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ROOTING PATTERN AND NITROGEN USE EFFICIENCY IN COTTON (GOSSYPIUM HIRSUTUM L.) UNDER MOISTURE STRESS CONDITIONS.

Byline: Mahmood-ul-Hassan, M. Maqsood, S. A. Wajid and A.M. Ranjha

ABSTRACT

Roots play an important role in exploring the plant's ability to explore the available soil volume for water and nutrients. Among abiotic stresses, moisture stress is one of the most imperative factor that exerts substantial impact on root growth, nutrients use efficiency, and seed cotton yield. Field experiments were conducted during 2008-09, to elucidate the effect of moisture stress on rooting pattern, seed cotton yield, and nitrogen use efficiency (NUE) of different genotypes grown in alkaline calcareous soils.

Three factors were: {three genotypesviz.V1 = NIAB-846, V2 = NIAB-824, and V3 = CIM-496); four moisture stresses(viz.I1 = local control-eight irrigations (all applied at 50% available soil moisture depletion level, ASMDL),I2 = moisture stress at inter-node elongation stage- in July up to 80% ASMDL, I3 = moisture stress at vegetative growth stage- in September up to 80% ASMDL,and I4 = moisture stress at inter-node elongation and at vegetative growth stage-in July and September up to 80% ASMDL)); and three nitrogen doses (viz. N1 = 50 kg ha-1, N2 = 100 kg ha-1, and N3 = 150 kg ha-1.)}arranged in Randomized Completed Block Design with split-split plot arrangements replicated thrice while keeping genotypes in main plots, moisture stresses in split plots, and nitrogen levels in split-split plots. Interaction treatments (IxNxV) significantly affected root:shoot ratio, seed cotton yield, and NUE.

During 2008, highest root:shoot ratio (0.413) was recorded in NIAB-824 byI2xN1xV2 followed by 0.333 root:shoot ratio in NIAB-846 byI2xN1xV1treatment.During 2009, highest root:shoot ratio (0.412) was recorded in CIM-496 by I3xN1xV3treatment. Under higher N dose (150 kg N ha-1), root:shoot ratio didn't vary significantly by different moisture stress treatments in all genotypes. Results showed that, highest seed cotton yield of 4871 and 4853 kg ha-1 was achieved in NIAB-846 and NIAB-824 by I3xN3xV2 and I1xN2 xV2, respectively (during 2008);and 5709 and 5634 kg ha-1in NIAB-824 by treatments I3xN3xV2 and I1xN2xV2,(during 2009), respectively. During 2008, highest NUE of 105.09, 92.92, and 92.54 kg yield kg-1 N applied was obtained in I1xN1xV1, I1xN1xV2, I3xN1xV3, respectively. Similar trend was observed during 2009 with highest NUE in I1 and I3 treatments. Non-significant difference in highest NUE in no stress (control) and moisture stress at vegetative growth stage was observed.

These results led towards the conclusion that N application @50 kg ha-1under moisture stress either in July or September causes higher root:shoot ratio in cotton genotypes and highest NUE in these genotypes can be achieved by imposing moisture stress at vegetative growth stage in September (by skipping one irrigation)coupled with 50 kg N ha-1.

Key words: Moisture stress, Gossypium hirsutum L., rooting pattern,nitrogen use efficiency.

INTRODUCTION

Plant's ability of root development under moisture stress helps in sustainable translocation of assimilates to the above ground plant's shoots. Genotypes significantly differ in root/shoot characteristics under moisture stress (Jamal et al., 2014). Plant's ability to sustain water stress under dry environment is attributed to its potential in maintenance of photosynthesis rate upto desired level (Niu et al., 2005). Roots are main source of nutrients supply to shoots; therefore, these are interdependent to each other. Any adjustment in root due to moisture stress in the soil will change shoot physiological processes including photosynthesis.

In some crops like sorghum, wheat, maize and sunflower, moisture stress have shown drasticeffects on root/shoot dry weights (Bibi et al., 2012),however, in case of cotton, moisture stress is beneficial in terms of improvement of water use efficiency without significant yield loss (Jamal et al., 2012). For evaluation of drought resistance, root vigour is a reliable and sensitive indicator (Wang et al., 2006). Root vigour reflects the ability of plants for water and nutrients absorption under drought stress conditions. Alternate deficit irrigation may lead towards deeper roots in cotton as compared to shallow roots in well irrigated no stress field (Sampathkumar et al., 2012). Deficit irrigation is more economical due to water saving (up to 22%) and more area under cultivation as compared to little yield loss due to deficit irrigation (Mustafa et al., 2011).

Under severe water stress, an increase in root growth and decrease in shoot growth was observed (Maranov et al., 1998) due to utilization of limited available water by root and transportation of a small amount of water towards shoot. Drought also effects leaf expansion and root growth (Ball et al., 1994).

