Mid Season Research Articles

2D Geo-electrical imaging for shallow depth investigation in Doon Valley Sub-Himalaya, Uttarakhand, India

A 2D geo-electric profiling was executed close to Rajpur area in Doon Valley Sub-Himalaya, Dehradun, Uttarakhand. Profiling was executed at the site Civil Services Institute (CSI) close to Morvian Institute, Rajpur Road in Dehradun for possible shallow subsurface groundwater aquifer. Two resistivity and IP profiles were carried out to discover the conceivable groundwater zones in this area. It has been discovered that there are two inimitable palaeochannels found in these areas. These two channels act an erosional channel which was before happened to be a little stream. Beneath this, there is thick gravel and coarse sand stores in the close surface which is arranged at a profundity of 0.5–5 m with a thickness of 10 m. This zone goes about as brilliant potential for shallow groundwater pockets. Besides, inside the surroundings of these rock stores, fine to medium sand is likewise present in the vast majority of the zones which also may likewise goes about as potential groundwater resources at a shallow depth. Notwithstanding, this groundwater pockets may not be adequate to address the issues of water in the mid year season and is very much prescribed to search for more profound aquifer in the study area.

Longitudinal Changes and Seasonal Variation in Body Composition in Professional Australian Football Players.

To compare development and variations in body composition of early-, mid-, and late-career professional Australian Football (AF) players over 3 successive seasons. Regional and total-body composition (body mass [BM], fat mass [FM], fat-free soft-tissue mass [FFSTM], and bone mineral content [BMC]) were assessed 4 times, at the same time of each season-start preseason (SP), end preseason (EP), midseason (MS), and end season (ES)-from 22 professional AF players using pencil-beam dual-energy X-ray absorptiometry. Nutritional intake for each player was evaluated concomitantly using 3-d food diaries. Players were classified according to their age at the beginning of the observational period as either early- (<21 y, n = 8), mid- (21 to 25 y, n = 9), or late- (>25 y, n = 5) career athletes. Early-career players had lower FFSTM, BMC, and BM than mid- and late-career throughout. FM and %FM had greatest variability, particularly in the early-career players. FM reduced and FFSTM increased from SP to EP, while FM and FFSTM decreased from EP to MS. FM increased and FFSTM decreased from MS to ES, while FM and FFSTM increased during the off-season. Early-career players may benefit from greater emphasis on specific nutrition and resistance-training strategies aimed at increasing FFSTM, while all players should balance training and diet toward the end of season to minimize increases in FM.

Soil moisture prediction, evapotranspiration, yield and water use efficiency of soybean (Glycine max L.) crop under variable weather conditions in a semi-arid environment

A field experiment was conducted during kharif season of 2009 and 2010 in a sandy loam soil of New Delhi to study the effect of weather, achieved by sowing at normal (D1) and late (D2), on soil moisture prediction, evapotranspiration (ET), yield and water use efficiency (WUE) of three varieties (V1: JS 335, V2: Pusa 9712 and Pusa 9814) of soybean. Study of soybean phenology showed that there was reduction in the number of days taken for the crop to complete life cycle with delayed sowing. The agrometeorological water balance model could satisfactorily predict soil moisture content during soybean crop growth period with RMSE (%) varying between 6.27 to 12.06 and correlation coefficient between 0.828 to 0.982. The ET decreased significantly with delay in sowing; however there was no significant variation among the varieties. Among the stages of the soybean crop, mid season stage had highest ET followed by development stage, late season stage and initial stage. Normal sowing resulted in higher yield but lower WUE than the late sowing. Among the cultivars, JS 335 resulted in lower yield and WUE than Pusa 9712 and Pusa 9814. It may be recommended that, Pusa 9712 or Pusa 9814 may be sown during first and second week of July (normal sowing) to achieve higher yield in the semi-arid environment of Delhi region.

