Karatun yanayi na GDD

Kwanakin digiri na girma (GDD), wanda kuma ake kira raka'a na digiri na girma, kayan aiki ne na heuristic a cikin ilimin halitta. GDD ma'auni ne na tarin zafi da masu aikin lambu, masu lambu, da manoma ke amfani da su don hango hasashen tsire-tsire da ƙimar ci gaban dabbobi kamar ranar da furen zai yi fure, kwari zai fito daga barci, ko kuma amfanin gona zai kai ga balaga. GDD an fara bayyana shi ne ta hanyar Reaumur a cikin shekara ta 1735. 

## Gabatarwa
Idan babu matsanancin yanayi kamar fari ko cututtuka, tsire-tsire suna girma a cikin hanyar da zafin jiki ke tasiri sosai. Kwanakin digiri na girma suna la'akari da fannoni na yanayin gida kuma suna ba da damar masu lambu su hango (ko, a cikin ɗakunan lambu, har ma da sarrafawa) saurin tsire-tsire zuwa balaga.

Sai dai idan wasu abubuwan muhalli kamar danshi sun jaddada su, yawan ci gaba daga fitowa zuwa balaga ga tsire-tsire da yawa ya dogara da zafin iska na yau da kullun. Saboda yawancin abubuwan ci gaba na tsire-tsire da kwari sun dogara da tarin takamaiman yawan zafi, yana yiwuwa a hango lokacin da waɗannan abubuwan ya kamata su faru a lokacin girma ba tare da la'akari da bambance-bambance a yanayin zafi daga shekara zuwa shekara ba. An bayyana digiri masu girma (GDs) a matsayin yawan digiri na zafin jiki sama da wani ƙofar zafin jiki, wanda ya bambanta tsakanin nau'ikan amfanin gona. Tushen zafin jiki shine wannan zafin jiki wanda ke ƙasa da shi girma shine sifili. Ana lissafin GDs kowace rana a matsayin matsakaicin zafin jiki tare da mafi ƙarancin zafin jiki da aka raba da 2, rage yawan zafin jiki. Ana tara GDUs ta hanyar ƙara gudummawar GDs ta kowace rana yayin da kakar ke ci gaba.

Ana iya amfani da GDUs don: tantance dacewa da yanki don samar da wani amfanin gona; kimanta matakan girma na amfanin gona, ciyawa ko ma matakan rayuwa na kwari; hango tsufa da yanke kwanakin amfanin gona na abinci; hango mafi kyawun lokacin taki ko aikace-aikacen maganin ƙwayoyin cuta; kimanta yanayin zafi akan amfanin gona. Takamaiman alamun amfanin gona waɗanda ke amfani da ma'auni daban-daban don tasirin mafi ƙarancin yau da kullun (lokacin dare) da matsakaicin yanayin zafi (lokacin rana) akan girma ana kiransu raka'a na zafi na amfanin gona (CHUs).

## Kula da annoba
Wasu manoma da masu horticulturalists suna amfani da ci gaban Kwari da kwanakin girma don yin amfani da kwayoyin halitta ko wasu hanyoyin Kula da kwari don haka suna amfani da hanya ko magani a inda kwari ya fi fuskantar rauni. Misali, lokacin amfani da tushe na 10 °C::

* Black cutworm larvae sun girma sosai don fara haifar da lalacewar tattalin arziki a 166 GDD 
* Manya masu aikin ganye na Boxwood sun fito ne a kusan 139 GDD 
* Zamani na farko na shekara-shekara na birch leafminer manya sun fito tsakanin 48 da 203 GDD da kuma ƙarni na biyu na shekara- shekara-sheko tsakanin 319 da 524 GDD 
* Shekarar farko ta shekara-shekara ta tsutsotsi na fall webworm ta fito tsakanin 350 da 749 GDD, ta biyu tsakanin 791 da 1540 GDD, kuma ta uku tsakanin 1580 da 1790 
* Mimosa webworm larvae bayyanar farko ta matsakaicin 543 GDD 
* Kwayar kwai ta farko ta shekara-shekara ta Oak lace ta faru tsakanin 311 da 652 GDD, ta biyu tsakanin 869 da 1048 GDD, kuma ta uku tsakanin 1260 da 1306 GDD 
* Pine needle scale ta farko shekara-shekara kwai hatch ya faru tsakanin 35 da 526 GDD kuma na biyu tsakanin 1110 da 1511 GDD 

## Manazarta