Nitrogen application under moisture stress also influences cotton plants by decreasing soil relative water content, but leaf area, dry matter production, nitrogen accumulation, root:shoot ratio, and root-N:shoot-N ratios may be increased (Liu et al., 2008). Nitrogen application enhances peroxidase (POD) and catalase (CAT) activities of cotton root under moisture stress, however, superoxide dismutase (SOD) activity is reduced during water stress and recovery period. Malondialdehyde (MDA) content significantly (Pless than 0.05) increased. Nitrogen also affects rooting pattern of plants and have a significant impact on root-shoot relationship (Lioert et al., 1999).Significance of N on plant responses under soil moisture stress is well documented (Shangguan et al., 2000; Stroup et al., 2003).

Seed cotton yield and nitrogen use efficiency is linked with moderate application of N (Dongmei et al., 2012).The information about impact of genotypic- specific nitrogen and moisture stress interaction on rooting pattern and nitrogen use efficiency of cotton grown on alkaline calcareous soils is missing. This research was conducted to explore the impact of moisture stress at certain growth stages of cotton plant on rooting pattern, nitrogen use efficiency and ultimately yield. The aim was also to see whether deficit irrigation at certain growth stages of cotton with optimum N level is beneficial and useful in saving of irrigation water and urea fertilizer.

MATERIALS AND METHODS

Experimental site, design and treatments detail: Field experiments were conducted (2008-09) on wheat fallow plots at Nuclear Institute for Agriculture and Biology (NIAB), Faisalabad, Pakistan, located 31, 23' North latitude and 73, 2' East longitude.Soil (0-30 cm depth) of experimental fields was alkaline calcareous, with low organic matter, low saturation%, lower nitrogen and phosphorus, deficient in zinc and boron, and adequate in potash and iron (Table 1). The soil of selected field pertained to Lyallpur soil series, belonging to US Soil Taxonomy Subgroup Udic Ustochrept (Soil Survey of Pakistan, 1968).Experiments were designed by using three factors (moisture stress, nitrogen, and genotypes) in randomized complete block design with split plots arrangements in three replications.

Moisture stress treatments used were: local control = eight irrigations as recommended by Govt. Agri. Extension Departments (I1)- all irrigations were applied at 50% ASMDL, moisture stress at inter-node elongation stage (MSI) = withholding of irrigation in July up to 80 % ASMDL (I2), moisture stress at vegetative growth stage (MSV) = withholding irrigation in September up to 80 % ASMDL (I3), and moisture stress at inter-node elongation and vegetative growth stage (MSI+ MSV) = withholding irrigation in July and September at 80 % ASMDL (I4). Three nitrogen levels N1 = 50, N2 = 100, and N3 =150 kg ha-1); and three genotypes of cotton V1 = NIAB-846, V2 = NIAB-824, and V3 = CIM-496 were used in this field experiment.

Crop husbandry: During both the years wheat fallow plots were selected for field experiments. Prior to sowing, experimental field was disc ploughed and cultivated twice followed by planking with tractor for preparation of fine seed bed. Field layout was done according to experimental design by using adjustable marker. Fertilizers application was made as per treatments in every plot. At sowing P2O5 fertilizer was uniformly applied to all treatments @ 70 kg ha-1 in the form of Single Super Phosphate (18 % P2O5) and one-third amount of Urea (46% N) fertilizer as per treatments level, was mixed in upper soil 0-9 cm depth manually in different treatments. Urea application was made in three equal splits (at sowing, dense flowering, and at boll development stages). Experimental crop was planted on 20th May and 25th May during 2008 and2009, respectively, while using different fields both the years.

Dibbler method was used by placing 4-5 seeds per hill and maintaining rowxrow and plantxplant spacing of 75 cm and 30 cm, respectively while keeping net plot size of 3.6 x 3.0 m, and total seed rate of 20 kg ha-1. Canal water was used to apply irrigation treatments. Single plant per hill was maintained by thinning operation of experimental crop at three-leaf stage. Different pesticides for control of boll worms and sucking pests (mealy bug, jassids, thrips and white-fly insect-pests) used were; Confidor, Talstar, Curacuron, Acetamiprid and Tracer to control spotted bollworms, mealy bug, jassids, thrips and white-fly insect-pests. Weeds were controlled by using three-tined manually operated weeder. Weather data of experimental site was also recorded at nearest observatory of Agronomy Section of Ayub Agriculture Research Institute (located about 1000 m distance from experimental plots), Faisalabad.Mean maximum and mean minimum temperature of crop growing period is also given in Table 4.

Measured quantity of irrigation water was applied by using plastic container of known volume. The calculation of the amount of water applied was made by multiplying plot area with irrigation depth. Total amount of rainfall received was recorded and the remaining amount of water, as specified in treatments details, was applied by using container of known volume to maintain uniform application of total water (irrigation+rainfall) to each treatment during both years. Detail of the rainfall and irrigation application is given in (Table 2 and 3).