Reproductive response of mature and nulliparous yearling ewes to the ram effect during the non-breeding season

Sudden introduction of rams to ewes that remained isolated from males during the non-breeding season induces ovulation and thus out-of-season breeding. The aim of this study was to compare the reproductive response of mature and nulliparous yearling ewes to the ram effect during the non-breeding season. The experiment was performed during October–November (mid non-breeding season) with 122 Merilin ewes 56 were mature multiparous (group ME) and 66 nulliparous, 1year old ewe lambs (group HE) that previously remained isolated from males. All ewes were pretreated with intravaginal sponges for 6days before the introduction of the rams. More ME than HE ewes ovulated (87.5 vs 66.7%, P<0.01), and come into oestrus (66.1 vs 30.3%, P<0.0001), and the ovulation rate was also greater in ME than HE (1.27±0.05 vs 1.10±0.04, P<0.05). The pregnancy rate in the first oestrus period was also greater in ME than in HE ewes (39.3 vs 16.7%, P<0.01). Overall, yearling ewes can respond to the ram effect ovulating and becoming pregnant during the non-breeding season. However, the reproductive response was lower compared with that of mature ewes.

English

Many simulation models found in the literature integrates data on climate and crop characteristics to provide great information on the season for different crops. The objectives of this study were: a) to measure soil water balance components of a wheat crop to determine its evapotranspiration (ETc) and crop coefficients (Kc) during the growing season; b) to use experimental data to evaluate the performance of SMA-C in estimating evapotranspiration for a wheat in Paran&aacute; State, Brazil; and c) to make adjustments to improve mod`el estimates. Two weighing lysimeters cultivated with a wheat crop were used to measure soil water storage and ETc during the growing season of a wheat crop. Reference evapotranspiration (ETo) was determined by FAO 56 method using data from a local weather station. Wheat crop coefficients were calculated by the ratio ETc/ETo, were 0.7, 1.5 and 0.6, for initial, mid and late season, respectively. The comparison of SMA-C simulations with the observed data showed inaccuracies in estimation of soil water storage due to model underestimation for ETc. Estimates were improved by adjusting the model to consider Kc measured in the field. &nbsp; Key words: Models, lysimeters, decision-making support.

Effects of stubble length of rice in mitigating soil moisture stress and on yield of lentil (Lens culinaris Medik) in rice-lentil relay crop

Opportunity to utilize carry-over residual soil moisture to produce lentil crop in rice-fallows was one of the basic and strategic research objectives of the present experiment. Lentil (Lens culinaris Medik, variety B-77) was broadcasted upon two rice habits viz. short-duration (SD, 110days) and long-duration (LD, 140days) in the end of October and first fortnight of November during 2011–2012, 2012–2013 and 2013–2014 seasons, in a clay loam Inceptisol of the Gangetic alluvium of eastern India. Two stubbles heights, viz. short (10cm) and long (20cm) were kept as standing residues at the time of harvesting of rice. Late sown lentil with short stubble residues faced surface soil drying earlier than early sown lentil or late sown lentil with tall stubble residues. Tall stubble height contributes only 1–4% higher soil water during vegetative to flowering stages than short stubble height. Stress was experienced when soil moisture content in the root-zone reached <22% in this soil and such stress decreased the leaf relative water content (RWC). Retaining tall rice stubbles on the soil surface decreased daytime soil temperature by 9.4–14.6°C and modified the crop coefficient (Kc) by increasing transpiration and reducing evaporation, thereby maintaining higher leaf area index (LAI). The Kc values for the initial, development, mid and late season stages of lentil under relay cropping were 0.48, 0.54, 0.82 and 0.48, respectively, with short and tall standing stubble heights. Root length density (RLD) values increased at a faster rate in 200–400mm layer, especially in tall stubble than short. Soil moisture stress was negatively related (R2=0.66, P<0.05) to RWC, however, RLD maintained an asymptotic relationship with RWC. Actual evapotranspiration (ETa) of lentil amounted to 154.8mm and the ETa in broadcasted upon SD rice was 14% higher than ETa in LD rice. Lentil in tall stubbles amounted to 150.6mm ETa, which was 7% more than that in short stubbles. Yield of lentil broadcasted upon SD was 20% higher than 20days delay with LD rice, and tall stubbles produced 18% more yield than short stubbles. The water productivity (WP) of lentil under SD rice was only 6% higher than lentil in LD rice; however, tall stubbles produced 11% higher WP than short standing stubbles. Keeping stubbles height of SD or LD rice may be an efficient way of using the existing land and water resources for mitigating soil moisture stress and maintaining grain yield and water productivity of lentil relayed with short- and long-duration rice habits.

