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Studies were conducted in ‘Chandler’ strawberry with the aim to optimize planting time and mulching material under the semi-arid region of north Indian plains. Three planting times viz., mid-September, mid-October and mid-November and three mulch materials viz., black polyethylene (50 μm), clear polyethylene (50 μm) and paddy straw (10 cm thickness) were tried with three replications in a split plot design. Mid-September planting favoured plant growth, enhanced flowering (77.3 days), which resulted in production of significantly larger fruit (13.0 g) and higher yield (174.4 g/plant) with fruit having higher TSS (9.23%), acidity (1.22%) and ascorbic acid content (44.1 mg/100 g of pulp) with lesser incidence of albinism (9.6%) and botrytis rot (8.1%) than other plantings. Plants mulched with black polyethylene have significantly better growth, and they flowered (80.2 days) and fruited early (29.2 days), and produced larger fruit (12.6 g) and higher yield (172.4 g/plant), with slightly higher incidence of albinism (20.1%), but with lower incidence of botrytis rot (7.3%) than those mulched either with clear polyethylene or paddy straw. Planting time × mulching interaction has significantly influenced plant growth; flowering and fruiting; fruit yield and quality, and albinism and botrytis rot. Plants have best growth parameters like, plant height (11.2 cm), crown spread (24.1 cm) and leaf area (87.9 cm 2 ), they took lesser days to flowering (73.7 days) and fruiting (31.3 days), produced larger fruit (13.7 g) and higher yield (191.3 g/plant) with fruit having higher TSS (9.41%), acidity (1.17%) and higher ascorbic acid content (46.4 mg/100 g pulp) with a slightly higher incidence of albinism (10.3%), but comparatively lower incidence of botrytis rot (5.2%) when planted during mid-September and mulched with black polyethylene than other plantings and mulched either with clear polyethylene or paddy straw. These studies indicated that strawberry could be planted in mid-September with black polyethylene mulch under semi-arid regions of India for early fruiting, and higher yield of better quality fruits.

Global warming due to greenhouse effect is expected to cause major changes in climate of some areas. The change in climate is likely to have a profound effect on hydrological cycle viz. precipitation, evapotranspiration, soil moisture etc. Evapotranspiration (ET) being the major component of hydrological cycle will affect crop water requirement and future planning and management of water resources. In the present study, an attempt has been made to study the sensitivity of evapotranspiration to global warming for arid regions of Rajasthan (India). The Penman–Monteith equation was used to estimate reference evapotranspiration, and sensitivity of ET has been studied in terms of change in temperature, solar radiation, wind speed and vapor pressure within a possible range of ±20% from the normal long-term meteorological parameters of 32 years (1971–2002). Changes in precipitation and stomatal resistance to increased CO 2 concentration have not been considered in the present study. The study suggests an increase of 14.8% of total ET demand with increase in temperature by 20% (maximum 8 °C). ET is less sensitive (11%) to increase in net solar radiation, followed by wind speed (7%) in comparison to temperature. Increase in vapor pressure (20%) has a small negative effect on ET (−4.31%). A 10% increase in temperature and actual vapor pressure coupled with 10% decrease in net solar radiation could result even in marginal decrease of total ET (0.30%). Increase of 10% in temperature alone, with 10% decrease in net solar radiation, actual vapor pressure and wind velocity could also result in marginal decrease in total ET (0.36%). A marginal increase in ET demand due to global warming will have a larger impact on resource-poor, fragile arid zone ecosystem of Rajasthan. It is high time for planners/users to think in terms of expected change in water requirement due to global warming while planning for development of future water resources in the arid region of Rajasthan. A wide spectrum climate change scenario is discussed in the paper as guideline for future development of water resources.

The shallow conical micro-catchments of 1.0 m radius constructed around the plant saplings were used to establish jujube ( Zizyphus mauritiana ) in arid conditions. The catchment surface was also lined with different waste materials like polythene bags, newspaper, stone and marble pieces. Results of the 2-year study showed significant treatment effects on the growth of jujube plants. Catchment lining also helped in maintaining the higher soil moisture status over the control (unlined) catchment. The stone and marble piece linings significantly increased the plant height by 40–48% over the control, the effect of other treatments are statistically similar. It was also found that the plants with micro-catchment have better chances of establishment in rainfed conditions as compared to conventional plantation technique.

Studies were performed in anesthetized opossums to investigate the electrical activity that may characterize the lower esophageal sphincter. The stomach and lower end of the esophagus were immobilized on a specially prepared stage to eliminate movement artifacts. Extracellular electrical activity was recorded with bipolar needle electrodes. The sphincter pressure was measured with a continuously perfused catheter system. The lower esophageal sphincter showed continuous spike activity with or without phasic variations in their occurrence. The usual frequency of the spikes was 20 to 50 per min, and their duration was 81.2 ± 8.9 msec (mean ± se). The spike potentials ceased with esophageal distention, which also caused a fall in the sphincter pressure. The spikes were abolished by isoproterenol and they increased with bethanechol. Correlation of the spike activity with the pressure revealed that the sphincter pressure was higher when the spike potentials were present, but a major part of the pressure existed in the absence of any spike activity. These studies show that: (1) the opossum lower esophageal sphincter is characterized by continuous spike potentials, and (2) the major fraction of the basal pressure is, however, independent of the spike potentials.

Studies were performed in anesthetized and awake opossums to define the genesis of resting pressure and opening of the upper esophageal sphincter. Intraluminal pressures were measured with low compliance, perfused catheters. Electromyograms were recorded using miniature concentric bipolar electrodes from the cricopharyngeus, inferior pharyngeal constrictor, middle pharyngeal constrictor, proximal end of the esophagus, and geniohyoid muscles. Upper esophageal sphincter pressure showed radial as well as axial asymmetry; the pressures were higher in awake than in anesthetized animals. Electromyographically, only the cricopharyngeus and inferior pharyngeal constrictor fired continuously at rest and ceased to fire during swallowing. d -Tubocurarine or section of the motor nerve abolished electrical activity in the cricopharyngeus and inferior pharyngeal constrictor and caused marked reduction but not obliteration of upper esophageal sphincter pressure. Contraction of the geniohyoid muscle abolished the remaining pressure in the upper esophageal sphincter. Moreover, contraction of the geniohyoid muscle caused a fall in upper esophageal sphincter pressure, even when the cricopharyngeus and inferior pharyngeal constrictor were kept contracted. These studies indicate: (1) upper esophageal sphincter corresponds mainly to the cricopharyngeus and inferior pharyngeal constrictor; (2) the resting upper esophageal sphincter pressure is attributable to continuous active muscle contraction as well as the elasticity of the surrounding structures; and (3) the opening of the upper esophageal sphincter is attributable to inhibition of the contraction of the cricopharyngeus and inferior pharyngeal constrictor and the forward displacement of the larynx by the geniohyoid muscle.

Gastrin I or pentagastrin caused contraction of the lower esophageal sphincter in anesthetized opossums. The contraction was not modified, either qualitatively or quantitatively, by 30 or 1000 μg per kg atropine pretreatment. Moreover, neural block with tetrodotoxin did not influence the effect of gastrin on the sphincter pressure. H 2 receptor antagonist, metiamide, did not modify the magnitude of the contractile response of the lower esophageal sphincter to gastrin I. These studies show: a) gastrin does not cause sphincter contraction by stimulating cholinergic neurons; and b) gastrin does not exert an inhibitory effect on the sphincter pressure by stimulating H 2 receptors. We suggest that gastrin may contract the lower esophageal sphincter by a direct action on the sphincter muscle.