Influence of Nitrogen Timing and Levels on Yield and Yield Components of Canola

The experiment on response of nitrogen application timing and levels on yield and yield components of canola was conducted at New Developmental Farm the University Agriculture Peshawar, during Rabi season 2013-2014. The experiment consist of three timing (full at sowing, split application and rosette stage) and levels 80 and 120kg N ha-¹ of nitrogen. The experiment was designed in randomized complete block with three replications. Canola Cultivar  Abasin-95 was used as testing crop. The results indicated that more number of branches plant-¹ (7), number of pods plant-¹ (276), grain pod-¹ (21), biological yield (3659kgha-1), grain yield (1337kg ha-1), thousand grain weight (4g) and harvest index (12%) were significantly affected except number of branches plant-1. Split application were proved more effective as compared  full at sowing or rosette stage of both nitrogen levels 80 and 120kg N ha-1 to obtain higher yield in agro- ecological conditions of Peshawar. Keywords: Nitrogen, full sowing, rosette stage and canola cultivars

Nitrogen Partitioning and Translocation in Wheat under Fertilizer-N Levels, Application Time and Decapitation Stress

The decapitation stress in dual purpose wheat can be managed by adopting proper fertilizer-N partitioning and translocation to get both more grain and fodder with higher amount of N-content. The fertilizer-N levels improved N-content at boot stage (24.37 g kg-1), at anthesis stage (13.45 g kg-1), at maturity stage (4.92 g kg-1), grain N-content (18.38 g kg-1), straw N uptake (43.34 kg ha-1), grain N-uptake (58.81 kg ha-1), apparent nitrogen re-translocation (14.88) and apparent nitrogen re-translocation efficiency (57.89) whereas reduced nitrogen harvest index (74.97 %) and nitrogen use efficiency (15.97) as compare to control. The decapitation stress reduced N-content at anthesis stage 12.90 g kg-1, straw N-uptake (37.55 kg ha-1), grain N-uptake (53.68 kg ha-1), apparent nitrogen retranslocation (13.98), apparent nitrogen re-translocation efficiency (56.56) whereas enhanced nitrogen use efficiency (NUE), by 17.02 %. The increase in fertilizer-N level improved linearly N-content at boot stage (25.24 g kg-1), at anthesis stage (13.71 g kg-1), at maturity stage (5.11 g kg-1), straw N-uptake (48.23 kg ha-1), grain N-uptake (63.26 N kg ha-1) but NHI (75.92 %), apparent nitrogen re-translocation (15.62) showed parabolic trend fertilizer-N level while the NUE reduced (13.21 % with 200 kg N ha-1). The two equal split of fertilizer-N application time proved superior in the enhancement of N-content at boot stage, at anthesis stage, straw N-uptake (45.08 kg ha-1) and NUE while the full with 2nd irrigation application improved N-content at anthesis stage (13.87 g kg-1),  straw N-uptake (44.35 kg ha-1), apparent nitrogen re-translocation (15.88), apparent nitrogen re-translocation efficiency (59.91). Results suggest that NUE was increased with decapitation compared to non decapitated plants. Late application of N as full dose or even two equal splits applications at sowing and/or with 2nd irrigation had improved the N content , total  N uptake, N re-translocation and its efficiency, grain protein, and NUE. The fertilizer-N level enhanced N-content at all growth stages, straw and grain. But NHI and apparent nitrogen re-translocation showed parabolic trend while reduced NUE. Keywords: Nitrogen, Fertilizer-N, Fertilizer-N time, Fertilizer-N levels, Translocation, Re-translocation, nitrogen harvest index and NUE

Morphophysiological Responses of Oat (Avena sativa L.) Genotypes from Pakistan’s Semiarid Regions to Salt Stress

