PAKISTAN JOURNAL OF AGRICULTURAL RESEARCH

The following are the titles and abstracts of the research papers published in April-June, 2000,Vol. 16 No.2 of Pakistan Journal of Agricultural Research:

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EFFECT OF N FERTILIZATION ON ROOTING DENSITY OF WHEAT UNDER RAINFED CONDITIONS

Two varieties of wheat viz., Kanchan and Sonalika were grown with 0, 40, 80 and 120 kg N/ha at Dinajpur, northern Bangladesh. Nitrogen fertilization could not significantly increase root length density, 30, 65 and 95 days after sowing. Root length increased by applying 80 kg N/ha but remained the same or decreased at 120 kg N/ha at the three sampling times. There were differences between the varieties in the distribution of roots. Kanchan had a longer root system than Sonalika below 30 cm. Fertilizer significantly increased yield and highest yield (2.79 t/ha) was obtained from Kanchan at 120 kg N/ha. There were differences in the water use among nitrogen levels and varieties. Perusal of data revealed that high rates of N fertilization may decrease root length density but varietal effects on root growth are linked to patterns of water use and yield formation of wheat.

BULKED SEGREGANT ANALYSIS AND RAPD MARKERS FOR DROUGHT RESISTANCE IN WHEAT
Tanwir Ahmad Malik, Adam Price and David Wright
Random amplified polymorphic DNA (RAPD) was used to detect DNA polymorphism between two wheat genotypes, PK81 (drought resistant) and Low-ABA18 (drought susceptible). In total 160 primers (10-mer oligonucleotide) were used in RAPD reactions and 87 reproducible polymorphisms were detected between the genotypes. As much as 100 plants of an F2 population of the cross between PK81 and Low-ABA18 which segregated for drought resistance traits (net photosynthesis, water-use-efficiency and excised leaf water loss) were screened under drought. Bulked segregant analysis using the F2 population was used to find any of the 87 DNA polymorphism between the parent genotypes linked to the drought resistance traits. The study revealed that RAPD technique has great potential to find DNA based polymorphisms between genotypes of the same species. Bulked segregant analysis using an F2 population is unable to identify RAPD marker(s) linked to a quantitative trait like drought resistance.

Genetic variability and the estimates of broad sense heritability observed in F₂ population of Oryza sativa L. were significant for all the traits evaluated except for number of tillers per plant and panicle length. Heritability estimates were maximum for plant height, 100-seed weight, number of tillers per plant, spikelet density and panicle length but maximum genetic gain relative to the mean was expected for number of tillers per plant, plant height and spikelet density. Expected relative genetic advance was the function of heritability and coefficient of genotypic variability, latter being more important.

The effect of sodium carbonate (Na₂CO₃), sodium bicarbonate (NaHCO₃) and high pressure steam treatment on the composition and digestibility of rice straw by ruminants were studied. About 3% reduction in silica contents was observed after treatment with NaHCO₃ or Na₂CO₃ while it was 4.2% when rice straw was successively treated with Na₂CO₃ in the presence of steam under pressure. Reduction in neutral detergent fibre especially in hemicellulose (upto 9.3%) alongwith threefold reduction in sugars was noted. A significant reduction in lignin content was also observed due to the action of these alkalies alone or in combination with steam treatment. Organic matter digestibility of rice straw on treatment with NaHCO₃ and Na₂CO₃ increased by 15.4% and 19.9%, respectively, whereas it was only 9.5% with high pressure steam treatment. The digestibility increased upto 21.1% due to combined effect of Na₂CO₃ and steam. Moreover, digestibility of cellulose was also improved as a result of these treatments.

