Cloning and Phylogenetic Analysis of Coat Protein of Barley yellow dwarf virus Isolates from Different Regions of Pakistan

Barley yellow dwarf virus (BYDVs) is an emerging threat for wheat and may seriously threaten its production, especially as climate change may result in increased infestation by aphids, the insect vectors of the virus. To assess the possibility of using pathogen‐derived resistance against the virus, the genetic diversity of BYDVs originating from different wheat‐growing areas of Pakistan where its incidence has been higher was investigated. Wheat samples with suspected symptoms of BYDVs were screened for the presence of Barley yellow dwarf and Cereal yellow dwarf viruses (B/CYDVs) subgroup 1 (Barley yellow dwarf virus‐PAV, BYDV‐MAV, BYDV‐SGV) and subgroup II (BYDV‐RPV, CYDV‐RPV, BYDV‐GPV) by PCR using basic multiplex oligonucleotides designed on coat protein (CP) of the virus. Of 37 samples tested, 13 were positive for BYDV subgroup I and only one sample was positive for BYDV subgroup II. Samples positive for subgroup I were further tested by PCR, and results showed that 10 samples were positive for BYDV‐PAV and three for BYDV‐MAV. DNA sequences of CP region of nine isolates (BYDV‐PAV) were determined and compared with available sequences in databases. Sequence analysis showed that three isolates (from Fatehjang, Nowshera and Attock districts) had maximum identity (92.8–94.6%) to BYDV‐PAS, and six isolates (from Peshawar, Islamabad Swabi and Faisalabad districts) had maximum identity (99.3–99.7%) to BYDV‐PAV. Thus BYDV‐PAV species may be dominant in northern wheat‐growing areas of Pakistan. The conserved nature of the BYDVs suggests that pathogen‐derived resistance strategies targeting the coat protein of the virus are likely to provide protection under field conditions.     

Retracted: Screening of candidate genes and fine mapping of drought tolerance quantitative trait loci on chromosome 4 in rice (Oryza sativa L.) under drought stress

Due to severe water resource shortage, genetics of and breeding for DT (drought tolerance) in rice (Oryza sativa L.) have become one of the hot research topics. Identification of grain yield QTLs (quantitative trait loci) directly related to the DT trait of rice can provide useful information for breeding new drought‐resistant and water‐saving rice varieties via marker‐assisted selection. A population of 105 advanced BILs (backcross introgression lines) derived from a cross between Zhenshan97B and IRAT109 in Zhenshan97B background were grown under drought stress in a field experiment and phenotypic traits were investigated. The results showed that in the target interval of RM273‐RM255 on chromosome 4, three main‐effect QTLs related to panicle length, panicle number, and spikelet number per panicle were identified (LOD [logarithm of the odds] > 2.0). The panicle length‐related QTL had two loci located in the neighboring intervals of RM17308‐RM17305 and RM17349‐RM17190, which explained 18.80% and 20.42%, respectively, of the phenotypic variation, while the panicle number‐related QTL was identified in the interval of RM1354‐RM17308, explaining 11.47% of the phenotypic variation. As far as the spikelet number per panicle‐related QTL was concerned, it was found to be located in the interval of RM17308‐RM17305, which explained 28.08% of the phenotypic variation. Using the online Plant‐GE query system, a total of 13 matched ESTs (expressed sequence tags) were found in the target region, and of the 13 ESTs, 12 had corresponding predicted genes. For instance, the two ESTs CB096766 and CA765747 were corresponded to the same predicted gene LOC_Os04g46370, while the other four ESTs, CA754286, CB000011, CX056247, and CX056240, were corresponded to the same predicted gene LOC_Os04g46390.     