Soil salinity is a major constraint to modern agriculture, with around 20% of the previously irrigated area becoming salt affected. Identifying suitable salt stress-tolerant genotypes based on their agronomic and physiological traits remains a herculean challenge in forage-type Oat (Avena sativa L.) breeding. The present study was designed to investigate the response of oat crop plants against the salt (NaCl) stress in Mardan, Pakistan. The experiment was carried out in complete randomized design (CRD) with two factors trail comprising of the performance of four different genotypes of oat (NARC oat, PARC oat, Green Gold and Islamabad oat) in response to four levels of saline stress (0, 25, 50 and 75 mmol L-1 NaCl). Plant growth and physiological parameters including germination (G, %); fresh shoot weight (FSW, g); fresh root weight (FRW, g); chlorophyll-a, chlorophyll-b, total chlorophyll, and total carotenoids were analyzed for identifying salt tolerance. Germination (%) of oat genotypes was negatively affected by higher salt stress. Mean values showed that maximum germination (57.5%) was recorded for control while minimum germination (48.75%) was recorded for 25 mmol L-1 NaCl and that maximum germination (58%) was recorded for PARC oat. The root and shoot fresh weight of all genotypes declined with increasing salt stress, while NARC and Green Gold oat showed considerably higher values than the other genotypes. Although chlorophyll and carotenoids were found to be negatively affected by increasing salt concentrations, NARC and Green Gold oat genotypes performed considerably better at 75 mmol L-1 NaCl when compared to the other genotypes. Based on the mean shoot dry weight ratio ± one standard error, the four Oat genotypes were categorized as salt-tolerant (Green Gold), moderately tolerant (PARC and NARC), and salt-sensitive (Islamabad). The more salt-tolerant genotype (Green Gold) demonstrated relatively high salinity tolerance and may be useful for developing high-yielding oat hybrids in future breeding programs under salt stress conditions

Canola Seed Priming and Its Effect on Gas Exchange, Chlorophyll Photobleaching, and Enzymatic Activities in Response to Salt Stress

Canola is the second-largest oil seed crop in the world, providing oil mainly composed of long-chain fatty acids (C14 to C20). When mixed with fossil-diesel, canola-based biofuel can be used in passenger vehicles, trucks, or even in aviation. Canola is the most productive type of biofuel due to its oil’s long-chain and unbranched fatty acid composition, which makes it more fluid. However, canola yields are constrained by drought and salinity that can aggravate climate change, resulting in negative consequences. Therefore, it is becoming necessary for studies that involved the canola salt-tolerant genotypes to consider soil salinization by use of saline soil or salinized soil by a non-efficient irrigation method. This study was carried out to assess the effects of salinity on seed germination and the effect of CaCl2 (ψs = −1.2 MPa) on the promotion of regenerated plant memory when a new cycle of stress occurs. Our experiment shows that salt-stressed canola plants resulted in a high reduction in chlorophylls and carotenoids, with a high impact on gas exchange and a reduction in the efficiency of the chloroplast electron chain transporter, producing the negative effect of reduced molecules that affect the membrane integrity. However, canola seed priming could produce a memory in the regenerated plants when the second round of salt stress was applied. This research concludes that canola genotypes appear to have a tolerance mechanism against salt stress which could be an important trait for developing high-yielding canola varieties in future breeding programs under salt stress conditions

Changes in Leaf Structural and Functional Characteristics when Changing Planting Density at Different Growth Stages Alters Cotton Lint Yield under a New Planting Model

Manipulation of planting density and choice of variety are effective management components in any cropping system that aims to enhance the balance between environmental resource availability and crop requirements. One-time fertilization at first flower with a medium plant stand under late sowing has not yet been attempted. To fill this knowledge gap, changes in leaf structural (stomatal density, stomatal length, stomata width, stomatal pore perimeter, and leaf thickness), leaf gas exchange, and chlorophyll fluorescence attributes of different cotton varieties were made in order to change the planting densities to improve lint yield under a new planting model. A two-year field evaluation was carried out on cotton varieties—V1 (Zhongmian-16) and V2 (J-4B)—to examine the effect of changing the planting density (D1, low, 3 × 104; D2, moderate, 6 × 104; and D3, dense, 9 × 104) on cotton lint yield, leaf structure, chlorophyll fluorescence, and leaf gas exchange attribute responses. Across these varieties, J-4B had higher lint yield compared with Zhongmian-16 in both years. Plants at high density had depressed leaf structural traits, net photosynthetic rate, stomatal conductance, intercellular CO2 uptake, quenching (qP), actual quantum yield of photosystem II (ΦPSII), and maximum quantum yield of PSII (Fv/Fm) in both years. Crops at moderate density had improved leaf gas exchange traits, stomatal density, number of stomata, pore perimeter, length, and width, as well as increased qP, ΦPSII, and Fv/Fm compared with low- and high-density plants. Improvement in leaf structural and functional traits contributed to 15.9%–10.7% and 12.3%–10.5% more boll m−2, with 20.6%–13.4% and 28.9%–24.1% higher lint yield averaged across both years, respectively, under moderate planting density compared with low and high density. In conclusion, the data underscore the importance of proper agronomic methods for cotton production, and that J-4B and Zhongmian-16 varieties, grown under moderate and lower densities, could be a promising option based on improved lint yield in subtropical regions