton productivity under water stress conditions

Drought is one of the most emerging threat that causes a severe reduction in cotton plant growth and development. Being cotton is a major cash crop has great threat to prevailing drought events in Pakistan. A field experiment was conducted in Kharif season 2018 at Research Area of MNS-University of Agriculture, Multan, Pakistan to assess the role of foliar applied kaolin and jasmonic acid on vegetative growth, gas exchange and reproductive traits of cotton under normal irrigated and artificial water deficit conditions. The experiment was laid -out in a factorial randomized complete block design with split – split plot arrangement. Main plots were allocated for irrigation levels, sub-plots for two -cotton genotypes viz. NIAB − 878 and SLH − 19 while sub – sub plots for treatments of kaolin and Jasmonic acid. Water deficit stress was created by skipping irrigation at flowering for 21 days. Foliar sprays of Kaolin (5%, w/v) and Jasmonic acid (100 μM) were applied alone or in combination at 60 days after planntinon both to normal irrigated and water-stresse skip irrigation while irrigation water alone was sprayed in control plots. Both cotton genotypes responded variably to normal irrigated and skip conditions. Skipping irrigation for up to 21 days at flowering caused a significant decrease in leaf relative water content, SPAD values, net photosynthetic rate and seed cotton yield in both the genotypes. Seed cotton yield showed an overall decline of 24.7% in skip over Normal irrigated crop. The genotype NIAB − 878 produced maximum seed cotton yield of 3.304 Mg ha⁻¹ in normal that dropped to 2.579 Mg ha⁻¹ in skip, thus showing an average decline of 21.9 %. Similarly, SLH − 19 produced 2.537 Mg ha⁻¹ seed cotton under normal that dropped to 1.822 Mg ha⁻¹ in skip, showing an average decline of 28.2%. The Application of Kaolin and JA Jasmonic acid, either applied individually or in combination, improved vegetative and reproductive development of both cotton varieties in normal and skip regimes. However, combined kaolin and Jasmonic Acid application proved to be more beneficial in terms of seed cotton production and other parameters studied.     

Effect of ethephon and calcium chloride on growth and biochemical attributes of sugarcane bud chips

The present study was aimed at improving sprouting and establishment of bud chip seed stocks of sugarcane cultivar CoSe 92423 by pre-planting soaking in growth-promoting chemicals viz ethephon (0.1 g dm⁻³) and calcium chloride (1 g dm⁻³) along with water-soaked control for 24 h. Treated bud chips recorded higher bud sprouting, shoot height, root number, fresh weight of leaves, shoot and roots, and plant vigor index. In both the treatments, reducing sugars contents, acid invertase, and ATPase activity increased in developing sprouts; increase was about 86.5 and 40.7% in reducing sugars, 28 and 70% in acid invertase, and 15 and 23% in ATPase activities over control by ethephon and calcium chloride treatment, respectively. Reducing sugars contents and activity of acid invertase and ATPase enzymes of sprouted buds exhibited significant positive correlation with bud sprouting and plant vigor index. These findings indicate that soaking of bud chips in growth-promoting chemicals viz ethephon (0.1 g dm⁻³) and calcium chloride (1 g dm⁻³) solutions helps in enhancing bud sprouting, root growth, and plant vigor by altering some of the key biochemical attributes essential for the early growth and better establishment of bud chips under field conditions which is otherwise poor in untreated chips.     

Growing vetches (Vicia villosa Roth) in irrigated cotton systems: inputs of fixed N, N fertiliser savings and cotton productivity

We compared symbiotic N₂ fixation by winter forage legumes (clovers, medics and vetches) using the ¹⁵N natural abundance technique in three experiments. Vetches (Vicia spp.) were the most productive legumes, and woollypod vetch fixed (shoot+root) up to 265 kg N ha^–1 (mean 227 kg N ha^–1) during a 4–5 months period over winter and early spring. Balansa and Berseem clovers, and Gama medic were highly productive in the first experiment, but fixed significantly less N than woollypod vetch in the second experiment. A 6-year study (1997–2003) compared cotton (Gossypium hirsutum L.) systems with and without vetch, or with faba beans (Vicia faba L.) to assess the effects of these crops on cotton production. Woollypod vetch was grown either between annual cotton crops, or between wheat (Triticum aestivumL.) and cotton crops. Vetch added 230 kg N ha^–1 (174 kg fixed N ha^–1) to the soil when incorporated as a green manure. Faba bean shoot residues and nodulated roots contributed 108 kg fixed N ha^–1 to the soil, following the removal of 80 kg N ha^–1 in the harvested seed (meaned over three crops). Lablab (Lablab purpureus L. – summer-growing and irrigated) added 277 kg N ha^–1 (244 kg fixed N ha^–1) before incorporation as a green manure in the first year of the experiment. The economic optimum N fertiliser rate for each cropping system was determined every second year when all systems were sown to cotton. Cotton following cotton required 105 kg fertiliser N ha^–1, but only 40 kg N ha^–1 when vetch was grown between each cotton crop. Cotton following wheat required 83 kg fertiliser N ha^–1 but no N fertiliser was needed when vetch was grown after wheat (the highest yielding system). Cotton following faba beans also required no N fertiliser. The vetch-based systems became more N fertile over the course of the experiment and produced greater lint yields than the comparative non-legume systems, and required less N fertiliser. While no cash flow was derived from growing vetch, economic benefits accrued from enhanced cotton yields, reduced N fertiliser requirements and improved soil fertility. These findings help explain the rotational benefits of vetches observed in other regions of the world.