Session RPE During Prolonged Exercise Training

Introduction: Various strategies are used to monitor training intensity and permit the calculation of training load. Traditional measures such as speed, heart rate (HR) and blood lactate (HLa) are widely used. The session RPE (sRPE) has been used as an alternative method of training monitoring. PURPOSE: This study compared the evolution of speed, HR, HLa and sRPE during an intensive swimming training session. METHODS: Collegiate swimmers (NCAA Div III), during mid preparatory season, performed 4 x 10 x 100 yd, on a 1:15-1:30 sendoff, and with 10 min rest between sets. Speed and HR were measured after each repetition, and averaged per set. HLa was measured immediately after each set. sRPE was measured after each set, but asking the athlete to rate the effort “as if this was the completion of the workout.” RESULTS: Speed, HR and HLa were essentially constant across the training session, indicating that both the external and internal training load was constant and only dependent on volume of training. The sRPE increased significantly from set to set. CONCLUSIONS: The progressive increase in sRPE suggests that it reflects some aspect of internal training load not reflected by the objective measures.

Relationship between Maximum Oxygen Consumption and Muscle Oxygenation During a Cross Country Season

The purpose of this study was to examine the relationship between maximum oxygen consumption and muscle tissue oxygenation of collegiate cross country runners throughout their season. Seven collegiate cross country runners (six female and one male, 18.8±0.9 yrs) were studied early season (T1), mid season (T2), directly after their last meet (T3), and one week after their season was completed (T4). Each subject completed a graded exercise test to exhaustion on a motor driven treadmill. Subjects began running at seven mile per hour for two minutes. The elevation of the treadmill was gradually increased to volitional fatigue. A Parvo Medics TrueOne 2400 metabolic measurement system was used to determine oxygen consumption, expired ventilation, and respiratory exchange ratio at each exercise level and at maximum. Maximum oxygen consumption (VO2max) was then determined. Near‐infrared spectroscopy (Portamon, Artinis Inc.) was used to measure oxygenated hemoglobin, deoxygenated hemoglobin, total hemoglobin, and tissue saturation index (TSI) for each stage of the graded exercise test. The Portamon was placed over the vastus lateralis and secured. TSI is used as an index of muscle tissue oxygenation. In this study, the slope of the decline in TSI was determined and used to quantify the muscle oxygenation response. TSI data was smoothed via a moving average filter width of 5 seconds. The moving average filter calculates the unweighted mean of the measured data over the filter width. Overall, the TSI deceased at a slower rate during mid season (T2) compared to the early season (T1) testing (Slope: T1=−0.091±0.016; T2=−0.021±0.007). Furthermore, VO2 Max increased between T1 to T2 (VO2 Max: T1=58.5±9.1 ml//kg/min; T2=62.35±12.03 ml/kg/min). Muscle oxygenation declined at the fastest rate during the early part of the cross‐country season relative to mid‐season. At the same time, VO2max significantly increased between those two time points. Taken together, this suggests that adaptive changes as result of cross country training enables runners to be more efficient at utilizing oxygen probably as a result of adaptive metabolic changes in skeletal muscle.

Feasibility study on two schemes for alleviating the underground heat accumulation of the ground source heat pump

The long time running of the ground source heat pump (GSHP) system in cooling dominated areas will cause heat accumulation and then the temperature increase under the ground, resulting in the cooling performance degradation of the GSHP system, as well as other problems, such as the change of thermal and microbial environment, and even the organic carbon reserves in the soil. In order to attemper the heat accumulation, a scheme that the cooling tower be operated in transitional (mid) seasons is proposed for the hybrid GSHP system assisted with cooling tower. The temperature difference (Δt) between the air wet-bulb temperature and the ground temperature is defined as the threshold for the cooling tower to start up in transitional seasons. It has been found that the scheme can effectively alleviate the increase of the ground temperature by simulating the system performance with TRNSYS software. However, the system’s total power consumption in 30 years increases due to the extra running time of the cooling tower. 8∼12°C is found to be the optimum range of Δt for the studied hybrid GSHP systems by comparing the system performances under different set values of Δt. In order to find further efficient scheme, a hybrid GSHP system combined with a chiller cooling system is also proposed and studied. However, the simulation result shows that the system power consumption has not got down effectively, for the reason that the energy efficiency ratio (EER) of the chiller used in the TRNSYS model is lower than that of the heat pump.

