Journal of Research on Crop Ecophysiology
Volume:11 Issue: 2, Spring 2016

 In order to evaluate genetic variation and drought tolerance of safflower cultivars (Carthamus tinctorius L.), an experiment was conducted using fifteen cultivars in a randomized complete block design with three replications under drought and normal conditions during 2014-2015 farming season. Drought tolerance indices, such as tolerance (TOL), stress tolerance index (STI), stress susceptibility index (SSI), mean productivity (MP) and geometric mean productivity (GMP) were calculated to distinguish cultivars having the best seed yield as well as drought tolerance. The correlation coefficients illustrated that STI and GMP were the best and efficient selection criteria to distinguish drought tolerant and high-yielding cultivars. Significant and positive correlation was found between yield in both stress and normal conditions with GMP, MP and STI. Principal component analysis (PCA) showed that first and second PC accounted for 97.1% of the total variation. Biplot graphical display represented that lines 2, 11, 14 and 15 were highly adapted to the both normal, stress conditions, and classified them in high-yielding and drought tolerant groups, while genotypes numbered as 10, 12 and 13 were potential and stable under normal. condition. Based on data analysis, cultivars numbered as 1, 5, 6 and 9 had lowest yield under both moisture regimes, lines 3, 4, 7 and 8 showed high-yielding under stress regimes. Cluster analysis ordered the genotypes into six groups with 5, 3, 2, 2, 2 and 1 genotypes, respectively. In conclusion, present investigation revealed that drought conditions induced reduction of yield of some cultivars, while others were tolerant to drought stress. Hence, breeders can select drought tolerant safflower lines based on the GMP and STI indices.

 Nitrogen (N) is commonly applied in equal split during different growth stages of rice. However, higher requirement of N during panicle initiation (PI) stage emphasizes relatively higher N dose at that particular stage. A field experiment was conducted during dry seasons (November-May) of two consecutive years from 2013 to 2015 to determine appropriate timing and amount of N application and its effect on yield and N use efficiency. Two modern rice varieties (BRRI dhan28 and BRRI dhan29) under six N management options viz. i) One third of N was applied at initiation of tillering (IT) stage + one third at active tillering (AT) stage + one-third at panicle initiation (PI) stage (N1)(Recommended practice); ii) One-half at IT stage + another-half at PI stage (N2); iii) One third at IT stage + two-third at PI stage (N3); (iv) One-fourth at IT stage + one-fourth at AT stage+ half at PI stage (N4); v) One-half at IT stage + another half at AT stage (N5); and vi) N-control (N6)  were evaluated in randomized complete block design with three replications. Recommended practice and application of higher dose at PI stage gave similar yields in BRRI dhan28 and BRRI dhan29 in both the years. Agronomic use efficiency showed similar trend of results. Therefore, inadequate N application at early growth stages for any inevitable circumstances could be compensated by higher N application at PI stage.

In order to study the effect of sowing date and plant density on essential oil, yield and water use efficiency (WUE) of fennel, an experiment was conducted in research field of Islamic Azad University, Birjand branch, Iran as a split-plot experiment based on a randomized complete block design with nine treatments and three replications. The main plot was sowing date at three levels of March 19, April 9 and April 20. The sub-plot was plant density at three levels of 6.7, 10 and 20 plants m-2. According to the results of analysis of variance, seed, biological and essential oil yield and WUE were significantly affected by sowing date, plant density and their interaction at 1% probability level, but the interaction between sowing date and plant density did not significantly affect essential oil percentage. As means comparison showed, delay in sowing from March 19 to April 20 led to 85.6 and 85.6% loss of seed yield and biological yield, respectively. Despite higher essential oil percentage at delayed sowing, the highest oil yield was obtained at sowing date of March 19 with the average amount of 20.96 L ha-1 which was 5.82 times as high as that at the sowing date of April 20. The sowing date of March 19 had higher water use efficiency (WUE) for seed and oil production than the sowing date of April 20 by 5.5 and 3.67%, respectively. However, it increased biological yield and WUE for seed, biomass and essential oil production by 71.8, 64, 44.9 and 74.9%, respectively. The highest seed yield with the average amount of 726.90 kg ha-1 was obtained at the density of 20 plants m-2 which was 16 and 62% higher than that at the densities of 10 and 6.7 plants m-2. Lower densities had lower essential oil yield despite higher oil percentage. In general, it is recommended to use sowing date of March 19 with the density of 20 plants m-2 for the cultivation of fennel because of having the highest seed and essential oil yield and WUE.

Twenty-seven soybean genotypes were assessed for twelve morphological traits in a randomized complete block design with three replications throughout Rabi season, 2014 at field laboratory of Sher-e-Bangla Agricultural University, Dhaka, Bangladesh. Significant variations were found among the genotypes for all the traits. Stover yield, seed yield, single pod weight per plant, 100-seed weight, number of branches per plant and number of pods per plant exhibited that they were governed by additive gene action and selection for the improvement of these characters would be fecund. The phenotypic variance was higher than the corresponding genotypic variance for all the characters. All the traits showed moderate to low phenotypic and genotypic coefficient of variation. The yield had significant positive correlations with number of branches per plant followed by stover yield and number of pod per plant. Number of branches per plant and stover yield had also the highest positive direct effect as well as significant and positively highest correlation with yield. Days to first flowering and number of pod per plant had negative direct effect on seed yield but they are significantly and positively correlated with yield. Considering genetic variability, correlation and path analysis emphasis should be given on the number of branches per plant, stover yield, number of pod per plant and single pod weight per plant during the breeding program to improve the seed yield of soybean.

Boron (B) is a necessary micronutrient for higher plants and plays a part in germination and pollen tube growth. The purpose of this research was to determine the best levels of B spray on Tagetes flowers and to study the effects of these sprays on number of flower buds and flowers in short-stemmed Tagetes. A pot experiment in completely randomized design with 3 replications was conducted that included 4 B spray treatments (control: T0, 0.5 PPt: T1, 0.75 PPt: T2, and 1 PPt: T3). Results indicated that maximum number of flower buds belonged to the T3, followed by T2, and T1 treatments with 67.06, 63, and 43.71% increases in the number of flower buds, respectively, compared to the control. Moreover, B sprays at 1, 0.75, and 0.5 PPt yielded the largest number of flowers (1.55, 1.22, and 0.65, respectively). Therefore, B spray at 1 PPt yielded the best results in this research.

 In order to investigate the effect of cutting height and cutting date of seed on grain yield and yield components of berseem clover, a factorial experiment randomized complete block design with three replications was carried out in Ahvaz in 2014-2015. The experimental factors included seed cutting date in three levels (February 3, February 18 and March 5) and three levels of cutting height (2, 6 and 10 cm). The results showed that cutting height caused the significant increase   of grain yield, number of plants per m2, number of inflorescences per plant, and 1000-grain weight. The highest grain yield (68.95 g/m2) belonged to the treatment with the cutting height of 6 cm and the lowest grain yield (42.9 g/m2) belonged to cutting height of 2 cm. Moreover, seed cutting date also significantly increased grain yield and yield components. The highest grain yield by the mean of 75 g/m2 belonged to cutting date of February 18, and the lowest grain yield by 39.6 g/m2 belonged to cutting date of March 5. In general, cutting height of 6 cm and the cutting date of February 18 had the highest potential to achieve maximum yield in berseem clover.