Procedure for recording observations

Seed cotton yield: At 50% bolls opening stage in the month of October, first picking of central rows from every plot was done manually at 8-10% moisture contents in seed cotton. Border lines were picked separately and that produce was not used in per plot yield in order to avoid border effects. Second picking of central lines from every plot was made at crop maturity in the month of November, when 90% bolls were opened. At completion of second picking, five randomly selected plants from every plot were selected and tagged for their roots observations while remaining plants were harvested at ground level. The harvested plants were also tagged and kept outside the field for 2 weeks for opening. Then picking of leftover unopened bolls from all harvested and standing plants was made. Total quantity of picked seed cotton was weighed by electronic balance for recording of yield per plot and then seed cotton yield per hectare was calculated.

Root- shoot ratio: For cotton roots study methodology developed by Prior et al., (1994) was followed. Five randomly selected standing plants in every plot for roots study were cut at 1st coteledonary nodeand roots were excavated upto 90 cm soil depth by drain spade.The taproots and attached lateral roots were retrieved after loosening the soil carefully with drain spade to avoid any damage to the roots. Individual plants (shoots) and their respective roots were labeled by permanent marker, washed with water to remove attached soil particles and placed in air forced oven at 60C temperature for drying till constant weigh ratio was determined by using the procedure given below:

Root shoot ratio = Dry root weight / Dry shoot weight

Nitrogen use efficiency: The nitrogen use efficiency (NUE) was calculated as:

NUE = Seed cotton yield kg/ha / Nitrogen applied kg/ha (Thind et al., 2008)

The NUE has been reported as kg seed cotton kg-1 N applied.

Statistical analysis: Data collected were tabulated and analyzed by Randomized Complete Block 3-factors split- split plot design ANOVA process by using Fisher's analysis of variance technique. Factor effects were considered significant at the P=0.05. Where F values were significant, means were separated by least significant difference (LSD) at 5% probability level (Steel and Torrie, 1997). Computer software packages Minitab-15, Statistix version 8.1, and Microsoft excel version 2010 were used for data analysis and preparation of graphs.

Table 1. Soil properties of experimental fields (0-30 cm).

###DTPA-

###Organic###Nitrogen###NaHCO3- NH4 OAc-###Boron

###Saturation###CaCO3###Zn###Iron

Year###pH###matter###(NO2)###P###K###(mg kg-

###(% )###(%)###(mg kg-###1)###(mg kg-1)

###(%)###(mg kg-1)###(mg kg-1) (mg kg-1)###1)

2008###26###8.10###12###0.41###7.70###4.00###180###0.70###0.48###5.80

2009###30###8.40###13###0.66###8.70###5.30###200###0.52###0.50###5.25

Table 2. Rainfall and irrigation received by different treatments during 2008.

###Treatments

Irrigation and rainfall

###I1 (mm)###I2 (mm)###I3 (mm)###I4 (mm)

###detail

###Rainfall Irrigation Rainfall Irrigation Rainfall Irrigation###Rainfall Irrigation

July###63.40###200.00###63.40###100###63.40###200###63.40###100

August###273.00###-###273.00###-###273.00###-###273.00###-

September###37.00###200.00###37.00###200###37.00###100###37.00###100

October###-###100.00###-###100###-###100###-###100

Total###373.40###500.00###373.40###400###373.40###400###373.40###300

Irrigation +###873.40###773.40###773.40###673.40

rainfall (mm)

Table 3. Amount of water received by different treatments during 2009.

###Treatments

###Irrigation and

###I1 (mm)###I2 (mm)###I3 (mm)###I4 (mm)

###rainfall detail

###Rainfall###Irrigation###Rainfall Irrigation Rainfall Irrigation###Rainfall###Irrigation

###July###52.50###210.90###52.50###110.90###52.50###210.90###52.50###110.90

###August###137.40###135.60###137.40###135.60###137.40###135.60###137.40###135.60

###September###30.20###206.80###30.20###206.80###30.20###106.80###30.20###106.80

###October###14.80###85.20###14.80###85.20###14.80###85.20###14.80###85.20

###Total###234.90###638.90###234.90###538.90###234.90###538.90###234.90###438.90

###Irrigation###873.40###773.40###773.40###673.40

###+ rainfall (mm)

Table 4. Mean maximum and mean minimum temperature during crop growing seasons 2008 and 2009

Climatic factor/growing###season###May###June###July August September October November December Mean

###2008###38.40###37.80###37.70 35.00###35.30###33.70###28.30###22.90###33.44

###Mean Max. Temp

###2009###40.10###40.90###37.90 36.50###36.10###33.40###26.30###22.90###34.26

###2008###23.40###26.90###27.70 26.00###23.20###19.90###10.80###7.80###19.96

###Mean Min. Temp.

