1. Introduction
2. Research Programme
3. Achievements
4. Other Divisions

Mining of nutrients by high yielding varieties of crops leads to depletion of macro- as well as micro-nutrients in soil. Therefore, replenishment of nutrients through chemical and/or biological means is essential to restore and maintain soil fertility. Research efforts are focused on integrated plant nutrient management to improve soil fertility, fertilizer use efficiency and reduce cost of production for sustainable and profitable agriculture. Major emphasis is on the efficient use of macronutrients such as N, P and K.  It has been adequately established that micronutrient deficiencies of economic importance in fields prevail in case of Zn, B, and Fe only. Research efforts have been made to devise practices to manage micronutrient deficiencies in different crops.

Soil salinity is a serious problem of agriculture in Pakistan. Salt-affected soils alone occur on more than six million hectares and more than 70% of the tube-wells in saline areas are pumping out brackish water. The problem is more severe in Sindh and Southern Punjab than other parts of the country. These problems are threatening the whole production system of arid and semi-arid areas of the third world. These areas are now subjected to severe degradation and desertification. Efforts have been made to learn to live with salinity and make profitable use of saline land and water resources.

The country is also facing severe water shortage over the last several years, so there is dire need to save water and use it efficiently. Work is in progress to develop/evaluate water saving technologies and to identify/develop plants with high water use efficiency. [top]

Research Programme

1. Improving soil fertility, fertilizer use efficiency and soil health

2. Screening and selection of salt and drought tolerant plant species/varieties for profitable utilization of saline soils and saline groundwater

3. Studies on physiology of plants to enhance their tolerance under salt/drought stress

4. Development of Biosaline Agriculture Technology, its demonstration and transfer to end-users

5. Soil physics and hydrology

Soil Fertility, Fertilizer Use Efficiency and Soil Health

Improving N and P fertilizer use efficiency

Urea is the major N fertilizer used in Pakistan. However, about 30% of urea-N applied to soil is lost in gaseous form that lowers its efficiency. Ten percent or even higher increase in wheat yield is possible if urea fertilizer is applied after mixing with P fertilizer in 1:1 ratio or with calcium ammonium nitrate fertilizer in 1:1.5.

Studies were carried out to improve N economy and to increase crop yields under normal and stress conditions. The results showed that a good mixture of NH₄⁺ and NO₃^- is appropriate for wheat production on saline soils. Plant residues having narrow C/N ratio and that are easily decomposable can substantially replace chemical N fertilizers.

Nitrogen fertilizer loss through denitrification measured from an irrigated wheat-maize cropping system suggested that substantial N loss through this process occurs from irrigated croplands particularly during summer thus appropriate N fertilizer management practices are essential to reduce this loss.

Results of studies carried out to quantify N₂O emissions from cotton and wheat-maize cropping system suggested that high soil moisture and temperature prevailing under flood irrigated systems in Punjab are conducive for N₂O reduction thus leading to low N₂O emission, which is much less than 1 % of the applied fertilizer N.

Management of micronutrient deficiencies

Application of Zn and B fertilizers to rice, wheat and cotton can result in 10-30 % increase in crop yields. In Zn deficient soils, soil application of 25 kg ZnSO₄ ha^-1 at sowing is enough for 4-5 years for growing rice, wheat and cotton successfully. The use of Zn enriched rice nursery(20 kg Zn ha^-1 to nursery) is the most economical method to cure Zn deficiency with a value cost ratio (VCR) of 1:40. To cure B deficiency in rice, wheat and cotton soils, application of 10 kg boric acid ha^-1 or 18 kg borax ha^-1 proved effective for 4-5 years. It was found that in case of cotton, Zn and B as 0.1 % solution can be applied economically along with insecticides through foliar spray. Value cost ratio for B use in these crops has been very attractive, particularly in case of cotton in which it ranged from 1:5 to 1:13 by soil application and 1:20 by foliar application.