Crop coefficient for cotton under plastic mulch and drip irrigation based on eddy covariance observation in an arid area of northwestern China

Crop coefficient (Kc) is an important parameter in irrigation management. Kc values published by Food and Agriculture Organization (FAO) are subject to uncertainties and adjustment when applied to different areas under different climates and/or irrigation methods. This study investigated Kc of cotton in an experimental site under plastic mulch and drip irrigation in the Tarim River Basin in northwestern China through a 3-year crop evapotranspiration (ETc) observation by using the eddy covariance system. The average ETc during the growing seasons in 3 years is 526mm, and the locally developed Kc values during the initial, mid, and late seasons are 0.23, 0.88, and 0.44, respectively. The relationships between Kc and leaf area index (LAI), Kc and growing degree days (GDD), and Kc and growing days after sowing (GD) were further analyzed. The relationship between weekly Kc and GDD, as well as weekly Kc and GD, during the growth stage after sowing is fitted to a third-order polynomial model (R2=0.96 and 0.95, respectively). Meanwhile, the relationship between weekly Kc and LAI is suitably described using a logarithmic model (R2=0.87). As LAI was not measured every day, daily and weekly models were reestablished based on LAI measurement days. The performance of the LAI model is low on a weekly basis (R2=0.88, 0.88, 0.72 for GD, GDD, and LAI models, respectively) but accurate on a daily basis (R2=0.81, 0.81, 0.89 for GD, GDD, and LAI models, respectively). GD is a reliable indicator to estimate Kc of cotton under plastic mulch and drip irrigation and provides a basis for evapotranspiration estimation in cotton fields by using the FAO-56 method. This study provides valuable supplementary and reference information for efficient water management in cotton cropping systems in arid regions.

Evaluation of reference evapotranspiration models and determination of crop coefficient for Momordica charantia and Capsicum annuum

Studies on water balance and irrigation at agricultural areas require accurate values of reference evapotranspiration (ETo). This study was conducted in the agricultural farm in the Modern Agriculture Centre in Kluang, Malaysia, to determine the crop coefficients of bittergourd (Momordica charantia) and chili (Capsicum annuum) by choosing the best ETo model. The experiment was conducted for two different crop cycles between October 2013 and May 2014. An automatic weather station was installed to record weather parameter at 30min interval. Twenty six ETo models which were classified into four different groups were employed. The performance of the models was evaluated using Class A pan evaporation data from Kluang weather station. Eight statistical tests were used to assess and rank the accuracy of these 26 models. The ET values from the best ETo model of each group were then modeled with weather variables using multiple regression technique. Crop coefficient (Kc) curves were developed as the ratio between actual crop evapotranspiration measured by minilysimeters and the ET values of the best model. The temperature based models tend to overestimate observed pan ET values, thus were not recommended at this site. Results of the mass transfer based Penman model show comparatively better ETo estimates among others. The total water requirement for bittergourd for the whole growing period is 153mm while chili recorded 229mm. The Kc values for the bittergourd were 0.58, 0.88 and 0.69 while for chili were 0.58, 0.95 and 0.73 for the initial, mid and end growth stages, respectively. The present results show very similar mid and end season chili Kc values with a study from Ghana while the mid and end season Kc of bittergourd is quite similar with a study in Florida, USA using cucumber. The values obtained can help farmers to determine the water requirement of these vegetable crops so that proper irrigation can be applied according to its growth stage and weather condition.

Geospatial approach for assessment of biophysical vulnerability to agricultural drought and its intra-seasonal variations.