###2009###24.30###25.60###26.50 26.40###23.40###16.20###10.00###4.60###19.63

RESULTS

Moisture stress, nitrogen, and genotypic interaction effect on root:shoot ratio: Analysis of variance revealed significant (P=0.05) effects of moisture stress (I) on root:shoot ratio (Table 5) with highest root:shoot ratios of 0.226 and 0.333 from I3and I4 treatments during 2008 and 2009, respectively (Table 8). Similarly genotypic (V) main effect were significant during 2008, exhibiting highest root: shoot ratio of 0.248 in NIAB-846 (V1), however during 2009 main effects of V were non- significant. Main effects of N were non-significant both the year. Two way interaction effects IxV, NxV and three way interaction IxNxV found significant (Table 8) during 2008-09. However, two way interaction I x N remained significant during 2008but non-significant during 2009.

Three way interaction (IxNxV) effect on root: shoot ratio of cotton genotypes found significant during both years and is presented in Fig. 1.a,b. Highest root: shoot ratio of 0.413 during 2008 was achieved by treatment I2xN1xV2 (MSI x 50 kg N ha-1 x NIAB-824) followed by 0.333 and 0.305 root: shoot ratios by treatments I2xN1xV1 (MSI x 50 kg N ha-1 x NIAB-846) and I1xN2xV3 (LC x 100 kg N ha-1 x CIM-496), respectively (Fig.1.a). During 2009, maximum root: shoot ratio of 0.412 was recorded by I3xN1xV3 (MSV x 50 kg N ha-1 x CIM-496) and least root: shoot ratio (Fig. 1.b) was found from I2xN2xV2 (MSI x 100 kg N ha-1 x NIAB-824) and I1xN3xV1 (LC x 150 kg N ha-1 x NIAB-846) treatments.

Table 5. Analysis of variance of root:shoot ratio as affected by moisture stress, nitrogen, and genotypic interaction

Treatments###2008###2009

###df###SS###MS###F value###P value###SS###MS###F value###P value

Replication###2###0.00071###0.00036###0.02887###0.01444

Irrigation (I)###3###0.03236###0.01079###12.72###0.0000###0.03659###0.01220###6.26###0.0008

Nitrogen (N)###2###0.00591###0.00295###0.19###0.8311###0.00164###0.00082###0.42###0.6578

Genotypes (V)###2###0.01978###0.00989###5.42###0.0065###0.00259###0.00130###0.66###0.5178

IA-N###6###0.08681###0.01447###8.67###0.0000###0.02208###0.00368###1.89###0.0950

IA-V###6###0.02624###0.00437###1.30###0.2671###0.04953###0.00826###4.23###0.0011

NA-V###4###0.02253###0.00563###5.82###0.0004###0.03642###0.00910###4.67###0.0021

IA-NA-V###12###0.16059###0.01338###2.64###0.0056###0.05156###0.00430###2.20###0.0205

Error###70###0.15097###0.00216###0.13648###0.00195

Total###107###0.50590###0.36577

Grand mean###0.2296###0.3100

C.V###20.22###14.25

Table 6. Analysis of variance of seed cotton yield as affected by moisture stress, nitrogen, and genotypic interaction.

Treatments###2008###2009

###df###SS###MS###F value###P-value###SS###MS###F- value###P- value

Replication###2###1216206###608103###47501

Irrigation(I)###3###4.100E+07###1.366E+07###42.55###0.0000###7539326###2513109###21.12###0.0000

Nitrogen (N)###2###2135221###1067610###3.32###0.0418###56075.4###28038###0.24###0.7907

Genotypes###2###6846677###3423339###10.66###0.0001###3571941###1785971###15.01###0.0000

(V)

IA-N###6###4036520###672753###2.09###0.0647###3262051###543675###4.57###0.0006

IA-V###6###8698811###1449802###4.51###0.0006###1827834###304639###2.56###0.0267

NA-V###4###6799716###1699929###5.29###0.0009###133817###33454###0.28###0.8892

IA-NA-V###12###7.874E+07###6561723###20.43###0.0000###3698798###308233###2.59###0.0066

Error###70###2.249E+07###321220###8328151###118974

Total###107###1.720E+08###2.851E+07

Grand mean###3561.8###Grand mean###4040.90

C.V###15.91###C.V###8.54

Table 7. Analysis of variance of nitrogen use efficiency as affected by moisture stress, nitrogen, and genotypes of cotton

Treatments###2008###2009

###df###SS###MS###F value###P value###SS###MS###F value###P value

Replication###2###0.00071###0.00036###0.03112###0.01037

Irrigation (I)###3###0.03236###0.01079###5.00###0.0034###0.02917###0.01459###5.32###0.0000

Nitrogen (N)###2###0.00591###0.00295###1.37###0.2609###0.01384###0.00692###7.48###0.0000

Genotypes (V)###2###0.01978###0.00989###4.59###0.0134###0.03178###0.00530###3.55###0.0001