It was observed that application of B significantly enhanced rice yield, mainly because of increase in the panicle fertility. Application of B also minimized the adverse effects of water stress in crop plants. Severe attack of rust was observed on B-deficient wheat plants exposed to water stress, whereas no incidence of disease was found in the B treated plants.

The work carried out to study the effect of organic matter on micronutrient availability showed that poultry waste not only increased Cu availability to maize crop but also increased Cu concentration in soil after maize harvest. Similarly, FYM application to wheat also increased micronutrient concentration in plants.

Integrated plant nutrient management

The use of industrial by-products like Dicalcium phosphate (DCP), Filter press mud (FPM) indicated that DCP was also a good source of P, while integrating 2/3 P from organic source (FPM) with 1/3 from mineral fertilizer like SSP, resulted in higher crop yield than their individual application.

Application of SSP to wheat and maize after incubating with poultry litter resulted in higher P fertilizer efficiency as it produced significantly higher yield.

Legumes add N to soil through nitrogen fixation whereas green manuring leads to increase in soil organic matter content. The preliminary studies in rice area showed that short duration mungbean variety (NM-92) could easily be grown after wheat as a third crop in wheat-rice rotation system. After removing mungbean pods, the remaining plant could be ploughed under as green manure. In this way, the farmers can obtain additional income and green manuring is expected to reduce the input of chemical fertilizer to rice, for economical crop production and for restoring soil fertility.

Soil health and plant nutrition

Experiments on wheat and maize indicated that under both the plant species, ammonium compared to nitrate nutrition significantly increased the microbial biomass, dehydrogenase activity and aerobic/anaerobic respiration in the rhizospheric soil. The stimulatory effect of NH₄⁺ on rhizospheric microbial activity was mainly via stimulation of the root sugar exudation.

Agricultural lands in Faisalabad were found to be contaminated with several heavy metals including cadmium and uranium. Some heavy metals were also detected in the edible components of many crops. The primary source of these metals was found to be main Rakh Branch canal whereas raw sewage water was the secondary source. Phytoremediation study to decontaminate these lands showed that heavy metals were not in plant-available form and need to be solublized before employing phytoremediation technology.

Fertilizer management for salt-affected soils

Nutrient availability in wheat, rice and cotton growing tracts of Punjab was ascertained. Available N was low in 64% wheat soils, 44% rice soils and 22% cotton soils. Available P was low in 83% wheat soils, 33% rice soils and 66% cotton soils. Therefore, fertilization of many salt-affected soils with these nutrients preferably on soil test basis is recommended to obtain economical/good yields of these crops.  Available K was adequate in most of the wheat and rice soils and in more than 80% of the soils under cotton cultivation.

Fertilizer management practices for salt-affected soils have been recommended. Calcium ammonium nitrate is more suitable fertilizer than urea for wheat. Any P fertilizer can be used for wheat because all the P fertilizers tried were not much different in their effectiveness. Phosphoric acid was tried as a new P fertilizer for increasing wheat yield on salt-affected soils and was found superior to single superphosphate. Phosphoric acid of agriculture grade is being produced by the Sitara Chemical Industries, Faisalabad and is available to the farmers from local markets. In case of wheat, whole P in the form of phosphoric acid can be applied either before sowing or with first irrigation.

It was observed that ammonia losses from N fertilizer applied to salt-affected soils were 15 times higher as compared to those from N applied to normal soils. Press mud, gypsum and calcium chloride amendments were observed to markedly reduce ammonia losses from urea applied to salt-affected soils.

Rhizospheric microbial functions of saline soils

Studies were carried out to isolate, screen, characterize and identify the Exo-polysaccharides (EPS) producing bacteria associated with roots of the crop plants grown under salt stress conditions and to explore their role in improving rhizospheric soil microbial activities for increasing crop yields. Results of the greenhouse and laboratory studies have established that the EPS-producing G+ve bacilli are more prevalent in these soils and inoculation of the bacteria could mitigate negative effects of salinity on growth of the plants by increasing extent of soil aggregation around roots of the plants and also in other ways.