The study presents a methodology to assess and map agricultural drought vulnerability during main kharif crop season at local scale and compare its intra-seasonal variations. A conceptual model of vulnerability based on variables of exposure, sensitivity, and adaptive capacity was adopted, and spatial datasets of key biophysical factors contributing to vulnerability were generated using remote sensing and GIS for Rajasthan State of India. Hazard exposure was based on frequency and intensity of gridded standardized precipitation index (SPI). Agricultural sensitivity was based on soil water holding capacity as well as on frequency and intensity of normalized difference vegetation index (NDVI)-derived trend adjusted vegetation condition index (VCITadj). Percent irrigated area was used as a measure of adaptive capacity. Agricultural drought vulnerability was derived separately for early, mid, late, and whole kharif seasons by composting rating of factors using linear weighting scheme and pairwise comparison of multi-criteria evaluation. The regions showing very low to extreme rating of hazard exposure, drought sensitivity, and agricultural vulnerability were identified at all four time scales. The results indicate that high to extreme vulnerability occurs in more than 50% of net sown area in the state and such areas mostly occur in western, central, and southern parts. The higher vulnerability is on account of non-irrigated croplands, moderate to low water holding capacity of sandy soils, resulting in higher sensitivity, and located in regions with high probability of rainfall deficiency. The mid and late season vulnerability has been found to be much higher than that during early and whole season. Significant correlation of vulnerability rating with food grain productivity, drought recurrence period, crop area damaged in year 2009 and socioeconomic indicator of human development index (HDI) proves the general soundness of methodology. Replication of this methodology in other areas is expected to lead to better preparedness and mitigation-oriented management of droughts.

Effect of Green Manure, Sesbania bispinosa Wight Amendment on Incidence of Sucking Insect Pests, their Predators and Yield in Organic Cotton

Cotton holds the key importance in the economy of Pakistan, but its yield is severely affected due to the infestation of many insect pests. Farmers mostly rely on chemicals to control pests but their adverse effects on human health and their interests are also considerable. Therefore, this study was conducted over two years to evaluate the influence of amendment of soil with green manure (GM) Dhancha, Sesbania bispinosaWight on the population of cotton sucking insect pests and their predators. Significant impact of GM was found in lowering the population of sucking pests of cotton i.e., Thrips tabaci(Lind), Bemisia tabaci (Gennadus), Amrasca bigutulla bigutulla (Ishida) and Tetranychus urticae (Koch) during both years. Population of predators i.e., Chrysoperla carnea, Geocoris punctipesand Orius sp. was also higher in dhancha treated plots in comparison to control. Application of neem oil was found effective in lowering the population of sucking insect pests during 2014; whereas, application of C. carnea cards showed significant impact after the mid cotton season during 2015. Overall growth and yield parameters were better in dhancha amended organic cotton treatment in comparison to control.

Effect of mid season drought on phenolic compounds in peanut genotypes with different levels of resistance to drought

Drought is a major constraint in peanut production. Drought not only reduces pod yield but also may affect phenolic compounds in peanut. This experiment was conducted for two years under field conditions. Soil moisture levels (field capacity and mid season drought stress) were assigned as main plots, and five peanut genotypes were assigned as sub plots. Peanut seeds were analyzed for phenolic compounds at harvest. Leaves and stems were also analyzed at 30 and 60 days after planting (DAP), and at harvest. Water regimes did not result in significant differences for phenolic compounds in seeds, whereas peanut genotypes were significantly different for this trait. Drought increased phenolic contents in leaves at 60 DAP and phenolic contents were reduced during the recovery period. The production of leaf phenolic compounds differed among genotypes. Mid season drought increased phenolic compounds in stems during the drought period and levels of phenolic production were different depending on peanut genotype. Breeding for high phenolic content and drought tolerance in peanut should be possible because mid season drought did not affect phenolic content in seeds.

Assessment of the IEQ in Two High Schools by Means of Monitoring, Surveys and Dynamic Simulation

This work presents an assessment of schools’ indoor environmental quality, based on investigations carried out in three Italian classrooms in Treviso, in the North-East of Italy. A first monitoring campaign was performed during the mid season (May-June), a second one during the heating period (January-February). At a first stage, the study was focused on two different approaches, an objective and a subjective one, in order to compare the objective responses with the occupants’ subjective sensations. The first method consisted of physical observations and field measurements of thermal environmental parameters, used to calculate Fanger's comfort indices and to apply a comfort adaptive model. The subjective approach was managed by giving students and teachers a survey about their personal judgment concerning the level of comfort perceived. Finally, a simulation model has been built-up and calibrated using the indoor values of air temperature and air humidity trends collected by data loggers. A generic optimization program has been used to calibrate the thermal model. The responses from measurements, surveys and simulations were integrated, analyzed and compared, obtaining a good agreement between the three approaches in assessing the classroom thermal comfort category.