IA-N###6###0.08681###0.01447###6.71###0.0000###0.01428###0.00238###2.72###0.0000

IA-V###6###0.02624###0.00437###2.03###0.0733###0.02830###0.00707###1.22###0.0000

NA-V###4###0.02253###0.00563###2.61###0.0427###0.05193###0.00433###3.63###0.0000

IA-NA-V###12###0.16059###0.01338###6.20###0.0000###0.13648###0.00195###2.22###0.0000

Error###70###0.15097###0.00216###0.36577

Total###107###0.50590###0.02887###0.01444

Grand mean###0.2296###0.3100

C.V###20.22###14.25

Table 8. Effects of moisture stress, nitrogen, and genotypes on root: shoot ratio and nitrogen use efficiency in cotton.

###Seed cotton yield###NUE

###Root: shoot ratio

###Factors###(kg ha-1)###(kg seed cotton kg-1 N applied

###2008###2009###2008###2009###2008###2009

###Moisture stress (I)

###I1###0.189 c###0.302 bc###4087 a###4284 a###51.56 a###53.01 a

###I2###0.237 b###0.320 ab###3360 b###3891 b###36.46 c###48.37 b

###I3###0.266 a###0.284 c###4158 a###4305 a###47.93 b###52.30 a

###I4###0.226 b###0.333 a###2642 c###3683 c###32.78 d###44.21 c

LSD (P0.05)###0.025###0.024###307.65###187.23###1.88###1.63

###Nitrogen levels (N)

###N1###0.230 a###0.305 a###3729 a###4017###64.65 a###79.98 a

###N2###0.226 a###0.310 a###3571 ab###4072###39.27 b###41.07 b

###N3###0.232 a###0.314 a###3385 b###4034###22.62 c###27.38 c

LSD (P less than 0.05)###NS###NS###266.43###NS###1.63###1.41

###Genotypes (V)

###V1###0.248 a###0.304 a###3918 a###4232 a###42.13###49.64 a

###V2###0.228 ab###0.309 a###3380 b###4094 a###42.12###51.00 a

###V3###0.213 b###0.316 a###3387 b###3796 b###42.29###47.79 b

LSD (P less than 0.05)###0.022###NS###266.43###162.15###NS###1.41

###Interaction^^

###IA-N###0.044###NS###NS###324.29###3.26###2.82

###IA-V###0.044###0.041###532.86###324.29###3.26###2.83

###NA-V###0.038###0.036###461.47###NS###2.82###2.45

###IA-NA-V###0.076###0.072###922.95###61.69###5.64###4.89

Grand mean###0.230###0.310###3562###4041###42.18###49.48

###CV###20.22###14.25###15.91###8.54###8.22###6.07

Moisture stress, nitrogen, and genotypic interaction effect on seed cotton yield: For seed cotton yield analysis of variance (P=0.05) revealed significant effect of moisture stress, and genotypes during both cropping seasons, as shown in Table 6. However, nitrogen main effects on seed cotton yield remained significant during 2008and non-significant during 2009 (Table 8). During 2008, highest seed cotton yield of 4158 kg ha-1 and 4087 kg ha-1 was achieved by I1 and I3, and highest seed cotton yield (during 2009) of 4305 kg ha-1 and 4284 kg ha-1 was found by I1 (LC) and I3 (MSI) treatments, respectively(Table 8). Seed cotton yield was significantly affected by N levels during 2008 resulting highest yield of 3729 kg ha-1 by N1 (50 kg N ha-1), however during 2009, N didn't showed significant effect on yield.

Interaction of moisture stress, nitrogen, and genotypes (IxNxV) significantly exhibited seed cotton yield during two years studies (Fig. 2.a,b). During 2009, highest seed cotton yield of 5709 kg ha-1 (Fig. 2.b) was achieved by I3xN3xV2 (MSV x 150 kg N ha-1 x NIAB-824) treatment followed by 5634 kg ha-1 seed cotton yield of the same genotype from treatment I1xN2xV2 (LC x 100 kg N ha-1 x NIAB-824). In NIAB-846, highest seed cotton yield of 5469 kg ha-1 was obtained from treatment I1xN3xV1 (LC x 150 kgha-1N x NIAB-846) followed by 4843 kg ha-1 seed cotton yield from I3xN2xV1 (MSV x 100 kg ha-1 N x NIAB-846) treatment. In CIM-496 (V3), highest seed cotton yields of 5296 kg ha-1 was recorded from I2xN2xV3 (MSI x 100 kg ha-1 N x CIM-496) and 5255 kg ha-1 by I1xN1xV3 (LC x 50 kg ha-1 N x CIM-496) followed by 5005 kg ha-1 seed cotton yield by I3xN2xV3 (MSV x 100 kg ha-1 N x CIM-496).