Salt Tolerant Plants

A large number of plant species/varieties have been screened for salt tolerance using gravel/hydroponics technique (Table 1). The research group has also been able to identify one salt tolerant variety of cotton (NIAB-999) and one salt tolerant variety of wheat (Sarsabz) for salt-affected areas. Two salt tolerant mutants, one each of mungbean and cowpea have also been developed. Mungbean mutants viz., NM-ST-1 and NM-ST-2 (salt tolerant) were crossed with NM-98 and NM-9800, the salt sensitive but well adapted high yielding mungbean cultivars. The selected mutants were successfully intercropped with cotton on saline marginal land (EC = 8 dS m^-1).

Stress Physiology

Screening technique like cell membrane stability in wheat for drought tolerance, thermostability for heat tolerance in maize and dry matter stress tolerance index, seedling stress tolerance index and root length stress tolerance index for salt tolerance in different crops have been developed. Mechanism of stress tolerance in Brassica species, cotton, wheat, sorghum, rice, grasses and guar has also been established. Some physiological and biochemical markers for stress tolerance have also been identified for these crops. It has been shown that exogenous application of ascorbic acid as an antioxidant against oxidative stress is successful in enhancing heat tolerance potential in maize.

This group is also working on oxidative stress in plants as it is related to the development of high temperature/drought/heavy metal tolerance. Wheat, rice, maize and grasses are being used to study the role of oxidative stress defense enzymes such as catalase and superoxide dismutase. Foliar application of glycinebetaine and salicylic acid are effective in increasing the salt tolerance potential in mungbean and sunflower. Similarly, it was observed that ABA and IAA enhanced the drought tolerance potential in sunflower and barley by adjusting stomatal conductance and transpiration and increasing water use efficiency (WUE).

Biosaline Agriculture Technology

A permanent solution to the salinity problem is leaching and drainage which is much expensive, so efforts have been made to learn to live with salinity and make profitable use of saline land and water resources. In this context, a reasonable progress has been made and several plants having an economic value as food, forage, timber or fire wood have been selected for profitable use of salt-affected soils irrigated with brackish water. These plants are also playing an effective role in environmental improvement.

This “Biosaline Agriculture Technology” is a low input technology and is very appropriate under socio-economic conditions of the developing countries for the utilization and improvement of the salt-affected soils and saline water for developing sustainable farming systems involving agroforestry and livestock.

To demonstrate the feasibility of Biosaline Agriculture Technology in areas facing salinity problem, the first Biosaline Research Station (BSRS-I) of NIAB was established on 150 acres of highly salt-affected land at Rakh Dera Chal near Lahore and field scale activities were continued for about 25 years on different aspects of productive use of saline land and brackish groundwater. The experience clearly showed that the saline wastelands and water could be utilized profitably.

NIAB established its second Biosaline Research Station (BSRS-II) at Pakka Anna near Faisalabad, on 1000 acres of saline land. Using brackish groundwater for irrigation, a number of plant species/varieties of barley, forage grasses, saltbushes, and tree species were evaluated under saline field conditions.

Selected salt tolerant fodders include Kallar grass (Leptochloa fusca), Sporobolus arabicus, Para grass, Swank (Echinochola sp.), Sesbania and Atriplex spp., varieties of barley (Hordeum vulgare), wheat (Triticum avestivum) and Brassica spp.

Agroforestry has been proven as a good system for economically sustainable biomass production on saline land. Large scale tree/shrub plantation developed at the station includes Eucalyptus camaldulensis, Acacia ampliceps, Acacia nilotica, mesquite (Prosopis juliflora), Parkinsonia, Frash (Tamarix), Neem (Azadirchta indica) and Iple iple. Eucalyptus camaldulensis and Acacia ampliceps proved the best among tree species.