Grain Yield and Quality of Foxtail Millet (Setaria italica L.) in Response to Tribenuron-Methyl

Foxtail millet (Setaria italica L.) is cultivated around the world for human and animal consumption. There is no suitable herbicide available for weed control in foxtail millet fields during the post-emergence stage. In this study, we investigated the effect and safety of the post-emergence herbicide tribenuron-methyl (TBM) on foxtail millet in terms of grain yield and quality using a split-plot field design. Field experiments were conducted using two varieties in 2013 and 2014, i.e., high-yielding hybrid Zhangzagu 10 and high-quality conventional Jingu 21. TBM treatments at 11.25 to 90 g ai ha⁻¹ reduced root and shoot biomass and grain yield to varying degrees. In each of the two years, grain yield declined by 50.2% in Zhangzagu 10 with a herbicide dosage of 45 g ai ha⁻¹ and by 45.2% in Jingu 21 with a herbicide dosage of 22.5 g ai ha⁻¹ (recommended dosage). Yield reduction was due to lower grains per panicle, 1000-grain weight, panicle length, and panicle diameter. Grain yield was positively correlated with grains per panicle and 1000-grain weight, but not with panicles ha⁻¹. With respect to grain protein content at 22.5 g ai ha⁻¹, Zhangzagu 10 was similar to the control, whereas Jingu 21 was markedly lower. An increase in TBM dosage led to a decrease in grain Mn, Cu, Fe, and Zn concentrations. In conclusion, the recommended dosage of TBM was relatively safe for Zhangzagu 10, but not for Jingu 21. Additionally, the hybrid variety Zhangzagu 10 had a greater tolerance to TBM than the conventional variety Jingu 21.     

Genome mapping of kernel characteristics in hard red spring wheat breeding lines

Kernel characteristics, particularly kernel weight, kernel size, and grain protein content, are important components of grain yield and quality in wheat. Development of high performing wheat cultivars, with high grain yield and quality, is a major focus in wheat breeding programs worldwide. Here, we report chromosome regions harboring genes that influence kernel weight, kernel diameter, kernel size distribution, grain protein content, and grain yield in hard red spring wheat breeding lines adapted to the Upper Midwest region of the United States. A genetic linkage map composed of 531 SSR and DArT marker loci spanned a distance of 2,505 cM, covering all 21 chromosomes of wheat. Stable QTL clusters influencing kernel weight, kernel diameter, and kernel size distribution were identified on chromosomes 2A, 5B, and 7A. Phenotypic variation explained by individual QTL at these clusters varied from 5 to 20% depending on the trait. A QTL region on chromosome 2B confers an undesirable pleiotropic effect or a repulsion linkage between grain yield (LOD = 6.7; R ² = 18%) and grain protein content (LOD = 6.2; R ² = 13.3%). However, several grain protein and grain yield QTL independent of each other were also identified. Because some of the QTL identified in this study were consistent across environments, DNA markers will provide an opportunity for increasing the frequency of desirable alleles through marker-assisted selection.     

Chickpea varietal response to integrated weed management under different irrigation regimes