Lowest seed cotton yield of 1447, 1560, and 1830 kg ha-1 was recorded by treatments I4xN2xV2 (MSI+MSV x 100 kg ha-1 N x NIAB-824) followed by 1560 kg ha-1 in treatment I4xN3xV1 (MSI+MSV x 150 kg ha-1 N x NIAB-846) and 1830 kg ha-1 in I4xN1xV3 (MSI+MSV x 50 kg ha-1 N x CIM-496). In all the genotypes lowest seed cotton yield was recorded from I4 (MSI+MSV) treatments (Fig. 2.a,b).

Moisture stress, nitrogen, and genotypic interaction effect on nitrogen use efficiency: Treatments impact on nitrogen use efficiency (NUE) was significant during both the years (Table 6). During 2008, highest NUE (51.56 kg seed cotton yield kg-1 of N applied) was recorded from I1 (LC) where as NUE, 53.01 and 52.30 kg seed cotton yield kg of N applied found in I1 and I3 treatments, respectively. In case of N treatments, 50 kg N ha-1 (N1) gave highest NUE during both cropping seasons. Among genotypes, NIAB-824 and NIAB-846 showed maximum NUE, 51.00 and 49.64 kg seed cotton yield kg-1 of N applied, respectively. (Table 7). During2008 (Fig. 3.a), highest NUE of 105.09 kg SCY kg-1 N applied was noted from I1xN1xV3 treatment followed by NUE values of 92.92 and 92.54 kg SCY kg-1 N applied by I1xN1xV1 and I3xN1xV2 treatments, respectively.

Lowest NUE of 10.40, 13.14, and 14.47 kg SCY kg-1 N applied, were found in I4xN3xV1 (MSI+MSV x 150 kg ha-1 N x NIAB-846), I2xN3xV3 (MSI x 150 kg ha-1 N x CIM-496), and I4xN2xV2 (MSI+MSV x 100 kg ha-1 N x NIAB-824) treatments, respectively (Fig. 3.a). During 2009, highest NUE values of 97.06 and 95.97 kg SCY kg-1 N applied were obtained by treatments, I3xN1xV2 (MSV x 50 kg ha N x NIAB-824) and I1xN1 xV1 (LC x 50 kg ha-1 N x NIAB-846), respectively (Fig. 3.b).

Highest nitrogen use efficiency (NUE) was recorded in cotton genotypes in well water and moisture stress at vegetative growth stage treatments with lower N dose.

DISCUSSION

Roots growth under abiotic stresses is an important indicator of drought tolerance of any plant. The results obtained from the present field study clearly depicted divergent root: shoot ratio response of genotypes under moisture stress and nitrogen treatments (Fig. 1.a,b).During 2008, greater root: shoot ratio of NIAB-846 and NIAB-824 was observed when moisture stress was imposed at inter-node elongation stage in the month of July coupled with lower application of nitrogen @50 kg ha-1 (Fig 1.a). However, during 2009, these two genotypes exhibited higher root: shoot ratios in treatments where moisture was applied at vegetative growth stage in September with lower N levels (50 and 100 kg ha-1).In CIM-496 different response was observed with highest root: shoot ratios of 0.305 and 0.408 in I1 (LC) treatments during 2008 and 2009, respectively.

These results indicate diversity in rooting pattern among cotton genotypes due to their diverse genetic background as well as variation in soil fertility status on which these genotypes were grown. In previous studies rooting diversity in different cotton genotypes was observed under same set of environments (Kasperbauer and Busscher, 1990). Genotypes NIAB-846 and NIAB-824 exhibited higher root: shoot ratio by moisture stress at early growth stage in the month of July which depicts greater genetic potential of these genotypes towards more development of their rooting system for tolerance to moisture stress. These genotypes had shown ability to enhance root: shoot ratio under deficit moisture in the rooting zone leading towards an increase in transfer of assimilates from shoots to roots in establishing the root vigour to maintain the moisture and nutrients balance in the plant system.

In previous it was observed that crop plants which have ability of drought tolerance, a greater portion of assimilates was transferred towards roots and caused an increase in root: shoot ratio (Jamal et al., 2012, and Riaz et al., 2013).It has also been reported that impact of moisture stress on root; shoot ratio vary from crop to crop like cotton and maize with different response exhibiting a significant impact of moisture stress on root: shoot ratio in cotton (Jamal et al., 2014).However in some cultivars of sorghum, wheat, maize and sunflower, drastic effects of moisture stress on root: shoot ratio may occur (Bibi et al., 2012). Nitrogen application to cotton crop under moisture stress conditions is also very important. In this study, highest root: shoot ratios (Fig. 1.a,b) with lower N levels (50 and 100 kg N ha-1) coupled with moisture stress as compared higher N application (@150 kg ha-1) was observed.