In a provenance-family trial with 120 seedlots belonging to 15 provenances (14 Australian and one Pakistani) of E. camaldulensis, a significant genetic variation between provenances and families-within-provenances was observed. Provenance from DeGrey River (Western Austraila) proved the best, however few individual families from Pakistan had comparable growth. In other trials, 33 seedlots of this species have been established at BSRS-II, Pakka Anna and 45 seedlots were evaluated under sodic conditions at BSRS, Lahore. These tree stands offer a rich genetic base for quality seed production and also for use in tree improvement research programmes.

In another trial, 75 seedlots (60 from Australia and 15 from Pakistan) of Acacia ampliceps were evaluated under saline conditions at BSRS-II, Pakka Anna. A wide variation existed between provenances for growth, flowering and frost tolerance. Provenance Nos. 14631, 15738 and 15762 proved the best on growth rate basis. The seedlots originating from earlier grown trees of provenance 15762 had even better growth than parent. These results indicate the potential for tree improvement through natural selection. This stand is now serving as a seed source for revegetation projects.

The work on value addition to biomass produced on the station includes:

1. Goat rearing activity to convert salt tolerant fodders/shrub biomass into meat with benefit/cost ratio (BCR) of 1.3.

2. Development of low-cost aquaculture technology on saline wasteland using water, with BCR of 1.4.

3. Pilot scale production of Eucalyptus oil with indigenously fabricated plant, with BCR of 2.1.

During the last few years the station has attained the status of technology development-cum-technology transfer and salt tolerant germplasm seed supply center.

The Biosaline Agriculture Technology has been demonstrated on field stations of NIAB and at similar such stations in 10 different countries in the Middle East and North Africa through an IAEA project INT/5144 led by NIAB.

Saline Agriculture Farmer Participatory Development Project (SAFPDP)

The technology of revegetation of salt-affected soils has been mainly developed on government owned farms without involvement of farmers. Therefore, farmers need to be educated for large scale adoption of this technology. Realizing the missing link, Pakistan Atomic Energy Commission took care of this need through a “Saline Agriculture Farmer Participatory Development Project in Pakistan (SAFPDP)”. The project was launched in four provinces of Pakistan initially on 10,000 hectares of salt-affected land as a pilot project with the provision of extension to other areas. Experience gained with farmers and their salt-affected land in Phase-I has led to the development and execution of an effective, comprehensive, and environmentally, socially and economically sustainable system to revegetate vast areas of salt-affected land in Pakistan.

The SAFPDP has introduced new practices, new thinking and new forms of community engagement. Development is seen as a process where the community takes charge of their own development. Government agencies facilitate this process with staff working with the people. SAFPDP and line departments provided advice/consultancy and arranged training courses and workshops, lend expertise or provided technical support in some form. SAFPDP program was participatory and consensus based and incorporated most current issues confronting the farmers in salt-affected areas and the consultancy required actions for their resolution.

Farmers in the SAFPD project area were organized into “Saline Agriculture Farmer Associations” (SAFA). These associations are acting as conduits for SAFPDP programme for the provision of farm machinery, tube wells and other development activities. As an outcome, about 3500 ha of salt-affected land at the two project sites managed by NIAB in Shorkot and Lodhran have been rehabilitated. The main activities included: tree plantation 260 ha; agronomic practices 500 ha; and laser land levelling, acid application, tillage practices on 2000 ha. Under the project, dairy animals were provided with vaccination and multi-nutrient feed blocks. Aquaculture was established and demonstrated at several places on 24 ha (60 fish ponds of 1 acre).

Tree water use

Water Management

The growth of Kallar grass on a highly salt-affected soil using brackish irrigation water clearly demonstrated improvement in the soil physical, chemical and mineralogical properties. Hydrological studies using isotopic techniques carried out in Faisalabad area explored the subsurface aquifer characteristics, water chemistry and sources of recharge in different areas causing water-logging and salinity. A technique has been established for screening of high water use efficient plants (trees, grasses, bushes and crop plants) for dry areas using neutron moisture meter. The relationship of water use efficiency (WUE) with Carbon Isotope Discrimination (∆) has also been found useful to screen many plant species for their water use efficiency. So far, 6 plant species have been screened successfully for their WUE including Leptochloa fusca, Sporobolus arabicus, Eucalyptus camaldulensis, Acacia ampliceps, Barley and Atriplex.

