Editing Green Revolution (section)

===Technological Developments===

The Green Revolution spread technologies that already existed but had not been widely implemented outside industrialized nations. Two kinds of technologies were used in the Green Revolution, on the issues of cultivation and breeding. The technologies in cultivation are targeted at providing excellent growing conditions, which include modern [[irrigation]] projects, [[pesticide]]s, and [[synthetic nitrogen fertilizer]]. The breeding technologies aimed at improving crop varieties developed through science-based methods including [[hybrid (biology)|hybrids]], combining modern genetics with plant-breeding trait selections.<ref name=":0" />

==== High-yielding varieties ====

The novel technological development of the Green Revolution was the production of novel wheat [[cultivars]]. [[Agronomist]]s bred [[high-yielding varieties]] of corn, wheat, and rice. HYVs have higher nitrogen-absorbing potential than other varieties. Since cereals that absorbed extra nitrogen would typically lodge, or fall over before harvest, semi-dwarfing [[gene]]s were bred into their [[genome]]s. A Japanese dwarf wheat cultivar [[Norin 10 wheat|Norin 10]] developed by Japanese agronomist [[Gonjiro Inazuka]], which was sent to [[Orville Vogel]] at [[Washington State University]] by [[Cecil Salmon]], was instrumental in developing Green Revolution wheat cultivars. In the 1960s, with a food crisis in Asia, the spread of high-yielding variety rice greatly increased.<ref>{{Cite book |last=Dana G. |first=Dalrymple |title=Development and spread of high-yielding rice varieties in developing countries |publisher=International Rice Research Institute |year=1986 |isbn=978-9-7110-4159-5 |page=1}}</ref>

Dr. [[Norman Borlaug]], the "Father of the Green Revolution", bred rust-resistant cultivars which have strong and firm stems, preventing them from falling over under extreme weather at high levels of fertilization. [[International Maize and Wheat Improvement Center|CIMMYT]] (Centro Internacional de Mejoramiento de Maiz y Trigo{{snd}}International Center for Maize and Wheat Improvements) conducted these breeding programs and helped spread high-yielding varieties in Mexico and countries in Asia like India and [[Agriculture in Pakistan|Pakistan]]. These programs led to the doubling of harvests in these countries.<ref name=":0"/>

Plant scientists figured out several parameters related to the high yield and identified the related genes which control the plant height and tiller number.<ref name="Sakamoto Matsuoka 2004">{{cite journal | last1=Sakamoto | first1=Tomoaki | last2=Matsuoka | first2=Makoto | title=Generating high-yielding varieties by genetic manipulation of plant architecture | journal=Current Opinion in Biotechnology | publisher=Elsevier | volume=15 | issue=2 | year=2004 | doi=10.1016/j.copbio.2004.02.003 | pages=144–147| pmid=15081053 }}</ref> With advances in [[molecular genetics]], the [[mutant]] [[genes]] responsible for ''[[Arabidopsis thaliana]]'' genes (GA 20-oxidase,<ref>{{cite journal |author1=Xu, Y.L. |author2=Li, L. |author3=Wu, K. |author4=Peeters, A.J. |author5=Gage, D.A. |author6=Zeevaart, J.A. |title=The GA5 locus of ''Arabidopsis thaliana'' encodes a multifunctional gibberellin 20-oxidase: molecular cloning and functional expression |journal=Proc. Natl. Acad. Sci. U.S.A. |volume=92 |issue=14 |pages=6640–6644 |date=July 1995 |pmid=7604047 |pmc=41574 |doi=10.1073/pnas.92.14.6640 |bibcode=1995PNAS...92.6640X |doi-access=free}}</ref> ''ga1'',<ref>{{cite journal |author1=Silverstone, A.L. |author2=Chang, C. |author3=Krol, E. |author4=Sun, T.P. |title=Developmental regulation of the gibberellin biosynthetic gene GA1 in Arabidopsis thaliana |journal=Plant J. |volume=12 |issue=1 |pages=9–19 |date=July 1997 |pmid=9263448 |doi=10.1046/j.1365-313X.1997.12010009.x|doi-access=free}}</ref> ''ga1-3''<ref>{{cite journal |author1=Silverstone, A.L. |author2=Ciampaglio |author3=C.N. |author4=Sun, T. |title=The Arabidopsis RGA gene encodes a transcriptional regulator repressing the gibberellin signal transduction pathway |journal=Plant Cell |volume=10 |issue=2 |pages=155–69 |date=February 1998 |pmid=9490740 |pmc=143987 |doi=10.1105/tpc.10.2.155}}</ref>), wheat reduced-height genes (''Rht'')<ref>{{cite journal |author=Appleford NE |title=Decreased shoot stature and grain alpha-amylase activity following ectopic expression of a gibberellin 2-oxidase gene in transgenic wheat |journal=J. Exp. Bot. |volume=58 |issue=12 |pages=3213–26 |year=2007 |pmid=17916639 |doi=10.1093/jxb/erm166 |author2=Wilkinson, M.D. |author3=Ma, Q. |display-authors=3 |last4=Evans |first4=D. J. |last5=Stone |first5=M.C. |last6=Pearce |first6=S. P. |last7=Powers |first7=S. J. |last8=Thomas |first8=S. G. |last9=Jones |first9=H. D. |df=dmy-all |doi-access=free}}</ref>  and <!--''slender rice (slr1)'' This gene makes rice's height taller. --> a rice semidwarf gene (''sd1'')<ref>{{cite journal |author=Monna, L. |title=Positional cloning of rice semidwarfing gene, sd-1: rice "green revolution gene" encodes a mutant enzyme involved in gibberellin synthesis |journal=DNA Res. |volume=9 |issue=1 |pages=11–17 |date=February 2002 |pmid=11939564 |doi=10.1093/dnares/9.1.11 |last2=Kitazawa |first2=N. |author3=Yoshino, R. |display-authors=3 |last4=Suzuki |first4=J. |last5=Masuda |first5=H. |last6=Maehara |first6=Y. |last7=Tanji |first7=M. |last8=Sato |first8=M |last9=Nasu |first9=S. |doi-access=free}}</ref> were [[cloned]]. These were identified as [[gibberellin]] [[biosynthesis]] genes or [[Cell signaling|cellular signaling]] component genes. [[Plant stem|Stem]] growth in the mutant background is significantly reduced leading to the [[Dwarf plant|dwarf]] [[phenotype]]. [[Photosynthetic]] investment in the stem is reduced dramatically as the shorter plants are inherently more stable mechanically. Assimilates become redirected to grain production, amplifying in particular the effect of chemical fertilizers on commercial yield.{{Citation needed|date=June 2021}}

High-yielding varieties significantly outperform traditional varieties in the presence of adequate irrigation, pesticides, and fertilizers. In the absence of these inputs, traditional varieties may outperform high-yielding varieties. Therefore, several authors have challenged the apparent superiority of high-yielding varieties not only compared to the traditional varieties alone, but by contrasting the monocultural system associated with high-yielding varieties with the polycultural system associated with traditional ones.<ref>{{cite journal |last=Igbozurike |first=U.M. |title=Polyculture and Monoculture: Contrast and Analysis |journal=GeoJournal |volume=2 |issue=5 |pages=443–49 |year=1978 |doi=10.1007/BF00156222 |bibcode=1978GeoJo...2..443I }}</ref>