use (Walker and Miller, 1986; Paje et al., 1988). Higher levels of leaf epicuticular wax have been shown to be The epicuticular wax load (EWL) on leaves reduces surface transpicorrelated with seedling drought tolerance in Eragrostis ration and thus improves crop water use efficiency. The objectives of this study were to evaluate peanut (Arachis hypogaea L.) genotypes lahmanniana Nees (Wright and Dobrenz, 1973), with for their ELW and also to determine the influence of water deficit relative drought tolerance in oat (Avena sativa L.) cultistress on EWL. Peanut genotypes were grown in fields in two dry sea- vars (Bengston et al., 1978), and with greater water use sons (2000 and 2001) and one rainy (2000) season. Withholding irrigaefficiency in wheat (Triticum aestivum L.) (Johnson et tion water resulted in a significant increase in water saturation deficit al., 1983). Recently, it has been shown that in cocoa in the stressed crop. At 45 d after sowing (DAS), significant genotypic (Theobroma cacoa L.), the leaf epicuticular wax content differences were observed in EWL of 12 genotypes grown in the rainy increases with increased in soil moisture deficit (Anseason (2000). The values of EWL ranged from 0.91 mg dm Ϫ2 in Chico twi, 1999). to 1.74 mg dm Ϫ2 in PBS 11049, with a mean of 1.27 mg dm Ϫ2 . AmongCompared with several other crops, peanut has some six genotypes, which were also sampled subsequently, the mean values drought tolerance. Specific leaf area has been shown to were 1.10, 1.58, 2.05 mg dm Ϫ2 at 45, 75, and 95 DAS, respectively. In both dry seasons, significant genotypic differences were found in the be inversely related to drought tolerance potential of EWL. In the dry season of 2001, the effect of various moisture deficit peanut genotypes (Nageswara Rao and Wright, 1994). treatments and their interactions with the genotypes were highly sig-However, a comprehensive understanding of the contrinificant. The values ranged from 0.653 to 2.878 mg dm Ϫ2 . On an averbutions of various factors to imparting drought tolerage, the highest EWL was found in PBS 11049 (2.24 mg dm Ϫ2 ). Even ance in peanut is lacking. There are reports that indicate under irrigated conditions, in summer 2001, the EWL increased with accumulation of sucrose, proline, and amino acids in increased age of the crop. However, there was a greater increasethe leaves of peanut plant as a consequence of water in the treatments that were subjected to moisture deficit stress. It was deficit stress (Misra et al., 1991;Yadav et al., 1993). concluded that genotypic differences exist in EWL of peanut andEarlier work on peanut did not indicate any accumulaalso that EWL increases with increased crop age. This increase is tion of wax on leaves either in response to drought or more pronounced in plants that are subjected to protracted moisture deficit stress.
The response of eight long-duration pigeonpea [Cajanus cajan (L) Millsp.] genotypes to irrigation was studied at Gwalior in Central India during the 1990-91, 1991-92 and 1992-93 growing seasons on an Inceptisol. The crop was grown at two spacings as it was expected that crop density could interact with the crop's ability to extract soil moisture. The irrigation treatment received furrow irrigation four times during the 1990-91 and 1992-93 seasons and twice during the 1991-92 season. Grain yields of all genotypes were 11 % higher when planted at higher density than at low density. There was a differential variation in yield and harvest index among genotypes due to season but not due to spacing and irrigation suggesting the validity of the present approach of testing genotypes under optimum conditions. Grain yield declined by 21 % from the 1990 to 1992 season. The decline was 1 t\ha in some cultivars (ICPL 366, GW3), and between 0n5 and 1n0 t\ha in others (NP [WR] 15, ICP 87143 and ICPL 84072). In others (Bahar, ICP 9174, ICP 8860) the yield fluctuation was 0n5 t\ha. The genotypes' mean yields were as high as 2n7 t\ha for ICPL 87143, ICPL 84072 and ICPL 366. There was a significant reduction in both grain yield (16 %), and also above-ground plant dry mass (18 %) due to soil moisture limitation in the unirrigated treatment. Both the above-ground plant dry mass and grain yields were significantly more at high plant density than at lower plant density especially with irrigation. The genotypes were found to differ in their response to production environment (irrigation, spacing and to the undefined differences of the 3 years). Genotypic variation in yield within a production environment was found to vary in relation to changes in harvest index and across environment (irrigation, seasons) due to variation in total dry matter production. A lack of negative relationship between the total dry matter and harvest index suggests the possibility of optimizing both for obtaining higher yield from long-duration genotypes.