A. ampliceps showed 4-5 times more biomass yield and 5-9 times more water use efficiency than E. camaldulensis. Large biomass yield and high WUE of Acacia under high salinity and drought conditions distinguish it as a fast growing tree suitable for salt-affected lands in semi-arid to arid areas. On the other hand Eucalyptus, a highly salt and moderately drought tolerant tree is recommended for areas of no water shortage.

Sporobolus showed higher WUE than Kallar grass however, this grass showed better value of yield response factor as compared to Sporobolus over the entire growing season. These grasses can be grown successfully in water-limited environments by selecting an optimum soil moisture level for maximum biomass production. Data confirm that both are C₄ plants and ∆  was significantly and negatively correlated with WUE of the two species.  Leaf ∆ can be used as a good predictor of WUE in C₄ plants. Atriplex amnicola showed double biomass yield and higher WUE under low-watered condition compared to A. lentiformis.

Water saving technologies

Fresh water is a scarce commodity and we need to adapt to water crisis reality. The issues are being addressed at NIAB with research on water saving technologies and sustainable use of brackish  groundwater. The emphasis is on evaluation of different irrigation techniques and cultural practices and selection of suitable crop varieties (ideotypes).

Water saving through various technologies has been found different. For example, it is possible to save water by 25-30% with bed-and-corrugation irrigation, 20% with zero-tillage, 20-25% with laser land levelling and up to 60% with drip irrigation. Experience at NIAB confirms that drip irrigation is the most efficient water saving technology and it saves water up to 60% (compared to flood irrigation) on cotton, up to 20% (compared to furrow irrigation method) on onion and up to 32% on sorghum.

It is emphasized that negligible adverse effects of use of brackish groundwater were observed on the health of soil and plant when it was acidified and used through drip irrigation. In this context, NIAB is likely to divert more R&D efforts to drip irrigation system to effectively tackle the water scarcity issues and some supplementary issues like fertilizer use efficiency and sub-terrain application of pesticides. As a related matter, research is also being taken up on the development of drip compatible crop ideotypes and salt and drought tolerant crop varieties.

Use of Carbon Isotope Discrimination (D) for screening/ selection of plants for high yield and water use efficiency

Selection of plants for high water use efficiency is desirable to improve crop production in different environments. Genetic increases in crop yields in dry areas have not been as great as in favourable environments or where sufficient irrigation water is available. A likely reason for this is that dry environments are characterized by unpredictable and highly variable seasonal rainfall, resulting in highly variable yields. In drought environments, the high environmental variability results in slowing of genetic advances in breeding programmes because genetic variation for yield is masked by large genotype x year and/or genotype x location interactions.  Even though yield increases have been greater in favourable environments, progress is not keeping up with the demand. Carbon isotope discrimination (∆) has shown to have substantial potential application to increase yield under variable environments. The application of ∆ technique as a screening tool in such programmes can increase the rate of genetic increase in yield. Introduction of new improved varieties using this technique suitable for target environment is the only solution to improve crop production.

Water use efficiency in plants

Studies in this direction were initiated at NIAB to screen drought tolerant plants for salt-affected areas. Initially a new method of screening plants for drought tolerance (Water use & Transpiration Efficiency) in cemented lysimeters using neutron moisture probe was established. The technique is very useful and uptill now several species of grasses, trees & crop plants (kallar grasss, Sporobolus, Eucalyptus camaldulensis, Acacia ampliceps, Barley and Atriplex) have been screened successfully for their yield and WUE.