Plant regeneration was investigated from seed derived callus-cultures in three varieties of rice Oryza sativa L. viz. Basmati-370, Basmati-385 and KS-282. Seeds were cultured on Murashige & Skoog (MS) medium supplemented with 2 mg/l 2,4-dichlorophenoxy acetic acid (2,4-D). KS-282 exhibited a high embryogenic callus induction efficiency (31.25%) followed by Basmati-385 (17.60%) and Basmati-370 (6.50%). Calli were maintained for 90 days on the same medium by regular sub-culturing after every 15 days. Then they were transferred to Linsmaier and Skoog (LS) supplemented with various concentrations napthalene acetic acid (NAA) and benzyle amino purine (BAP). Plant regeneration frequencies were found the highest when NAA and BAP were used @ 0.4-0.5 mg/l and 0.8-1.0 mg/l, respectively.

Dry matter accumulation pattern and water requirements of maize (Zea mays L.) experiments were studied during kharif 1992 and 1993 on a loam soil having pH of 8.0. Maize showed sigmoid response curve for dry matter accumulation vs. days after planting. Crop growth rates were high from 9^th leaf stage to grain formation during both years. Water requirements of maize were determined by using climatological approach. Water requirements for maize growth cycle were expressed on dekad basis. Total water requirements varied depending on crop growth, potential evapotranspiration and crop coefficients. The total water requirements for maize were 382.8 mm from sowing upto its physiological maturity. However, when it was harvested as fodder at milk stage, water requirements were 367.9 mm. Overall rainfall was more than the water requirements of maize under rainfed condition of Islamabad.

Interactive effect of phosphorus (P) and copper (Cu) on maize growth was studied in pots. Phosphorus @ 0, 25, 50 mg/kg and copper @ 0, 2.5, 5 mg/kg were applied in all possible combinations to a sandy loam soil. Five plants of maize in each pot were grown to tasseling stage which receive N and K @ 75 and 50 mg/kg, respectively. Fresh and dry weight of maize fodder increased with the P and Cu application but decreased at their higher combinations. Nitrogen concentration was increased with Cu application whereas, P concentration decreased. Phosphorus application increased P concentration while decreased the Cu concentration in the maize plants, leading to conclude that an interaction between P and Cu in soil occurs which affects the production of maize fodder significantly.

The study revealed that the wax content correlate positively with count strength product (CSP) value, yarn elongation and rupture per kilometer (RKM) value of yarn, in some medium-stapled varieties/strains of cotton grown at AARI, Faisalabad and CRS, Sahiwal. The cotton varieties/strains i.e., FH-2/66, FH-355, FH-367, FH-368,
FH-387, FH-672, FH-682, FH-684, LH-119, CIM-109, MNH-93, SLH-41 and SLS-1, were under study. Higher wax content produced the better qualitative yarn with higher values of CSP, elongation and RKM value.

Effects of gamma radiations were studied on two varieties of cotton viz., MNH93 and NIAB78. The dosages used were 0, 25, 30 and 35 kiloradians (KR). The data on mean germination percentage, survival percentage, seedling height, plant height, days to flowering and maturity indicate that gamma radiation would be quite effective for production of variability in this crop. Gamma irradiation decreased germination percentages, survival percentage, seedling and plant height while days to flowering and maturity increased significantly. Treatment and varietal values were highly significant, treatment vs variety interaction was significant for seedling height, plant height and maturity while for germination, survival and flowering time no significant interaction was observed.

Eight hundred and ten(810) lentil germplasm accessions obtained from exotic and local sources were evaluated under laboratory conditions against a virulent isolate of Ascochyta lentis from Pakistan. Variability in disease reaction was observed among genotypes. All the lines from Pakistan, Nepal, Bangladesh, Jordan and Turkey were susceptible to blight. Only 11 lines such as Matador, Indianhead (Canadian origin), 72583, 72597, 72647, 72816 and 72819 (Indian origin), 71724 (Iranian origin) and ICARDA crosses developed at Horsham, Australia i.e., 204*2 (89), 204*4(89) and 204*1 (89) were found resistant to Ascochyta blight. This study reports some additional sources of resistance in world collection of lentil germplasm against a virulent isolate of A. lentis from Pakistan.

