Onion­sNZ Inc.

Less yield vari­abil­ity, bet­ter qual­ity

NZ Grower - - Contents - By Sally An­der­son JAMES KU­PE­RUS Busi­ness Man­ager | Onion­sNZ Inc.

Mea­sure­ment of onion crops at the three-leaf de­vel­op­men­tal stage was found to be the most pre­dic­tive of fu­ture po­ten­tial yields.

This vari­abil­ity af­fects bulb qual­ity and as a down­stream con­se­quence af­fects the value of Class 1 onions for ex­port. Be­ing an in­dus­try that fo­cuses 80 per­cent of its pro­duc­tion on ex­ports, the vari­abil­ity of yield and qual­ity of onion crops is an is­sue af­fect­ing fu­ture growth po­ten­tial of the in­dus­try.

Onions New Zealand, the grower rep­re­sen­ta­tive or­gan­i­sa­tion, part­nered with Plant & Food Re­search and LandWise Farms in this Sus­tain­able Farm­ing Fund project, SFF 408098, to iden­tify the causes and mea­sure onion vari­abil­ity in the field. The pro­gramme had a two-pronged ap­proach; first to de­velop sen­sor tech­nolo­gies to mea­sure and map this in-field vari­abil­ity early in the de­vel­op­men­tal stage of an onion crop, and se­cond to un­der­stand the un­der­ly­ing causes of this vari­abil­ity and com­bine this with the sen­sor in­for­ma­tion to de­fine Man­age­ment Ac­tion Zones (MAZ) based on the de­gree of field vari­a­tion ob­served. A trac­tor-mounted smart­phone cam­era cap­tured ground images and then im­age anal­y­sis soft­ware was used to process these images to mea­sure the green in­dex of onion plants. Mea­sure­ment of onion crops at the three-leaf de­vel­op­men­tal stage was found to be the most pre­dic­tive of fu­ture po­ten­tial yields. Once a map was de­vel­oped of the onion canopy cover, ar­eas hav­ing dif­fer­ent yields could be pre­dicted. Vari­able ar­eas were iden­ti­fied, mon­i­tored and man­aged over three years of field tri­als.

For this re­search New Zealand onion crops grown un­der op­ti­mal con­di­tions were found to have a base­line co­ef­fi­cient of vari­a­tion of 38 per­cent for bulb size. The bulk of vari­abil­ity, 61 per­cent, was due to growth rate dif­fer­ences be­tween in­di­vid­ual plants with the bal­ance of the vari­abil­ity, 39 per­cent, be­ing split, where 31 per­cent was due to the spread of seedling emer­gence and

eight per­cent be­cause of dif­fer­ences in plant-avail­able space. This high­lights the fact that man­age­ment at sow­ing and in the early phase of crop growth is key for en­sur­ing the onion crop is as uni­form as pos­si­ble. Soil com­paction, wa­ter­log­ging and in­ad­e­quate ir­ri­ga­tion were iden­ti­fied as key man­age­ment fac­tors caus­ing more vari­abil­ity in crops.

The two work streams con­verged with the de­vel­op­ment of SmartFarm, a web-based de­ci­sion sup­port tool to process the cap­tured im­age data with crop mod­el­ling to iden­tify MAZs where the plant pop­u­la­tions were be­low tar­get or plant growth was be­low ex­pec­ta­tions. The MAZs were field tested over two years of com­mer­cial scale field tri­als with good re­sults, thus in­di­cat­ing the value for grow­ers. James Ku­pe­rus, the busi­ness man­ager for Onions NZ, said that from the pro­gramme the in­dus­try now had a tool that can help onion grow­ers make early man­age­ment de­ci­sions to im­prove their qual­ity and their yields.

“The MAZs can iden­tify ar­eas in the field that might need ad­di­tional fer­tiliser ap­pli­ca­tions, im­proved drainage or ir­ri­ga­tion,” he said.

“By hav­ing a tool that es­ti­mates yields means that grow­ers can pro­vide ex­porters and dis­trib­u­tors pre­dic­tions of what their ex­pected vol­umes will be.”

“By hav­ing a tool that es­ti­mates yields means that grow­ers can pro­vide ex­porters and dis­trib­u­tors pre­dic­tions of what their ex­pected vol­umes will be.”

These ad­vances would not have been pos­si­ble with­out the col­lab­o­ra­tive re­search ef­forts of Plant & Food Re­search and LandWise, and the sup­port of the Sus­tain­able Farm­ing Fund.

Sally An­der­son is the re­search man­ager for Onions NZ.

Newspapers in English

Newspapers from New Zealand

© PressReader. All rights reserved.