Screening of Rice germplasm

Five rice mutants were found high water use efficient with high grain yield under low, medium and well-watered conditions using ∆ technique. Macro-yield trial of these mutants was conducted including 2 approved varieties as a control/check. Mean grain yield (GY) ranged from 3899 to 7277 kgha^-1. Genotype DM38/88 produced highest GY (7277 kgha^-1) followed by 7168 and 6773 kgha^-1 by DM-63275 and DM-64198, respectively. DM 38/88 showed 20% higher yield compared with niab-irri-9 and 23% higher yield than KS-282. The high yield of genotype DM38/88 was attributed to higher number of grains per panicle and more primary branches compared with other genotypes.

Leaf D values of two top yielding genotypes DM-38/88 and DM-64198 were high but similar and DM-64198 showed higher mean straw and grain D. The genotype DM-64198 showed highest grain based water use efficiency (WUE_G) and leaf, grain and straw D with minimum number of maturity days. Under well-watered (WW) conditions, DM-38/88 showed highest grain yield, WUE_G and high D but higher number of maturity days. The selected genotype may represent a better genetic resource for drought and well-watered conditions. Two rice lines RSP-1 and RSP-2 were included in national uniform rice yield (NURY) trials during previous two years. On country basis, line RSP-2 produced 17.5% higher yield (5570 kgha^-1) than check variety KS-282 (4788 kgha^-1). Seeds of both candidate lines have been sent to Federal Seed Certification and Registration Dept. for inclusion in crop variety registration trials. Two more lines RSP-3 & RSP-4 have been included in NURY trials.

Screening/development of high yielding wheat germplasm

Studies are underway to screen/develop high water use efficient wheat genotypes for variable environments using ∆ technique with following objectives:

1. To screen wheat genotypes (local and exotic) for high water use efficiency and to identify the most promising genotypes for variable environments.

2.  To evolve new wheat germplasm for higher yield by crossing high yielding genotypes of contrasting ∆.

3.  To establish a general relationship between Carbon isotope discrimination (Δ) and water use efficiency in wheat.

130 bread wheat (Triticum aestivum L.) lines obtained from CIMMYT and local sources were grown to maturity under irrigated conditions without water stress. Carbon isotope discrimination  (δ¹³C or ∆) was determined on early leaf and grain samples. 111 genotypes were well adapted under local conditions. Grain yield was positively and significantly correlated with harvest index. Six genotypes with leaf ∆ values 18 - 18.99 ‰ were ranked low, 55 with ∆ values 19 - 20.99 ‰ were ranked medium, 10 genotypes with ∆ values 22 - 22.99 ‰ were ranked high, and one with a ∆ value of 23.01 ‰ was ranked very high. Due to insufficient variability in ∆ among these genotypes, a crossing and generation programme was initiated to evolve new genotypes with a larger variation in ∆. The advancement phase is in progress. Meanwhile, eight genotypes were selected from the 111 adapted varieties based upon grain yield and variation in ∆, for testing under four soil moisture regimes, i.e. well-, medium-, low-watered and stored soil moisture conditions. The aim is to identify promising lines for target environments and to establish relationships between grain yield and Δ, water use efficiency (WUE) and other plant attributes.

The selected 8 genotypes exhibited higher leaf than grain D under the four water regimes, with a variation of 1.35 and 0.91 ‰, respectively. Water stress reduced both leaf and grain D, which were significantly and positively correlated. An increase in soil moisture stress decreased grain yield in all genotypes. Grain yield and grain WUE were positively correlated with leaf and grain D, harvest index, spike length and 1000 grain weight, and were negatively correlated with number of tillers and time to heading. Genotypes Sitta and FD-83 had high yield with greater increases in WUE under water stress. Sitta produced the highest grain yield of 4400 kg ha^-1 with the highest grain WUE of 16.99 kg ha^-1mm^-1, and can be exploited to obtain high grain yield in rain-fed and water limited environments.

Table 1. Salt tolerance limits, i.e. root zone salinity causing 50% relative-to-control reduction in yield, of plants studied at NIAB using gravel culture

Common/local names are given in parentheses.