Pakistan ranks third among the chickpea growing countries of the world. Chickpea need less water that is why it is preferred by the farmers of the arid and semi- arid zone. The chickpea crop is severely infested by many weeds which reduce its yield and also deteriorate the quality of the grains. The un-availability of high competitive cultivars also had impact on the annual yield production of chickpea crop. The focus of the study was to evaluate sound, feasible and economic weed management strategies to uplift the yield of chickpea crop. The Southern districts of Khyber Pakhtunkhwa are the major producer of chickpea crop. Therefore keeping in view the importance of the crop and as well as the problems associated with the crops, the experiments were conducted at Ahmad Wala Research Station Karak during years 2011^–12 and 2012–13 with Randomized Complete Block design with split split arrangement having four replications. Sowing was done on October 16th during both the studied years. To evaluate the potential of irrigation verses rainfed conditions five cultivars i.e. Karak-1, Karak-2, Sheenghar, Lawaghar and KC-98 and ten weed management techniques i.e. Stomp 330 EC (Pendimethalin), Stomp 330 EC + Hand Weeding (HW) at 60 DAS, Dual Gold 960 EC (S-Metolachlor), Dual Gold 960 EC + HW at 60 DAS, HW one time at (30 DAS), HW two times at (30 and 60 DAS), HW three times at (30, 60 and 90 DAS), White plastic mulch, Black plastic mulch and weedy check were tested. The data was recorded on the below mentioned parameters i.e. weed density m^?2 at 60 DAS, number of productive branches plant^?1, number of pods plant^?1, number of grain pods^?1, number of nodules plant^?1, grain yield (kg ha^?1) and Cost-benefit ratio (CBR). Results of the two years study revealed that with the exception of number of grains pods^?1, and cost benefit ratio, all the vegetative and yield parameters were significantly different during both the studied years. Comparing the effect of irrigation regimes versus rainfed conditions significantly (p < .05) difference was recorded in all parameters while the maximum values were in irrigated plots as compared to rainfed conditions. Significant (p < .05) difference was recorded in weeds density at 60 DAS (64.13 m^?2) found in irrigated plots as compared to rainfed conditions. The year wise comparison of the varieties was significant (p < .05) in number of pods plant^?1, grain yield (kg ha^?1). The varieties were also found with significant difference. After 60 days the minimum weed density (60.68 m^?2) was found in Karak-2 and the maximum weed density at 60 DAS (62.42 m^?2) was recorded in Sheenghar. Among the varieties the maximum values were found number of productive branches plant^?1 (15.89), number of pods plant^?1 (45.52), was found in Karak-1.The maximum number of grains pod^?1 (l.93) was found in Karak-2. The maximum number of nodules plant^?1 (28.54) in Sheenghar and grain yield (1484.1 kg ha^?1) and cost benefit ratio (3.32) was recorded in Lawaghar. The year wise comparison of weed management parameters was also significant in different parameters. However among the treatments after 60 DAS the minimum weed density (51.15 m^?2) was recorded in black and white plastic and the maximum weed density (99.54 m^?2) was recorded in the weedy check. Among the applied treatments for weed management the maximum number of productive branches plant^?1 (16.83), number of pods plant^?1 (52.46), number of grains pod^?1 (2.16) and grain yield (1659.75 kg ha^?1) was recorded in HW three times treatments while on the other hand maximum number of nodules plant^?1 (29.96) was recorded in both black and white plastic mulches. The maximum cost benefit ratio (3.39) was recorded in Stomp 330 EC. The minimum number of nodules plant^?1 (25.35) was found in Dual Gold EC 960 treated plots. The minimum number of productive branches plant^?1 (13.32), number of pods plant^?1 (31.47), number of grains pod^?1 (l.68) and grain yield (1148.4 kg ha^?1) was found in weedy check. The minimum cost benefit ratio (2.54) was found in black plastic mulches treated plots. From the above findings it is concluded that chickpea variety Lawaghar grown in the arid zone need subsequent irrigation. HW, black and white plastic mulches were found efficient for weed management but costly. However, the herbicide Stomp 330 EC was found efficient in weed control and gained maximum CBR in the experimental trial at Southern districts of Khyber Pakhtunkhwa province of Pakistan.     

Interaction between barley yellow dwarf virus and rust in wheat, barley and oats, and the effects on grain yield and quality

In three separate experiments, the upper leaf surface of the fifth formed leaf of wheat cv. Highbury, the fourth and fifth leaves of barley cv. Julia and the third and fourth leaves of oat cv. Mostyn were inoculated in a spore settling tower with wheat brown rust (Puccinia recondita f. sp. tritici), barley brown rust (P. hordei) or oat crown rust (P. coronata f. sp. avenae), respectively. Fewer pustules developed on distal portions of leaves of plants infected with barley yellow dwarf virus (BYDV) than on similar portions of leaves from virus-free plants. There were no significant differences in the number of pustules on proximal leaf portions. In barley and oats, the number of pustules on distal leaf portions was negatively correlated with the amount of yellowing of the leaf areas scored. In wheat, symptoms of BYDV were mild and leaves were little affected by yellowing. The latent period of rust on wheat and oats was not affected by BYDV. In barley, BYDV reduced the latent period of rust on leaf 5, but not on leaf 4, and reduced it on proximal, but not distal, leaf portions. In other experiments, BYDV reduced the yield of wheat and oats by 44% and 66%, respectively, while BYDV-infected barley was almost sterile. The appropriate rust reduced the yield of wheat, barley and oats by 33%, 13% and 86%, respectively. When infected with both BYDV and rust, yield of wheat and oats was reduced by 63% and 91%, respectively. Neither BYDV nor rust affected the percentage crude protein content of wheat grain, nor did rust affect that of barley. In oats, BYDV and rust each significantly increased crude protein of grain, but rust infection of BYDV-infected plants tended to reduce it.     