In cotton lower N application under drought is more beneficial as compared to higher N dose (Liu et al., 2008).An increase in N dose under moisture stress contributed in enhancing of root growth, but caused a decrease in shoots growth (Maranov et al., 1998). This was due to consumption of major portion of the limited water absorbed by roots in roots development and transportation of only a smaller fraction of absorbed water towards shoots. It is prevalent that genotypic response for changes in root: shoot ratios by moisture stress and nitrogen under field conditions depends upon varietal-specific morphological response that may vary in different genotypes of the same crop.

Higher seed cotton yield of any genotype grown in the field under different stresses depicts its tolerance for adverse conditions. Under moisture stress at vegetative growth stage (I1), best seed cotton yield of NIAB-846 was obtained (Fig. 2.a,b) evenby the use of lower dose of N (50 kg N -1) as compared to well water control (I1, LC) treatment where higher dose of N (150 kg ha-1) gave highest seed cotton yield. Because in both cases, the seed cotton yield was statistically at par, so nitrogen as well as irrigation water saving is possible by using NIAB-846 and imposing moisture stress at vegetative growth stage and N management by use of lower dose. However, the NIAB-824, at higher N levels (150 kg ha-1) produced highest seed cotton yield with vegetative stage moisture stress, I3 (MSV). The CIM-496 (Fig. 2.a,b) when put under stress at vegetative growth stage (I3), gave the best yield with N2 (100 kg N ha-1). Both the years lowest seed cotton yields were achieved by treatments with I4 (MSI+MSV).

However, during 2009 overall higher seed cotton yield in all genotypes was achieved by different interaction treatments.

Temperature variability significantly affects fruit setting and yield of cotton genotypes (Lou, 2011). However, mean maximum and mean minimum temperature didn't significantly differ during crop growing periods of 2008 and 2009 (Table 4). The higher seed cotton yield during 2009 may be attributed to the better fertility status of experimental plot (Table 2.The experimental plot selected for field experiment during 2009 was having higher organic matter and nitrogen, as well as with greater available P2O5 and K2O.

Above mentioned results advocated that moisture stress at vegetative growth stage (I3) has favourable impact on seed cotton yield of NIAB-846, NIAB-824, and CIM-496 genotypes due to non- significant yield loss as compared to well water (LC, I1) treatment (Falkenberg et al., 2007)even in some cases higher yield as compared to well watered treatment. However, these genotypes differed in NxI3 interaction that may be due to diverse genetic background of these genotypes exhibiting different morphological responses of plants under moisture stress.

To enhance NUE under moisture stress was the main aim of this study. If we compare the highest NUE of three genotypes during 2008 (Fig. 3.a) with control treatments (I1xN3xV1, I1xN3xV2, I1xN3xV3), 60.76% increase in NUE of NIAB-846 (by treatment I1xN1xV1), 82.19% increase in NUE of NIAB-824 (by treatment I3xN1xV2), and 73.86% increase in NUE in CIM-496 (by treatment I1xN1xV3) over control was recorded. Similar trend was observed during 2009, where 69.20% higher NUE in NIAB-846 (by treatment I1xNxV1), 72.06% higher NUE in NIAB-824 (by treatment (I3 x N1 x V2), and 64.29% higher NUE in CIM-496 (by treatment I2xN1xV3), was achieved over control (Fig. 3.b). During 2009, higher seed cotton yield was achieved by same N levels due to more favourable soil's environmental conditions (Table 4). Which resulted higher NUE of cotton genotypes. Cotton genotypes differ in NUE under moisture stress due to diversity in plant morphology and nitrogen x genotypic interaction.

Above mentioned results indicate that higher NUE in all genotypes is achieved by lower N level (50 kg N ha-1) as compared to higher level of N (150 kg N ha-1). In these genotypes excessive use of N may be uneconomical and even in some cases yield limiting (Howard et al., 2001). High level of N use in cotton may cause in shifting of crop growth balance towards higher vegetative growth as compared to reproductive growth leading towards delayed maturity and a reduction in seed cotton yield (Nicholos et al., 2004).

Conclusion: In cotton, root:shoot ratio is sensitive to growth stage and nitrogen application which depends upon varietal-specific morphological response. Genotypes NIAB-846 and NIAB-824exhibited higher NUE by moisture stress at vegetative growth stage in September coupled with lower use of nitrogen (50 kg N ha-1).

Acknowledgments: This research article consists of a part of PhD studies. The authors acknowledge the support of Pakistan Atomic Energy Commission and Department of Agronomy, UAF for providing facilities for PhD research work. We are also grateful to the anonymous reviewers for their very useful suggestions to improve this manuscript.

REFERENCES

Bibi, A., H.A. Sadaqat, M.H. Tahir and N. Akram (2012). Screening sorghum (Sorghum bicolour Var Moench) for drought tolerance at seedling stage in Polyethylene Glycol. J. Anim. Plan Sci. 22(3): 671-678.

