Assessment of regional temperature extremes,and study the impact of asymmetric warming on yield and quality of two contrasting.pdf

1、At regional levels, IPCC scenarios are not helpful and uncertainties exist in thedegree of warming and may have positive or negative impacts on different crops.Therefore assessment of long-term regional trend in temperat

2、ure is mandatory tounderstand potential impacts of future climates.Here, we have put a deliberate effort toanalyze the historical weather data of Jiangsu Province located at lower reaches of YRV toascertain changing tren

3、d in temperature extremes and its derived stress days and nightsduring RGP as proxy of rice sterility in this region.Asymmetric seasonal changes in dailymaximum (TMX) and minimum (TMN) temperatures resulted in reduced di

4、urnaltemperature range (DTR) during studied period.Mean relative humidity also decreased atdifferent temporal scales, though regional variations exist.Frequency of hot nights (HN)and heatwave-B (HW-B) substantially incre

5、ased in the last 20 years resulted in increasedoccurrence of severe hot days (SHD) and severe heatwave (SHW) when both TMX andTMN are higher than described critical limit.Hot nights (HN) were observed only in thesecond h

6、alf (SH) of the dataset, while their intensity has been increasing with time.Episodic sterility occurs in the absence of extreme heat events, and we have herebyconfirmed the increasing trend of HNs and days with both hig

7、her TMX and TMN (SHD,severe hot days) associated with this crucial issue.Stagnant observation of TMX, hot days(HDs), and heatwave-A (HW-A) while, increasing trend of TMN, HN, (HW-B), SHD and(SHW) are main features of cha

8、nging climate in the region.
　　Experiments aimed to study responses of crops to rising temperature are mainlyconducted under controlled cover conditions like greenhouses, open-top chamber etc.These indoor facilities c

9、annot mimic predicted climatic conditions and can significantlyalter crop microclimate.These potential artifacts can have undesirable impacts of plantgrowth and developmental processes.Use of infrared heaters (IRH) is on

10、e of the attractivealternatives which can provide reliable and reproducible canopy wanning for differentcrops in similar way they are heated by solar radiation.As compared to warming ingreenhouses, open-top champers and

11、other similar warming facilities, these IRHs haveminimum impacts on crop microclimate.Kimball et al.(2008) arranged six IRHs in anarray of 3-meter-dimater to uniformly warm wheat canopy.Due to lower turbulence andclosed

12、stomata, IRH can cause greater increase in canopy temperature during nighttimethan during daytime.Rice production is suffering from asymmetric rise in day and nighttemperature which is evident from warming trend observed

13、 for Jiangsu province in thisstudy. In addition to changes in yield components, Post-anthesis B1 warming inducedchanges in the grain appearance quality, protein fractions (albumins-globulins, prolaminand glutelins) a

14、nd amino acid contents of both hybrids.Warming during grain fillingenhanced formation of chalky grain and reduced the perfect grains.Grain internal structurewas also damages by the warming.Genotypic differences in their

15、protein fractions andamino acid contents existed among the tested cultivars.Warming treatments inducedincreased in protein contents and amino acids significantly.Amino acids like cysteine,isoleucine, lysine and phenylala

16、nine were not affected by warming treatments for bothcultivars, while other amino acids were significantly affected by temperature treatments.Different asymmetric temperature conditions exist between the quantities of ea

17、ch proteinfraction.From these results it was concluded that grain appearance quality and internalstructures were significantly deteriorated by post-anthesis asymmetric warming andgenotypic variations in protein fractions