In a laboratory experiment treatments comprising adequate irrigation (field capacity), deficit irrigation (1/3 field capacity), Terrasorb, Aquasorb, Hydrogrow-400 in addition to farmyard manure (FYM) were tried to evaluate their water use efficiency (WUE) and nutrient uptake in sunflower. Average plant height and total leaf area per plant reduced markedly under deficit irrigation. Application of various polymers and FYM, under moisture deficit did not increase plant height and leaf area but these parameters and total biomass under adequate irrigation increased significantly. Seasonal water used by crop under adequate irrigation was maximum (1408 ml) to be followed by Terrasorb and Hydrogrow-400. Minimum water used (219 ml/g) to produce unit weight of plant showed that water use efficiency under adequate irrigation was maximum. Water use efficiency remained low even after incorporating various polymers. In this context, role of polymers under dry land conditions needs further studies prior to adoption for commercial use. Concentration of P in plant tissues was low under adequate irrigation, but no regular trend with respect to Na and K concentrations was observed in other treatments. Concentration of K in tissues was maximum and that of Na minimum in Terrasorb. All other polymers were intermediate with respect to tissue concentrations of Na and K.

Thirty genotypes of diverse origin of Brassica napus L. were grown to determine correlations and path coefficient among different parameters, to differentiate the contribution made by each parameter in the final seed yield. Branches per plant had the highest correlation (0.397) followed by pods per plant (0.282) and plant height (0.030). Path coefficient analysis revealed that branches per plant had a direct effect (0.649) on seed yield followed by 1000-seed weight (0.338) and pods per plant (0.066). 1000-seed weight has a negative indirect effect via branches per plant (-0.263) and pod length
(-0.295) on seed yield. The important characters effecting seed yield in this study were branches per plant, 1000-seed weight and pods per plant.

Studies on the effect of fertilizer mixture on growth of tea cuttings in nursery were conducted at the National Tea Research Institute (NTRI) Shinkiari (District Mansehra) during 1993 and 1994. Standard fertilizer mixture 35 parts of (NH₄)₂SO₄ and 10 parts of K₂SO₄ was prepared and applied at different levels/doses in combination with Mg and Zn. Data on growth parameters (roots, shoots and number of leaves) was recorded with the intervals of six months and one year of cuttings plantation/insertion. The mixture significantly increased the soil acidity as compared to control. Significant improvement was also observed in root growth, plant height and number of leaves per plant by doubling the dose of the mixture. Similar response to Zn was also seen while Mg had no significant effect on the growth.

Foliar application of zinc, manganese and boron alone and in various combinations were applied to sweet orange trees @ 0.4, 0.2 and 0.04 kg in the presence of 1.56 kg N (urea) and 0.4 kg surf/ha dissolved in 400 litres of water. The main effects and interactions of foliar spray of Zn, Mn and B in factorial combinations were studied relative to micronutrient concentration in citrus leaves and fruit yield of sweet orange. Zinc significantly increased leaf Zn contents and fruit yield as compared to trees where Zn was not included in foliar spray. The highest yield of 105.3 kg/tree was obtained from trees sprayed with Zn alone. Application of Mn significantly increased leaf Mn content, fruit yield and intensified the red colour of skin and juice. Application of boron significantly increased total yield, but did not influence leaf boron content. On the basis of VCR and maximum net return 0.4 kg of Zn/ha in the presence of 1.56 kg of N/ha (urea) and surf 0.4 kg/ha is recommended for higher production of citrus and for curing the zinc deficiency in Peshawar valley.

The competitive effects of weeds on crops and that of crops on weeds were measured by calculating the loss of crop and weed dry matter due to competition. The competitive ability of volunteers and that of crops was measured as aggressivity. In the experimental grounds of the University of Reading, U.K., five volunteer crops namely, Avena sativa (cultivated oats), Pisum sativum (peas), Brassica napus (oilseed rape), Sinapis alba (mustard), Lolium perenne (perennial ryegrass) and an absolute weed Avena fatua (wild oats) were grown in combination with four crops e.g. wheat (cv. Axona), barley (cv. Golf), field beans (cv. Tico) and oilseed rape (cv. Lirawell). Monoculture of weeds and crops were also maintained. Results revealed that L. perenne was the most competitive followed by P. sativum. A. sativa was the least competitive species. No significant interaction between crops and weeds occurred in determining their competitive abilities. However, among the crop species, wheat was slightly more competitive than others.

