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In order to assess the climatological risk in terms of the dry week probabilities and length of the growing period of Indian Sundarbans region for successful crop planning, the present study was conducted using long term rainfall data from 1984 to 2018 received in Gosaba CD (Community Development) block of Indian Sundarbans. The probability of a rainfall events with 25 %, 50%, 75 % probabilities were estimated. Markov Chain model was used to estimate the initial, conditional probabilities of dry and wet weeks along with the probability of two consecutive wet and dry weeks considering 10 mm and 20 mm rainfall thresholds. Length of growing period (LGP) was calculated using Moisture adequacy index computed by the soil water balance method of Thornthwaite and Mather. Weekly rainfall varied from 1.11 mm in 51st Standard Meteorological Week (SMW) with standard deviation of ± 3.41 to 88.49 mm in 29th SMW with standard deviation of ± 58.19.50 % chance of getting more than 20 mm and 10 mm weekly rainfall was observed from 20th (23.37 mm) to 41st SMW (30.64 mm) and 17th (14.63 mm) to 42nd SMW (16.87 mm) respectively. The risk of dry spells was very higher from 42nd to 17th SMW. Average LGP of the study area was 237.4 days with standard deviation of ± 29.88.Probability of a week being stress free growing period and moderately drought period was more than 50 % from 18th to 48th SMW and 49th to 5th SMW respectively. Grass pea, potato with straw mulch and green gram can be included in the rice based cropping system during winter and summer seasons for sustainable intensification of the cropping systems in Indian Sundarbans region.

An experiment was conducted to study regrowth and yield of coriander influenced by nitrogen (N) with five different urea doses (0, 1.5, 2.0, 2.5, 3.0% by volume) as foliar spray. Spraying of urea has a significant impact on growth and yield in the second cut. Leaf emergence rate (LER) was higher during initial growth phase and then drastically reduced until first cutting, whereas the stem elongation rate (SER) recorded its peak value during 75-105 DAS. Impact of foliar spray was conspicuous during the later phase of regrowth with the treatment of 2.5% urea achieving the highest SER. Additional return due to spraying was positive up to a dose of 2.5% urea and decreased thereafter. Hence, the study indicated that a foliar spray of nitrogen (2.5% urea) may be beneficial for coriander leaf production under multicut system and the crop is sensitive to rainfall, phototemperature, and morning humidity.

A field experiment was conducted during the post-monsoon season for two consecutive years 2005-06 and 2006-07 to study the effect of date of sowing and irrigation regime on yield and water use in chickpea (Cicer arietinum L.). The results revealed that 1st date of sowing (20 November) recorded the maximum seed yield (1474.24 and 1442.58 kg ha-1 during 1st and 2nd year, respectively) as well as plant height and dry matter accumulation. The daily moisture use rate of chickpea during early vegetative stage was slightly higher with earlier sowing as compared to that of late sowing in both the experimental years. But during reproductive stage i. e. after flowering, late sown crop recorded higher moisture use. But the overall consumptive use was higher under late sown condition. Application of two irrigations at branching and pod formation resulted in higher seed yield, whereas the consumptive use was higher when the irrigation was applied at branching and flower initiation. Total moisture use was lowest under rainfed condition that led to lower seed as well as biomass yield. However, the chance of rainfall (Kal Baisakhi) during March in the new alluvial zone of West Bengal must be taken into consideration while scheduling irrigation during pod formation.