Analysis of long-term weather, snow and avalanche data at Glacier National Park, B.C., Canada

Long-term changes of the global climate system have been observed. However, the effect of long-term changes in the climate system on avalanche hazard in mountainous areas remains inconclusive. For this study we analyzed long-term weather, snow cover, and avalanche data from Glacier National Park. Weather and snow cover data were measured at two sites (1315m and 1905ma.s.l.). The avalanche data were observed along the section of the Trans Canada Highway within the park. Meteorological data were analyzed by winter season, i.e. early, mid and late winter, represented by three-month periods between September and May. Increasing trends were found for the mean seasonal air temperature at both stations during the mid season. Trends for the solid precipitation rate were not significant, indicating no trend towards more rain events. Decreasing trends of the maximum snow depth were only found for the lower elevation station at Rogers Pass for the mid and late season, which is consistent with decreasing trends for all seasons of the mean 24-hour new snow amounts at the lower elevation and for the mid season at the higher elevation station at Mt. Fidelity. Due to uncertainty arising from changes in explosive control, we draw no conclusions regarding the regional change of avalanche activity. However, the weather and snowpack trends observed in Glacier National Park are consistent with longer time series from mountains with similar latitudes and elevations in France and Switzerland.

Reduced grazing pressure delivers production and environmental benefits for the typical steppe of north China.

Degradation by overgrazing is common in many areas of the world and optimising grassland functions depends upon finding suitable grazing tactics. This four-year study on the northern China steppe investigated combinations of rest, moderate or heavy grazing pressure early in the summer growing season, then moderate or heavy grazing in the mid and late season. Results showed that moderate grazing pressure (~550 sheep equivalent (SE) grazing days ha−1 year−1) gave the optimal balance between maintaining a productive and diverse grassland, a profitable livestock system, and greenhouse gas mitigation. Further analyses identified that more conservative stocking (~400 SE grazing days ha−1 year−1) maintained a desirable Leymus chinensis composition and achieved a higher live weight gain of sheep. Early summer rest best maintained a desirable grassland composition, but had few other benefits and reduced incomes. These findings demonstrate that reducing grazing pressure to half the current district stocking rates can deliver improved ecosystem services (lower greenhouse gases and improved grassland composition) while sustaining herder incomes.

Quantifying Growth and Developmental Responses of Sweetpotato to Mid‐ and Late‐Season Temperature

The growth and developmental responses of sweetpotato [Ipomoea batatas(L.) Lam.] to a wide range of temperatures have not been addressed extensively. The objectives of this study were to quantify temperature effects on growth, development, and biomass yield of sweetpotato during mid and late season. Four day/night temperature treatments, 25/17, 30/22, 35/27, and 40/32°C, were imposed after the storage root initiation stage, 17 d after transplanting (DAT). Growth and developmental parameters were recorded from plants harvested at 91 DAT. Vine length and nodes showed sigmoidal and linear patterns, respectively, with time across all temperatures. The vine elongation rate during the linear growth phase and node addition rate during the whole season increased linearly with temperature. Temperature optimum for whole‐plant leaf area was 26.7°C. Leaf area declined more sharply at higher than at lower temperatures relative to rates at the optimum temperature. The total biomass showed a quadratic trend with maximum biomass yield at optimum temperature, 26.5°C, and declined linearly at higher temperatures. The optimum temperatures for storage root fresh and dry weights were 24.0 and 25.6°C, respectively, and weights declined by 101.5 and 13.1 g °C−1, respectively, at temperatures higher than optimum. The fraction of biomass partitioned to various plant parts showed quadratic trends. High temperatures during mid and late season promoted more shoot but less root growth, affecting the final storage root yield. The quantified temperature‐dependent growth and developmental responses will be useful for crop production management decisions and for the development of sweetpotato crop models.