Ball, R.A., D.M. Oosterhuis andA. Mauromoustakos (1994). Growth dynamics of the cotton plant during water-deficit stress. Agron. J. 86: 788- 795.

Dongmei, Z., W. Li, C. Xin, A.E. Eneji and H. Dong (2012). Lint yield and nitrogen use efficiency of field-grown cotton vary with soil salinity and nitrogen application rate. Field Crop. Res. 138: 63-70.

Howard, D.D., C.O. Gwathmey, M.E. Essington, R.K. Roberts and M.D. Mullen (2001).Nitrogen fertilization of no-till cotton on loess-derived soils. Agron. J.93:157-163.

Jamal, A., M.N. Shahid, B. Aftab, B. Rashid, M.B. Sarwar, B.B. Mohamed, S. Hassan and T. Hussain (2014). Water stress mediated changes in morphology and physiology of Gossypium arboreum (var FDH-786). J. Plant Sci. 2(5): 179-86.

Kasperbauer, M.J.and W.J.Busscher (1990). Genotypic Differences in Cotton Root Penetration of a Compacted Subsoil Layer. Crop Sci. 31(5): 1376-1378.

Lioert, F., C. Casanovas and J. Penuelas (1999). Seedling survival of Mediterranean shrub land species in relation to root: shoot ratio, seed size and water and nitrogen use. Functional Ecol. 13: 210-216.

Liu, R., Z. Zhi-Guo, G. Wen-Qi, C. Bing-Lin and M. Derrick Oosterhuis (2008). Effects of N fertilization on root development and activity of water-stressed cotton (Gossypium hirsutum L.) plants. Agric. Water Manage. 95: 1261-1270.

Lou Q. (2011). Temperature thresholds and crop production: a review. Climatic Change. 109:583-598.

Maranov, A., A. Samedovam and T. Shirvany (1998). Root-shoot relationships in plant adaptation to nitrogen deficiency. Plant and Soil. 82: 147-154.

Meredith, W.R., J.J. Heitholt Jr., W.T. Pettigrow and S.T. Rayburn Jr. (1997). Comparison of obsolete and modern cotton cultivars a two nitrogen levels. Crop Sci. 37:1453-1457.

Mustafa, U., R. Kanber, D. Levent Koc, S. Tekin and B. Kapur (2011). Effect of deficit irrigation on the yield and yield components of drip irrigated cotton in a mediterranean environment. Agric. Water Manage. 98: 597-605.

Nicholos, S.P., C.E. Snipes and M.A. Jones (2004), Cotton growth, lint yield, and fibre quality as affected by row spacing and cultivar. J. Cotton Sci. 8: 1-12.

Niu, S.L., G.M. Jiang, S.Q. Wan, M.Z. Liu, L.M. Gao andY.G. Li (2005). Ecophysiological acclimation to different soil moisture in plants from a semi-arid sandland. J. Arid Environ. 63: 353-365.

Riaz, M., J. Farooq, G. Sakhawat, A. Mahmood, M.A. Sadiq and M. Yaseen (2013). Genotypic variability for root/shoot parameters under water stress in some advanced lines of cotton (Gossypium hirsutum L.). Genet. Mol. Res. 12: 552-561.

Sam, G. and R. Dirk (2009). Deficit irrigation as an on- farm strategy to maximize crop water productivity. Agric. Water Manage. 96: 1275- 1284.

Sampathkumar, T., B.J. Pandian and S. Mahimairaja (2012). Soil moisture distribution and root characters as influenced by deficit irrigation through drip irrigation system in cotton-maize cropping sequence. Agric. Water Manage. 103: 43-53.

Shangguan, Z.P., M.A. Shao andJ. Dyckmans (2000). Nitrogen nutrition and water stress effects on leaf photosynthetic gas exchange and water use efficiency in winter wheat. Environ. Exp. Bot. 44: 141-149.

Soil Survey of Pakistan (1968) Reconnaissance Soil Survey Report for Sheikhupura Area. Soil Survey of Pakistan, Lahore.

Steel, R.G.D., J.H. Torrie and D.A. Dickey (1997). Principles and Procedures of Statistics. A biometrical approach.3rd Ed., McGraw Hill Book Co., New York, USA.

Stroup, J.A., M.A. Sanderson, J.P. Muir, M.J McFarland and R.L. Read (2003). Comparison of growth and performance in upland and lowland switch grass types to water and nitrogen stress. Bioresource Tech. 86: 65-72.

Thind, H.S., M.S. Aujla and G.S. Buttar (2008). Response of cotton to various levels of nitrogen and water applied to normal and paired sown cotton under drip irrigation in relation to check- basin. Agric. Water Manage. 95: 25-34.

Wang, H.F., Y.H. Zhu and H.J. Sun (2006). Determination of drought tolerance using root activities in Robina pseudoacacia 'Idaho' transformed with mtl-D gene. For. Stud. China., 8: 75-81.
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