Straighthead disease of rice (Oryza sativa L.) induced by arsenic toxicity

Straighthead disease is a physiological disorder of rice (Oryza sativa L.) characterized by sterility of the florates/spikelets leading to reduced grain yield. Though the exact cause of straighthead is unknown, a glass house experiment was conducted to investigate the effect of inorganic arsenic on straighthead disease in rice (Oryza sativa L.). BRRI dhan 29, a popular Bangladeshi rice strain, was grown in soils spiked with arsenic (prepared from sodium arsenate, Na₂HAsO₄·7H₂O) at the rate of 10, 20, 30, 40, 50, 60, 70, 80 and 90 mg of As kg^?1 and one control treatment was also run to compare the results. Although there may be some other soil physico-chemical factors involved, arsenic concentration was found to be closely associated with straighthead of rice. With the increase of soil arsenic concentration, the severity of straighthead increased significantly. Up to the 50 mg of As kg^?1 soil treatments, the severity of straighthead incidences were not prevalent. Straighthead resulted in sterile florets with distorted lemma and palea, reduced plant height, tillering, panicle length and grain yield. Straighthead caused approximately 17–100% sterile florates/spikelets formation and about 16–100% loss of grain yield. Straighthead also causes the reduction of panicle formation and panicle length significantly (p < 0.01). In the present study, panicle formation was found to be reduced by 21–95% by straighthead.     

Some effects of barley yellow dwarf virus on spring and winter cereals in field trials

The tolerance of spring and winter cultivars of wheat, barley and oats to infection by barley yellow dwarf virus (BYDV) was examined in field tests. Sererely affected plants were stunted and grain yields were considerably reduced. These changes in infected spring barley cultivars were associated with decreases in both ear length and number and sizes of grain. Most barley and oat cultivars were more susceptible than wheat cultivars. Yield losses decreased with successively later dates of inocultaiton, the yield response being characteristic of the tolerance of individual cultivars. Differences between tolerant and susceptible cultivars were insignificant in most cases where infection occurred after growth stage 7. Individual seedling symptoms assessed in April and May were more closely related to each other and to yield losses than those recorded in March and June. The incorporation of seedling symptoms into indices of infection permits estimates of decrease in yield to be made by applying the formulae, DY = (LC+LA+SH)/3 to barley cultivars and DY = 1.7 × (LC+LA+SH)/3 - 7 to oat cultivars. Thus decreases in grain yield (DY) can be related to decreases in seedling height (SH) and increases in percentage of leaf area discoloured (LA) and intensity of discoloration (LC). Plot symptoms of infection, scored on a 0–7 scale, offered a more convenient method of assessment than individual seedling symptoms. Plot scores (PA) were closely correlated with other seedling symptoms and with decreases in grain yield (DY), and can thus be used to estimate yield losses by substituting into the formula, DY = 14PA (April)-8. This formula was found to be applicable to all cereal cultivars examined in N.I.A.B. trials, there being no distinction between wheat, barley and oats.     

Distributions of invasive weed Parthenium (Parthenium hysterophorus L.) in the University campus Peshawar KPK