Water use and crop coefficient of the wheat–maize strip intercropping system for an arid region in northwestern China

Relay strip intercropping of spring wheat and maize is practiced on a large scale in arid regions of northwestern China. In this study, a field experiment was carried out during 2012 and 2013 growing seasons to examine water use and crop coefficient of this system in an arid environment. The experiment comprised three treatments: sole-cropped wheat, sole-cropped maize, and wheat–maize intercropping. The grain yields of both intercropped wheat and maize were enhanced by intercropping. The gross economic profit for wheat–maize intercropping was 16.4% lower than that of sole maize and 95.4% higher than that of sole wheat. The overall land use efficiency was improved by intercropping. The time course of leaf area index in intercropping had the similar trends to those in sole crops with relatively low values, which never exceeded 3.0m2m−2 throughout both growing seasons. Compared to weighted means of the sole-cropping systems, wheat–maize intercropping used 26% and 24% more water in 2012 and 2013, respectively. The water-use efficiency of intercropping was nearly the same as the weighted means of the sole crops. Due to the incomplete groundcover in intercropping plots, more water was consumed as soil evaporation. Averaged over two seasons, the ratio of soil evaporation to actual evapotranspiration was 33.4, 20.7 and 24.1% for intercropping system, sole-cropped wheat and sole-cropped maize, respectively. Crop coefficient (Kc) of sole-cropped wheat was 0.19±0.02, 1.05±0.07, and 0.42±0.09 at the initial, mid and late season in two seasons, respectively. Kc value of the sole-cropped maize was 0.22±0.03, 1.10±0.06 and 0.60±0.02 at the initial, mid and late season, respectively. The Kc values of the wheat–maize intercropping system varied in 0.21±0.03, 0.89±0.05, and 0.78±0.06 at the initial, middle and late wheat growing season, and in 0.85±0.03 and 0.61±0.01 at the middle and late maize growing season, respectively. Therefore, longer growing season and incomplete ground cover are the main factors that resulted in higher water use for wheat–maize intercropping compared to sole crops. Results of this study can help to improve the irrigation efficiency for the wheat–maize strip intercropping system.

Interannual variability of the Indian summer monsoon associated with the air–sea feedback in the northern Indian Ocean

Using observation-based analyses, this study identifies the leading interannual pattern of the Indian summer monsoon rainfall (ISMR) independent of ENSO and examines the potential mechanisms of its formation. For this purpose, an objective procedure is used to isolate the variability of the summer precipitation associated with the contemporary ENSO state and in previous winter–spring, which influence the Indian summer monsoon (ISM) region in opposite ways. It is shown that the leading pattern of these ENSO-related monsoon rainfall anomalies reproduces some major ISMR features and well represents its connections to the global-scale ENSO features in both lower and upper troposphere. On the other hand, the leading pattern derived from the precipitation anomalies with the ENSO component removed in the ISM and surrounding region also accounts for a substantial amount of the monsoon precipitation centered at the eastern coast of the subtropical Arabian Sea, extending into both the western Indian Ocean and the Indian subcontinent. The associated atmospheric circulation change is regional in nature, mostly confined in the lower to mid troposphere centered in the Arabian Sea, with a mild connection to an opposite tendency centered at the South China Sea. Further analyses show that this regional pattern is associated with a thermodynamic air–sea feedback during early to mid summer season. Specifically, before the monsoon onset, an anomalous atmospheric high pressure over the Arabian Sea causes excessive shortwave radiation to the sea surface and increases SST in May. The warm SST anomalies peak in June and reduce the sea level pressure. The anomalous cyclonic circulation generates regional convection and precipitation, which also induces subsidence and anticyclonic circulation over the South China Sea. The combined cyclonic–anticyclonic circulation further transport moisture from the western Pacific into the Indian Ocean and causes its convergence into the Arabian Sea. As a result, the regional cyclone is further enhanced and expanded to the Indian subcontinent in July. The substantial reduction of the solar radiation, however, cools down the sea surface and causes the decay of the circulation in August. This study suggests that the pre-monsoon Arabian Sea condition may be an important contributor to the ISM predictability from monthly to seasonal scales.