Poplar clone Kranti was selected to assess the morphological, physiological and biochemical responses under drought at different levels of water stress, as it is a common clone used to be grown in Uttarakhand for making paper and plywood. The cuttings of Populus deltoides L. (clone Kranti) were exposed to four different watering regimes (100, 75, 50 and 25% of the field capacity) and changes in physiological and biochemical parameters related with drought tolerance were recorded. Alterations in physiological (i.e. decrease in relative water content) and biochemical parameters (i.e. increase in proline and soluble sugar content and build-up of malondialdehyde by-products) occurred in all the three levels of water stress, although drought represented the major determinant. Drought treatments (75%, 50% and 25% FC) decreased plant height, radial stem diameter, harvest index, total biomass content and RWC in all the three watering regimes compared to control (100% FC). Biochemical parameters like proline, soluble sugar and MDA content increased with severity and duration of stress, which helped plants to survive under severe stress. It was analyzed that for better wood yield poplar seedlings should avail either optimum amount of water (amount nearly equal to field capacity of soil) or maximum withdrawal up to 75% of field capacity up to seedling establishment period (60 days). Furthermore, this study manifested that acclimation to drought stress is related with the rapidity, severity, and duration of the drought event of the poplar species.

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Field experiments were conducted at the Directorate of Rice Research experimental farm, ICRISAT campus, Patancheru, Hyderabad, during 1998-2000 for five consecutive seasons (three wet and two dry seasons) with five treatments [T1 -100 % straw incorporation; T2 -50 % straw incorporation; T3 -100 % straw + green manure (GM) incorporation; T4 -100 % straw burning and T5 -100 % straw removal (control)] along with the recommended dose of fertilizers to evaluate the effect of different crop residue management (CRM) practices on yield components and yield of rice in rice-rice cropping sequence. The ammonium N measured at active tillering was higher in 100 % straw-added plots over 50 % straw addition and straw removal with maximum values in the straw + GM-incorporated plots. Among the yield components, tillers, panicles and spikelets were influenced from the second season of residue incorporation with significant increase in 100 % straw-added treatments. The increase in tiller and panicle number could be attributed to the increased NH 4 -N in these treatments, which is evident from the significant correlation between tiller number and NH 4 -N (r ¼ 0.82**) and panicle number and NH 4 -N (r ¼ 0.87**). The influence of residue treatments on rice grain yield was observed from the third season onwards where incorporation of straw alone or in combination with GM and burning of straw significantly increased grain and straw yields. Grain yield showed significant positive correlation with the number of tillers (r ¼ 0.74*-0.81**) and panicles (r ¼ 0.74*-0.84**) in three treatments (T1, T3 andT4) where grain yields were significantly higher. The regression analysis showed that 57-66 % and 64-75 % of the variation in yield could be explained by tillers and panicles together in these three treatments during wet and dry seasons respectively. Thus, CRM practices such as addition of 100 % straw either alone or with GM and straw burning influenced the yield components (tillers, panicles and spikelets) positively and thereby increased rice grain yields.

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Rice–wheat cropping system (RWCS) is considered as the furthermost vital system in the Indo-Gangetic Plains of South-Asia, including India, Pakistan, Bangladesh, and Nepal. Recently, the deficiency of micronutrients like zinc (Zn) has emerged as one of the prime limitations for the sustainability issues of this RWCS in Zn deficient calcareous soils, particularly in India, as a result of the calcareous typic ustifluvents taxonomic nature of the soils. Therefore, a new Zn fertilization approach for soils is very much needed in the intensive RWCS. Thus, a six-year-long investigation was designed with three different modes of Zn application, viz., the application of Zn only in the first year of study, application in alternative years, and application in every year. Four different rates of Zn applications in a hectare of area for a single year, viz., 2.5, 5.0, 7.5, and 10 kg ha−1 year−1, and times of Zn application, viz., only at first year, alternative years, and in each year. The major aims of the study were to determine Zn concentration in soil; yield; and Zn accumulation by wheat crop under different application methods of Zn. From this study, it was found that a large portion of the applied Zn was present in the residual fraction, and it was also revealed that increasing the frequency of Zn application resulted in the increment in the crystalline fraction. Significant correlation of water-soluble and exchangeable Zn (WS+EX-Zn), complexed Zn (COM-Zn), amorphous Zn (AMO-Zn), organic Zn (ORG-Zn), total Zn (TOT-Zn), grain yield, and grain Zn uptake by wheat indicated that these Zn fractions were dominant forms in the soil to be utilized by plants under rice–wheat rotation. Concerning yield and Zn uptake by wheat, it was noted that the Zn application at 10 kg ha−1 in alternate years was the best Zn application method, while application of Zn at 7.5 kg ha−1 in each year also resulted in comparable yield.