A very interesting survey was performed to measure the distribution of invasive Parthenium (Parthenium hysterophorus L.) weed in the University Campus, Peshawar, the capital city of Khyber Pakhtunkhwa province. The University Campus comprised on; The University of Peshawar, Islamia College University, The University of Agriculture Peshawar, Pakistan Forest Institute and the New Developmental Research Farm. In these selected areas Parthenium weed distribution was measured in particular the academic, residential and research farm. Moreover, the survey also investigated the impact of parthenium weed upon native weeds flora inside the University campus. A 1m² quadrat was used to collect the data. During the survey, a total of 32 weeds species were recorded belonging to 18 different families and 32 genera, the life cycle of 23 weeds were annual while 9 weeds have a perennial. The data were recorded on absolute density (%), relative density (%), absolute frequency (%), relative frequency (%) and importance values (%) of parthenium weed and others flora. The collected data show that parthenium weed was the most dominant species having 76.8 m^?2 plants density in the NDF and (32.0 m^?2) at Islamia College University. However, the highest frequency (100%) of Parthenium was observed for The University of Agriculture, while minimum (80%) occurred in the Agronomy field. A More, the relative frequency of Parthenium was maximum (25%) in Islamia College; whereas, it's minimum (12.9%) at Agronomy field. Finally, the Importance Value of Parthenium indicates the highest (45.98%) at Dairy Farm followed by (40.33%) at the Horticulture field's area. In short, the Parthenium weed becomes more problematic and replaces all the native flora in the non-crop area specially Dicanthium annulatum L. a native grass species on the ridges of the field being replaced by parthenium. Due to no proper management and high growth rate, nowadays it becomes like a superweed in the KPK and especially in Pakistan. So, the management of Parthenium weed requires the call attention from the Govt. policymaker and proper quarantine inspection to conserve the native flora and field crops to get maximum crop yield.     

Identification and characterization of quantitative trait loci for grain yield and its components under different nitrogen fertilization levels in rice (<Emphasis Type="Italic">Oryza sativa</Emphasis> L.)

A set of rice (Oryza sativa L.) recombinant inbred lines from a cross between Zhenshan 97 (indica) and HR5 (indica) was planted for four different growing seasons in two locations at three nitrogen (N) fertilization levels (N300, 300 kg urea/ha; N150, 150 kg urea/ha; and N0, 0 kg urea/ha). Grain yield and its components were evaluated, including grain yield per plant (GYPP), panicle number per plant (PNPP), grain number per panicle (GNPP), filled grains per panicle (FGPP), spikelet fertility percentage (SFP) and 100-grain weight (HGW). Correlation and path analysis indicated that SFP had the greatest contribution to GYPP at the N300 and N150 levels, but FGPP contributed the most to GYPP at the N0 level. Quantitative trait loci (QTL) were mapped based on a mixed linear model; genetic components (main effects, epistatic effects and QTL-by-environment interactions) were estimated separately. Six to 15 QTL with main effects were detected for each trait except SFP. Clusters of main-effect QTL associated with PNPP, GNPP, SFP and HGW were observed in regions on chromosomes 1, 2, 3, 5, 7 and 10. The main-effect QTL (qGYPP-4b and qGNPP-12) were only detected at the N0 level and explained 10.9 and 10.2% of the total phenotypic variation, respectively. A total of 33 digenic interactions among grain yield and its components were also identified. The identification of genomic regions associated with yield and its components at different nitrogen levels will be useful in marker-assisted selection for improving the nitrogen use efficiency of rice.     

Boron application through seed coating improves the water relations, panicle fertility, kernel yield, and biofortification of fine grain aromatic rice

This study was conducted to evaluate the influence of boron (B) application through seed coating on leaf elongation, tillering, water relations, panicle sterility, kernel yield, and grain biofortification of fine grain aromatic rice. Boron was applied as seed coating at 1.0, 1.5, 2.0, 2.5, and 3.0 g B kg^?1 seed in two rice cultivars Super Basmati and Shaheen Basmati. Boron seed coating significantly affected the leaf elongation, water relations, panicle fertility, kernel yield and grain biofortification in both rice cultivars. However, seed coating with 1.0–2.0 g B kg^?1 seed was effective in improving the leaf emergence and elongation, and tillering. Whereas water relations (water and osmotic potential) were improved by all B seed coating treatments, but pressure potential was only improved from seed coating with 2.0–3.0 g B kg^?1 seed. Kernel yield was improved by all B seed coating treatments; however seed coating with 2 g B kg^?1 seed was the most effective treatment in this regard. Increase in kernel yield, by B seed coating, was attributed to decrease in panicle sterility. Leaf and kernel B contents were increased with increase in B concentration in seed coating.     