Winter pigeon pea can be considered as an alternative to boro rice cultivation particularly in the places where over exploitation of ground water is a potential threat to sustainability. The present experiment was aimed at quantifying the meteorological factors that limit the cultivation of rabi pigeon pea particularly in the upland and medium land condition. The experiment was conducted for three consecutive years during 2003-06 in the University Farm at (BCKV) Kalyani W.B. The treatments comprised different dates of sowing at seven days interval between 20 September and 7 December. The influence of meteorological factors on phenological development and yield was statistically analysed. The results revealed that the length of vegetative phase was inversely correlated to the afternoon vapour pressure deficit, average BSH and diurnal variation in temperature. On the other hand, night temperature and daylength were negatively correlated with the reproductive duration. The regression analysis showed that bright sunny days with high atmospheric vapour demanded not only induced early flowering but they also had suppressed the grain yield. Higher accumulation of GDD and PTU during vegetative phase resulted in higher grain production. On the other hand, the average day temperature, night temperature and day length during reproductive phase had negative correlation with grain yield of pigeon pea. These parameters may be considered as limiting factors for higher production. Besides that, rainfall during March had severely hampered pod formation when sown late.

Frequency and depth of irrigation play crucial role in crop yield and use efficiency of water resource. To test this hypothesis a field study was carried out in November to January of 2001�2002 to 2003�2004 on a sandy loam (Aeric haplaquept) for quantifying the frequency and depth of irrigation on growth, curd yield (CY) and water use pattern of cauliflower (Brassica oleracea L. var. botrytis). Four irrigation frequencies depending on the attainment of cumulative pan evaporation (CPE) values of: 25 (CPE25), 31(CPE31), 38 (CPE38) and 45 (CPE45) mm were placed in main-plots, with three depth of irrigation (IW) of 35 (IW35), 30 (IW30) and 25 (IW25) mm in sub-plots. Water use efficiency (WUE), net evapotranspiration efficiency (WUEET) and irrigation water use efficiency (WUEI) were computed. Marginal water use efficiency (MWUE) and elasticity of water productivity (EWP) were calculated using the relationship between CY and seasonal actual evapotranspiration (SET). A continuous increasing trend in growth parameters, yield and WUEI was recorded with the increase in SET from CPE45�IW25 to CPE31�IW30. However with further increase in SET the same decreased up to CPE25�IW35 regime. Highest WUE and WUEET obtained under CPE38�IW35 regime where SET value was 5% lower than the status of SET under CPE31�IW30. This study confirmed that critical levels of SET needed to obtain maximum curd yield or WUE, could be obtained more precisely from the knowledge of MWUE and EWP.

The amount of water used by any crop largely depends on the extent to which the soil water depletion from the root zone is being recharged by appropriate depth of irrigation. To test this hypothesis a field study was carried out in November–March of 2002–2003 and 2003–2004 on a sandy loam (Aeric haplaquept) to quantify the effect of depth of irrigation applied through micro-sprinklers on onion (Allium cepa L.) bulb yield (BY) and water use patterns. Seven irrigation treatments consisted of six amounts of sprinkler applied water relative to compensate crop (Kc) and pan (Kp) coefficient-based predicted evapotranspiration loss from crop field (ETp) (i) 160% of ETp (1.6ETp); (ii) 1.4ETp; (iii) 1.2ETp; (iv) 1.0ETp; (v) 0.8ETp; (vi) 0.6ETp; (vii) 40 mm of surface applied water whenever cumulative pan evaporation equals to 33 mm. Water use efficiency (WUE), net evapotranspiration efficiency (WUEET) and irrigation water use efficiency (WUEI) were computed. Marginal water use efficiency (MWUE) and elasticity of water productivity (EWP) of onion were calculated using the relationship between BY and measured actual evapotranspiration (ETc). Yield increased with increasing sprinkler-applied water from 0.6 to 1.4ETp. Relative to the yield obtained at 0.6ETp, yield at 1.0ETp increased by 23–25% while at 1.4ETp it was only 3–9% greater than that at 1.0ETp. In contrast, yield at 1.6ETp was 9–12% less than that at 1.4ETp. Maximum WUE (7.21 kg m−3) and WUEET (13.87 kg m−3) were obtained under 1.0ETp. However, the highest WUEI (3.83 kg m−3) was obtained with 1.2ETp. The ETc associated with the highest WUE was 20% less than that required to obtain the highest yields. This study confirmed that critical levels of ETc needed to obtain maximum BYs, or WUE, could be obtained more precisely from the knowledge of MWUE and EWP.