A study on grey goral (Nemorhaedus goral) was conducted in the Margalla Hills National Park (MHNP) to determine its distribution and population status. They were confined to the steep slopes and difficult terrain. They were usually found very close to the ridges. Presently, 28% of total park area is occupied by goral and 21% of the park area has similar habitat, but without any goral occurrence there. Among 40-60 animals living in the park, it was observed that 72% were adults and 28% were juveniles. Juveniles were accompanied by adults on 80% occasions and sex ratio was near 1:1.

A study was conducted on grey goral (Nemorhaedus goral ) for its feeding habits and food in the Margalla Hills National Park. Goral mostly foraged early in the morning at sunrise and late in the evening before sunset (75%). Their major food consisted of leaves of certain trees and shrubs when green grass was not available. They changed their foraging activities almost entirely to grazing on green grass during the spring and summer. Vegetation analysis of goral habitat revealed that about 60% of the vegetation consisted of plant species commonly eaten by goral. These species included Themeda anathera, Chrysopogon aucheri, Carissa opaca, Acacia modesta, Mimosa rubicaulis and Ipomoea hispida. Clumps of chir pine (Pinus roxburghii) were found on higher ridges with scattered grasses and shrubs as understorey cover. Vegetation cover comprised 47.1% grasses, 33.4% shrubs and 19.5% trees. The frequency occurrence of grasses, shrubs and trees was 81.5%, 14.5% and 4.0%, respectively. Total ground cover was almost the same on both the northern and southern slopes. Livestock competed with goral for forage in most of its habit area.

D. rapae and A. colemani are two parasitoid species, differ in their life time performance when reared on the same aphid species. Differences in development time, potential fecundity, longevity, generation time were considerable. The intrinsic rate of population increase was greater for D. rapae (0.223) than for A. colemani (0.183). Using r_m an index of fitness, D. rapae was the superior species in terms of parasitoid fitness of biological control, because its generation time was shorter than that of A. colemani.

The study was conducted at Hattar industrial area, about 69 km north of Islamabad, to determine the impact of industrial effluents on the population dynamics of aquatic insects. The water quality of Khanpur canal before industrialization of area confirmed the set National Environmental Quality Standards (NEQS). The water quality, since then, has deteriorated in terms of its pH, Biological Oxygen Demand, Chemical Oxygen Demand, chloride, nitrate and total suspended solids were manifold higher than NEQS. The deterioration of water quality has a direct impact on the population of species of aquatic insects. The species which were undetectable included Diplacoides, Rhyothemis, Tramea (Anisoptera); Ischnura sp. (Zygoptera); Sialis (Megaloptera); Ambrysus (Hemiptera); Thalassotrechus, Macrovatellus, Celina, Dineutus, Narpus, Heterelmis, Amphizoa (Coleoptera); Blepharicera, Bibiocephala, Philorus, Gymnopais, Parasimulium, Prosimulium, Cnephia, Pentaneura flavifrons (Joh.), Pelopia, Anatopynia (Diptera); Bourletiella, Isotomurus (Collembolla). This study supports the hypothesis that the aquatic species of insects can be used as tools or indicator to monitor the health of ecosystem.

Screening and selection of four promising tea varieties of Chinese origin (five years old) were made at National Tea Research Station , Shinkiari. Early growth of shoot, its vigour and number of plucking points were recorded for further selection. It was observed that the varieties showed different responses under the same environmental conditions. Initially in the month of April, the new growth was early and faster in Ruopi as compared to others varieties but in the month of July, Qi-men performed better in giving more number of plucking points, whereas the Chuye remained the poorest. The Ruopi variety stood the best one among all the others tea varieties under observation by giving maximum number of 117.33 branches per plant and 15 roots with 5506gms fresh pruning weight/plant. The highest number of 202 plucking points wee recorded in Qi-Men but dry weight of 0.29 gms/plant of roots was recorded in Chuye variety.

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