Studies on the nature of relationships between grain size,spikelet number,grain yield and spikelet filling in late duration varieties of rice (Oryza sativa L.)

Summary Studies on the nature of relationship between grain size (in terms of thousand grain weight), grain number, rate of filling and yield have been worked out with late duration (140–150 days) rice varieties. Grain number per m², grains per panicle and yield showed a negative relationship with grain size. There was no compensatory balance between grain size and grain number within a range of thousand grain weight of 15 to 30 g. Based on the peaks in grain filling activity, the varieties were classified into four groups. There was no relationship between grain size and rate of grain filling thereby suggesting that grain filling is determined by inherent endogenous factors.     

Effect of varying periods of inoculation ofAzolla pinnata R. Brown on its growth,nitrogen fixation and response to rice crop

Summary Inoculation of water fernAzolla pinnata R. Brown (Bangkok isolate) at the rate of 500kg fresh weight ha⁻¹ in rice fields at weekly intervals after planting in addition to 30 kg N ha⁻¹ as urea showed a decrease in its growth and N₂-fixation with delay in application. Use of Azolla up to 3 weeks after planting (WAP) during wet and 4 WAP during dry season produced significantly more grain yield than 30 kg N ha⁻¹, whereas its application upto one WAP produced more grain yield than 60 kg N ha⁻¹. Grain yield with Azolla applied at the time of planting was similar to that of 60 kg N treatment during the wet season. Higher grain yields in zero and one WAP Azolla treatments resulted due to increase in both number of panicles m⁻² and number of grains/panicle while the subsequent Azolla inoculations increased grain yield mainly by producing more number of grains/panicle. Dry matter and total N yields at maturity of rice crop were more with Azolla application upto 3 WAP during wet and 2 WAP during dry season while the reduction in sterility (%) was observed upto one WAP over 30 kg N ha⁻¹ during both seasons. Number of tillers m⁻² and dry matter production at maximum tillering and flowering were more than 30 kg N ha⁻¹ with the use of Azolla upto one WAP. Increased grain N yield was observed with the use of Azolla upto 4 WAP during two seasons whereas straw N yield increased upto one WAP during wet and 2 WAP during dry season.     

Genetic divergence among rice strains

Summary For screening better types among 10 strains with the help of the D ² statistic, an experiment was conducted in randomized block design with three replications. 10 plants in each plot were randomly selected and observations were recorded on final plant height, heading duration, effective tillers, number of grains per panicle, yield per plant and 100 grain weight.The observations were analyzed and found to be significant at 1% level.In the study of distance relations the contribution of grain number per panicle to D ² values was found to be maximum. Again, this technique also helped in grouping the 10 strains into four clusters, viz. A, B, C and D, of which B possessed six strains out of 10; A possessed two and C and D one each.Group A comprised 2 selections from the same cross. Group D was composed of a selection from a cross involving Dular and Taichung Native-1 as parents. Group B possessed Dular, two selections from a cross involving Dular as one of the parents, Dharial and N.C.-1626. The constituents of A are expected to be transgressive segregates.Group A was maximally distantly related with D followed in order by C and B. The distance between B and C was small.Group D was found to be the best of all strains studied, followed by B, C and A.Dedicated to Prof. J. Straub on the occasion of his 60th birthday.     

利用最大似然法进行水稻产量性状基因的分子作图

本研究根据对估计标记－数量性状基因座位（ＱＴＬ）之间重组率的两种分析方法（矩量法和最大似然法）、两种方差模型（ＱＴＬ基因型之间的方差同质和异质模型）的分析,揭示了ＬＯＤ值在标记－ＱＴＬ连锁检测上所得结果的相关性高于重组率估计值的相关性。采用最大似然法和异质方差模型,估计了水稻产量构成有关的ＱＴＬ与分布于１１对染色体上的５１个限制性片段长度多态性（ＲＦＬＰ）标记之间的重组率,并对似然比（以ＬＯＤ值表示）进行Ｘ￣２检验,发现７个存在显著连锁关系的标记－性状组合,其平均重组率为１０．０％。这些标记分布于第１、５、６、８和１１等５对染色体上,涉及７个ＲＦＬＰ标记和３个产量构成性状,即每穗颖花数（ＲＧ５７３、ＲＺ６１７、ＲＧ１０３）、单株穗数（ＲＧ６４Ｂ）和每穗实粒数（ＲＧ１０１、ＲＧ２４４、ＲＧ６５３）。     

Interference of horse purslane (Trianthema portulacastrum L.) and other weeds affect yield of autumn planted maize (Zea mays L.)