The soybean crop is highly sensitive to climate change associated events viz., global warming, drought, and water-logging at the time of highly sensitive flowering and grain filling stage, causing a shortfall in production and supply of quality seed to the country. Under prevailing high-density planting, at the seed rate of 70 kg ha-1 and flatbed sowing method, plant growth is restricted due to limitation of radiation and nutrients. Hence, the seed rate and sowing method need revision in an era of climate change. Therefore, we hypothesized that adopting a lower seed rate under ridges and furrow sowing would improve seed yield and quality over the prevailing seed rate of 70 kg ha-1 and flatbed sowing method. In order to test our hypothesis, an experiment was conducted to study the effect of various seed rates and sowing methods on growth and productivity of soybean. Studies revealed that a seed rate of 70 kg ha-1 shows superiority in terms of seed yield (3873.70 kg ha-1) which was at par with 60 kg ha-1 (3359.40 kg ha-1). Lower seed rate of 60 kg ha-1 was superior in terms of seed yield per plant (8.99 g plant-1), biological yield (6310 kg ha-1), Harvest index (35.69%), dry matter accumulation in pods at 61 DAS (1.74 g). Ridges and furrow sowing method was found superior for biological yield (26.33 g plant-1) and (6958.90 kg ha-1), dry matter accumulation in pods at 61 DAS (1.84 g), Leaf Area Duration at 71 DAS (19535.00 cm2.days). Interaction studies revealed that 60 kg ha-1 seed rate with ridge and furrow stand superior in terms of seed yield per plant 10.65 g plant-1 which was attributed to maximum harvest index (29.58%), dry matter accumulation in pod at 61 DAS (2.13 g), Leaf Area Duration at 71-81 DAS (22069.00 cm2.days). In contrary, highest seed yield(4018.89 kg ha-1) was observed for seed rate of 70 kg ha-1 with flat bed sowing. Hence it can be concluded that, under low productive environment the efficient dry matter accumulation, leaf area development and number of branches under low density planting will not compensate for the higher plant stand induced yield increment due to high density planting. Therefore, higher seed rate of 70 kg/ha with ridge and furrow sowing will be recommended to the farmers to get higher yield of soybean under rainfed and low productive environment.
Nine peanut genotypes were evaluated in two seasons under irrigated and simulated mid-season drought conditions to investigate the influence of water stress on some phenological, morpho-physiological, and yield traits. Analysis of variance revealed significant genotypic differences for all the traits studied. Water saturation deficit and epicuticular wax load increased in response to water stress and age of the crop, while specific leaf area decreased with water stress and age of the crop. In general, correlations of water saturation deficit (WSD), epicuticular wax load (EWL), and specific leaf area (SLA) with yield traits were fairly weak. WSD in the early stage under irrigated conditions was found to be positively associated with pod yield under water stress; EWL in the early stage was negatively associated with harvest index (HI) under stress. Although significant and negative correlations of SLA were found only when it was recorded in the early stage under stress and the later stage under irrigated conditions with HI and pod yield (PY), both under irrigated conditions, the trends of its associations showed that SLA had rather weak and negative correlations with PY and HI both under irrigated and stress conditions. Genotypes that accumulated flowers sooner after initiation showed less yield reduction. The negative association between HI under stress and its reduction deems HI under moisture stress an important criterion of selection for drought tolerance in peanut.
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