B cells interacting with helper t cells are stimulated to differentiate when _____.
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When is the best time to harvest crops? why?
Correct timing of harvest is crucial to crop loss prevention. Grain losses may occur caused by rats, birds, lodging, insects, and shattering. Timely harvesting ensures good grain quality and high market value.
Harvesting too early will result in a higher percentage of unfilled or immature grains, which will lower the yield and cause higher grain breakage during milling. Harvesting too late will lead to excessive losses and increased breakage in rice. Harvest time also affects the germination potential of rice seed.
There are different ways to determine the correct harvest time:
Moisture content
Grain moisture content ideally is between 20−25% (wet basis). Grains should be firm but not brittle when squeezed between the teeth.
Ripe grains per panicle
The crop should be cut when 80−85% of the grains are straw (i.e., yellow-colored).
Number of days after sowing
Generally, the ideal harvest time lies between 130 and 136 days after sowing for late, 113 and 125 for medium, and 110 days for early-maturing varieties.
Number of days after heading
For dry season harvesting, an optimum time is 28 to 35 days after heading. In wet season harvest, optimum time is 32 to 38 days after heading.
Other considerations
Harvesting also needs to be timed so that threshing can be done as soon as possible after cutting to avoid rewetting and to reduce grain breakage.
If the crop has a lot of surface moisture, (e.g. from previous rainfall or early in the morning), it is advisable to wait until the surface moisture dries off.