To assess comparative losses of Trianthema portulacastrum (HP) relative to other weeds, the experiment was set during consecutive summer seasons 2018 and 2019 at the Research Farm MNS-University of Agriculture, Multan, Pakistan. Experiment consisted three replications which were laid out under randomized complete block design. Experiment consisted of ten treatments viz: weeds free (whole season), HP free till 20 Days after emergence (DAE), HP free till 40 DAE, HP free till 60 DAE, all weeds free 20 DAE, all weeds free 40 DAE, all weeds free 60 DAE, weedy check (all weeds), weedy check except HP and weedy check containing only HP. During 2018 in all weeds weedy check, maximum HP relative density (33.33%) was observed while in 2019, plot where weeds were controlled from growing till 20 DAE showed (80%) relative density at 30 DAE. HP maximum frequency (66.67%, 77.78%) and relative frequency (66%, 100%) was recorded at 45 DAE in plots where HP was kept controlled till 20 DAE and all weeds kept controlled till 20 DAE, respectively. Maximum number of grains per cob (738, 700.68), 1000 grain weight (306.66, 271.51 g) and grain yield (6150, 8015 kg hec^-1) were recorded in plots which were kept all weed free till 60 DAE. As the competition period of weeds increased over 40 DAE, it substantially reduced yield of maize. Keeping the plots HP free till 40 DAE in the maize fields with HP as the major dominating weed, likely increase in maize grain yield is up to 30% compared to the fields where HP left un attended throughout the growing season. However, if maize field is infested with a mix of weeds with more than one dominating weeds including HP, compared to weedy situation the whole season, 30% higher grain yield can be obtained if all weeds are kept controlled till 40 DAE. Hence it can be concluded that whether the farmers face heavy HP infestation only or the mix of weeds as dominating weeds, in either case farmer should control weeds within first 40 days in maize field for better grain yield.     

Multivariate analysis for various quantitative traits in wheat advanced lines

Genetic diversity play key role in the germplasm improvement which is directly correlated with the crop production. Various statistical techniques have been used to study diversity among different genotypes. Among these techniques multivariate is most frequently used one for the genetic association of genotypes. In the present study a total of 64 advance lines included one check cultivar were evaluated under the field conditions of Cereal Crop Research Institute, Pirsabaq Nowshera, Pakistan during September 2017. Data were recorded for nine different parameters. Multivariate analysis divided the total 64 genotypes into four groups. The first five PCs with Eigen values > 1 contributed 86.95% of the variability amongst genotypes. Characters with maximum values in PC1 were Spikelets spike^-1 (SPPS) (0.732), spike length (SPL) (0.722) and biological yield (BY) (0.607), PC2 comprised of 100-grain weight (TGW) (0.605), grain yield (GY) (0.482) while days to heading (DH) (0.393), for PC3 major contributors were BY (0.550) and number of tillers meter square^-1 (NTPS) (0.289), the contribution of PC4 were flag leaf area (FLA) (0.716) and SPL (0.298) and the maximum values for various traits in PC5 were SPPS (0.732), SPL (0.722) and BY (0.607). From the findings of present study best performing lines can be directly recommended for general cultivation or to be used in future breeding programs.     

Consecutive seasonal effect on yield and water productivity of drip deficit irrigated sorghum in saline soils

Drought stress destructively affects the growth and productivity of sorghum crop, especially under saline soils. Therefore, Field trials were performed to determine the influence of water stress on water productivity (water productivity for grain, (G-WP) and water productivity for forage, (F-WP), yield of sorghum and soil properties in salt-affected soil (8.20 dS m^?1) under different sowing dates and irrigation regimes. The summer sowing (SS) was performed on 1 April while fall sowing (FS) was established on 2 August. The irrigation regimes were; 100, 90, 80, and 70% of crop evapotranspiration (ETc). The findings displayed that the fodder and grain yields were increased by 23% and 26% under SS compared to FS over the two seasons 2017 and 2018, respectively. Among irrigation levels, the maximum values of grain and fodder yield were given by 100% of ETc, while a non-significant difference was observed between 100% and 90% of ETc. Moreover, the maximum values of G-WP (1.31%) and F-WP (9.00%) were recorded for 90% of ETc. Interestingly, the soil salinity was decreased in 0–0.6 m depth, and more decline was noted in 0–0.2 m depth using 90% of ETc. The highest salt accumulation withinside the soil profile was recorded under 70% of ETc in comparison to 100% of ETc. Thereupon, under water scarcity, application of 90% of ETc is recommended with SS to save 10% of the applied irrigation water without a significant decrease in grain yield (GY).     

In vitro selection and field responses of somaclonal variant plants of rice cv PR113 for drought tolerance

Drought is the major environmental stress that limits rice productivity worldwide. In vitro somaclonal variation using different selection agents has been used for crop improvement. Here, rice plants of cv PR113 were selected in vitro on 30, 50 and 70 g L^-1 polyethylene glycol 6,000 (PEG). Callus growth, proliferation, calli volume (first and second culture) and plantlet regeneration (third culture) were found to be decreased upto a certain level to acquire tolerance to PEG-induced drought. From the field data, 30 g L^-1 PEG lines showed higher vegetative growth (plant height, tiller number, leaf number, shoot weight and root growth) as compared with 50 g L^-1 PEG selected somaclone lines under limited irrigation. The yield parameters-panicle length, panicle weight, grains per panicle, 1,000-grain weight, grain yield per plant, harvest index and grain straw ratio were also higher in 30 g L^-1 PEG lines as compared with 50 g L^-1 PEG lines. The results, therefore indicate that 30 g L^-1 PEG selected somaclone lines were more suited than 50 g L^-1 PEG selected somaclone lines under stress as compared with WT. The finding suggests that rice cv PR113 somaclones generated on PEG are found to be drought tolerant under field condition with better yield.     

Assessment of testcross performance and genetic diversity of yellow endosperm maize lines derived from adapted × exotic backcrosses

Introduction of exotic maize (Zea mays L.) into adapted tropical germplasm may enhance genetic variability and lead to greater progress from selection. The first objective of this study was to determine if yellow endosperm lines derived from adapted × exotic backcrosses contain exotic alleles that are superior to the recurrent adapted parental line for yield and other agronomic traits in tropical environments. Thirteen exotic yellow maize inbred lines were crossed to an adapted orange line (KUSR) and the F₁s were backcrossed to KUSR to generate the first backcrosses. Fifty BC₁F₄ lines derived from these backcrosses and the recurrent parent were crossed to a common inbred tester (L4001) to form testcrosses, which were evaluated at eight environments in Nigeria. Testcrosses of the BC-derived lines differed significantly for grain yield and other agronomic traits. Only two testcrosses yielded significantly less than L4001 × KUSR, with the best 15 testcrosses producing between 289 and 1,056 kg/ha more grain yield than L4001 × KUSR. The best testcrosses were similar to or better than L4001 × KUSR for other agronomic traits. The second objective of this study was to assess the extent of genetic diversity present among the BC-derived lines. We genotyped 46 BC-derived lines including KUSR and L4001 with 10 AFLP primer pairs and found 491 polymorphic fragments. The average allelic diversity of the lines was 0.30 ± 0.01. The genetic distance of each BC-derived line from KUSR ranged between 0.49 and 0.91. The average genetic distance for all pairs of the BC-derived lines was 0.68 ± 0.004, varying from 0.34 to 0.92. The increased grain yield and genetic diversity observed in these studies provide evidence that exotic germplasm can contribute new alleles to expand the genetic base of tropical maize and develop high-yielding hybrids.